diff options
Diffstat (limited to 'lib/ssh/doc')
20 files changed, 738 insertions, 28508 deletions
diff --git a/lib/ssh/doc/src/notes.xml b/lib/ssh/doc/src/notes.xml index 9d498c0fdc..8fb689fdd5 100644 --- a/lib/ssh/doc/src/notes.xml +++ b/lib/ssh/doc/src/notes.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2004</year><year>2014</year> + <year>2004</year><year>2015</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -30,6 +30,341 @@ <file>notes.xml</file> </header> +<section><title>Ssh 4.2</title> + + <section><title>Fixed Bugs and Malfunctions</title> + <list> + <item> + <p> + Better error handling in ssh_file. There was some rare + errors when a NFS-mounted file was opened by ssh_file and + then remotely deleted during reading. That caused an + endless loop. </p> + <p> + That bug is now fixed.</p> + <p> + Own Id: OTP-12699 Aux Id: OTP-11688 </p> + </item> + <item> + <p> + Fixed a bug in the compression algorithm + [email protected].</p> + <p> + Own Id: OTP-12759</p> + </item> + <item> + <p> + It is now possible to start more than one daemon with a + file descriptor given in option fd. Each daemon must of + course have a unique file descriptor.</p> + <p> + Own Id: OTP-12966 Aux Id: seq12945 </p> + </item> + <item> + <p> + Fixed a bug that caused the option <c>dh_gex_limit</c> to + be ignored.</p> + <p> + Own Id: OTP-13029</p> + </item> + <item> + <p> + A problem is fixed with the <c>ssh:connect</c> option + <c>pref_public_key_algs</c> specifying user keys.</p> + <p> + Own Id: OTP-13158</p> + </item> + </list> + </section> + + + <section><title>Improvements and New Features</title> + <list> + <item> + <p> + Document updates in the ssh reference manual: app doc + file and ssh_connection.</p> + <p> + Own Id: OTP-12003</p> + </item> + <item> + <p> + The authorization phase is made stateful to prevent ssh + acting on messages sent in wrong order.</p> + <p> + Own Id: OTP-12787</p> + </item> + <item> + <p> + Testcases for bad message lengths and for bad subfield + lengths added.</p> + <p> + Own Id: OTP-12792 Aux Id: Codenomicon #5214, 6166 </p> + </item> + <item> + <p> + The 'ecdsa-sha2-nistp256', 'ecdsa-sha2-nistp384' and + 'ecdsa-sha2-nistp521' signature algorithms for ssh are + implemented. See RFC 5656.</p> + <p> + Own Id: OTP-12936</p> + </item> + <item> + <p> + The crypto algorithms 'aes192-ctr' and 'aes256-ctr' are + implemented. See RFC 4344.</p> + <p> + Own Id: OTP-12939</p> + </item> + <item> + <p> + The ciphers and macs AEAD_AES_128_GCM and + AEAD_AES_256_GCM are implemented but not enabled per + default. See the SSH App Reference Manual and RFC5647 for + details.</p> + <p> + The ciphers [email protected] and + [email protected] are also implemented and available + in the default configuration.</p> + <p> + Own Id: OTP-13018</p> + </item> + <item> + <p> + The ssh:daemon option dh_gex_groups is extended to read a + user provided ssh moduli file with generator-modulus + pairs. The file is in openssh format.</p> + <p> + Own Id: OTP-13052 Aux Id: OTP-13054 </p> + </item> + <item> + <p> + There is now a file (public_key/priv/moduli) which lists + size-generator-modulus triples. The purpose is to give + servers the possibility to select the crypto primes + randomly among a list of pregenerated triples. This + reduces the risk for some attacks on diffie-hellman + negotiation.</p> + <p> + See the reference manual for public_key:dh_gex_group/4 + where the handling of this is described.</p> + <p> + The ssh server (ssh:daemon) uses this.</p> + <p> + Own Id: OTP-13054 Aux Id: OTP-13052 </p> + </item> + <item> + <p> + The ssh:daemon option pwdfun now also takes a fun/4. This + enables the user to 1) check userid-password in another + way than the builtin algorithm, 2) implement rate + limiting per user or source IP or IP+Port, and 3) + implement blocking of missbehaving peers.</p> + <p> + The old fun/2 still works as previously.</p> + <p> + Own Id: OTP-13055 Aux Id: OTP-13053 </p> + </item> + <item> + <p> + There is now a new option to make the server limit the + size range of moduli available for the diffie-hellman + group exchange negotiation. See option <c> + {dh_gex_limits,{Min,Max}}</c> in ssh:daemon/3.</p> + <p> + Own Id: OTP-13066</p> + </item> + <item> + <p> + Ecdh key exchange now validates compressed and + uncompressed keys as defined in rfc5656</p> + <p> + Own Id: OTP-13067</p> + </item> + <item> + <p> + Search order for the .ssh directory are changed so + <c>$HOME</c> is tried before + <c>init:get_argument(home)</c>.</p> + <p> + Own Id: OTP-13109</p> + </item> + <item> + <p> + The sftp receive window handling is optimized so it will + not update the remote end too often. This makes "sftp + mget" considerable faster.</p> + <p> + Own Id: OTP-13130</p> + </item> + <item> + <p> + The option <c>key_cb</c> is extended to take an optional + list that is passed to the callback module as an option. + With this it is possible to have different keys depending + on which host that is connected. Another possibility is + to write a callback module that fetches keys etc from a + database.</p> + <p> + Thanks to Vipin Nair.</p> + <p> + Own Id: OTP-13156</p> + </item> + </list> + </section> + +</section> + +<section><title>Ssh 4.1.3</title> + + <section><title>Known Bugs and Problems</title> + <list> + <item> + <p> + SSH_MSG_KEX_DH_GEX_REQUEST_OLD implemented to make PuTTY + work with erl server.</p> + <p> + Own Id: OTP-13140</p> + </item> + </list> + </section> + +</section> + +<section><title>Ssh 4.1.2</title> + + <section><title>Fixed Bugs and Malfunctions</title> + <list> + <item> + <p> + Add a 1024 group to the list of key group-exchange groups</p> + <p> + Own Id: OTP-13046</p> + </item> + </list> + </section> + +</section> + +<section><title>Ssh 4.1.1</title> + + <section><title>Improvements and New Features</title> + <list> + <item> + <p> + A new option <c>max_channels</c> limits the number of + channels with active server-side subsystems that are + accepted.</p> + <p> + Own Id: OTP-13036</p> + </item> + </list> + </section> + +</section> + +<section><title>Ssh 4.1</title> + + <section><title>Fixed Bugs and Malfunctions</title> + <list> + <item> + <p> + Send an understandable disconnect message when the key + exchange phase can't find a common algorithm. There are + also some test cases added.</p> + <p> + Own Id: OTP-11531</p> + </item> + <item> + <p> + The third parameter in <c>ssh_sftp:write_file</c> is now + accepting iolists again. Unicode handling adjusted.</p> + <p> + Own Id: OTP-12853 Aux Id: seq12891 </p> + </item> + </list> + </section> + + + <section><title>Improvements and New Features</title> + <list> + <item> + <p> + First part of ssh test suite re-organization and + extension.</p> + <p> + Own Id: OTP-12230</p> + </item> + <item> + <p> + The key exchange algorithms 'ecdh-sha2-nistp256', + 'ecdh-sha2-nistp384' and 'ecdh-sha2-nistp521' are + implemented. See RFC 5656.</p> + <p> + This raises the security level considerably.</p> + <p> + Own Id: OTP-12622 Aux Id: OTP-12671, OTP-12672 </p> + </item> + <item> + <p> + The key exchange algorithm 'diffie-hellman-group14-sha1' + is implemented. See RFC 4253.</p> + <p> + This raises the security level.</p> + <p> + Own Id: OTP-12671 Aux Id: OTP-12672, OTP-12622 </p> + </item> + <item> + <p> + The key exchange algorithms + 'diffie-hellman-group-exchange-sha1' and + 'diffie-hellman-group-exchange-sha256' are implemented. + See RFC 4419.</p> + <p> + This raises the security level.</p> + <p> + Own Id: OTP-12672 Aux Id: OTP-12671, OTP-12622 </p> + </item> + <item> + <p> + Adding random length extra padding as recommended in RFC + 4253 section 6.</p> + <p> + Own Id: OTP-12831</p> + </item> + <item> + <p> + New test library for low-level protocol testing. There is + also a test suite using it for some preliminary tests. + The intention is to build on that for more testing of + individual ssh messages. See + <c>lib/ssh/test/ssh_trpt_test_lib.erl</c> and + <c>ssh_protocol_SUITE.erl</c> in the same directory.</p> + <p> + Own Id: OTP-12858</p> + </item> + <item> + <p> + Increased default values for + diffie-hellman-group-exchange-sha* to Min = 1024, N = + 6144, Max = 8192.</p> + <p> + Added 6144 and 8192 bit default gex groups.</p> + <p> + Own Id: OTP-12937</p> + </item> + <item> + <p> + The mac algorithm 'hmac-sha2-512' is implemented. See RFC + 6668.</p> + <p> + Own Id: OTP-12938</p> + </item> + </list> + </section> + +</section> + <section><title>Ssh 4.0</title> <section><title>Fixed Bugs and Malfunctions</title> @@ -82,9 +417,9 @@ <p> Thanks to Simon Cornish</p> <p> - Own Id: OTP-12760 Aux Id: <a + Own Id: OTP-12760 Aux Id: <url href="https://github.com/erlang/otp/pull/715">pull req - 715</a> </p> + 715</url> </p> </item> <item> <p> @@ -250,13 +585,13 @@ </item> <item> <p> - Made Codenomicon Defensics test suite pass: <list> + Made Codenomicon Defensics test suite pass:</p> <list> <item>limit number of algorithms in kexinit message</item> <item>check 'e' and 'f' parameters in kexdh</item> <item>implement 'keyboard-interactive' user authentication on server side</item> <item> return plain text message to bad version exchange message</item> - </list></p> + </list> <p> Own Id: OTP-12784</p> </item> diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml index d24025ca4d..850557444d 100644 --- a/lib/ssh/doc/src/ssh.xml +++ b/lib/ssh/doc/src/ssh.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>2004</year><year>2014</year> + <year>2004</year><year>2015</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -32,28 +32,33 @@ <modulesummary>Main API of the ssh application</modulesummary> <description> <p>Interface module for the <c>ssh</c> application.</p> + <p>See <seealso marker="ssh:SSH_app#supported">ssh(6)</seealso> for details of supported version, + algorithms and unicode support.</p> </description> - <section> - <title>SSH</title> - <marker id="supported"/> - <list type="bulleted"> - <item>For application dependencies see <seealso marker="SSH_app"> ssh(6)</seealso> </item> - <item>Supported SSH version is 2.0.</item> - <item>Supported public key algorithms: ssh-rsa and ssh-dss.</item> - <item>Supported MAC algorithms: hmac-sha2-256 and hmac-sha1.</item> - <item>Supported encryption algorithms: aes128-ctr, aes128-cb and 3des-cbc.</item> - <item>Supported key exchange algorithms: diffie-hellman-group1-sha1.</item> - <item>Supported compression algorithms: none, zlib, [email protected],</item> - <item>Supports unicode filenames if the emulator and the underlaying OS support it. - See section DESCRIPTION in the - <seealso marker="kernel:file">file</seealso> manual page in <c>kernel</c> - for information about this subject.</item> - <item>Supports unicode in shell and CLI.</item> - </list> - + <section> + <title>OPTIONS</title> + <p>The exact behaviour of some functions can be adjusted with the use of options which are documented together + with the functions. Generally could each option be used at most one time in each function call. If given two or more + times, the effect is not predictable unless explicitly documented.</p> + <p>The options are of different kinds:</p> + <taglist> + <tag>Limits</tag> + <item><p>which alters limits in the system, for example number of simultaneous login attempts.</p></item> + + <tag>Timeouts</tag> + <item><p>which give some defined behaviour if too long time elapses before a given event or action, + for example time to wait for an answer.</p></item> + + <tag>Callbacks</tag> + <item><p>which gives the caller of the function the possibility to execute own code on some events, + for example calling an own logging function or to perform an own login function</p></item> + + <tag>Behaviour</tag> + <item><p>which changes the systems behaviour.</p></item> + </taglist> </section> - + <section> <title>DATA TYPES</title> <p>Type definitions that are used more than once in @@ -80,6 +85,15 @@ <item><p><c>atom()</c> - Name of the Erlang module implementing the subsystem using the <c>ssh_channel</c> behavior, see <seealso marker="ssh_channel">ssh_channel(3)</seealso></p></item> + <tag><c>key_cb() =</c></tag> + <item> + <p><c>atom() | {atom(), list()}</c></p> + <p><c>atom()</c> - Name of the erlang module implementing the behaviours + <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso> or + <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso> as the + case maybe.</p> + <p><c>list()</c> - List of options that can be passed to the callback module.</p> + </item> <tag><c>channel_init_args() =</c></tag> <item><p><c>list()</c></p></item> @@ -192,26 +206,25 @@ <tag><c><![CDATA[{public_key_alg, 'ssh-rsa' | 'ssh-dss'}]]></c></tag> <item> <note> - <p>This option is kept for compatibility. It is ignored if the <c>preferred_algorithms</c> - option is used. The equivalence of <c>{public_key_alg,'ssh-dss'}</c> is - <c>{preferred_algorithms, [{public_key,['ssh-dss','ssh-rsa']}]}</c>.</p> + <p>This option will be removed in OTP 20, but is kept for compatibility. It is ignored if + the preferred <c>pref_public_key_algs</c> option is used.</p> </note> <p>Sets the preferred public key algorithm to use for user authentication. If the preferred algorithm fails, - the other algorithm is tried. The default is - to try <c><![CDATA['ssh-rsa']]></c> first.</p> + the other algorithm is tried. If <c>{public_key_alg, 'ssh-rsa'}</c> is set, it is translated + to <c>{pref_public_key_algs, ['ssh-rsa','ssh-dss']}</c>. If it is + <c>{public_key_alg, 'ssh-dss'}</c>, it is translated + to <c>{pref_public_key_algs, ['ssh-dss','ssh-rsa']}</c>. + </p> </item> <tag><c><![CDATA[{pref_public_key_algs, list()}]]></c></tag> <item> - <note> - <p>This option is kept for compatibility. It is ignored if the <c>preferred_algorithms</c> - option is used. The equivalence of <c>{pref_public_key_algs,['ssh-dss']}</c> is - <c>{preferred_algorithms, [{public_key,['ssh-dss']}]}</c>.</p> - </note> - <p>List of public key algorithms to try to use. - <c>'ssh-rsa'</c> and <c>'ssh-dss'</c> are available. - Overrides <c><![CDATA[{public_key_alg, 'ssh-rsa' | 'ssh-dss'}]]></c></p> + <p>List of user (client) public key algorithms to try to use.</p> + <p>The default value is + <c><![CDATA[['ssh-rsa','ssh-dss','ecdsa-sha2-nistp256','ecdsa-sha2-nistp384','ecdsa-sha2-nistp521'] ]]></c> + </p> + <p>If there is no public key of a specified type available, the corresponding entry is ignored.</p> </item> <tag><c><![CDATA[{preferred_algorithms, algs_list()}]]></c></tag> @@ -219,6 +232,7 @@ <p>List of algorithms to use in the algorithm negotiation. The default <c>algs_list()</c> can be obtained from <seealso marker="#default_algorithms/0">default_algorithms/0</seealso>. </p> + <p>If an alg_entry() is missing in the algs_list(), the default value is used for that entry.</p> <p>Here is an example of this option:</p> <code> {preferred_algorithms, @@ -229,9 +243,9 @@ {compression,[none,zlib]} } </code> - <p>The example specifies different algorithms in the two directions (client2server and server2client), for cipher but specifies the same -algorithms for mac and compression in both directions. The kex (key exchange) and public key algorithms are set to their default values, -kex is implicit but public_key is set explicitly.</p> + <p>The example specifies different algorithms in the two directions (client2server and server2client), + for cipher but specifies the same algorithms for mac and compression in both directions. + The kex (key exchange) is implicit but public_key is set explicitly.</p> <warning> <p>Changing the values can make a connection less secure. Do not change unless you @@ -240,6 +254,13 @@ kex is implicit but public_key is set explicitly.</p> </warning> </item> + <tag><c><![CDATA[{dh_gex_limits,{Min=integer(),I=integer(),Max=integer()}}]]></c></tag> + <item> + <p>Sets the three diffie-hellman-group-exchange parameters that guides the connected server in choosing a group. + See RFC 4419 for the function of thoose. The default value is <c>{1024, 6144, 8192}</c>. + </p> + </item> + <tag><c><![CDATA[{connect_timeout, timeout()}]]></c></tag> <item> <p>Sets a time-out on the transport layer @@ -260,11 +281,13 @@ kex is implicit but public_key is set explicitly.</p> password, if the password authentication method is attempted.</p> </item> - <tag><c><![CDATA[{key_cb, atom()}]]></c></tag> + <tag><c><![CDATA[{key_cb, key_cb()}]]></c></tag> <item> - <p>Module implementing the behaviour - <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso>. - Can be used to customize the handling of public keys. + <p>Module implementing the behaviour <seealso + marker="ssh_client_key_api">ssh_client_key_api</seealso>. Can be used to + customize the handling of public keys. If callback options are provided + along with the module name, they are made available to the callback + module via the options passed to it under the key 'key_cb_private'. </p> </item> <tag><c><![CDATA[{quiet_mode, atom() = boolean()}]]></c></tag> @@ -395,10 +418,10 @@ kex is implicit but public_key is set explicitly.</p> <c><![CDATA["publickey,keyboard-interactive,password"]]></c></p> </item> - <tag><c><![CDATA[{auth_method_kb_interactive_data, PromptTexts}]]> - <br/>where: - <br/>PromptTexts = kb_int_tuple() | fun(Peer::{IP::tuple(),Port::integer()}, User::string(), Service::string()) -> kb_int_tuple() - <br/>kb_int_tuple() = {Name::string(), Instruction::string(), Prompt::string(), Echo::boolean()}</c> + <tag><c><![CDATA[{auth_method_kb_interactive_data, PromptTexts}]]></c> + <br/><c>where:</c> + <br/><c>PromptTexts = kb_int_tuple() | fun(Peer::{IP::tuple(),Port::integer()}, User::string(), Service::string()) -> kb_int_tuple()</c> + <br/><c>kb_int_tuple() = {Name::string(), Instruction::string(), Prompt::string(), Echo::boolean()}</c> </tag> <item> <p>Sets the text strings that the daemon sends to the client for presentation to the user when using <c>keyboar-interactive</c> authentication. If the fun/3 is used, it is called when the actual authentication occurs and may therefore return dynamic data like time, remote ip etc.</p> @@ -428,6 +451,7 @@ kex is implicit but public_key is set explicitly.</p> <p>List of algorithms to use in the algorithm negotiation. The default <c>algs_list()</c> can be obtained from <seealso marker="#default_algorithms/0">default_algorithms/0</seealso>. </p> + <p>If an alg_entry() is missing in the algs_list(), the default value is used for that entry.</p> <p>Here is an example of this option:</p> <code> {preferred_algorithms, @@ -438,9 +462,9 @@ kex is implicit but public_key is set explicitly.</p> {compression,[none,zlib]} } </code> - <p>The example specifies different algorithms in the two directions (client2server and server2client), for cipher but specifies the same -algorithms for mac and compression in both directions. The kex (key exchange) and public key algorithms are set to their default values, -kex is implicit but public_key is set explicitly.</p> + <p>The example specifies different algorithms in the two directions (client2server and server2client), + for cipher but specifies the same algorithms for mac and compression in both directions. + The kex (key exchange) is implicit but public_key is set explicitly.</p> <warning> <p>Changing the values can make a connection less secure. Do not change unless you @@ -449,12 +473,82 @@ kex is implicit but public_key is set explicitly.</p> </warning> </item> - <tag><c><![CDATA[{pwdfun, fun(User::string(), password::string()) -> boolean()}]]></c></tag> + <tag><c><![CDATA[{dh_gex_groups, [{Size=integer(),G=integer(),P=integer()}] | {file,filename()} {ssh_moduli_file,filename()} }]]></c></tag> + <item> + <p>Defines the groups the server may choose among when diffie-hellman-group-exchange is negotiated. + See RFC 4419 for details. The three variants of this option are: + </p> + <taglist> + <tag><c>{Size=integer(),G=integer(),P=integer()}</c></tag> + <item>The groups are given explicitly in this list. There may be several elements with the same <c>Size</c>. + In such a case, the server will choose one randomly in the negotiated Size. + </item> + <tag><c>{file,filename()}</c></tag> + <item>The file must have one or more three-tuples <c>{Size=integer(),G=integer(),P=integer()}</c> + terminated by a dot. The file is read when the daemon starts. + </item> + <tag><c>{ssh_moduli_file,filename()}</c></tag> + <item>The file must be in + <seealso marker="public_key:public_key#dh_gex_group/4">ssh-keygen moduli file format</seealso>. + The file is read when the daemon starts. + </item> + </taglist> + <p>The default list is fetched from the + <seealso marker="public_key:public_key#dh_gex_group/4">public_key</seealso> application. + </p> + </item> + + <tag><c><![CDATA[{dh_gex_limits,{Min=integer(),Max=integer()}}]]></c></tag> + <item> + <p>Limits what a client can ask for in diffie-hellman-group-exchange. + The limits will be + <c>{MaxUsed = min(MaxClient,Max), MinUsed = max(MinClient,Min)}</c> where <c>MaxClient</c> and + <c>MinClient</c> are the values proposed by a connecting client. + </p> + <p>The default value is <c>{0,infinity}</c>. + </p> + <p>If <c>MaxUsed < MinUsed</c> in a key exchange, it will fail with a disconnect. + </p> + <p>See RFC 4419 for the function of the Max and Min values.</p> + </item> + + <tag><c><![CDATA[{pwdfun, fun(User::string(), Password::string(), PeerAddress::{ip_adress(),port_number()}, State::any()) -> boolean() | disconnect | {boolean(),any()} }]]></c></tag> + <item> + <p>Provides a function for password validation. This could used for calling an external system or if + passwords should be stored as a hash. The fun returns: + </p> + <list type="bulleted"> + <item><c>true</c> if the user and password is valid and</item> + <item><c>false</c> otherwise.</item> + </list> + <p>This fun can also be used to make delays in authentication tries for example by calling + <seealso marker="stdlib:timer#sleep/1">timer:sleep/1</seealso>. To facilitate counting of failed tries + the <c>State</c> variable could be used. This state is per connection only. The first time the pwdfun + is called for a connection, the <c>State</c> variable has the value <c>undefined</c>. + The pwdfun can return - in addition to the values above - a new state + as: + </p> + <list type="bulleted"> + <item><c>{true, NewState:any()}</c> if the user and password is valid or</item> + <item><c>{false, NewState:any()}</c> if the user or password is invalid</item> + </list> + <p>A third usage is to block login attempts from a missbehaving peer. The <c>State</c> described above + can be used for this. In addition to the responses above, the following return value is introduced: + </p> + <list type="bulleted"> + <item><c>disconnect</c> if the connection should be closed immediately after sending a SSH_MSG_DISCONNECT + message.</item> + </list> + </item> + + <tag><c><![CDATA[{pwdfun, fun(User::string(), Password::string()) -> boolean()}]]></c></tag> <item> <p>Provides a function for password validation. This function is called with user and password as strings, and returns <c><![CDATA[true]]></c> if the password is valid and <c><![CDATA[false]]></c> otherwise.</p> + <p>This option (<c>{pwdfun,fun/2}</c>) is the same as a subset of the previous + (<c>{pwdfun,fun/4}</c>). It is kept for compatibility.</p> </item> <tag><c><![CDATA[{negotiation_timeout, integer()}]]></c></tag> @@ -485,6 +579,15 @@ kex is implicit but public_key is set explicitly.</p> </p> </item> + <tag><c><![CDATA[{max_channels, pos_integer()}]]></c></tag> + <item> + <p>The maximum number of channels with active remote subsystem that are accepted for + each connection to this daemon</p> + <p>By default, this option is not set. This means that the number is not limited. + </p> + </item> + + <tag><c><![CDATA[{parallel_login, boolean()}]]></c></tag> <item> <p>If set to false (the default value), only one login is handled at a time. @@ -516,11 +619,13 @@ kex is implicit but public_key is set explicitly.</p> </p> </item> - <tag><c><![CDATA[{key_cb, atom()}]]></c></tag> + <tag><c><![CDATA[{key_cb, key_cb()}]]></c></tag> <item> - <p>Module implementing the behaviour - <seealso marker="ssh_server_key_api">ssh_server_key_api</seealso>. - Can be used to customize the handling of public keys. + <p>Module implementing the behaviour <seealso + marker="ssh_server_key_api">ssh_server_key_api</seealso>. Can be used to + customize the handling of public keys. If callback options are provided + along with the module name, they are made available to the callback + module via the options passed to it under the key 'key_cb_private'. </p> </item> diff --git a/lib/ssh/doc/src/ssh_app.xml b/lib/ssh/doc/src/ssh_app.xml index 4c85585820..f6ce44c015 100644 --- a/lib/ssh/doc/src/ssh_app.xml +++ b/lib/ssh/doc/src/ssh_app.xml @@ -4,7 +4,7 @@ <appref> <header> <copyright> - <year>2012</year><year>2013</year> + <year>2012</year><year>2015</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -41,15 +41,18 @@ <section> <title>DEPENDENCIES</title> - <p>The <c>ssh</c> application uses the applications <c>public_key</c> and - <c>crypto</c> to handle public keys and encryption. Hence, these + <p>The <c>ssh</c> application uses the applications + <seealso marker="public_key:public_key">public_key</seealso> and + <seealso marker="crypto:crypto">crypto</seealso> + to handle public keys and encryption. Hence, these applications must be loaded for the <c>ssh</c> application to work. In an embedded environment this means that they must be started with - <c>application:start/[1,2]</c> before the <c>ssh</c> application is started. + <seealso marker="kernel:application#start/1">application:start/1,2</seealso> before the + <c>ssh</c> application is started. </p> </section> - <section> + <section> <title>CONFIGURATION</title> <p>The <c>ssh</c> application does not have an application- @@ -62,10 +65,13 @@ <item><c>authorized_keys2</c></item> <item><c>id_dsa</c></item> <item><c>id_rsa</c></item> + <item><c>id_ecdsa</c></item> <item><c>ssh_host_dsa_key</c></item> <item><c>ssh_host_rsa_key</c></item> + <item><c>ssh_host_ecdsa_key</c></item> </list> <p>By default, <c>ssh</c> looks for <c>id_dsa</c>, <c>id_rsa</c>, + <c>id_ecdsa_key</c>, <c>known_hosts</c>, and <c>authorized_keys</c> in ~/.ssh, and for the host key files in <c>/etc/ssh</c>. These locations can be changed by the options <c>user_dir</c> and <c>system_dir</c>. @@ -79,7 +85,7 @@ </section> <section> <title>Public Keys</title> - <p><c>id_dsa</c> and <c>id_rsa</c> are the users private key files. + <p><c>id_dsa</c>, <c>id_rsa</c> and <c>id_ecdsa</c> are the users private key files. Notice that the public key is part of the private key so the <c>ssh</c> application does not use the <c>id_<*>.pub</c> files. These are for the user's convenience when it is needed to convey the user's @@ -104,8 +110,8 @@ <section> <title>Host Keys</title> <p>RSA and DSA host keys are supported and are - expected to be found in files named <c>ssh_host_rsa_key</c> and - <c>ssh_host_dsa_key</c>. + expected to be found in files named <c>ssh_host_rsa_key</c>, + <c>ssh_host_dsa_key</c> and <c>ssh_host_ecdsa_key</c>. </p> </section> <section> @@ -114,6 +120,198 @@ </section> <section> + <marker id="supported"/> + <title>SUPPORTED SPECIFICATIONS AND STANDARDS</title> + <p>The supported SSH version is 2.0.</p> + </section> + <section> + <title>Algorithms</title> + <p>The actual set of algorithms may vary depending on which OpenSSL crypto library that is installed on the machine. + For the list on a particular installation, use the command + <seealso marker="ssh:ssh#default_algorithms/0">ssh:default_algorithms/0</seealso>. + The user may override the default algorithm configuration both on the server side and the client side. + See the option <c>preferred_algorithms</c> in the <seealso marker="ssh:ssh#daemon/1">ssh:daemon/1,2,3</seealso> and + <seealso marker="ssh:ssh#connect/3">ssh:connect/3,4</seealso> functions. + </p> + + <p>Supported algorithms are:</p> + + <taglist> + <tag>Key exchange algorithms</tag> + <item> + <list type="bulleted"> + <item>ecdh-sha2-nistp256</item> + <item>ecdh-sha2-nistp384</item> + <item>ecdh-sha2-nistp521</item> + <item>diffie-hellman-group-exchange-sha1</item> + <item>diffie-hellman-group-exchange-sha256</item> + <item>diffie-hellman-group14-sha1</item> + <item>diffie-hellman-group1-sha1</item> + </list> + </item> + + <tag>Public key algorithms</tag> + <item> + <list type="bulleted"> + <item>ecdsa-sha2-nistp256</item> + <item>ecdsa-sha2-nistp384</item> + <item>ecdsa-sha2-nistp521</item> + <item>ssh-rsa</item> + <item>ssh-dss</item> + </list> + </item> + + <tag>MAC algorithms</tag> + <item> + <list type="bulleted"> + <item>hmac-sha2-256</item> + <item>hmac-sha2-512</item> + <item>hmac-sha1</item> + </list> + </item> + + <tag>Encryption algorithms (ciphers)</tag> + <item> + <list type="bulleted"> + <item>[email protected] (AEAD_AES_128_GCM)</item> + <item>[email protected] (AEAD_AES_256_GCM)</item> + <item>aes128-ctr</item> + <item>aes192-ctr</item> + <item>aes256-ctr</item> + <item>aes128-cbc</item> + <item>3des-cbc</item> + </list> + <p>Following the internet de-facto standard, the cipher and mac algorithm AEAD_AES_128_GCM is selected when the + cipher [email protected] is negotiated. The cipher and mac algorithm AEAD_AES_256_GCM is selected when the + cipher [email protected] is negotiated. + </p> + <p>See the text at the description of <seealso marker="#rfc5647_note">the rfc 5647 further down</seealso> + for more information. + </p> + </item> + + <tag>Compression algorithms</tag> + <item> + <list type="bulleted"> + <item>none</item> + <item>[email protected]</item> + <item>zlib</item> + </list> + </item> + </taglist> + </section> + <section> + <title>Unicode support</title> + <p>Unicode filenames are supported if the emulator and the underlaying OS support it. See section DESCRIPTION in the + <seealso marker="kernel:file">file</seealso> manual page in <c>kernel</c> for information about this subject. + </p> + <p>The shell and the cli both support unicode. + </p> + </section> + + <section> + <title>Rfcs</title> + <p>The following rfc:s are supported:</p> + <list type="bulleted"> + <item><url href="https://tools.ietf.org/html/rfc4251">RFC 4251</url>, The Secure Shell (SSH) Protocol Architecture. + <p>Except</p> + <list type="bulleted"> + <item>9.4.6 Host-Based Authentication</item> + <item>9.5.2 Proxy Forwarding</item> + <item>9.5.3 X11 Forwarding</item> + </list> + <p/> + </item> + + <item><url href="https://tools.ietf.org/html/rfc4252">RFC 4252</url>, The Secure Shell (SSH) Authentication Protocol. + <p>Except</p> + <list type="bulleted"> + <item>9. Host-Based Authentication: "hostbased"</item> + </list> + <p/> + </item> + + <item><url href="https://tools.ietf.org/html/rfc4253">RFC 4253</url>, The Secure Shell (SSH) Transport Layer Protocol. + <p></p> + </item> + + <item><url href="https://tools.ietf.org/html/rfc4254">RFC 4254</url>, The Secure Shell (SSH) Connection Protocol. + <p>Except</p> + <list type="bulleted"> + <item>6.3. X11 Forwarding</item> + <item>7. TCP/IP Port Forwarding</item> + </list> + <p/> + </item> + + <item><url href="https://tools.ietf.org/html/rfc4256">RFC 4256</url>, Generic Message Exchange Authentication for + the Secure Shell Protocol (SSH). + <p>Except</p> + <list type="bulleted"> + <item><c>num-prompts > 1</c></item> + <item>password changing</item> + <item>other identification methods than userid-password</item> + </list> + <p/> + </item> + + <item><url href="https://tools.ietf.org/html/rfc4419">RFC 4419</url>, Diffie-Hellman Group Exchange for + the Secure Shell (SSH) Transport Layer Protocol. + <p/> + </item> + + <item><url href="https://tools.ietf.org/html/rfc4716">RFC 4716</url>, The Secure Shell (SSH) Public Key File Format. + <p/> + </item> + + <item><url href="https://tools.ietf.org/html/rfc5647">RFC 5647</url>, AES Galois Counter Mode for + the Secure Shell Transport Layer Protocol. + <p><marker id="rfc5647_note"/>There is an ambiguity in the synchronized selection of cipher and mac algorithm. + This is resolved by OpenSSH in the ciphers [email protected] and [email protected] which are implemented. + If the explicit ciphers and macs AEAD_AES_128_GCM or AEAD_AES_256_GCM are needed, + they could be enabled with the option preferred_algorithms. + </p> + <warning> + <p> + If the client or the server is not Erlang/OTP, it is the users responsibility to check that + other implementation has the same interpretation of AEAD_AES_*_GCM as the Erlang/OTP SSH before + enabling them. The aes*[email protected] variants are always safe to use since they lack the + ambiguity. + </p> + </warning> + <p>The second paragraph in section 5.1 is resolved as:</p> + <list type="ordered"> + <item>If the negotiated cipher is AEAD_AES_128_GCM, the mac algorithm is set to AEAD_AES_128_GCM.</item> + <item>If the negotiated cipher is AEAD_AES_256_GCM, the mac algorithm is set to AEAD_AES_256_GCM.</item> + <item>If the mac algorithm is AEAD_AES_128_GCM, the cipher is set to AEAD_AES_128_GCM.</item> + <item>If the mac algorithm is AEAD_AES_256_GCM, the cipher is set to AEAD_AES_256_GCM.</item> + </list> + <p>The first rule that matches when read in order from the top is applied</p> + </item> + + <item><url href="https://tools.ietf.org/html/rfc5656">RFC 5656</url>, Elliptic Curve Algorithm Integration in + the Secure Shell Transport Layer. + <p>Except</p> + <list type="bulleted"> + <item>5. ECMQV Key Exchange</item> + <item>6.4. ECMQV Key Exchange and Verification Method Name</item> + <item>7.2. ECMQV Message Numbers</item> + <item>10.2. Recommended Curves</item> + </list> + <p/> + </item> + + <item><url href="https://tools.ietf.org/html/rfc6668">RFC 6668</url>, SHA-2 Data Integrity Verification for + the Secure Shell (SSH) Transport Layer Protocol + <p>Comment: Defines hmac-sha2-256 and hmac-sha2-512 + </p> + </item> + + </list> + + </section> + + <section> <title>SEE ALSO</title> <p><seealso marker="kernel:application">application(3)</seealso></p> </section> diff --git a/lib/ssh/doc/src/ssh_connection.xml b/lib/ssh/doc/src/ssh_connection.xml index 9a7bb09b12..150d46a9a2 100644 --- a/lib/ssh/doc/src/ssh_connection.xml +++ b/lib/ssh/doc/src/ssh_connection.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>2008</year> - <year>2014</year> + <year>2015</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> @@ -31,15 +31,15 @@ <rev></rev> </header> <module>ssh_connection</module> - <modulesummary>This module provides API functions to send - <url href="http://www.ietf.org/rfc/rfc4254.txt"> SSH Connection Protocol </url> - events to the other side of an SSH channel. + <modulesummary> + This module provides API functions to send SSH Connection Protocol + events to the other side of an SSH channel. </modulesummary> <description> - <p>The SSH Connection Protocol is used by clients and servers, - that is, SSH channels, to communicate over the SSH connection. The - API functions in this module send SSH Connection Protocol events, + <p>The <url href="http://www.ietf.org/rfc/rfc4254.txt">SSH Connection Protocol</url> + is used by clients and servers, that is, SSH channels, to communicate over the + SSH connection. The API functions in this module send SSH Connection Protocol events, which are received as messages by the remote channel. If the receiving channel is an Erlang process, the messages have the format @@ -373,6 +373,9 @@ <desc> <p>Is to be called by client- and server-channel processes to send data to each other. </p> + <p>The function <seealso marker="ssh:ssh_connection#subsystem/4">subsystem/4</seealso> and subsequent + calls of <c>send/3,4,5</c> must be executed in the same process. + </p> </desc> </func> @@ -454,6 +457,9 @@ <p>Is to be called by a client-channel process for requesting to execute a predefined subsystem on the server. </p> + <p>The function <c>subsystem/4</c> and subsequent calls of + <seealso marker="ssh:ssh_connection#send/3">send/3,4,5</seealso> must be executed in the same process. + </p> </desc> </func> diff --git a/lib/ssh/doc/src/ssh_server_key_api.xml b/lib/ssh/doc/src/ssh_server_key_api.xml index efb2c436e8..a0694ca8d9 100644 --- a/lib/ssh/doc/src/ssh_server_key_api.xml +++ b/lib/ssh/doc/src/ssh_server_key_api.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>2012</year> - <year>2013</year> + <year>2015</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> @@ -75,7 +75,7 @@ <d>Host key algorithm. Is to support <c>'ssh-rsa' | 'ssh-dss'</c>, but more algorithms can be handled.</d> <v>DaemonOptions = proplists:proplist()</v> - <d>Options provided to <seealso marker="ssh#daemon-2">ssh:daemon/[2,3]</seealso>.</d> + <d>Options provided to <seealso marker="ssh#daemon-2">ssh:daemon/[2,3]</seealso>.</d> <v>Key = private_key()</v> <d>Private key of the host matching the <c>Algorithm</c>.</d> <v>Reason = term()</v> diff --git a/lib/ssh/doc/src/ssh_sftp.xml b/lib/ssh/doc/src/ssh_sftp.xml index 17800fac5d..c6ca0f161a 100644 --- a/lib/ssh/doc/src/ssh_sftp.xml +++ b/lib/ssh/doc/src/ssh_sftp.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>2005</year><year>2014</year> + <year>2005</year><year>2015</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -61,20 +61,23 @@ <funcs> <func> - <name>apread(ChannelPid, Handle, Position, Len) -> {async, N} | {error, Error}</name> - <v>ChannelPid = pid()</v> - <v>Handle = term()</v> - <v>Position = integer()</v> - <v>Len = integer()</v> - <v>N = term()</v> - <v>Reason = term()</v> - - <desc><p>The <c><![CDATA[apread]]></c> function reads from a specified position, - combining the <c><![CDATA[position]]></c> and <c><![CDATA[aread]]></c> functions.</p> + <name>apread(ChannelPid, Handle, Position, Len) -> {async, N} | {error, Reason}</name> + <fsummary>Reads asynchronously from an open file.</fsummary> + <type> + <v>ChannelPid = pid()</v> + <v>Handle = term()</v> + <v>Position = integer()</v> + <v>Len = integer()</v> + <v>N = term()</v> + <v>Reason = term()</v> + </type> + + <desc><p>The <c><![CDATA[apread]]></c> function reads from a specified position, + combining the <c><![CDATA[position]]></c> and <c><![CDATA[aread]]></c> functions.</p> <p><seealso marker="#apread-4">ssh_sftp:apread/4</seealso></p> </desc> - </func> - - <func> + </func> + + <func> <name>apwrite(ChannelPid, Handle, Position, Data) -> ok | {error, Reason}</name> <fsummary>Writes asynchronously to an open file.</fsummary> <type> diff --git a/lib/ssh/doc/src/using_ssh.xml b/lib/ssh/doc/src/using_ssh.xml index 91185a0f6e..6826f20fb3 100644 --- a/lib/ssh/doc/src/using_ssh.xml +++ b/lib/ssh/doc/src/using_ssh.xml @@ -234,7 +234,7 @@ <title>SFTP Client with TAR Compression and Encryption</title> <p>Example of writing and then reading a tar file follows:</p> - <code type="erlang"> + <code type="erl"> {ok,HandleWrite} = ssh_sftp:open_tar(ChannelPid, ?tar_file_name, [write]), ok = erl_tar:add(HandleWrite, .... ), ok = erl_tar:add(HandleWrite, .... ), @@ -249,10 +249,10 @@ </code> <p>The previous write and read example can be extended with encryption and decryption as follows:</p> - <code type="erlang"> + <code type="erl"> %% First three parameters depending on which crypto type we select: Key = <<"This is a 256 bit key. abcdefghi">>, -Ivec0 = crypto:rand_bytes(16), +Ivec0 = crypto:strong_rand_bytes(16), DataSize = 1024, % DataSize rem 16 = 0 for aes_cbc %% Initialization of the CryptoState, in this case it is the Ivector. diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-architecture-15.2.ps b/lib/ssh/doc/standard/draft-ietf-secsh-architecture-15.2.ps deleted file mode 100644 index d766a933b4..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-architecture-15.2.ps +++ /dev/null @@ -1,3315 +0,0 @@ -%!PS-Adobe-3.0 -%%BoundingBox: 75 0 595 747 -%%Title: Enscript Output -%%For: Magnus Thoang -%%Creator: GNU enscript 1.6.1 -%%CreationDate: Fri Oct 31 13:31:26 2003 -%%Orientation: Portrait -%%Pages: 15 0 -%%DocumentMedia: A4 595 842 0 () () -%%DocumentNeededResources: (atend) -%%EndComments -%%BeginProlog -%%BeginProcSet: PStoPS 1 15 -userdict begin -[/showpage/erasepage/copypage]{dup where{pop dup load - 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matrix invertmatrix matrix concatmatrix - matrix invertmatrix put -%%EndSetup -%%Page: (0,1) 1 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 1 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 701 M -(Network Working Group T. Ylonen) s -5 690 M -(Internet-Draft SSH Communications Security Corp) s -5 679 M -(Expires: March 31, 2004 D. Moffat, Ed.) s -5 668 M -( Sun Microsystems, Inc) s -5 657 M -( Oct 2003) s -5 624 M -( SSH Protocol Architecture) s -5 613 M -( draft-ietf-secsh-architecture-15.txt) s -5 591 M -(Status of this Memo) s -5 569 M -( This document is an Internet-Draft and is in full conformance with) s -5 558 M -( all provisions of Section 10 of RFC2026.) s -5 536 M -( Internet-Drafts are working documents of the Internet Engineering) s -5 525 M -( Task Force \(IETF\), its areas, and its working groups. Note that other) s -5 514 M -( groups may also distribute working documents as Internet-Drafts.) s -5 492 M -( Internet-Drafts are draft documents valid for a maximum of six months) s -5 481 M -( and may be updated, replaced, or obsoleted by other documents at any) s -5 470 M -( time. It is inappropriate to use Internet-Drafts as reference) s -5 459 M -( material or to cite them other than as "work in progress.") s -5 437 M -( The list of current Internet-Drafts can be accessed at http://) s -5 426 M -( www.ietf.org/ietf/1id-abstracts.txt.) s -5 404 M -( The list of Internet-Draft Shadow Directories can be accessed at) s -5 393 M -( http://www.ietf.org/shadow.html.) s -5 371 M -( This Internet-Draft will expire on March 31, 2004.) s -5 349 M -(Copyright Notice) s -5 327 M -( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s -5 305 M -(Abstract) s -5 283 M -( SSH is a protocol for secure remote login and other secure network) s -5 272 M -( services over an insecure network. This document describes the) s -5 261 M -( architecture of the SSH protocol, as well as the notation and) s -5 250 M -( terminology used in SSH protocol documents. It also discusses the SSH) s -5 239 M -( algorithm naming system that allows local extensions. The SSH) s -5 228 M -( protocol consists of three major components: The Transport Layer) s -5 217 M -( Protocol provides server authentication, confidentiality, and) s -5 206 M -( integrity with perfect forward secrecy. The User Authentication) s -5 195 M -( Protocol authenticates the client to the server. The Connection) s -5 184 M -( Protocol multiplexes the encrypted tunnel into several logical) s -5 173 M -( channels. Details of these protocols are described in separate) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 1]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 2 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( documents.) s -5 668 M -(Table of Contents) s -5 646 M -( 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 635 M -( 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 624 M -( 3. Specification of Requirements . . . . . . . . . . . . . . . 3) s -5 613 M -( 4. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 602 M -( 4.1 Host Keys . . . . . . . . . . . . . . . . . . . . . . . . . 4) s -5 591 M -( 4.2 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 5) s -5 580 M -( 4.3 Policy Issues . . . . . . . . . . . . . . . . . . . . . . . 5) s -5 569 M -( 4.4 Security Properties . . . . . . . . . . . . . . . . . . . . 6) s -5 558 M -( 4.5 Packet Size and Overhead . . . . . . . . . . . . . . . . . . 6) s -5 547 M -( 4.6 Localization and Character Set Support . . . . . . . . . . . 7) s -5 536 M -( 5. Data Type Representations Used in the SSH Protocols . . . . 8) s -5 525 M -( 6. Algorithm Naming . . . . . . . . . . . . . . . . . . . . . . 10) s -5 514 M -( 7. Message Numbers . . . . . . . . . . . . . . . . . . . . . . 11) s -5 503 M -( 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 11) s -5 492 M -( 9. Security Considerations . . . . . . . . . . . . . . . . . . 12) s -5 481 M -( 9.1 Pseudo-Random Number Generation . . . . . . . . . . . . . . 12) s -5 470 M -( 9.2 Transport . . . . . . . . . . . . . . . . . . . . . . . . . 13) s -5 459 M -( 9.2.1 Confidentiality . . . . . . . . . . . . . . . . . . . . . . 13) s -5 448 M -( 9.2.2 Data Integrity . . . . . . . . . . . . . . . . . . . . . . . 16) s -5 437 M -( 9.2.3 Replay . . . . . . . . . . . . . . . . . . . . . . . . . . . 16) s -5 426 M -( 9.2.4 Man-in-the-middle . . . . . . . . . . . . . . . . . . . . . 17) s -5 415 M -( 9.2.5 Denial-of-service . . . . . . . . . . . . . . . . . . . . . 19) s -5 404 M -( 9.2.6 Covert Channels . . . . . . . . . . . . . . . . . . . . . . 19) s -5 393 M -( 9.2.7 Forward Secrecy . . . . . . . . . . . . . . . . . . . . . . 20) s -5 382 M -( 9.3 Authentication Protocol . . . . . . . . . . . . . . . . . . 20) s -5 371 M -( 9.3.1 Weak Transport . . . . . . . . . . . . . . . . . . . . . . . 21) s -5 360 M -( 9.3.2 Debug messages . . . . . . . . . . . . . . . . . . . . . . . 21) s -5 349 M -( 9.3.3 Local security policy . . . . . . . . . . . . . . . . . . . 21) s -5 338 M -( 9.3.4 Public key authentication . . . . . . . . . . . . . . . . . 22) s -5 327 M -( 9.3.5 Password authentication . . . . . . . . . . . . . . . . . . 22) s -5 316 M -( 9.3.6 Host based authentication . . . . . . . . . . . . . . . . . 23) s -5 305 M -( 9.4 Connection protocol . . . . . . . . . . . . . . . . . . . . 23) s -5 294 M -( 9.4.1 End point security . . . . . . . . . . . . . . . . . . . . . 23) s -5 283 M -( 9.4.2 Proxy forwarding . . . . . . . . . . . . . . . . . . . . . . 23) s -5 272 M -( 9.4.3 X11 forwarding . . . . . . . . . . . . . . . . . . . . . . . 24) s -5 261 M -( Normative References . . . . . . . . . . . . . . . . . . . . 24) s -5 250 M -( Informative References . . . . . . . . . . . . . . . . . . . 25) s -5 239 M -( Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 27) s -5 228 M -( Intellectual Property and Copyright Statements . . . . . . . 28) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 2]) s -_R -S -PStoPSsaved restore -%%Page: (2,3) 2 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 3 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -(1. Contributors) s -5 668 M -( The major original contributors of this document were: Tatu Ylonen,) s -5 657 M -( Tero Kivinen, Timo J. Rinne, Sami Lehtinen \(all of SSH Communications) s -5 646 M -( Security Corp\), and Markku-Juhani O. Saarinen \(University of) s -5 635 M -( Jyvaskyla\)) s -5 613 M -( The document editor is: [email protected]. Comments on this) s -5 602 M -( internet draft should be sent to the IETF SECSH working group,) s -5 591 M -( details at: http://ietf.org/html.charters/secsh-charter.html) s -5 569 M -(2. Introduction) s -5 547 M -( SSH is a protocol for secure remote login and other secure network) s -5 536 M -( services over an insecure network. It consists of three major) s -5 525 M -( components:) s -5 514 M -( o The Transport Layer Protocol [SSH-TRANS] provides server) s -5 503 M -( authentication, confidentiality, and integrity. It may optionally) s -5 492 M -( also provide compression. The transport layer will typically be) s -5 481 M -( run over a TCP/IP connection, but might also be used on top of any) s -5 470 M -( other reliable data stream.) s -5 459 M -( o The User Authentication Protocol [SSH-USERAUTH] authenticates the) s -5 448 M -( client-side user to the server. It runs over the transport layer) s -5 437 M -( protocol.) s -5 426 M -( o The Connection Protocol [SSH-CONNECT] multiplexes the encrypted) s -5 415 M -( tunnel into several logical channels. It runs over the user) s -5 404 M -( authentication protocol.) s -5 382 M -( The client sends a service request once a secure transport layer) s -5 371 M -( connection has been established. A second service request is sent) s -5 360 M -( after user authentication is complete. This allows new protocols to) s -5 349 M -( be defined and coexist with the protocols listed above.) s -5 327 M -( The connection protocol provides channels that can be used for a wide) s -5 316 M -( range of purposes. Standard methods are provided for setting up) s -5 305 M -( secure interactive shell sessions and for forwarding \("tunneling"\)) s -5 294 M -( arbitrary TCP/IP ports and X11 connections.) s -5 272 M -(3. Specification of Requirements) s -5 250 M -( All documents related to the SSH protocols shall use the keywords) s -5 239 M -( "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",) s -5 228 M -( "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" to describe) s -5 217 M -( requirements. They are to be interpreted as described in [RFC2119].) s -5 195 M -(4. Architecture) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 3]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 4 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -(4.1 Host Keys) s -5 668 M -( Each server host SHOULD have a host key. Hosts MAY have multiple) s -5 657 M -( host keys using multiple different algorithms. Multiple hosts MAY) s -5 646 M -( share the same host key. If a host has keys at all, it MUST have at) s -5 635 M -( least one key using each REQUIRED public key algorithm \(DSS) s -5 624 M -( [FIPS-186]\).) s -5 602 M -( The server host key is used during key exchange to verify that the) s -5 591 M -( client is really talking to the correct server. For this to be) s -5 580 M -( possible, the client must have a priori knowledge of the server's) s -5 569 M -( public host key.) s -5 547 M -( Two different trust models can be used:) s -5 536 M -( o The client has a local database that associates each host name \(as) s -5 525 M -( typed by the user\) with the corresponding public host key. This) s -5 514 M -( method requires no centrally administered infrastructure, and no) s -5 503 M -( third-party coordination. The downside is that the database of) s -5 492 M -( name-to-key associations may become burdensome to maintain.) s -5 481 M -( o The host name-to-key association is certified by some trusted) s -5 470 M -( certification authority. The client only knows the CA root key,) s -5 459 M -( and can verify the validity of all host keys certified by accepted) s -5 448 M -( CAs.) s -5 426 M -( The second alternative eases the maintenance problem, since) s -5 415 M -( ideally only a single CA key needs to be securely stored on the) s -5 404 M -( client. On the other hand, each host key must be appropriately) s -5 393 M -( certified by a central authority before authorization is possible.) s -5 382 M -( Also, a lot of trust is placed on the central infrastructure.) s -5 360 M -( The protocol provides the option that the server name - host key) s -5 349 M -( association is not checked when connecting to the host for the first) s -5 338 M -( time. This allows communication without prior communication of host) s -5 327 M -( keys or certification. The connection still provides protection) s -5 316 M -( against passive listening; however, it becomes vulnerable to active) s -5 305 M -( man-in-the-middle attacks. Implementations SHOULD NOT normally allow) s -5 294 M -( such connections by default, as they pose a potential security) s -5 283 M -( problem. However, as there is no widely deployed key infrastructure) s -5 272 M -( available on the Internet yet, this option makes the protocol much) s -5 261 M -( more usable during the transition time until such an infrastructure) s -5 250 M -( emerges, while still providing a much higher level of security than) s -5 239 M -( that offered by older solutions \(e.g. telnet [RFC-854] and rlogin) s -5 228 M -( [RFC-1282]\).) s -5 206 M -( Implementations SHOULD try to make the best effort to check host) s -5 195 M -( keys. An example of a possible strategy is to only accept a host key) s -5 184 M -( without checking the first time a host is connected, save the key in) s -5 173 M -( a local database, and compare against that key on all future) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 4]) s -_R -S -PStoPSsaved restore -%%Page: (4,5) 3 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 5 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( connections to that host.) s -5 668 M -( Implementations MAY provide additional methods for verifying the) s -5 657 M -( correctness of host keys, e.g. a hexadecimal fingerprint derived from) s -5 646 M -( the SHA-1 hash of the public key. Such fingerprints can easily be) s -5 635 M -( verified by using telephone or other external communication channels.) s -5 613 M -( All implementations SHOULD provide an option to not accept host keys) s -5 602 M -( that cannot be verified.) s -5 580 M -( We believe that ease of use is critical to end-user acceptance of) s -5 569 M -( security solutions, and no improvement in security is gained if the) s -5 558 M -( new solutions are not used. Thus, providing the option not to check) s -5 547 M -( the server host key is believed to improve the overall security of) s -5 536 M -( the Internet, even though it reduces the security of the protocol in) s -5 525 M -( configurations where it is allowed.) s -5 503 M -(4.2 Extensibility) s -5 481 M -( We believe that the protocol will evolve over time, and some) s -5 470 M -( organizations will want to use their own encryption, authentication) s -5 459 M -( and/or key exchange methods. Central registration of all extensions) s -5 448 M -( is cumbersome, especially for experimental or classified features.) s -5 437 M -( On the other hand, having no central registration leads to conflicts) s -5 426 M -( in method identifiers, making interoperability difficult.) s -5 404 M -( We have chosen to identify algorithms, methods, formats, and) s -5 393 M -( extension protocols with textual names that are of a specific format.) s -5 382 M -( DNS names are used to create local namespaces where experimental or) s -5 371 M -( classified extensions can be defined without fear of conflicts with) s -5 360 M -( other implementations.) s -5 338 M -( One design goal has been to keep the base protocol as simple as) s -5 327 M -( possible, and to require as few algorithms as possible. However, all) s -5 316 M -( implementations MUST support a minimal set of algorithms to ensure) s -5 305 M -( interoperability \(this does not imply that the local policy on all) s -5 294 M -( hosts would necessary allow these algorithms\). The mandatory) s -5 283 M -( algorithms are specified in the relevant protocol documents.) s -5 261 M -( Additional algorithms, methods, formats, and extension protocols can) s -5 250 M -( be defined in separate drafts. See Section Algorithm Naming \(Section) s -5 239 M -( 6\) for more information.) s -5 217 M -(4.3 Policy Issues) s -5 195 M -( The protocol allows full negotiation of encryption, integrity, key) s -5 184 M -( exchange, compression, and public key algorithms and formats.) s -5 173 M -( Encryption, integrity, public key, and compression algorithms can be) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 5]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 6 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( different for each direction.) s -5 668 M -( The following policy issues SHOULD be addressed in the configuration) s -5 657 M -( mechanisms of each implementation:) s -5 646 M -( o Encryption, integrity, and compression algorithms, separately for) s -5 635 M -( each direction. The policy MUST specify which is the preferred) s -5 624 M -( algorithm \(e.g. the first algorithm listed in each category\).) s -5 613 M -( o Public key algorithms and key exchange method to be used for host) s -5 602 M -( authentication. The existence of trusted host keys for different) s -5 591 M -( public key algorithms also affects this choice.) s -5 580 M -( o The authentication methods that are to be required by the server) s -5 569 M -( for each user. The server's policy MAY require multiple) s -5 558 M -( authentication for some or all users. The required algorithms MAY) s -5 547 M -( depend on the location where the user is trying to log in from.) s -5 536 M -( o The operations that the user is allowed to perform using the) s -5 525 M -( connection protocol. Some issues are related to security; for) s -5 514 M -( example, the policy SHOULD NOT allow the server to start sessions) s -5 503 M -( or run commands on the client machine, and MUST NOT allow) s -5 492 M -( connections to the authentication agent unless forwarding such) s -5 481 M -( connections has been requested. Other issues, such as which TCP/) s -5 470 M -( IP ports can be forwarded and by whom, are clearly issues of local) s -5 459 M -( policy. Many of these issues may involve traversing or bypassing) s -5 448 M -( firewalls, and are interrelated with the local security policy.) s -5 426 M -(4.4 Security Properties) s -5 404 M -( The primary goal of the SSH protocol is improved security on the) s -5 393 M -( Internet. It attempts to do this in a way that is easy to deploy,) s -5 382 M -( even at the cost of absolute security.) s -5 371 M -( o All encryption, integrity, and public key algorithms used are) s -5 360 M -( well-known, well-established algorithms.) s -5 349 M -( o All algorithms are used with cryptographically sound key sizes) s -5 338 M -( that are believed to provide protection against even the strongest) s -5 327 M -( cryptanalytic attacks for decades.) s -5 316 M -( o All algorithms are negotiated, and in case some algorithm is) s -5 305 M -( broken, it is easy to switch to some other algorithm without) s -5 294 M -( modifying the base protocol.) s -5 272 M -( Specific concessions were made to make wide-spread fast deployment) s -5 261 M -( easier. The particular case where this comes up is verifying that) s -5 250 M -( the server host key really belongs to the desired host; the protocol) s -5 239 M -( allows the verification to be left out \(but this is NOT RECOMMENDED\).) s -5 228 M -( This is believed to significantly improve usability in the short) s -5 217 M -( term, until widespread Internet public key infrastructures emerge.) s -5 195 M -(4.5 Packet Size and Overhead) s -5 173 M -( Some readers will worry about the increase in packet size due to new) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 6]) s -_R -S -PStoPSsaved restore -%%Page: (6,7) 4 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 7 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( headers, padding, and MAC. The minimum packet size is in the order) s -5 679 M -( of 28 bytes \(depending on negotiated algorithms\). The increase is) s -5 668 M -( negligible for large packets, but very significant for one-byte) s -5 657 M -( packets \(telnet-type sessions\). There are, however, several factors) s -5 646 M -( that make this a non-issue in almost all cases:) s -5 635 M -( o The minimum size of a TCP/IP header is 32 bytes. Thus, the) s -5 624 M -( increase is actually from 33 to 51 bytes \(roughly\).) s -5 613 M -( o The minimum size of the data field of an Ethernet packet is 46) s -5 602 M -( bytes [RFC-894]. Thus, the increase is no more than 5 bytes. When) s -5 591 M -( Ethernet headers are considered, the increase is less than 10) s -5 580 M -( percent.) s -5 569 M -( o The total fraction of telnet-type data in the Internet is) s -5 558 M -( negligible, even with increased packet sizes.) s -5 536 M -( The only environment where the packet size increase is likely to have) s -5 525 M -( a significant effect is PPP [RFC-1134] over slow modem lines \(PPP) s -5 514 M -( compresses the TCP/IP headers, emphasizing the increase in packet) s -5 503 M -( size\). However, with modern modems, the time needed to transfer is in) s -5 492 M -( the order of 2 milliseconds, which is a lot faster than people can) s -5 481 M -( type.) s -5 459 M -( There are also issues related to the maximum packet size. To) s -5 448 M -( minimize delays in screen updates, one does not want excessively) s -5 437 M -( large packets for interactive sessions. The maximum packet size is) s -5 426 M -( negotiated separately for each channel.) s -5 404 M -(4.6 Localization and Character Set Support) s -5 382 M -( For the most part, the SSH protocols do not directly pass text that) s -5 371 M -( would be displayed to the user. However, there are some places where) s -5 360 M -( such data might be passed. When applicable, the character set for the) s -5 349 M -( data MUST be explicitly specified. In most places, ISO 10646 with) s -5 338 M -( UTF-8 encoding is used [RFC-2279]. When applicable, a field is also) s -5 327 M -( provided for a language tag [RFC-3066].) s -5 305 M -( One big issue is the character set of the interactive session. There) s -5 294 M -( is no clear solution, as different applications may display data in) s -5 283 M -( different formats. Different types of terminal emulation may also be) s -5 272 M -( employed in the client, and the character set to be used is) s -5 261 M -( effectively determined by the terminal emulation. Thus, no place is) s -5 250 M -( provided for directly specifying the character set or encoding for) s -5 239 M -( terminal session data. However, the terminal emulation type \(e.g.) s -5 228 M -( "vt100"\) is transmitted to the remote site, and it implicitly) s -5 217 M -( specifies the character set and encoding. Applications typically use) s -5 206 M -( the terminal type to determine what character set they use, or the) s -5 195 M -( character set is determined using some external means. The terminal) s -5 184 M -( emulation may also allow configuring the default character set. In) s -5 173 M -( any case, the character set for the terminal session is considered) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 7]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 8 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( primarily a client local issue.) s -5 668 M -( Internal names used to identify algorithms or protocols are normally) s -5 657 M -( never displayed to users, and must be in US-ASCII.) s -5 635 M -( The client and server user names are inherently constrained by what) s -5 624 M -( the server is prepared to accept. They might, however, occasionally) s -5 613 M -( be displayed in logs, reports, etc. They MUST be encoded using ISO) s -5 602 M -( 10646 UTF-8, but other encodings may be required in some cases. It) s -5 591 M -( is up to the server to decide how to map user names to accepted user) s -5 580 M -( names. Straight bit-wise binary comparison is RECOMMENDED.) s -5 558 M -( For localization purposes, the protocol attempts to minimize the) s -5 547 M -( number of textual messages transmitted. When present, such messages) s -5 536 M -( typically relate to errors, debugging information, or some externally) s -5 525 M -( configured data. For data that is normally displayed, it SHOULD be) s -5 514 M -( possible to fetch a localized message instead of the transmitted) s -5 503 M -( message by using a numerical code. The remaining messages SHOULD be) s -5 492 M -( configurable.) s -5 470 M -(5. Data Type Representations Used in the SSH Protocols) s -5 459 M -( byte) s -5 437 M -( A byte represents an arbitrary 8-bit value \(octet\) [RFC-1700].) s -5 426 M -( Fixed length data is sometimes represented as an array of bytes,) s -5 415 M -( written byte[n], where n is the number of bytes in the array.) s -5 393 M -( boolean) s -5 371 M -( A boolean value is stored as a single byte. The value 0) s -5 360 M -( represents FALSE, and the value 1 represents TRUE. All non-zero) s -5 349 M -( values MUST be interpreted as TRUE; however, applications MUST NOT) s -5 338 M -( store values other than 0 and 1.) s -5 316 M -( uint32) s -5 294 M -( Represents a 32-bit unsigned integer. Stored as four bytes in the) s -5 283 M -( order of decreasing significance \(network byte order\). For) s -5 272 M -( example, the value 699921578 \(0x29b7f4aa\) is stored as 29 b7 f4) s -5 261 M -( aa.) s -5 239 M -( uint64) s -5 217 M -( Represents a 64-bit unsigned integer. Stored as eight bytes in) s -5 206 M -( the order of decreasing significance \(network byte order\).) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 8]) s -_R -S -PStoPSsaved restore -%%Page: (8,9) 5 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 9 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( string) s -5 668 M -( Arbitrary length binary string. Strings are allowed to contain) s -5 657 M -( arbitrary binary data, including null characters and 8-bit) s -5 646 M -( characters. They are stored as a uint32 containing its length) s -5 635 M -( \(number of bytes that follow\) and zero \(= empty string\) or more) s -5 624 M -( bytes that are the value of the string. Terminating null) s -5 613 M -( characters are not used.) s -5 591 M -( Strings are also used to store text. In that case, US-ASCII is) s -5 580 M -( used for internal names, and ISO-10646 UTF-8 for text that might) s -5 569 M -( be displayed to the user. The terminating null character SHOULD) s -5 558 M -( NOT normally be stored in the string.) s -5 536 M -( For example, the US-ASCII string "testing" is represented as 00 00) s -5 525 M -( 00 07 t e s t i n g. The UTF8 mapping does not alter the encoding) s -5 514 M -( of US-ASCII characters.) s -5 492 M -( mpint) s -5 470 M -( Represents multiple precision integers in two's complement format,) s -5 459 M -( stored as a string, 8 bits per byte, MSB first. Negative numbers) s -5 448 M -( have the value 1 as the most significant bit of the first byte of) s -5 437 M -( the data partition. If the most significant bit would be set for a) s -5 426 M -( positive number, the number MUST be preceded by a zero byte.) s -5 415 M -( Unnecessary leading bytes with the value 0 or 255 MUST NOT be) s -5 404 M -( included. The value zero MUST be stored as a string with zero) s -5 393 M -( bytes of data.) s -5 371 M -( By convention, a number that is used in modular computations in) s -5 360 M -( Z_n SHOULD be represented in the range 0 <= x < n.) s -5 338 M -( Examples:) s -5 327 M -( value \(hex\) representation \(hex\)) s -5 316 M -( ---------------------------------------------------------------) s -5 305 M -( 0 00 00 00 00) s -5 294 M -( 9a378f9b2e332a7 00 00 00 08 09 a3 78 f9 b2 e3 32 a7) s -5 283 M -( 80 00 00 00 02 00 80) s -5 272 M -( -1234 00 00 00 02 ed cc) s -5 261 M -( -deadbeef 00 00 00 05 ff 21 52 41 11) s -5 217 M -( name-list) s -5 195 M -( A string containing a comma separated list of names. A name list) s -5 184 M -( is represented as a uint32 containing its length \(number of bytes) s -5 173 M -( that follow\) followed by a comma-separated list of zero or more) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 9]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 10 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( names. A name MUST be non-zero length, and it MUST NOT contain a) s -5 679 M -( comma \(','\). Context may impose additional restrictions on the) s -5 668 M -( names; for example, the names in a list may have to be valid) s -5 657 M -( algorithm identifier \(see Algorithm Naming below\), or [RFC-3066]) s -5 646 M -( language tags. The order of the names in a list may or may not be) s -5 635 M -( significant, also depending on the context where the list is is) s -5 624 M -( used. Terminating NUL characters are not used, neither for the) s -5 613 M -( individual names, nor for the list as a whole.) s -5 591 M -( Examples:) s -5 580 M -( value representation \(hex\)) s -5 569 M -( ---------------------------------------) s -5 558 M -( \(\), the empty list 00 00 00 00) s -5 547 M -( \("zlib"\) 00 00 00 04 7a 6c 69 62) s -5 536 M -( \("zlib", "none"\) 00 00 00 09 7a 6c 69 62 2c 6e 6f 6e 65) s -5 481 M -(6. Algorithm Naming) s -5 459 M -( The SSH protocols refer to particular hash, encryption, integrity,) s -5 448 M -( compression, and key exchange algorithms or protocols by names.) s -5 437 M -( There are some standard algorithms that all implementations MUST) s -5 426 M -( support. There are also algorithms that are defined in the protocol) s -5 415 M -( specification but are OPTIONAL. Furthermore, it is expected that) s -5 404 M -( some organizations will want to use their own algorithms.) s -5 382 M -( In this protocol, all algorithm identifiers MUST be printable) s -5 371 M -( US-ASCII non-empty strings no longer than 64 characters. Names MUST) s -5 360 M -( be case-sensitive.) s -5 338 M -( There are two formats for algorithm names:) s -5 327 M -( o Names that do not contain an at-sign \(@\) are reserved to be) s -5 316 M -( assigned by IETF consensus \(RFCs\). Examples include `3des-cbc',) s -5 305 M -( `sha-1', `hmac-sha1', and `zlib' \(the quotes are not part of the) s -5 294 M -( name\). Names of this format MUST NOT be used without first) s -5 283 M -( registering them. Registered names MUST NOT contain an at-sign) s -5 272 M -( \(@\) or a comma \(,\).) s -5 261 M -( o Anyone can define additional algorithms by using names in the) s -5 250 M -( format name@domainname, e.g. "[email protected]". The) s -5 239 M -( format of the part preceding the at sign is not specified; it MUST) s -5 228 M -( consist of US-ASCII characters except at-sign and comma. The part) s -5 217 M -( following the at-sign MUST be a valid fully qualified internet) s -5 206 M -( domain name [RFC-1034] controlled by the person or organization) s -5 195 M -( defining the name. It is up to each domain how it manages its) s -5 184 M -( local namespace.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 10]) s -_R -S -PStoPSsaved restore -%%Page: (10,11) 6 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 11 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -(7. Message Numbers) s -5 668 M -( SSH packets have message numbers in the range 1 to 255. These numbers) s -5 657 M -( have been allocated as follows:) s -5 624 M -( Transport layer protocol:) s -5 602 M -( 1 to 19 Transport layer generic \(e.g. disconnect, ignore, debug,) s -5 591 M -( etc.\)) s -5 580 M -( 20 to 29 Algorithm negotiation) s -5 569 M -( 30 to 49 Key exchange method specific \(numbers can be reused for) s -5 558 M -( different authentication methods\)) s -5 536 M -( User authentication protocol:) s -5 514 M -( 50 to 59 User authentication generic) s -5 503 M -( 60 to 79 User authentication method specific \(numbers can be) s -5 492 M -( reused for different authentication methods\)) s -5 470 M -( Connection protocol:) s -5 448 M -( 80 to 89 Connection protocol generic) s -5 437 M -( 90 to 127 Channel related messages) s -5 415 M -( Reserved for client protocols:) s -5 393 M -( 128 to 191 Reserved) s -5 371 M -( Local extensions:) s -5 349 M -( 192 to 255 Local extensions) s -5 305 M -(8. IANA Considerations) s -5 283 M -( The initial state of the IANA registry is detailed in [SSH-NUMBERS].) s -5 261 M -( Allocation of the following types of names in the SSH protocols is) s -5 250 M -( assigned by IETF consensus:) s -5 239 M -( o SSH encryption algorithm names,) s -5 228 M -( o SSH MAC algorithm names,) s -5 217 M -( o SSH public key algorithm names \(public key algorithm also implies) s -5 206 M -( encoding and signature/encryption capability\),) s -5 195 M -( o SSH key exchange method names, and) s -5 184 M -( o SSH protocol \(service\) names.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 11]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 12 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( These names MUST be printable US-ASCII strings, and MUST NOT contain) s -5 679 M -( the characters at-sign \('@'\), comma \(','\), or whitespace or control) s -5 668 M -( characters \(ASCII codes 32 or less\). Names are case-sensitive, and) s -5 657 M -( MUST NOT be longer than 64 characters.) s -5 635 M -( Names with the at-sign \('@'\) in them are allocated by the owner of) s -5 624 M -( DNS name after the at-sign \(hierarchical allocation in [RFC-2343]\),) s -5 613 M -( otherwise the same restrictions as above.) s -5 591 M -( Each category of names listed above has a separate namespace.) s -5 580 M -( However, using the same name in multiple categories SHOULD be avoided) s -5 569 M -( to minimize confusion.) s -5 547 M -( Message numbers \(see Section Message Numbers \(Section 7\)\) in the) s -5 536 M -( range of 0..191 are allocated via IETF consensus; message numbers in) s -5 525 M -( the 192..255 range \(the "Local extensions" set\) are reserved for) s -5 514 M -( private use.) s -5 492 M -(9. Security Considerations) s -5 470 M -( In order to make the entire body of Security Considerations more) s -5 459 M -( accessible, Security Considerations for the transport,) s -5 448 M -( authentication, and connection documents have been gathered here.) s -5 426 M -( The transport protocol [1] provides a confidential channel over an) s -5 415 M -( insecure network. It performs server host authentication, key) s -5 404 M -( exchange, encryption, and integrity protection. It also derives a) s -5 393 M -( unique session id that may be used by higher-level protocols.) s -5 371 M -( The authentication protocol [2] provides a suite of mechanisms which) s -5 360 M -( can be used to authenticate the client user to the server.) s -5 349 M -( Individual mechanisms specified in the in authentication protocol use) s -5 338 M -( the session id provided by the transport protocol and/or depend on) s -5 327 M -( the security and integrity guarantees of the transport protocol.) s -5 305 M -( The connection protocol [3] specifies a mechanism to multiplex) s -5 294 M -( multiple streams [channels] of data over the confidential and) s -5 283 M -( authenticated transport. It also specifies channels for accessing an) s -5 272 M -( interactive shell, for 'proxy-forwarding' various external protocols) s -5 261 M -( over the secure transport \(including arbitrary TCP/IP protocols\), and) s -5 250 M -( for accessing secure 'subsystems' on the server host.) s -5 228 M -(9.1 Pseudo-Random Number Generation) s -5 206 M -( This protocol binds each session key to the session by including) s -5 195 M -( random, session specific data in the hash used to produce session) s -5 184 M -( keys. Special care should be taken to ensure that all of the random) s -5 173 M -( numbers are of good quality. If the random data here \(e.g., DH) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 12]) s -_R -S -PStoPSsaved restore -%%Page: (12,13) 7 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 13 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( parameters\) are pseudo-random then the pseudo-random number generator) s -5 679 M -( should be cryptographically secure \(i.e., its next output not easily) s -5 668 M -( guessed even when knowing all previous outputs\) and, furthermore,) s -5 657 M -( proper entropy needs to be added to the pseudo-random number) s -5 646 M -( generator. RFC 1750 [1750] offers suggestions for sources of random) s -5 635 M -( numbers and entropy. Implementors should note the importance of) s -5 624 M -( entropy and the well-meant, anecdotal warning about the difficulty in) s -5 613 M -( properly implementing pseudo-random number generating functions.) s -5 591 M -( The amount of entropy available to a given client or server may) s -5 580 M -( sometimes be less than what is required. In this case one must) s -5 569 M -( either resort to pseudo-random number generation regardless of) s -5 558 M -( insufficient entropy or refuse to run the protocol. The latter is) s -5 547 M -( preferable.) s -5 525 M -(9.2 Transport) s -5 503 M -(9.2.1 Confidentiality) s -5 481 M -( It is beyond the scope of this document and the Secure Shell Working) s -5 470 M -( Group to analyze or recommend specific ciphers other than the ones) s -5 459 M -( which have been established and accepted within the industry. At the) s -5 448 M -( time of this writing, ciphers commonly in use include 3DES, ARCFOUR,) s -5 437 M -( twofish, serpent and blowfish. AES has been accepted by The) s -5 426 M -( published as a US Federal Information Processing Standards [FIPS-197]) s -5 415 M -( and the cryptographic community as being acceptable for this purpose) s -5 404 M -( as well has accepted AES. As always, implementors and users should) s -5 393 M -( check current literature to ensure that no recent vulnerabilities) s -5 382 M -( have been found in ciphers used within products. Implementors should) s -5 371 M -( also check to see which ciphers are considered to be relatively) s -5 360 M -( stronger than others and should recommend their use to users over) s -5 349 M -( relatively weaker ciphers. It would be considered good form for an) s -5 338 M -( implementation to politely and unobtrusively notify a user that a) s -5 327 M -( stronger cipher is available and should be used when a weaker one is) s -5 316 M -( actively chosen.) s -5 294 M -( The "none" cipher is provided for debugging and SHOULD NOT be used) s -5 283 M -( except for that purpose. It's cryptographic properties are) s -5 272 M -( sufficiently described in RFC 2410, which will show that its use does) s -5 261 M -( not meet the intent of this protocol.) s -5 239 M -( The relative merits of these and other ciphers may also be found in) s -5 228 M -( current literature. Two references that may provide information on) s -5 217 M -( the subject are [SCHNEIER] and [KAUFMAN,PERLMAN,SPECINER]. Both of) s -5 206 M -( these describe the CBC mode of operation of certain ciphers and the) s -5 195 M -( weakness of this scheme. Essentially, this mode is theoretically) s -5 184 M -( vulnerable to chosen cipher-text attacks because of the high) s -5 173 M -( predictability of the start of packet sequence. However, this attack) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 13]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 14 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( is still deemed difficult and not considered fully practicable) s -5 679 M -( especially if relatively longer block sizes are used.) s -5 657 M -( Additionally, another CBC mode attack may be mitigated through the) s -5 646 M -( insertion of packets containing SSH_MSG_IGNORE. Without this) s -5 635 M -( technique, a specific attack may be successful. For this attack) s -5 624 M -( \(commonly known as the Rogaway attack) s -5 613 M -( [ROGAWAY],[DAI],[BELLARE,KOHNO,NAMPREMPRE]\) to work, the attacker) s -5 602 M -( would need to know the IV of the next block that is going to be) s -5 591 M -( encrypted. In CBC mode that is the output of the encryption of the) s -5 580 M -( previous block. If the attacker does not have any way to see the) s -5 569 M -( packet yet \(i.e it is in the internal buffers of the ssh) s -5 558 M -( implementation or even in the kernel\) then this attack will not work.) s -5 547 M -( If the last packet has been sent out to the network \(i.e the attacker) s -5 536 M -( has access to it\) then he can use the attack.) s -5 514 M -( In the optimal case an implementor would need to add an extra packet) s -5 503 M -( only if the packet has been sent out onto the network and there are) s -5 492 M -( no other packets waiting for transmission. Implementors may wish to) s -5 481 M -( check to see if there are any unsent packets awaiting transmission,) s -5 470 M -( but unfortunately it is not normally easy to obtain this information) s -5 459 M -( from the kernel or buffers. If there are not, then a packet) s -5 448 M -( containing SSH_MSG_IGNORE SHOULD be sent. If a new packet is added) s -5 437 M -( to the stream every time the attacker knows the IV that is supposed) s -5 426 M -( to be used for the next packet, then the attacker will not be able to) s -5 415 M -( guess the correct IV, thus the attack will never be successfull.) s -5 393 M -( As an example, consider the following case:) s -5 360 M -( Client Server) s -5 349 M -( ------ ------) s -5 338 M -( TCP\(seq=x, len=500\) ->) s -5 327 M -( contains Record 1) s -5 305 M -( [500 ms passes, no ACK]) s -5 283 M -( TCP\(seq=x, len=1000\) ->) s -5 272 M -( contains Records 1,2) s -5 250 M -( ACK) s -5 217 M -( 1. The Nagle algorithm + TCP retransmits mean that the two records) s -5 206 M -( get coalesced into a single TCP segment) s -5 195 M -( 2. Record 2 is *not* at the beginning of the TCP segment and never) s -5 184 M -( will be, since it gets ACKed.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 14]) s -_R -S -PStoPSsaved restore -%%Page: (14,15) 8 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 15 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( 3. Yet, the attack is possible because Record 1 has already been) s -5 679 M -( seen.) s -5 657 M -( As this example indicates, it's totally unsafe to use the existence) s -5 646 M -( of unflushed data in the TCP buffers proper as a guide to whether you) s -5 635 M -( need an empty packet, since when you do the second write\(\), the) s -5 624 M -( buffers will contain the un-ACKed Record 1.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 15]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 16 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( On the other hand, it's perfectly safe to have the following) s -5 679 M -( situation:) s -5 646 M -( Client Server) s -5 635 M -( ------ ------) s -5 624 M -( TCP\(seq=x, len=500\) ->) s -5 613 M -( contains SSH_MSG_IGNORE) s -5 591 M -( TCP\(seq=y, len=500\) ->) s -5 580 M -( contains Data) s -5 558 M -( Provided that the IV for second SSH Record is fixed after the data for) s -5 547 M -( the Data packet is determined -i.e. you do:) s -5 536 M -( read from user) s -5 525 M -( encrypt null packet) s -5 514 M -( encrypt data packet) s -5 481 M -(9.2.2 Data Integrity) s -5 459 M -( This protocol does allow the Data Integrity mechanism to be disabled.) s -5 448 M -( Implementors SHOULD be wary of exposing this feature for any purpose) s -5 437 M -( other than debugging. Users and administrators SHOULD be explicitly) s -5 426 M -( warned anytime the "none" MAC is enabled.) s -5 404 M -( So long as the "none" MAC is not used, this protocol provides data) s -5 393 M -( integrity.) s -5 371 M -( Because MACs use a 32 bit sequence number, they might start to leak) s -5 360 M -( information after 2**32 packets have been sent. However, following) s -5 349 M -( the rekeying recommendations should prevent this attack. The) s -5 338 M -( transport protocol [1] recommends rekeying after one gigabyte of) s -5 327 M -( data, and the smallest possible packet is 16 bytes. Therefore,) s -5 316 M -( rekeying SHOULD happen after 2**28 packets at the very most.) s -5 294 M -(9.2.3 Replay) s -5 272 M -( The use of a MAC other than 'none' provides integrity and) s -5 261 M -( authentication. In addition, the transport protocol provides a) s -5 250 M -( unique session identifier \(bound in part to pseudo-random data that) s -5 239 M -( is part of the algorithm and key exchange process\) that can be used) s -5 228 M -( by higher level protocols to bind data to a given session and prevent) s -5 217 M -( replay of data from prior sessions. For example, the authentication) s -5 206 M -( protocol uses this to prevent replay of signatures from previous) s -5 195 M -( sessions. Because public key authentication exchanges are) s -5 184 M -( cryptographically bound to the session \(i.e., to the initial key) s -5 173 M -( exchange\) they cannot be successfully replayed in other sessions.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 16]) s -_R -S -PStoPSsaved restore -%%Page: (16,17) 9 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 17 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( Note that the session ID can be made public without harming the) s -5 679 M -( security of the protocol.) s -5 657 M -( If two session happen to have the same session ID [hash of key) s -5 646 M -( exchanges] then packets from one can be replayed against the other.) s -5 635 M -( It must be stressed that the chances of such an occurrence are,) s -5 624 M -( needless to say, minimal when using modern cryptographic methods.) s -5 613 M -( This is all the more so true when specifying larger hash function) s -5 602 M -( outputs and DH parameters.) s -5 580 M -( Replay detection using monotonically increasing sequence numbers as) s -5 569 M -( input to the MAC, or HMAC in some cases, is described in [RFC2085] />) s -5 558 M -( [RFC2246], [RFC2743], [RFC1964], [RFC2025], and [RFC1510]. The) s -5 547 M -( underlying construct is discussed in [RFC2104]. Essentially a) s -5 536 M -( different sequence number in each packet ensures that at least this) s -5 525 M -( one input to the MAC function will be unique and will provide a) s -5 514 M -( nonrecurring MAC output that is not predictable to an attacker. If) s -5 503 M -( the session stays active long enough, however, this sequence number) s -5 492 M -( will wrap. This event may provide an attacker an opportunity to) s -5 481 M -( replay a previously recorded packet with an identical sequence number) s -5 470 M -( but only if the peers have not rekeyed since the transmission of the) s -5 459 M -( first packet with that sequence number. If the peers have rekeyed,) s -5 448 M -( then the replay will be detected as the MAC check will fail. For) s -5 437 M -( this reason, it must be emphasized that peers MUST rekey before a) s -5 426 M -( wrap of the sequence numbers. Naturally, if an attacker does attempt) s -5 415 M -( to replay a captured packet before the peers have rekeyed, then the) s -5 404 M -( receiver of the duplicate packet will not be able to validate the MAC) s -5 393 M -( and it will be discarded. The reason that the MAC will fail is) s -5 382 M -( because the receiver will formulate a MAC based upon the packet) s -5 371 M -( contents, the shared secret, and the expected sequence number. Since) s -5 360 M -( the replayed packet will not be using that expected sequence number) s -5 349 M -( \(the sequence number of the replayed packet will have already been) s -5 338 M -( passed by the receiver\) then the calculated MAC will not match the) s -5 327 M -( MAC received with the packet.) s -5 305 M -(9.2.4 Man-in-the-middle) s -5 283 M -( This protocol makes no assumptions nor provisions for an) s -5 272 M -( infrastructure or means for distributing the public keys of hosts. It) s -5 261 M -( is expected that this protocol will sometimes be used without first) s -5 250 M -( verifying the association between the server host key and the server) s -5 239 M -( host name. Such usage is vulnerable to man-in-the-middle attacks.) s -5 228 M -( This section describes this and encourages administrators and users) s -5 217 M -( to understand the importance of verifying this association before any) s -5 206 M -( session is initiated.) s -5 184 M -( There are three cases of man-in-the-middle attacks to consider. The) s -5 173 M -( first is where an attacker places a device between the client and the) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 17]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 18 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( server before the session is initiated. In this case, the attack) s -5 679 M -( device is trying to mimic the legitimate server and will offer its) s -5 668 M -( public key to the client when the client initiates a session. If it) s -5 657 M -( were to offer the public key of the server, then it would not be able) s -5 646 M -( to decrypt or sign the transmissions between the legitimate server) s -5 635 M -( and the client unless it also had access to the private-key of the) s -5 624 M -( host. The attack device will also, simultaneously to this, initiate) s -5 613 M -( a session to the legitimate server masquerading itself as the client.) s -5 602 M -( If the public key of the server had been securely distributed to the) s -5 591 M -( client prior to that session initiation, the key offered to the) s -5 580 M -( client by the attack device will not match the key stored on the) s -5 569 M -( client. In that case, the user SHOULD be given a warning that the) s -5 558 M -( offered host key does not match the host key cached on the client.) s -5 547 M -( As described in Section 3.1 of [ARCH], the user may be free to accept) s -5 536 M -( the new key and continue the session. It is RECOMMENDED that the) s -5 525 M -( warning provide sufficient information to the user of the client) s -5 514 M -( device so they may make an informed decision. If the user chooses to) s -5 503 M -( continue the session with the stored public-key of the server \(not) s -5 492 M -( the public-key offered at the start of the session\), then the session) s -5 481 M -( specific data between the attacker and server will be different) s -5 470 M -( between the client-to-attacker session and the attacker-to-server) s -5 459 M -( sessions due to the randomness discussed above. From this, the) s -5 448 M -( attacker will not be able to make this attack work since the attacker) s -5 437 M -( will not be able to correctly sign packets containing this session) s -5 426 M -( specific data from the server since he does not have the private key) s -5 415 M -( of that server.) s -5 393 M -( The second case that should be considered is similar to the first) s -5 382 M -( case in that it also happens at the time of connection but this case) s -5 371 M -( points out the need for the secure distribution of server public) s -5 360 M -( keys. If the server public keys are not securely distributed then) s -5 349 M -( the client cannot know if it is talking to the intended server. An) s -5 338 M -( attacker may use social engineering techniques to pass off server) s -5 327 M -( keys to unsuspecting users and may then place a man-in-the-middle) s -5 316 M -( attack device between the legitimate server and the clients. If this) s -5 305 M -( is allowed to happen then the clients will form client-to-attacker) s -5 294 M -( sessions and the attacker will form attacker-to-server sessions and) s -5 283 M -( will be able to monitor and manipulate all of the traffic between the) s -5 272 M -( clients and the legitimate servers. Server administrators are) s -5 261 M -( encouraged to make host key fingerprints available for checking by) s -5 250 M -( some means whose security does not rely on the integrity of the) s -5 239 M -( actual host keys. Possible mechanisms are discussed in Section 3.1) s -5 228 M -( of [SSH-ARCH] and may also include secured Web pages, physical pieces) s -5 217 M -( of paper, etc. Implementors SHOULD provide recommendations on how) s -5 206 M -( best to do this with their implementation. Because the protocol is) s -5 195 M -( extensible, future extensions to the protocol may provide better) s -5 184 M -( mechanisms for dealing with the need to know the server's host key) s -5 173 M -( before connecting. For example, making the host key fingerprint) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 18]) s -_R -S -PStoPSsaved restore -%%Page: (18,19) 10 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 19 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( available through a secure DNS lookup, or using kerberos over gssapi) s -5 679 M -( during key exchange to authenticate the server are possibilities.) s -5 657 M -( In the third man-in-the-middle case, attackers may attempt to) s -5 646 M -( manipulate packets in transit between peers after the session has) s -5 635 M -( been established. As described in the Replay part of this section, a) s -5 624 M -( successful attack of this nature is very improbable. As in the) s -5 613 M -( Replay section, this reasoning does assume that the MAC is secure and) s -5 602 M -( that it is infeasible to construct inputs to a MAC algorithm to give) s -5 591 M -( a known output. This is discussed in much greater detail in Section) s -5 580 M -( 6 of RFC 2104. If the MAC algorithm has a vulnerability or is weak) s -5 569 M -( enough, then the attacker may be able to specify certain inputs to) s -5 558 M -( yield a known MAC. With that they may be able to alter the contents) s -5 547 M -( of a packet in transit. Alternatively the attacker may be able to) s -5 536 M -( exploit the algorithm vulnerability or weakness to find the shared) s -5 525 M -( secret by reviewing the MACs from captured packets. In either of) s -5 514 M -( those cases, an attacker could construct a packet or packets that) s -5 503 M -( could be inserted into an SSH stream. To prevent that, implementors) s -5 492 M -( are encouraged to utilize commonly accepted MAC algorithms and) s -5 481 M -( administrators are encouraged to watch current literature and) s -5 470 M -( discussions of cryptography to ensure that they are not using a MAC) s -5 459 M -( algorithm that has a recently found vulnerability or weakness.) s -5 437 M -( In summary, the use of this protocol without a reliable association) s -5 426 M -( of the binding between a host and its host keys is inherently) s -5 415 M -( insecure and is NOT RECOMMENDED. It may however be necessary in) s -5 404 M -( non-security critical environments, and will still provide protection) s -5 393 M -( against passive attacks. Implementors of protocols and applications) s -5 382 M -( running on top of this protocol should keep this possibility in mind.) s -5 360 M -(9.2.5 Denial-of-service) s -5 338 M -( This protocol is designed to be used over a reliable transport. If) s -5 327 M -( transmission errors or message manipulation occur, the connection is) s -5 316 M -( closed. The connection SHOULD be re-established if this occurs.) s -5 305 M -( Denial of service attacks of this type \("wire cutter"\) are almost) s -5 294 M -( impossible to avoid.) s -5 272 M -( In addition, this protocol is vulnerable to Denial of Service attacks) s -5 261 M -( because an attacker can force the server to go through the CPU and) s -5 250 M -( memory intensive tasks of connection setup and key exchange without) s -5 239 M -( authenticating. Implementors SHOULD provide features that make this) s -5 228 M -( more difficult. For example, only allowing connections from a subset) s -5 217 M -( of IPs known to have valid users.) s -5 195 M -(9.2.6 Covert Channels) s -5 173 M -( The protocol was not designed to eliminate covert channels. For) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 19]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 20 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( example, the padding, SSH_MSG_IGNORE messages, and several other) s -5 679 M -( places in the protocol can be used to pass covert information, and) s -5 668 M -( the recipient has no reliable way to verify whether such information) s -5 657 M -( is being sent.) s -5 635 M -(9.2.7 Forward Secrecy) s -5 613 M -( It should be noted that the Diffie-Hellman key exchanges may provide) s -5 602 M -( perfect forward secrecy \(PFS\). PFS is essentially defined as the) s -5 591 M -( cryptographic property of a key-establishment protocol in which the) s -5 580 M -( compromise of a session key or long-term private key after a given) s -5 569 M -( session does not cause the compromise of any earlier session. [ANSI) s -5 558 M -( T1.523-2001] SSHv2 sessions resulting from a key exchange using) s -5 547 M -( diffie-hellman-group1-sha1 are secure even if private keying/) s -5 536 M -( authentication material is later revealed, but not if the session) s -5 525 M -( keys are revealed. So, given this definition of PFS, SSHv2 does have) s -5 514 M -( PFS. It is hoped that all other key exchange mechanisms proposed and) s -5 503 M -( used in the future will also provide PFS. This property is not) s -5 492 M -( commuted to any of the applications or protocols using SSH as a) s -5 481 M -( transport however. The transport layer of SSH provides) s -5 470 M -( confidentiality for password authentication and other methods that) s -5 459 M -( rely on secret data.) s -5 437 M -( Of course, if the DH private parameters for the client and server are) s -5 426 M -( revealed then the session key is revealed, but these items can be) s -5 415 M -( thrown away after the key exchange completes. It's worth pointing) s -5 404 M -( out that these items should not be allowed to end up on swap space) s -5 393 M -( and that they should be erased from memory as soon as the key) s -5 382 M -( exchange completes.) s -5 360 M -(9.3 Authentication Protocol) s -5 338 M -( The purpose of this protocol is to perform client user) s -5 327 M -( authentication. It assumes that this run over a secure transport) s -5 316 M -( layer protocol, which has already authenticated the server machine,) s -5 305 M -( established an encrypted communications channel, and computed a) s -5 294 M -( unique session identifier for this session.) s -5 272 M -( Several authentication methods with different security) s -5 261 M -( characteristics are allowed. It is up to the server's local policy) s -5 250 M -( to decide which methods \(or combinations of methods\) it is willing to) s -5 239 M -( accept for each user. Authentication is no stronger than the weakest) s -5 228 M -( combination allowed.) s -5 206 M -( The server may go into a "sleep" period after repeated unsuccessful) s -5 195 M -( authentication attempts to make key search more difficult for) s -5 184 M -( attackers. Care should be taken so that this doesn't become a) s -5 173 M -( self-denial of service vector.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 20]) s -_R -S -PStoPSsaved restore -%%Page: (20,21) 11 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 21 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -(9.3.1 Weak Transport) s -5 668 M -( If the transport layer does not provide confidentiality,) s -5 657 M -( authentication methods that rely on secret data SHOULD be disabled.) s -5 646 M -( If it does not provide strong integrity protection, requests to) s -5 635 M -( change authentication data \(e.g. a password change\) SHOULD be) s -5 624 M -( disabled to prevent an attacker from modifying the ciphertext) s -5 613 M -( without being noticed, or rendering the new authentication data) s -5 602 M -( unusable \(denial of service\).) s -5 580 M -( The assumption as stated above that the Authentication Protocol only) s -5 569 M -( run over a secure transport that has previously authenticated the) s -5 558 M -( server is very important to note. People deploying SSH are reminded) s -5 547 M -( of the consequences of man-in-the-middle attacks if the client does) s -5 536 M -( not have a very strong a priori association of the server with the) s -5 525 M -( host key of that server. Specifically for the case of the) s -5 514 M -( Authentication Protocol the client may form a session to a) s -5 503 M -( man-in-the-middle attack device and divulge user credentials such as) s -5 492 M -( their username and password. Even in the cases of authentication) s -5 481 M -( where no user credentials are divulged, an attacker may still gain) s -5 470 M -( information they shouldn't have by capturing key-strokes in much the) s -5 459 M -( same way that a honeypot works.) s -5 437 M -(9.3.2 Debug messages) s -5 415 M -( Special care should be taken when designing debug messages. These) s -5 404 M -( messages may reveal surprising amounts of information about the host) s -5 393 M -( if not properly designed. Debug messages can be disabled \(during) s -5 382 M -( user authentication phase\) if high security is required.) s -5 371 M -( Administrators of host machines should make all attempts to) s -5 360 M -( compartmentalize all event notification messages and protect them) s -5 349 M -( from unwarranted observation. Developers should be aware of the) s -5 338 M -( sensitive nature of some of the normal event messages and debug) s -5 327 M -( messages and may want to provide guidance to administrators on ways) s -5 316 M -( to keep this information away from unauthorized people. Developers) s -5 305 M -( should consider minimizing the amount of sensitive information) s -5 294 M -( obtainable by users during the authentication phase in accordance) s -5 283 M -( with the local policies. For this reason, it is RECOMMENDED that) s -5 272 M -( debug messages be initially disabled at the time of deployment and) s -5 261 M -( require an active decision by an administrator to allow them to be) s -5 250 M -( enabled. It is also RECOMMENDED that a message expressing this) s -5 239 M -( concern be presented to the administrator of a system when the action) s -5 228 M -( is taken to enable debugging messages.) s -5 206 M -(9.3.3 Local security policy) s -5 184 M -( Implementer MUST ensure that the credentials provided validate the) s -5 173 M -( professed user and also MUST ensure that the local policy of the) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 21]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 22 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( server permits the user the access requested. In particular, because) s -5 679 M -( of the flexible nature of the SSH connection protocol, it may not be) s -5 668 M -( possible to determine the local security policy, if any, that should) s -5 657 M -( apply at the time of authentication because the kind of service being) s -5 646 M -( requested is not clear at that instant. For example, local policy) s -5 635 M -( might allow a user to access files on the server, but not start an) s -5 624 M -( interactive shell. However, during the authentication protocol, it is) s -5 613 M -( not known whether the user will be accessing files or attempting to) s -5 602 M -( use an interactive shell, or even both. In any event, where local) s -5 591 M -( security policy for the server host exists, it MUST be applied and) s -5 580 M -( enforced correctly.) s -5 558 M -( Implementors are encouraged to provide a default local policy and) s -5 547 M -( make its parameters known to administrators and users. At the) s -5 536 M -( discretion of the implementors, this default policy may be along the) s -5 525 M -( lines of 'anything goes' where there are no restrictions placed upon) s -5 514 M -( users, or it may be along the lines of 'excessively restrictive' in) s -5 503 M -( which case the administrators will have to actively make changes to) s -5 492 M -( this policy to meet their needs. Alternatively, it may be some) s -5 481 M -( attempt at providing something practical and immediately useful to) s -5 470 M -( the administrators of the system so they don't have to put in much) s -5 459 M -( effort to get SSH working. Whatever choice is made MUST be applied) s -5 448 M -( and enforced as required above.) s -5 426 M -(9.3.4 Public key authentication) s -5 404 M -( The use of public-key authentication assumes that the client host has) s -5 393 M -( not been compromised. It also assumes that the private-key of the) s -5 382 M -( server host has not been compromised.) s -5 360 M -( This risk can be mitigated by the use of passphrases on private keys;) s -5 349 M -( however, this is not an enforceable policy. The use of smartcards,) s -5 338 M -( or other technology to make passphrases an enforceable policy is) s -5 327 M -( suggested.) s -5 305 M -( The server could require both password and public-key authentication,) s -5 294 M -( however, this requires the client to expose its password to the) s -5 283 M -( server \(see section on password authentication below.\)) s -5 261 M -(9.3.5 Password authentication) s -5 239 M -( The password mechanism as specified in the authentication protocol) s -5 228 M -( assumes that the server has not been compromised. If the server has) s -5 217 M -( been compromised, using password authentication will reveal a valid) s -5 206 M -( username / password combination to the attacker, which may lead to) s -5 195 M -( further compromises.) s -5 173 M -( This vulnerability can be mitigated by using an alternative form of) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 22]) s -_R -S -PStoPSsaved restore -%%Page: (22,23) 12 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 23 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( authentication. For example, public-key authentication makes no) s -5 679 M -( assumptions about security on the server.) s -5 657 M -(9.3.6 Host based authentication) s -5 635 M -( Host based authentication assumes that the client has not been) s -5 624 M -( compromised. There are no mitigating strategies, other than to use) s -5 613 M -( host based authentication in combination with another authentication) s -5 602 M -( method.) s -5 580 M -(9.4 Connection protocol) s -5 558 M -(9.4.1 End point security) s -5 536 M -( End point security is assumed by the connection protocol. If the) s -5 525 M -( server has been compromised, any terminal sessions, port forwarding,) s -5 514 M -( or systems accessed on the host are compromised. There are no) s -5 503 M -( mitigating factors for this.) s -5 481 M -( If the client end point has been compromised, and the server fails to) s -5 470 M -( stop the attacker at the authentication protocol, all services) s -5 459 M -( exposed \(either as subsystems or through forwarding\) will be) s -5 448 M -( vulnerable to attack. Implementors SHOULD provide mechanisms for) s -5 437 M -( administrators to control which services are exposed to limit the) s -5 426 M -( vulnerability of other services.) s -5 404 M -( These controls might include controlling which machines and ports can) s -5 393 M -( be target in 'port-forwarding' operations, which users are allowed to) s -5 382 M -( use interactive shell facilities, or which users are allowed to use) s -5 371 M -( exposed subsystems.) s -5 349 M -(9.4.2 Proxy forwarding) s -5 327 M -( The SSH connection protocol allows for proxy forwarding of other) s -5 316 M -( protocols such as SNMP, POP3, and HTTP. This may be a concern for) s -5 305 M -( network administrators who wish to control the access of certain) s -5 294 M -( applications by users located outside of their physical location.) s -5 283 M -( Essentially, the forwarding of these protocols may violate site) s -5 272 M -( specific security policies as they may be undetectably tunneled) s -5 261 M -( through a firewall. Implementors SHOULD provide an administrative) s -5 250 M -( mechanism to control the proxy forwarding functionality so that site) s -5 239 M -( specific security policies may be upheld.) s -5 217 M -( In addition, a reverse proxy forwarding functionality is available,) s -5 206 M -( which again can be used to bypass firewall controls.) s -5 184 M -( As indicated above, end-point security is assumed during proxy) s -5 173 M -( forwarding operations. Failure of end-point security will compromise) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 23]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 24 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( all data passed over proxy forwarding.) s -5 668 M -(9.4.3 X11 forwarding) s -5 646 M -( Another form of proxy forwarding provided by the ssh connection) s -5 635 M -( protocol is the forwarding of the X11 protocol. If end-point) s -5 624 M -( security has been compromised, X11 forwarding may allow attacks) s -5 613 M -( against the X11 server. Users and administrators should, as a matter) s -5 602 M -( of course, use appropriate X11 security mechanisms to prevent) s -5 591 M -( unauthorized use of the X11 server. Implementors, administrators and) s -5 580 M -( users who wish to further explore the security mechanisms of X11 are) s -5 569 M -( invited to read [SCHEIFLER] and analyze previously reported problems) s -5 558 M -( with the interactions between SSH forwarding and X11 in CERT) s -5 547 M -( vulnerabilities VU#363181 and VU#118892 [CERT].) s -5 525 M -( X11 display forwarding with SSH, by itself, is not sufficient to) s -5 514 M -( correct well known problems with X11 security [VENEMA]. However, X11) s -5 503 M -( display forwarding in SSHv2 \(or other, secure protocols\), combined) s -5 492 M -( with actual and pseudo-displays which accept connections only over) s -5 481 M -( local IPC mechanisms authorized by permissions or ACLs, does correct) s -5 470 M -( many X11 security problems as long as the "none" MAC is not used. It) s -5 459 M -( is RECOMMENDED that X11 display implementations default to allowing) s -5 448 M -( display opens only over local IPC. It is RECOMMENDED that SSHv2) s -5 437 M -( server implementations that support X11 forwarding default to) s -5 426 M -( allowing display opens only over local IPC. On single-user systems) s -5 415 M -( it might be reasonable to default to allowing local display opens) s -5 404 M -( over TCP/IP.) s -5 382 M -( Implementors of the X11 forwarding protocol SHOULD implement the) s -5 371 M -( magic cookie access checking spoofing mechanism as described in) s -5 360 M -( [ssh-connect] as an additional mechanism to prevent unauthorized use) s -5 349 M -( of the proxy.) s -5 327 M -(Normative References) s -5 305 M -( [SSH-ARCH]) s -5 294 M -( Ylonen, T., "SSH Protocol Architecture", I-D) s -5 283 M -( draft-ietf-architecture-15.txt, Oct 2003.) s -5 261 M -( [SSH-TRANS]) s -5 250 M -( Ylonen, T., "SSH Transport Layer Protocol", I-D) s -5 239 M -( draft-ietf-transport-17.txt, Oct 2003.) s -5 217 M -( [SSH-USERAUTH]) s -5 206 M -( Ylonen, T., "SSH Authentication Protocol", I-D) s -5 195 M -( draft-ietf-userauth-18.txt, Oct 2003.) s -5 173 M -( [SSH-CONNECT]) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 24]) s -_R -S -PStoPSsaved restore -%%Page: (24,25) 13 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 25 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( Ylonen, T., "SSH Connection Protocol", I-D) s -5 679 M -( draft-ietf-connect-18.txt, Oct 2003.) s -5 657 M -( [SSH-NUMBERS]) s -5 646 M -( Lehtinen, S. and D. Moffat, "SSH Protocol Assigned) s -5 635 M -( Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct) s -5 624 M -( 2003.) s -5 602 M -( [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate) s -5 591 M -( Requirement Levels", BCP 14, RFC 2119, March 1997.) s -5 569 M -(Informative References) s -5 547 M -( [FIPS-186]) s -5 536 M -( Federal Information Processing Standards Publication,) s -5 525 M -( "FIPS PUB 186, Digital Signature Standard", May 1994.) s -5 503 M -( [FIPS-197]) s -5 492 M -( National Institue of Standards and Technology, "FIPS 197,) s -5 481 M -( Specification for the Advanced Encryption Standard",) s -5 470 M -( November 2001.) s -5 448 M -( [ANSI T1.523-2001]) s -5 437 M -( American National Standards Insitute, Inc., "Telecom) s -5 426 M -( Glossary 2000", February 2001.) s -5 404 M -( [SCHEIFLER]) s -5 393 M -( Scheifler, R., "X Window System : The Complete Reference) s -5 382 M -( to Xlib, X Protocol, Icccm, Xlfd, 3rd edition.", Digital) s -5 371 M -( Press ISBN 1555580882, Feburary 1992.) s -5 349 M -( [RFC0854] Postel, J. and J. Reynolds, "Telnet Protocol) s -5 338 M -( Specification", STD 8, RFC 854, May 1983.) s -5 316 M -( [RFC0894] Hornig, C., "Standard for the transmission of IP datagrams) s -5 305 M -( over Ethernet networks", STD 41, RFC 894, April 1984.) s -5 283 M -( [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",) s -5 272 M -( STD 13, RFC 1034, November 1987.) s -5 250 M -( [RFC1134] Perkins, D., "Point-to-Point Protocol: A proposal for) s -5 239 M -( multi-protocol transmission of datagrams over) s -5 228 M -( Point-to-Point links", RFC 1134, November 1989.) s -5 206 M -( [RFC1282] Kantor, B., "BSD Rlogin", RFC 1282, December 1991.) s -5 184 M -( [RFC1510] Kohl, J. and B. Neuman, "The Kerberos Network) s -5 173 M -( Authentication Service \(V5\)", RFC 1510, September 1993.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 25]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 26 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", RFC 1700,) s -5 679 M -( October 1994.) s -5 657 M -( [RFC1750] Eastlake, D., Crocker, S. and J. Schiller, "Randomness) s -5 646 M -( Recommendations for Security", RFC 1750, December 1994.) s -5 624 M -( [RFC3066] Alvestrand, H., "Tags for the Identification of) s -5 613 M -( Languages", BCP 47, RFC 3066, January 2001.) s -5 591 M -( [RFC1964] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", RFC) s -5 580 M -( 1964, June 1996.) s -5 558 M -( [RFC2025] Adams, C., "The Simple Public-Key GSS-API Mechanism) s -5 547 M -( \(SPKM\)", RFC 2025, October 1996.) s -5 525 M -( [RFC2085] Oehler, M. and R. Glenn, "HMAC-MD5 IP Authentication with) s -5 514 M -( Replay Prevention", RFC 2085, February 1997.) s -5 492 M -( [RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC:) s -5 481 M -( Keyed-Hashing for Message Authentication", RFC 2104,) s -5 470 M -( February 1997.) s -5 448 M -( [RFC2246] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A.) s -5 437 M -( and P. Kocher, "The TLS Protocol Version 1.0", RFC 2246,) s -5 426 M -( January 1999.) s -5 404 M -( [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO) s -5 393 M -( 10646", RFC 2279, January 1998.) s -5 371 M -( [RFC2410] Glenn, R. and S. Kent, "The NULL Encryption Algorithm and) s -5 360 M -( Its Use With IPsec", RFC 2410, November 1998.) s -5 338 M -( [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an) s -5 327 M -( IANA Considerations Section in RFCs", BCP 26, RFC 2434,) s -5 316 M -( October 1998.) s -5 294 M -( [RFC2743] Linn, J., "Generic Security Service Application Program) s -5 283 M -( Interface Version 2, Update 1", RFC 2743, January 2000.) s -5 261 M -( [SCHNEIER]) s -5 250 M -( Schneier, B., "Applied Cryptography Second Edition:) s -5 239 M -( protocols algorithms and source in code in C", 1996.) s -5 217 M -( [KAUFMAN,PERLMAN,SPECINER]) s -5 206 M -( Kaufman, C., Perlman, R. and M. Speciner, "Network) s -5 195 M -( Security: PRIVATE Communication in a PUBLIC World", 1995.) s -5 173 M -( [CERT] CERT Coordination Center, The., "http://www.cert.org/nav/) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 26]) s -_R -S -PStoPSsaved restore -%%Page: (26,27) 14 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 27 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( index_red.html".) s -5 668 M -( [VENEMA] Venema, W., "Murphy's Law and Computer Security",) s -5 657 M -( Proceedings of 6th USENIX Security Symposium, San Jose CA) s -5 646 M -( http://www.usenix.org/publications/library/proceedings/) s -5 635 M -( sec96/venema.html, July 1996.) s -5 613 M -( [ROGAWAY] Rogaway, P., "Problems with Proposed IP Cryptography",) s -5 602 M -( Unpublished paper http://www.cs.ucdavis.edu/~rogaway/) s -5 591 M -( papers/draft-rogaway-ipsec-comments-00.txt, 1996.) s -5 569 M -( [DAI] Dai, W., "An attack against SSH2 protocol", Email to the) s -5 558 M -( SECSH Working Group [email protected] ftp://) s -5 547 M -( ftp.ietf.org/ietf-mail-archive/secsh/2002-02.mail, Feb) s -5 536 M -( 2002.) s -5 514 M -( [BELLARE,KOHNO,NAMPREMPRE]) s -5 503 M -( Bellaire, M., Kohno, T. and C. Namprempre, "Authenticated) s -5 492 M -( Encryption in SSH: Fixing the SSH Binary Packet Protocol",) s -5 481 M -( , Sept 2002.) s -5 448 M -(Authors' Addresses) s -5 426 M -( Tatu Ylonen) s -5 415 M -( SSH Communications Security Corp) s -5 404 M -( Fredrikinkatu 42) s -5 393 M -( HELSINKI FIN-00100) s -5 382 M -( Finland) s -5 360 M -( EMail: [email protected]) s -5 327 M -( Darren J. Moffat \(editor\)) s -5 316 M -( Sun Microsystems, Inc) s -5 305 M -( 17 Network Circle) s -5 294 M -( Menlo Park CA 94025) s -5 283 M -( USA) s -5 261 M -( EMail: [email protected]) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 27]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 28 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -(Intellectual Property Statement) s -5 668 M -( The IETF takes no position regarding the validity or scope of any) s -5 657 M -( intellectual property or other rights that might be claimed to) s -5 646 M -( pertain to the implementation or use of the technology described in) s -5 635 M -( this document or the extent to which any license under such rights) s -5 624 M -( might or might not be available; neither does it represent that it) s -5 613 M -( has made any effort to identify any such rights. Information on the) s -5 602 M -( IETF's procedures with respect to rights in standards-track and) s -5 591 M -( standards-related documentation can be found in BCP-11. Copies of) s -5 580 M -( claims of rights made available for publication and any assurances of) s -5 569 M -( licenses to be made available, or the result of an attempt made to) s -5 558 M -( obtain a general license or permission for the use of such) s -5 547 M -( proprietary rights by implementors or users of this specification can) s -5 536 M -( be obtained from the IETF Secretariat.) s -5 514 M -( The IETF invites any interested party to bring to its attention any) s -5 503 M -( copyrights, patents or patent applications, or other proprietary) s -5 492 M -( rights which may cover technology that may be required to practice) s -5 481 M -( this standard. Please address the information to the IETF Executive) s -5 470 M -( Director.) s -5 448 M -( The IETF has been notified of intellectual property rights claimed in) s -5 437 M -( regard to some or all of the specification contained in this) s -5 426 M -( document. For more information consult the online list of claimed) s -5 415 M -( rights.) s -5 382 M -(Full Copyright Statement) s -5 360 M -( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s -5 338 M -( This document and translations of it may be copied and furnished to) s -5 327 M -( others, and derivative works that comment on or otherwise explain it) s -5 316 M -( or assist in its implementation may be prepared, copied, published) s -5 305 M -( and distributed, in whole or in part, without restriction of any) s -5 294 M -( kind, provided that the above copyright notice and this paragraph are) s -5 283 M -( included on all such copies and derivative works. However, this) s -5 272 M -( document itself may not be modified in any way, such as by removing) s -5 261 M -( the copyright notice or references to the Internet Society or other) s -5 250 M -( Internet organizations, except as needed for the purpose of) s -5 239 M -( developing Internet standards in which case the procedures for) s -5 228 M -( copyrights defined in the Internet Standards process must be) s -5 217 M -( followed, or as required to translate it into languages other than) s -5 206 M -( English.) s -5 184 M -( The limited permissions granted above are perpetual and will not be) s -5 173 M -( revoked by the Internet Society or its successors or assignees.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 28]) s -_R -S -PStoPSsaved restore -%%Page: (28,29) 15 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 29 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Protocol Architecture Oct 2003) s -5 690 M -( This document and the information contained herein is provided on an) s -5 679 M -( "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING) s -5 668 M -( TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING) s -5 657 M -( BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION) s -5 646 M -( HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF) s -5 635 M -( MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.) s -5 602 M -(Acknowledgment) s -5 580 M -( Funding for the RFC Editor function is currently provided by the) s -5 569 M -( Internet Society.) s -5 129 M -(Ylonen & Moffat Expires March 31, 2004 [Page 29]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -showpage -PStoPSsaved restore -%%Trailer -%%Pages: 29 -%%DocumentNeededResources: font Courier-Bold Courier -%%EOF diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-architecture-15.txt b/lib/ssh/doc/standard/draft-ietf-secsh-architecture-15.txt deleted file mode 100644 index 18070e8485..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-architecture-15.txt +++ /dev/null @@ -1,1624 +0,0 @@ - - - -Network Working Group T. Ylonen -Internet-Draft SSH Communications Security Corp -Expires: March 31, 2004 D. Moffat, Ed. - Sun Microsystems, Inc - Oct 2003 - - - SSH Protocol Architecture - draft-ietf-secsh-architecture-15.txt - -Status of this Memo - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that other - groups may also distribute working documents as Internet-Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at http:// - www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on March 31, 2004. - -Copyright Notice - - Copyright (C) The Internet Society (2003). All Rights Reserved. - -Abstract - - SSH is a protocol for secure remote login and other secure network - services over an insecure network. This document describes the - architecture of the SSH protocol, as well as the notation and - terminology used in SSH protocol documents. It also discusses the SSH - algorithm naming system that allows local extensions. The SSH - protocol consists of three major components: The Transport Layer - Protocol provides server authentication, confidentiality, and - integrity with perfect forward secrecy. The User Authentication - Protocol authenticates the client to the server. The Connection - Protocol multiplexes the encrypted tunnel into several logical - channels. Details of these protocols are described in separate - - - -Ylonen & Moffat Expires March 31, 2004 [Page 1] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - documents. - -Table of Contents - - 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3. Specification of Requirements . . . . . . . . . . . . . . . 3 - 4. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 3 - 4.1 Host Keys . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 4.2 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 5 - 4.3 Policy Issues . . . . . . . . . . . . . . . . . . . . . . . 5 - 4.4 Security Properties . . . . . . . . . . . . . . . . . . . . 6 - 4.5 Packet Size and Overhead . . . . . . . . . . . . . . . . . . 6 - 4.6 Localization and Character Set Support . . . . . . . . . . . 7 - 5. Data Type Representations Used in the SSH Protocols . . . . 8 - 6. Algorithm Naming . . . . . . . . . . . . . . . . . . . . . . 10 - 7. Message Numbers . . . . . . . . . . . . . . . . . . . . . . 11 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 11 - 9. Security Considerations . . . . . . . . . . . . . . . . . . 12 - 9.1 Pseudo-Random Number Generation . . . . . . . . . . . . . . 12 - 9.2 Transport . . . . . . . . . . . . . . . . . . . . . . . . . 13 - 9.2.1 Confidentiality . . . . . . . . . . . . . . . . . . . . . . 13 - 9.2.2 Data Integrity . . . . . . . . . . . . . . . . . . . . . . . 16 - 9.2.3 Replay . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 - 9.2.4 Man-in-the-middle . . . . . . . . . . . . . . . . . . . . . 17 - 9.2.5 Denial-of-service . . . . . . . . . . . . . . . . . . . . . 19 - 9.2.6 Covert Channels . . . . . . . . . . . . . . . . . . . . . . 19 - 9.2.7 Forward Secrecy . . . . . . . . . . . . . . . . . . . . . . 20 - 9.3 Authentication Protocol . . . . . . . . . . . . . . . . . . 20 - 9.3.1 Weak Transport . . . . . . . . . . . . . . . . . . . . . . . 21 - 9.3.2 Debug messages . . . . . . . . . . . . . . . . . . . . . . . 21 - 9.3.3 Local security policy . . . . . . . . . . . . . . . . . . . 21 - 9.3.4 Public key authentication . . . . . . . . . . . . . . . . . 22 - 9.3.5 Password authentication . . . . . . . . . . . . . . . . . . 22 - 9.3.6 Host based authentication . . . . . . . . . . . . . . . . . 23 - 9.4 Connection protocol . . . . . . . . . . . . . . . . . . . . 23 - 9.4.1 End point security . . . . . . . . . . . . . . . . . . . . . 23 - 9.4.2 Proxy forwarding . . . . . . . . . . . . . . . . . . . . . . 23 - 9.4.3 X11 forwarding . . . . . . . . . . . . . . . . . . . . . . . 24 - Normative References . . . . . . . . . . . . . . . . . . . . 24 - Informative References . . . . . . . . . . . . . . . . . . . 25 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 27 - Intellectual Property and Copyright Statements . . . . . . . 28 - - - - - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 2] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - -1. Contributors - - The major original contributors of this document were: Tatu Ylonen, - Tero Kivinen, Timo J. Rinne, Sami Lehtinen (all of SSH Communications - Security Corp), and Markku-Juhani O. Saarinen (University of - Jyvaskyla) - - The document editor is: [email protected]. Comments on this - internet draft should be sent to the IETF SECSH working group, - details at: http://ietf.org/html.charters/secsh-charter.html - -2. Introduction - - SSH is a protocol for secure remote login and other secure network - services over an insecure network. It consists of three major - components: - o The Transport Layer Protocol [SSH-TRANS] provides server - authentication, confidentiality, and integrity. It may optionally - also provide compression. The transport layer will typically be - run over a TCP/IP connection, but might also be used on top of any - other reliable data stream. - o The User Authentication Protocol [SSH-USERAUTH] authenticates the - client-side user to the server. It runs over the transport layer - protocol. - o The Connection Protocol [SSH-CONNECT] multiplexes the encrypted - tunnel into several logical channels. It runs over the user - authentication protocol. - - The client sends a service request once a secure transport layer - connection has been established. A second service request is sent - after user authentication is complete. This allows new protocols to - be defined and coexist with the protocols listed above. - - The connection protocol provides channels that can be used for a wide - range of purposes. Standard methods are provided for setting up - secure interactive shell sessions and for forwarding ("tunneling") - arbitrary TCP/IP ports and X11 connections. - -3. Specification of Requirements - - All documents related to the SSH protocols shall use the keywords - "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", - "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" to describe - requirements. They are to be interpreted as described in [RFC2119]. - -4. Architecture - - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 3] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - -4.1 Host Keys - - Each server host SHOULD have a host key. Hosts MAY have multiple - host keys using multiple different algorithms. Multiple hosts MAY - share the same host key. If a host has keys at all, it MUST have at - least one key using each REQUIRED public key algorithm (DSS - [FIPS-186]). - - The server host key is used during key exchange to verify that the - client is really talking to the correct server. For this to be - possible, the client must have a priori knowledge of the server's - public host key. - - Two different trust models can be used: - o The client has a local database that associates each host name (as - typed by the user) with the corresponding public host key. This - method requires no centrally administered infrastructure, and no - third-party coordination. The downside is that the database of - name-to-key associations may become burdensome to maintain. - o The host name-to-key association is certified by some trusted - certification authority. The client only knows the CA root key, - and can verify the validity of all host keys certified by accepted - CAs. - - The second alternative eases the maintenance problem, since - ideally only a single CA key needs to be securely stored on the - client. On the other hand, each host key must be appropriately - certified by a central authority before authorization is possible. - Also, a lot of trust is placed on the central infrastructure. - - The protocol provides the option that the server name - host key - association is not checked when connecting to the host for the first - time. This allows communication without prior communication of host - keys or certification. The connection still provides protection - against passive listening; however, it becomes vulnerable to active - man-in-the-middle attacks. Implementations SHOULD NOT normally allow - such connections by default, as they pose a potential security - problem. However, as there is no widely deployed key infrastructure - available on the Internet yet, this option makes the protocol much - more usable during the transition time until such an infrastructure - emerges, while still providing a much higher level of security than - that offered by older solutions (e.g. telnet [RFC-854] and rlogin - [RFC-1282]). - - Implementations SHOULD try to make the best effort to check host - keys. An example of a possible strategy is to only accept a host key - without checking the first time a host is connected, save the key in - a local database, and compare against that key on all future - - - -Ylonen & Moffat Expires March 31, 2004 [Page 4] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - connections to that host. - - Implementations MAY provide additional methods for verifying the - correctness of host keys, e.g. a hexadecimal fingerprint derived from - the SHA-1 hash of the public key. Such fingerprints can easily be - verified by using telephone or other external communication channels. - - All implementations SHOULD provide an option to not accept host keys - that cannot be verified. - - We believe that ease of use is critical to end-user acceptance of - security solutions, and no improvement in security is gained if the - new solutions are not used. Thus, providing the option not to check - the server host key is believed to improve the overall security of - the Internet, even though it reduces the security of the protocol in - configurations where it is allowed. - -4.2 Extensibility - - We believe that the protocol will evolve over time, and some - organizations will want to use their own encryption, authentication - and/or key exchange methods. Central registration of all extensions - is cumbersome, especially for experimental or classified features. - On the other hand, having no central registration leads to conflicts - in method identifiers, making interoperability difficult. - - We have chosen to identify algorithms, methods, formats, and - extension protocols with textual names that are of a specific format. - DNS names are used to create local namespaces where experimental or - classified extensions can be defined without fear of conflicts with - other implementations. - - One design goal has been to keep the base protocol as simple as - possible, and to require as few algorithms as possible. However, all - implementations MUST support a minimal set of algorithms to ensure - interoperability (this does not imply that the local policy on all - hosts would necessary allow these algorithms). The mandatory - algorithms are specified in the relevant protocol documents. - - Additional algorithms, methods, formats, and extension protocols can - be defined in separate drafts. See Section Algorithm Naming (Section - 6) for more information. - -4.3 Policy Issues - - The protocol allows full negotiation of encryption, integrity, key - exchange, compression, and public key algorithms and formats. - Encryption, integrity, public key, and compression algorithms can be - - - -Ylonen & Moffat Expires March 31, 2004 [Page 5] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - different for each direction. - - The following policy issues SHOULD be addressed in the configuration - mechanisms of each implementation: - o Encryption, integrity, and compression algorithms, separately for - each direction. The policy MUST specify which is the preferred - algorithm (e.g. the first algorithm listed in each category). - o Public key algorithms and key exchange method to be used for host - authentication. The existence of trusted host keys for different - public key algorithms also affects this choice. - o The authentication methods that are to be required by the server - for each user. The server's policy MAY require multiple - authentication for some or all users. The required algorithms MAY - depend on the location where the user is trying to log in from. - o The operations that the user is allowed to perform using the - connection protocol. Some issues are related to security; for - example, the policy SHOULD NOT allow the server to start sessions - or run commands on the client machine, and MUST NOT allow - connections to the authentication agent unless forwarding such - connections has been requested. Other issues, such as which TCP/ - IP ports can be forwarded and by whom, are clearly issues of local - policy. Many of these issues may involve traversing or bypassing - firewalls, and are interrelated with the local security policy. - -4.4 Security Properties - - The primary goal of the SSH protocol is improved security on the - Internet. It attempts to do this in a way that is easy to deploy, - even at the cost of absolute security. - o All encryption, integrity, and public key algorithms used are - well-known, well-established algorithms. - o All algorithms are used with cryptographically sound key sizes - that are believed to provide protection against even the strongest - cryptanalytic attacks for decades. - o All algorithms are negotiated, and in case some algorithm is - broken, it is easy to switch to some other algorithm without - modifying the base protocol. - - Specific concessions were made to make wide-spread fast deployment - easier. The particular case where this comes up is verifying that - the server host key really belongs to the desired host; the protocol - allows the verification to be left out (but this is NOT RECOMMENDED). - This is believed to significantly improve usability in the short - term, until widespread Internet public key infrastructures emerge. - -4.5 Packet Size and Overhead - - Some readers will worry about the increase in packet size due to new - - - -Ylonen & Moffat Expires March 31, 2004 [Page 6] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - headers, padding, and MAC. The minimum packet size is in the order - of 28 bytes (depending on negotiated algorithms). The increase is - negligible for large packets, but very significant for one-byte - packets (telnet-type sessions). There are, however, several factors - that make this a non-issue in almost all cases: - o The minimum size of a TCP/IP header is 32 bytes. Thus, the - increase is actually from 33 to 51 bytes (roughly). - o The minimum size of the data field of an Ethernet packet is 46 - bytes [RFC-894]. Thus, the increase is no more than 5 bytes. When - Ethernet headers are considered, the increase is less than 10 - percent. - o The total fraction of telnet-type data in the Internet is - negligible, even with increased packet sizes. - - The only environment where the packet size increase is likely to have - a significant effect is PPP [RFC-1134] over slow modem lines (PPP - compresses the TCP/IP headers, emphasizing the increase in packet - size). However, with modern modems, the time needed to transfer is in - the order of 2 milliseconds, which is a lot faster than people can - type. - - There are also issues related to the maximum packet size. To - minimize delays in screen updates, one does not want excessively - large packets for interactive sessions. The maximum packet size is - negotiated separately for each channel. - -4.6 Localization and Character Set Support - - For the most part, the SSH protocols do not directly pass text that - would be displayed to the user. However, there are some places where - such data might be passed. When applicable, the character set for the - data MUST be explicitly specified. In most places, ISO 10646 with - UTF-8 encoding is used [RFC-2279]. When applicable, a field is also - provided for a language tag [RFC-3066]. - - One big issue is the character set of the interactive session. There - is no clear solution, as different applications may display data in - different formats. Different types of terminal emulation may also be - employed in the client, and the character set to be used is - effectively determined by the terminal emulation. Thus, no place is - provided for directly specifying the character set or encoding for - terminal session data. However, the terminal emulation type (e.g. - "vt100") is transmitted to the remote site, and it implicitly - specifies the character set and encoding. Applications typically use - the terminal type to determine what character set they use, or the - character set is determined using some external means. The terminal - emulation may also allow configuring the default character set. In - any case, the character set for the terminal session is considered - - - -Ylonen & Moffat Expires March 31, 2004 [Page 7] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - primarily a client local issue. - - Internal names used to identify algorithms or protocols are normally - never displayed to users, and must be in US-ASCII. - - The client and server user names are inherently constrained by what - the server is prepared to accept. They might, however, occasionally - be displayed in logs, reports, etc. They MUST be encoded using ISO - 10646 UTF-8, but other encodings may be required in some cases. It - is up to the server to decide how to map user names to accepted user - names. Straight bit-wise binary comparison is RECOMMENDED. - - For localization purposes, the protocol attempts to minimize the - number of textual messages transmitted. When present, such messages - typically relate to errors, debugging information, or some externally - configured data. For data that is normally displayed, it SHOULD be - possible to fetch a localized message instead of the transmitted - message by using a numerical code. The remaining messages SHOULD be - configurable. - -5. Data Type Representations Used in the SSH Protocols - byte - - A byte represents an arbitrary 8-bit value (octet) [RFC-1700]. - Fixed length data is sometimes represented as an array of bytes, - written byte[n], where n is the number of bytes in the array. - - boolean - - A boolean value is stored as a single byte. The value 0 - represents FALSE, and the value 1 represents TRUE. All non-zero - values MUST be interpreted as TRUE; however, applications MUST NOT - store values other than 0 and 1. - - uint32 - - Represents a 32-bit unsigned integer. Stored as four bytes in the - order of decreasing significance (network byte order). For - example, the value 699921578 (0x29b7f4aa) is stored as 29 b7 f4 - aa. - - uint64 - - Represents a 64-bit unsigned integer. Stored as eight bytes in - the order of decreasing significance (network byte order). - - - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 8] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - string - - Arbitrary length binary string. Strings are allowed to contain - arbitrary binary data, including null characters and 8-bit - characters. They are stored as a uint32 containing its length - (number of bytes that follow) and zero (= empty string) or more - bytes that are the value of the string. Terminating null - characters are not used. - - Strings are also used to store text. In that case, US-ASCII is - used for internal names, and ISO-10646 UTF-8 for text that might - be displayed to the user. The terminating null character SHOULD - NOT normally be stored in the string. - - For example, the US-ASCII string "testing" is represented as 00 00 - 00 07 t e s t i n g. The UTF8 mapping does not alter the encoding - of US-ASCII characters. - - mpint - - Represents multiple precision integers in two's complement format, - stored as a string, 8 bits per byte, MSB first. Negative numbers - have the value 1 as the most significant bit of the first byte of - the data partition. If the most significant bit would be set for a - positive number, the number MUST be preceded by a zero byte. - Unnecessary leading bytes with the value 0 or 255 MUST NOT be - included. The value zero MUST be stored as a string with zero - bytes of data. - - By convention, a number that is used in modular computations in - Z_n SHOULD be represented in the range 0 <= x < n. - - Examples: - value (hex) representation (hex) - --------------------------------------------------------------- - 0 00 00 00 00 - 9a378f9b2e332a7 00 00 00 08 09 a3 78 f9 b2 e3 32 a7 - 80 00 00 00 02 00 80 - -1234 00 00 00 02 ed cc - -deadbeef 00 00 00 05 ff 21 52 41 11 - - - - name-list - - A string containing a comma separated list of names. A name list - is represented as a uint32 containing its length (number of bytes - that follow) followed by a comma-separated list of zero or more - - - -Ylonen & Moffat Expires March 31, 2004 [Page 9] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - names. A name MUST be non-zero length, and it MUST NOT contain a - comma (','). Context may impose additional restrictions on the - names; for example, the names in a list may have to be valid - algorithm identifier (see Algorithm Naming below), or [RFC-3066] - language tags. The order of the names in a list may or may not be - significant, also depending on the context where the list is is - used. Terminating NUL characters are not used, neither for the - individual names, nor for the list as a whole. - - Examples: - value representation (hex) - --------------------------------------- - (), the empty list 00 00 00 00 - ("zlib") 00 00 00 04 7a 6c 69 62 - ("zlib", "none") 00 00 00 09 7a 6c 69 62 2c 6e 6f 6e 65 - - - - -6. Algorithm Naming - - The SSH protocols refer to particular hash, encryption, integrity, - compression, and key exchange algorithms or protocols by names. - There are some standard algorithms that all implementations MUST - support. There are also algorithms that are defined in the protocol - specification but are OPTIONAL. Furthermore, it is expected that - some organizations will want to use their own algorithms. - - In this protocol, all algorithm identifiers MUST be printable - US-ASCII non-empty strings no longer than 64 characters. Names MUST - be case-sensitive. - - There are two formats for algorithm names: - o Names that do not contain an at-sign (@) are reserved to be - assigned by IETF consensus (RFCs). Examples include `3des-cbc', - `sha-1', `hmac-sha1', and `zlib' (the quotes are not part of the - name). Names of this format MUST NOT be used without first - registering them. Registered names MUST NOT contain an at-sign - (@) or a comma (,). - o Anyone can define additional algorithms by using names in the - format name@domainname, e.g. "[email protected]". The - format of the part preceding the at sign is not specified; it MUST - consist of US-ASCII characters except at-sign and comma. The part - following the at-sign MUST be a valid fully qualified internet - domain name [RFC-1034] controlled by the person or organization - defining the name. It is up to each domain how it manages its - local namespace. - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 10] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - -7. Message Numbers - - SSH packets have message numbers in the range 1 to 255. These numbers - have been allocated as follows: - - - Transport layer protocol: - - 1 to 19 Transport layer generic (e.g. disconnect, ignore, debug, - etc.) - 20 to 29 Algorithm negotiation - 30 to 49 Key exchange method specific (numbers can be reused for - different authentication methods) - - User authentication protocol: - - 50 to 59 User authentication generic - 60 to 79 User authentication method specific (numbers can be - reused for different authentication methods) - - Connection protocol: - - 80 to 89 Connection protocol generic - 90 to 127 Channel related messages - - Reserved for client protocols: - - 128 to 191 Reserved - - Local extensions: - - 192 to 255 Local extensions - - - -8. IANA Considerations - - The initial state of the IANA registry is detailed in [SSH-NUMBERS]. - - Allocation of the following types of names in the SSH protocols is - assigned by IETF consensus: - o SSH encryption algorithm names, - o SSH MAC algorithm names, - o SSH public key algorithm names (public key algorithm also implies - encoding and signature/encryption capability), - o SSH key exchange method names, and - o SSH protocol (service) names. - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 11] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - These names MUST be printable US-ASCII strings, and MUST NOT contain - the characters at-sign ('@'), comma (','), or whitespace or control - characters (ASCII codes 32 or less). Names are case-sensitive, and - MUST NOT be longer than 64 characters. - - Names with the at-sign ('@') in them are allocated by the owner of - DNS name after the at-sign (hierarchical allocation in [RFC-2343]), - otherwise the same restrictions as above. - - Each category of names listed above has a separate namespace. - However, using the same name in multiple categories SHOULD be avoided - to minimize confusion. - - Message numbers (see Section Message Numbers (Section 7)) in the - range of 0..191 are allocated via IETF consensus; message numbers in - the 192..255 range (the "Local extensions" set) are reserved for - private use. - -9. Security Considerations - - In order to make the entire body of Security Considerations more - accessible, Security Considerations for the transport, - authentication, and connection documents have been gathered here. - - The transport protocol [1] provides a confidential channel over an - insecure network. It performs server host authentication, key - exchange, encryption, and integrity protection. It also derives a - unique session id that may be used by higher-level protocols. - - The authentication protocol [2] provides a suite of mechanisms which - can be used to authenticate the client user to the server. - Individual mechanisms specified in the in authentication protocol use - the session id provided by the transport protocol and/or depend on - the security and integrity guarantees of the transport protocol. - - The connection protocol [3] specifies a mechanism to multiplex - multiple streams [channels] of data over the confidential and - authenticated transport. It also specifies channels for accessing an - interactive shell, for 'proxy-forwarding' various external protocols - over the secure transport (including arbitrary TCP/IP protocols), and - for accessing secure 'subsystems' on the server host. - -9.1 Pseudo-Random Number Generation - - This protocol binds each session key to the session by including - random, session specific data in the hash used to produce session - keys. Special care should be taken to ensure that all of the random - numbers are of good quality. If the random data here (e.g., DH - - - -Ylonen & Moffat Expires March 31, 2004 [Page 12] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - parameters) are pseudo-random then the pseudo-random number generator - should be cryptographically secure (i.e., its next output not easily - guessed even when knowing all previous outputs) and, furthermore, - proper entropy needs to be added to the pseudo-random number - generator. RFC 1750 [1750] offers suggestions for sources of random - numbers and entropy. Implementors should note the importance of - entropy and the well-meant, anecdotal warning about the difficulty in - properly implementing pseudo-random number generating functions. - - The amount of entropy available to a given client or server may - sometimes be less than what is required. In this case one must - either resort to pseudo-random number generation regardless of - insufficient entropy or refuse to run the protocol. The latter is - preferable. - -9.2 Transport - -9.2.1 Confidentiality - - It is beyond the scope of this document and the Secure Shell Working - Group to analyze or recommend specific ciphers other than the ones - which have been established and accepted within the industry. At the - time of this writing, ciphers commonly in use include 3DES, ARCFOUR, - twofish, serpent and blowfish. AES has been accepted by The - published as a US Federal Information Processing Standards [FIPS-197] - and the cryptographic community as being acceptable for this purpose - as well has accepted AES. As always, implementors and users should - check current literature to ensure that no recent vulnerabilities - have been found in ciphers used within products. Implementors should - also check to see which ciphers are considered to be relatively - stronger than others and should recommend their use to users over - relatively weaker ciphers. It would be considered good form for an - implementation to politely and unobtrusively notify a user that a - stronger cipher is available and should be used when a weaker one is - actively chosen. - - The "none" cipher is provided for debugging and SHOULD NOT be used - except for that purpose. It's cryptographic properties are - sufficiently described in RFC 2410, which will show that its use does - not meet the intent of this protocol. - - The relative merits of these and other ciphers may also be found in - current literature. Two references that may provide information on - the subject are [SCHNEIER] and [KAUFMAN,PERLMAN,SPECINER]. Both of - these describe the CBC mode of operation of certain ciphers and the - weakness of this scheme. Essentially, this mode is theoretically - vulnerable to chosen cipher-text attacks because of the high - predictability of the start of packet sequence. However, this attack - - - -Ylonen & Moffat Expires March 31, 2004 [Page 13] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - is still deemed difficult and not considered fully practicable - especially if relatively longer block sizes are used. - - Additionally, another CBC mode attack may be mitigated through the - insertion of packets containing SSH_MSG_IGNORE. Without this - technique, a specific attack may be successful. For this attack - (commonly known as the Rogaway attack - [ROGAWAY],[DAI],[BELLARE,KOHNO,NAMPREMPRE]) to work, the attacker - would need to know the IV of the next block that is going to be - encrypted. In CBC mode that is the output of the encryption of the - previous block. If the attacker does not have any way to see the - packet yet (i.e it is in the internal buffers of the ssh - implementation or even in the kernel) then this attack will not work. - If the last packet has been sent out to the network (i.e the attacker - has access to it) then he can use the attack. - - In the optimal case an implementor would need to add an extra packet - only if the packet has been sent out onto the network and there are - no other packets waiting for transmission. Implementors may wish to - check to see if there are any unsent packets awaiting transmission, - but unfortunately it is not normally easy to obtain this information - from the kernel or buffers. If there are not, then a packet - containing SSH_MSG_IGNORE SHOULD be sent. If a new packet is added - to the stream every time the attacker knows the IV that is supposed - to be used for the next packet, then the attacker will not be able to - guess the correct IV, thus the attack will never be successfull. - - As an example, consider the following case: - - - Client Server - ------ ------ - TCP(seq=x, len=500) -> - contains Record 1 - - [500 ms passes, no ACK] - - TCP(seq=x, len=1000) -> - contains Records 1,2 - - ACK - - - 1. The Nagle algorithm + TCP retransmits mean that the two records - get coalesced into a single TCP segment - 2. Record 2 is *not* at the beginning of the TCP segment and never - will be, since it gets ACKed. - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 14] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - 3. Yet, the attack is possible because Record 1 has already been - seen. - - As this example indicates, it's totally unsafe to use the existence - of unflushed data in the TCP buffers proper as a guide to whether you - need an empty packet, since when you do the second write(), the - buffers will contain the un-ACKed Record 1. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 15] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - On the other hand, it's perfectly safe to have the following - situation: - - - Client Server - ------ ------ - TCP(seq=x, len=500) -> - contains SSH_MSG_IGNORE - - TCP(seq=y, len=500) -> - contains Data - - Provided that the IV for second SSH Record is fixed after the data for - the Data packet is determined -i.e. you do: - read from user - encrypt null packet - encrypt data packet - - -9.2.2 Data Integrity - - This protocol does allow the Data Integrity mechanism to be disabled. - Implementors SHOULD be wary of exposing this feature for any purpose - other than debugging. Users and administrators SHOULD be explicitly - warned anytime the "none" MAC is enabled. - - So long as the "none" MAC is not used, this protocol provides data - integrity. - - Because MACs use a 32 bit sequence number, they might start to leak - information after 2**32 packets have been sent. However, following - the rekeying recommendations should prevent this attack. The - transport protocol [1] recommends rekeying after one gigabyte of - data, and the smallest possible packet is 16 bytes. Therefore, - rekeying SHOULD happen after 2**28 packets at the very most. - -9.2.3 Replay - - The use of a MAC other than 'none' provides integrity and - authentication. In addition, the transport protocol provides a - unique session identifier (bound in part to pseudo-random data that - is part of the algorithm and key exchange process) that can be used - by higher level protocols to bind data to a given session and prevent - replay of data from prior sessions. For example, the authentication - protocol uses this to prevent replay of signatures from previous - sessions. Because public key authentication exchanges are - cryptographically bound to the session (i.e., to the initial key - exchange) they cannot be successfully replayed in other sessions. - - - -Ylonen & Moffat Expires March 31, 2004 [Page 16] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - Note that the session ID can be made public without harming the - security of the protocol. - - If two session happen to have the same session ID [hash of key - exchanges] then packets from one can be replayed against the other. - It must be stressed that the chances of such an occurrence are, - needless to say, minimal when using modern cryptographic methods. - This is all the more so true when specifying larger hash function - outputs and DH parameters. - - Replay detection using monotonically increasing sequence numbers as - input to the MAC, or HMAC in some cases, is described in [RFC2085] /> - [RFC2246], [RFC2743], [RFC1964], [RFC2025], and [RFC1510]. The - underlying construct is discussed in [RFC2104]. Essentially a - different sequence number in each packet ensures that at least this - one input to the MAC function will be unique and will provide a - nonrecurring MAC output that is not predictable to an attacker. If - the session stays active long enough, however, this sequence number - will wrap. This event may provide an attacker an opportunity to - replay a previously recorded packet with an identical sequence number - but only if the peers have not rekeyed since the transmission of the - first packet with that sequence number. If the peers have rekeyed, - then the replay will be detected as the MAC check will fail. For - this reason, it must be emphasized that peers MUST rekey before a - wrap of the sequence numbers. Naturally, if an attacker does attempt - to replay a captured packet before the peers have rekeyed, then the - receiver of the duplicate packet will not be able to validate the MAC - and it will be discarded. The reason that the MAC will fail is - because the receiver will formulate a MAC based upon the packet - contents, the shared secret, and the expected sequence number. Since - the replayed packet will not be using that expected sequence number - (the sequence number of the replayed packet will have already been - passed by the receiver) then the calculated MAC will not match the - MAC received with the packet. - -9.2.4 Man-in-the-middle - - This protocol makes no assumptions nor provisions for an - infrastructure or means for distributing the public keys of hosts. It - is expected that this protocol will sometimes be used without first - verifying the association between the server host key and the server - host name. Such usage is vulnerable to man-in-the-middle attacks. - This section describes this and encourages administrators and users - to understand the importance of verifying this association before any - session is initiated. - - There are three cases of man-in-the-middle attacks to consider. The - first is where an attacker places a device between the client and the - - - -Ylonen & Moffat Expires March 31, 2004 [Page 17] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - server before the session is initiated. In this case, the attack - device is trying to mimic the legitimate server and will offer its - public key to the client when the client initiates a session. If it - were to offer the public key of the server, then it would not be able - to decrypt or sign the transmissions between the legitimate server - and the client unless it also had access to the private-key of the - host. The attack device will also, simultaneously to this, initiate - a session to the legitimate server masquerading itself as the client. - If the public key of the server had been securely distributed to the - client prior to that session initiation, the key offered to the - client by the attack device will not match the key stored on the - client. In that case, the user SHOULD be given a warning that the - offered host key does not match the host key cached on the client. - As described in Section 3.1 of [ARCH], the user may be free to accept - the new key and continue the session. It is RECOMMENDED that the - warning provide sufficient information to the user of the client - device so they may make an informed decision. If the user chooses to - continue the session with the stored public-key of the server (not - the public-key offered at the start of the session), then the session - specific data between the attacker and server will be different - between the client-to-attacker session and the attacker-to-server - sessions due to the randomness discussed above. From this, the - attacker will not be able to make this attack work since the attacker - will not be able to correctly sign packets containing this session - specific data from the server since he does not have the private key - of that server. - - The second case that should be considered is similar to the first - case in that it also happens at the time of connection but this case - points out the need for the secure distribution of server public - keys. If the server public keys are not securely distributed then - the client cannot know if it is talking to the intended server. An - attacker may use social engineering techniques to pass off server - keys to unsuspecting users and may then place a man-in-the-middle - attack device between the legitimate server and the clients. If this - is allowed to happen then the clients will form client-to-attacker - sessions and the attacker will form attacker-to-server sessions and - will be able to monitor and manipulate all of the traffic between the - clients and the legitimate servers. Server administrators are - encouraged to make host key fingerprints available for checking by - some means whose security does not rely on the integrity of the - actual host keys. Possible mechanisms are discussed in Section 3.1 - of [SSH-ARCH] and may also include secured Web pages, physical pieces - of paper, etc. Implementors SHOULD provide recommendations on how - best to do this with their implementation. Because the protocol is - extensible, future extensions to the protocol may provide better - mechanisms for dealing with the need to know the server's host key - before connecting. For example, making the host key fingerprint - - - -Ylonen & Moffat Expires March 31, 2004 [Page 18] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - available through a secure DNS lookup, or using kerberos over gssapi - during key exchange to authenticate the server are possibilities. - - In the third man-in-the-middle case, attackers may attempt to - manipulate packets in transit between peers after the session has - been established. As described in the Replay part of this section, a - successful attack of this nature is very improbable. As in the - Replay section, this reasoning does assume that the MAC is secure and - that it is infeasible to construct inputs to a MAC algorithm to give - a known output. This is discussed in much greater detail in Section - 6 of RFC 2104. If the MAC algorithm has a vulnerability or is weak - enough, then the attacker may be able to specify certain inputs to - yield a known MAC. With that they may be able to alter the contents - of a packet in transit. Alternatively the attacker may be able to - exploit the algorithm vulnerability or weakness to find the shared - secret by reviewing the MACs from captured packets. In either of - those cases, an attacker could construct a packet or packets that - could be inserted into an SSH stream. To prevent that, implementors - are encouraged to utilize commonly accepted MAC algorithms and - administrators are encouraged to watch current literature and - discussions of cryptography to ensure that they are not using a MAC - algorithm that has a recently found vulnerability or weakness. - - In summary, the use of this protocol without a reliable association - of the binding between a host and its host keys is inherently - insecure and is NOT RECOMMENDED. It may however be necessary in - non-security critical environments, and will still provide protection - against passive attacks. Implementors of protocols and applications - running on top of this protocol should keep this possibility in mind. - -9.2.5 Denial-of-service - - This protocol is designed to be used over a reliable transport. If - transmission errors or message manipulation occur, the connection is - closed. The connection SHOULD be re-established if this occurs. - Denial of service attacks of this type ("wire cutter") are almost - impossible to avoid. - - In addition, this protocol is vulnerable to Denial of Service attacks - because an attacker can force the server to go through the CPU and - memory intensive tasks of connection setup and key exchange without - authenticating. Implementors SHOULD provide features that make this - more difficult. For example, only allowing connections from a subset - of IPs known to have valid users. - -9.2.6 Covert Channels - - The protocol was not designed to eliminate covert channels. For - - - -Ylonen & Moffat Expires March 31, 2004 [Page 19] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - example, the padding, SSH_MSG_IGNORE messages, and several other - places in the protocol can be used to pass covert information, and - the recipient has no reliable way to verify whether such information - is being sent. - -9.2.7 Forward Secrecy - - It should be noted that the Diffie-Hellman key exchanges may provide - perfect forward secrecy (PFS). PFS is essentially defined as the - cryptographic property of a key-establishment protocol in which the - compromise of a session key or long-term private key after a given - session does not cause the compromise of any earlier session. [ANSI - T1.523-2001] SSHv2 sessions resulting from a key exchange using - diffie-hellman-group1-sha1 are secure even if private keying/ - authentication material is later revealed, but not if the session - keys are revealed. So, given this definition of PFS, SSHv2 does have - PFS. It is hoped that all other key exchange mechanisms proposed and - used in the future will also provide PFS. This property is not - commuted to any of the applications or protocols using SSH as a - transport however. The transport layer of SSH provides - confidentiality for password authentication and other methods that - rely on secret data. - - Of course, if the DH private parameters for the client and server are - revealed then the session key is revealed, but these items can be - thrown away after the key exchange completes. It's worth pointing - out that these items should not be allowed to end up on swap space - and that they should be erased from memory as soon as the key - exchange completes. - -9.3 Authentication Protocol - - The purpose of this protocol is to perform client user - authentication. It assumes that this run over a secure transport - layer protocol, which has already authenticated the server machine, - established an encrypted communications channel, and computed a - unique session identifier for this session. - - Several authentication methods with different security - characteristics are allowed. It is up to the server's local policy - to decide which methods (or combinations of methods) it is willing to - accept for each user. Authentication is no stronger than the weakest - combination allowed. - - The server may go into a "sleep" period after repeated unsuccessful - authentication attempts to make key search more difficult for - attackers. Care should be taken so that this doesn't become a - self-denial of service vector. - - - -Ylonen & Moffat Expires March 31, 2004 [Page 20] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - -9.3.1 Weak Transport - - If the transport layer does not provide confidentiality, - authentication methods that rely on secret data SHOULD be disabled. - If it does not provide strong integrity protection, requests to - change authentication data (e.g. a password change) SHOULD be - disabled to prevent an attacker from modifying the ciphertext - without being noticed, or rendering the new authentication data - unusable (denial of service). - - The assumption as stated above that the Authentication Protocol only - run over a secure transport that has previously authenticated the - server is very important to note. People deploying SSH are reminded - of the consequences of man-in-the-middle attacks if the client does - not have a very strong a priori association of the server with the - host key of that server. Specifically for the case of the - Authentication Protocol the client may form a session to a - man-in-the-middle attack device and divulge user credentials such as - their username and password. Even in the cases of authentication - where no user credentials are divulged, an attacker may still gain - information they shouldn't have by capturing key-strokes in much the - same way that a honeypot works. - -9.3.2 Debug messages - - Special care should be taken when designing debug messages. These - messages may reveal surprising amounts of information about the host - if not properly designed. Debug messages can be disabled (during - user authentication phase) if high security is required. - Administrators of host machines should make all attempts to - compartmentalize all event notification messages and protect them - from unwarranted observation. Developers should be aware of the - sensitive nature of some of the normal event messages and debug - messages and may want to provide guidance to administrators on ways - to keep this information away from unauthorized people. Developers - should consider minimizing the amount of sensitive information - obtainable by users during the authentication phase in accordance - with the local policies. For this reason, it is RECOMMENDED that - debug messages be initially disabled at the time of deployment and - require an active decision by an administrator to allow them to be - enabled. It is also RECOMMENDED that a message expressing this - concern be presented to the administrator of a system when the action - is taken to enable debugging messages. - -9.3.3 Local security policy - - Implementer MUST ensure that the credentials provided validate the - professed user and also MUST ensure that the local policy of the - - - -Ylonen & Moffat Expires March 31, 2004 [Page 21] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - server permits the user the access requested. In particular, because - of the flexible nature of the SSH connection protocol, it may not be - possible to determine the local security policy, if any, that should - apply at the time of authentication because the kind of service being - requested is not clear at that instant. For example, local policy - might allow a user to access files on the server, but not start an - interactive shell. However, during the authentication protocol, it is - not known whether the user will be accessing files or attempting to - use an interactive shell, or even both. In any event, where local - security policy for the server host exists, it MUST be applied and - enforced correctly. - - Implementors are encouraged to provide a default local policy and - make its parameters known to administrators and users. At the - discretion of the implementors, this default policy may be along the - lines of 'anything goes' where there are no restrictions placed upon - users, or it may be along the lines of 'excessively restrictive' in - which case the administrators will have to actively make changes to - this policy to meet their needs. Alternatively, it may be some - attempt at providing something practical and immediately useful to - the administrators of the system so they don't have to put in much - effort to get SSH working. Whatever choice is made MUST be applied - and enforced as required above. - -9.3.4 Public key authentication - - The use of public-key authentication assumes that the client host has - not been compromised. It also assumes that the private-key of the - server host has not been compromised. - - This risk can be mitigated by the use of passphrases on private keys; - however, this is not an enforceable policy. The use of smartcards, - or other technology to make passphrases an enforceable policy is - suggested. - - The server could require both password and public-key authentication, - however, this requires the client to expose its password to the - server (see section on password authentication below.) - -9.3.5 Password authentication - - The password mechanism as specified in the authentication protocol - assumes that the server has not been compromised. If the server has - been compromised, using password authentication will reveal a valid - username / password combination to the attacker, which may lead to - further compromises. - - This vulnerability can be mitigated by using an alternative form of - - - -Ylonen & Moffat Expires March 31, 2004 [Page 22] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - authentication. For example, public-key authentication makes no - assumptions about security on the server. - -9.3.6 Host based authentication - - Host based authentication assumes that the client has not been - compromised. There are no mitigating strategies, other than to use - host based authentication in combination with another authentication - method. - -9.4 Connection protocol - -9.4.1 End point security - - End point security is assumed by the connection protocol. If the - server has been compromised, any terminal sessions, port forwarding, - or systems accessed on the host are compromised. There are no - mitigating factors for this. - - If the client end point has been compromised, and the server fails to - stop the attacker at the authentication protocol, all services - exposed (either as subsystems or through forwarding) will be - vulnerable to attack. Implementors SHOULD provide mechanisms for - administrators to control which services are exposed to limit the - vulnerability of other services. - - These controls might include controlling which machines and ports can - be target in 'port-forwarding' operations, which users are allowed to - use interactive shell facilities, or which users are allowed to use - exposed subsystems. - -9.4.2 Proxy forwarding - - The SSH connection protocol allows for proxy forwarding of other - protocols such as SNMP, POP3, and HTTP. This may be a concern for - network administrators who wish to control the access of certain - applications by users located outside of their physical location. - Essentially, the forwarding of these protocols may violate site - specific security policies as they may be undetectably tunneled - through a firewall. Implementors SHOULD provide an administrative - mechanism to control the proxy forwarding functionality so that site - specific security policies may be upheld. - - In addition, a reverse proxy forwarding functionality is available, - which again can be used to bypass firewall controls. - - As indicated above, end-point security is assumed during proxy - forwarding operations. Failure of end-point security will compromise - - - -Ylonen & Moffat Expires March 31, 2004 [Page 23] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - all data passed over proxy forwarding. - -9.4.3 X11 forwarding - - Another form of proxy forwarding provided by the ssh connection - protocol is the forwarding of the X11 protocol. If end-point - security has been compromised, X11 forwarding may allow attacks - against the X11 server. Users and administrators should, as a matter - of course, use appropriate X11 security mechanisms to prevent - unauthorized use of the X11 server. Implementors, administrators and - users who wish to further explore the security mechanisms of X11 are - invited to read [SCHEIFLER] and analyze previously reported problems - with the interactions between SSH forwarding and X11 in CERT - vulnerabilities VU#363181 and VU#118892 [CERT]. - - X11 display forwarding with SSH, by itself, is not sufficient to - correct well known problems with X11 security [VENEMA]. However, X11 - display forwarding in SSHv2 (or other, secure protocols), combined - with actual and pseudo-displays which accept connections only over - local IPC mechanisms authorized by permissions or ACLs, does correct - many X11 security problems as long as the "none" MAC is not used. It - is RECOMMENDED that X11 display implementations default to allowing - display opens only over local IPC. It is RECOMMENDED that SSHv2 - server implementations that support X11 forwarding default to - allowing display opens only over local IPC. On single-user systems - it might be reasonable to default to allowing local display opens - over TCP/IP. - - Implementors of the X11 forwarding protocol SHOULD implement the - magic cookie access checking spoofing mechanism as described in - [ssh-connect] as an additional mechanism to prevent unauthorized use - of the proxy. - -Normative References - - [SSH-ARCH] - Ylonen, T., "SSH Protocol Architecture", I-D - draft-ietf-architecture-15.txt, Oct 2003. - - [SSH-TRANS] - Ylonen, T., "SSH Transport Layer Protocol", I-D - draft-ietf-transport-17.txt, Oct 2003. - - [SSH-USERAUTH] - Ylonen, T., "SSH Authentication Protocol", I-D - draft-ietf-userauth-18.txt, Oct 2003. - - [SSH-CONNECT] - - - -Ylonen & Moffat Expires March 31, 2004 [Page 24] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - Ylonen, T., "SSH Connection Protocol", I-D - draft-ietf-connect-18.txt, Oct 2003. - - [SSH-NUMBERS] - Lehtinen, S. and D. Moffat, "SSH Protocol Assigned - Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct - 2003. - - [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate - Requirement Levels", BCP 14, RFC 2119, March 1997. - -Informative References - - [FIPS-186] - Federal Information Processing Standards Publication, - "FIPS PUB 186, Digital Signature Standard", May 1994. - - [FIPS-197] - National Institue of Standards and Technology, "FIPS 197, - Specification for the Advanced Encryption Standard", - November 2001. - - [ANSI T1.523-2001] - American National Standards Insitute, Inc., "Telecom - Glossary 2000", February 2001. - - [SCHEIFLER] - Scheifler, R., "X Window System : The Complete Reference - to Xlib, X Protocol, Icccm, Xlfd, 3rd edition.", Digital - Press ISBN 1555580882, Feburary 1992. - - [RFC0854] Postel, J. and J. Reynolds, "Telnet Protocol - Specification", STD 8, RFC 854, May 1983. - - [RFC0894] Hornig, C., "Standard for the transmission of IP datagrams - over Ethernet networks", STD 41, RFC 894, April 1984. - - [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", - STD 13, RFC 1034, November 1987. - - [RFC1134] Perkins, D., "Point-to-Point Protocol: A proposal for - multi-protocol transmission of datagrams over - Point-to-Point links", RFC 1134, November 1989. - - [RFC1282] Kantor, B., "BSD Rlogin", RFC 1282, December 1991. - - [RFC1510] Kohl, J. and B. Neuman, "The Kerberos Network - Authentication Service (V5)", RFC 1510, September 1993. - - - -Ylonen & Moffat Expires March 31, 2004 [Page 25] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", RFC 1700, - October 1994. - - [RFC1750] Eastlake, D., Crocker, S. and J. Schiller, "Randomness - Recommendations for Security", RFC 1750, December 1994. - - [RFC3066] Alvestrand, H., "Tags for the Identification of - Languages", BCP 47, RFC 3066, January 2001. - - [RFC1964] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", RFC - 1964, June 1996. - - [RFC2025] Adams, C., "The Simple Public-Key GSS-API Mechanism - (SPKM)", RFC 2025, October 1996. - - [RFC2085] Oehler, M. and R. Glenn, "HMAC-MD5 IP Authentication with - Replay Prevention", RFC 2085, February 1997. - - [RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: - Keyed-Hashing for Message Authentication", RFC 2104, - February 1997. - - [RFC2246] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. - and P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, - January 1999. - - [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO - 10646", RFC 2279, January 1998. - - [RFC2410] Glenn, R. and S. Kent, "The NULL Encryption Algorithm and - Its Use With IPsec", RFC 2410, November 1998. - - [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an - IANA Considerations Section in RFCs", BCP 26, RFC 2434, - October 1998. - - [RFC2743] Linn, J., "Generic Security Service Application Program - Interface Version 2, Update 1", RFC 2743, January 2000. - - [SCHNEIER] - Schneier, B., "Applied Cryptography Second Edition: - protocols algorithms and source in code in C", 1996. - - [KAUFMAN,PERLMAN,SPECINER] - Kaufman, C., Perlman, R. and M. Speciner, "Network - Security: PRIVATE Communication in a PUBLIC World", 1995. - - [CERT] CERT Coordination Center, The., "http://www.cert.org/nav/ - - - -Ylonen & Moffat Expires March 31, 2004 [Page 26] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - index_red.html". - - [VENEMA] Venema, W., "Murphy's Law and Computer Security", - Proceedings of 6th USENIX Security Symposium, San Jose CA - http://www.usenix.org/publications/library/proceedings/ - sec96/venema.html, July 1996. - - [ROGAWAY] Rogaway, P., "Problems with Proposed IP Cryptography", - Unpublished paper http://www.cs.ucdavis.edu/~rogaway/ - papers/draft-rogaway-ipsec-comments-00.txt, 1996. - - [DAI] Dai, W., "An attack against SSH2 protocol", Email to the - SECSH Working Group [email protected] ftp:// - ftp.ietf.org/ietf-mail-archive/secsh/2002-02.mail, Feb - 2002. - - [BELLARE,KOHNO,NAMPREMPRE] - Bellaire, M., Kohno, T. and C. Namprempre, "Authenticated - Encryption in SSH: Fixing the SSH Binary Packet Protocol", - , Sept 2002. - - -Authors' Addresses - - Tatu Ylonen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - Darren J. Moffat (editor) - Sun Microsystems, Inc - 17 Network Circle - Menlo Park CA 94025 - USA - - EMail: [email protected] - - - - - - - - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 27] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - -Intellectual Property Statement - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementors or users of this specification can - be obtained from the IETF Secretariat. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights which may cover technology that may be required to practice - this standard. Please address the information to the IETF Executive - Director. - - The IETF has been notified of intellectual property rights claimed in - regard to some or all of the specification contained in this - document. For more information consult the online list of claimed - rights. - - -Full Copyright Statement - - Copyright (C) The Internet Society (2003). All Rights Reserved. - - This document and translations of it may be copied and furnished to - others, and derivative works that comment on or otherwise explain it - or assist in its implementation may be prepared, copied, published - and distributed, in whole or in part, without restriction of any - kind, provided that the above copyright notice and this paragraph are - included on all such copies and derivative works. However, this - document itself may not be modified in any way, such as by removing - the copyright notice or references to the Internet Society or other - Internet organizations, except as needed for the purpose of - developing Internet standards in which case the procedures for - copyrights defined in the Internet Standards process must be - followed, or as required to translate it into languages other than - English. - - The limited permissions granted above are perpetual and will not be - revoked by the Internet Society or its successors or assignees. - - - -Ylonen & Moffat Expires March 31, 2004 [Page 28] - -Internet-Draft SSH Protocol Architecture Oct 2003 - - - This document and the information contained herein is provided on an - "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING - TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING - BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION - HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF - MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - -Acknowledgment - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Moffat Expires March 31, 2004 [Page 29]
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matrix invertmatrix matrix concatmatrix - matrix invertmatrix put -%%EndSetup -%%Page: (0,1) 1 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 1 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 701 M -(Network Working Group T. Ylonen) s -5 690 M -(Internet-Draft SSH Communications Security Corp) s -5 679 M -(Expires: March 31, 2004 D. Moffat, Editor, Ed.) s -5 668 M -( Sun Microsystems, Inc) s -5 657 M -( Oct 2003) s -5 624 M -( SSH Connection Protocol) s -5 613 M -( draft-ietf-secsh-connect-18.txt) s -5 591 M -(Status of this Memo) s -5 569 M -( This document is an Internet-Draft and is in full conformance with) s -5 558 M -( all provisions of Section 10 of RFC2026.) s -5 536 M -( Internet-Drafts are working documents of the Internet Engineering) s -5 525 M -( Task Force \(IETF\), its areas, and its working groups. Note that other) s -5 514 M -( groups may also distribute working documents as Internet-Drafts.) s -5 492 M -( Internet-Drafts are draft documents valid for a maximum of six months) s -5 481 M -( and may be updated, replaced, or obsoleted by other documents at any) s -5 470 M -( time. It is inappropriate to use Internet-Drafts as reference) s -5 459 M -( material or to cite them other than as "work in progress.") s -5 437 M -( The list of current Internet-Drafts can be accessed at http://) s -5 426 M -( www.ietf.org/ietf/1id-abstracts.txt.) s -5 404 M -( The list of Internet-Draft Shadow Directories can be accessed at) s -5 393 M -( http://www.ietf.org/shadow.html.) s -5 371 M -( This Internet-Draft will expire on March 31, 2004.) s -5 349 M -(Copyright Notice) s -5 327 M -( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s -5 305 M -(Abstract) s -5 283 M -( SSH is a protocol for secure remote login and other secure network) s -5 272 M -( services over an insecure network.) s -5 250 M -( This document describes the SSH Connection Protocol. It provides) s -5 239 M -( interactive login sessions, remote execution of commands, forwarded) s -5 228 M -( TCP/IP connections, and forwarded X11 connections. All of these) s -5 217 M -( channels are multiplexed into a single encrypted tunnel.) s -5 195 M -( The SSH Connection Protocol has been designed to run on top of the) s -5 184 M -( SSH transport layer and user authentication protocols.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 1]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 2 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -(Table of Contents) s -5 668 M -( 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 657 M -( 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 646 M -( 3. Conventions Used in This Document . . . . . . . . . . . . . 3) s -5 635 M -( 4. Global Requests . . . . . . . . . . . . . . . . . . . . . . 3) s -5 624 M -( 5. Channel Mechanism . . . . . . . . . . . . . . . . . . . . . 4) s -5 613 M -( 5.1 Opening a Channel . . . . . . . . . . . . . . . . . . . . . 4) s -5 602 M -( 5.2 Data Transfer . . . . . . . . . . . . . . . . . . . . . . . 5) s -5 591 M -( 5.3 Closing a Channel . . . . . . . . . . . . . . . . . . . . . 6) s -5 580 M -( 5.4 Channel-Specific Requests . . . . . . . . . . . . . . . . . 7) s -5 569 M -( 6. Interactive Sessions . . . . . . . . . . . . . . . . . . . . 8) s -5 558 M -( 6.1 Opening a Session . . . . . . . . . . . . . . . . . . . . . 8) s -5 547 M -( 6.2 Requesting a Pseudo-Terminal . . . . . . . . . . . . . . . . 8) s -5 536 M -( 6.3 X11 Forwarding . . . . . . . . . . . . . . . . . . . . . . . 9) s -5 525 M -( 6.3.1 Requesting X11 Forwarding . . . . . . . . . . . . . . . . . 9) s -5 514 M -( 6.3.2 X11 Channels . . . . . . . . . . . . . . . . . . . . . . . . 10) s -5 503 M -( 6.4 Environment Variable Passing . . . . . . . . . . . . . . . . 10) s -5 492 M -( 6.5 Starting a Shell or a Command . . . . . . . . . . . . . . . 10) s -5 481 M -( 6.6 Session Data Transfer . . . . . . . . . . . . . . . . . . . 11) s -5 470 M -( 6.7 Window Dimension Change Message . . . . . . . . . . . . . . 12) s -5 459 M -( 6.8 Local Flow Control . . . . . . . . . . . . . . . . . . . . . 12) s -5 448 M -( 6.9 Signals . . . . . . . . . . . . . . . . . . . . . . . . . . 12) s -5 437 M -( 6.10 Returning Exit Status . . . . . . . . . . . . . . . . . . . 13) s -5 426 M -( 7. TCP/IP Port Forwarding . . . . . . . . . . . . . . . . . . . 14) s -5 415 M -( 7.1 Requesting Port Forwarding . . . . . . . . . . . . . . . . . 14) s -5 404 M -( 7.2 TCP/IP Forwarding Channels . . . . . . . . . . . . . . . . . 15) s -5 393 M -( 8. Encoding of Terminal Modes . . . . . . . . . . . . . . . . . 16) s -5 382 M -( 9. Summary of Message Numbers . . . . . . . . . . . . . . . . . 18) s -5 371 M -( 10. Security Considerations . . . . . . . . . . . . . . . . . . 18) s -5 360 M -( 11. iana cONSiderations . . . . . . . . . . . . . . . . . . . . 19) s -5 349 M -( 12. Intellectual Property . . . . . . . . . . . . . . . . . . . 19) s -5 338 M -( Normative References . . . . . . . . . . . . . . . . . . . . 19) s -5 327 M -( Informative References . . . . . . . . . . . . . . . . . . . 20) s -5 316 M -( Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 20) s -5 305 M -( Intellectual Property and Copyright Statements . . . . . . . 21) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 2]) s -_R -S -PStoPSsaved restore -%%Page: (2,3) 2 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 3 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -(1. Contributors) s -5 668 M -( The major original contributors of this document were: Tatu Ylonen,) s -5 657 M -( Tero Kivinen, Timo J. Rinne, Sami Lehtinen \(all of SSH Communications) s -5 646 M -( Security Corp\), and Markku-Juhani O. Saarinen \(University of) s -5 635 M -( Jyvaskyla\)) s -5 613 M -( The document editor is: [email protected]. Comments on this) s -5 602 M -( internet draft should be sent to the IETF SECSH working group,) s -5 591 M -( details at: http://ietf.org/html.charters/secsh-charter.html) s -5 569 M -(2. Introduction) s -5 547 M -( The SSH Connection Protocol has been designed to run on top of the) s -5 536 M -( SSH transport layer and user authentication protocols. It provides) s -5 525 M -( interactive login sessions, remote execution of commands, forwarded) s -5 514 M -( TCP/IP connections, and forwarded X11 connections. The service name) s -5 503 M -( for this protocol is "ssh-connection".) s -5 481 M -( This document should be read only after reading the SSH architecture) s -5 470 M -( document [SSH-ARCH]. This document freely uses terminology and) s -5 459 M -( notation from the architecture document without reference or further) s -5 448 M -( explanation.) s -5 426 M -(3. Conventions Used in This Document) s -5 404 M -( The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",) s -5 393 M -( and "MAY" that appear in this document are to be interpreted as) s -5 382 M -( described in [RFC2119].) s -5 360 M -( The used data types and terminology are specified in the architecture) s -5 349 M -( document [SSH-ARCH].) s -5 327 M -( The architecture document also discusses the algorithm naming) s -5 316 M -( conventions that MUST be used with the SSH protocols.) s -5 294 M -(4. Global Requests) s -5 272 M -( There are several kinds of requests that affect the state of the) s -5 261 M -( remote end "globally", independent of any channels. An example is a) s -5 250 M -( request to start TCP/IP forwarding for a specific port. All such) s -5 239 M -( requests use the following format.) s -5 217 M -( byte SSH_MSG_GLOBAL_REQUEST) s -5 206 M -( string request name \(restricted to US-ASCII\)) s -5 195 M -( boolean want reply) s -5 184 M -( ... request-specific data follows) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 3]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 4 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( Request names follow the DNS extensibility naming convention outlined) s -5 679 M -( in [SSH-ARCH].) s -5 657 M -( The recipient will respond to this message with) s -5 646 M -( SSH_MSG_REQUEST_SUCCESS or SSH_MSG_REQUEST_FAILURE if `want reply' is) s -5 635 M -( TRUE.) s -5 613 M -( byte SSH_MSG_REQUEST_SUCCESS) s -5 602 M -( ..... response specific data) s -5 580 M -( Usually the response specific data is non-existent.) s -5 558 M -( If the recipient does not recognize or support the request, it simply) s -5 547 M -( responds with SSH_MSG_REQUEST_FAILURE.) s -5 525 M -( byte SSH_MSG_REQUEST_FAILURE) s -5 492 M -(5. Channel Mechanism) s -5 470 M -( All terminal sessions, forwarded connections, etc. are channels.) s -5 459 M -( Either side may open a channel. Multiple channels are multiplexed) s -5 448 M -( into a single connection.) s -5 426 M -( Channels are identified by numbers at each end. The number referring) s -5 415 M -( to a channel may be different on each side. Requests to open a) s -5 404 M -( channel contain the sender's channel number. Any other) s -5 393 M -( channel-related messages contain the recipient's channel number for) s -5 382 M -( the channel.) s -5 360 M -( Channels are flow-controlled. No data may be sent to a channel until) s -5 349 M -( a message is received to indicate that window space is available.) s -5 327 M -(5.1 Opening a Channel) s -5 305 M -( When either side wishes to open a new channel, it allocates a local) s -5 294 M -( number for the channel. It then sends the following message to the) s -5 283 M -( other side, and includes the local channel number and initial window) s -5 272 M -( size in the message.) s -5 250 M -( byte SSH_MSG_CHANNEL_OPEN) s -5 239 M -( string channel type \(restricted to US-ASCII\)) s -5 228 M -( uint32 sender channel) s -5 217 M -( uint32 initial window size) s -5 206 M -( uint32 maximum packet size) s -5 195 M -( ... channel type specific data follows) s -5 173 M -( The channel type is a name as described in the SSH architecture) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 4]) s -_R -S -PStoPSsaved restore -%%Page: (4,5) 3 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 5 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( document, with similar extension mechanisms. `sender channel' is a) s -5 679 M -( local identifier for the channel used by the sender of this message.) s -5 668 M -( `initial window size' specifies how many bytes of channel data can be) s -5 657 M -( sent to the sender of this message without adjusting the window.) s -5 646 M -( `Maximum packet size' specifies the maximum size of an individual) s -5 635 M -( data packet that can be sent to the sender \(for example, one might) s -5 624 M -( want to use smaller packets for interactive connections to get better) s -5 613 M -( interactive response on slow links\).) s -5 591 M -( The remote side then decides whether it can open the channel, and) s -5 580 M -( responds with either) s -5 558 M -( byte SSH_MSG_CHANNEL_OPEN_CONFIRMATION) s -5 547 M -( uint32 recipient channel) s -5 536 M -( uint32 sender channel) s -5 525 M -( uint32 initial window size) s -5 514 M -( uint32 maximum packet size) s -5 503 M -( ... channel type specific data follows) s -5 481 M -( where `recipient channel' is the channel number given in the original) s -5 470 M -( open request, and `sender channel' is the channel number allocated by) s -5 459 M -( the other side, or) s -5 437 M -( byte SSH_MSG_CHANNEL_OPEN_FAILURE) s -5 426 M -( uint32 recipient channel) s -5 415 M -( uint32 reason code) s -5 404 M -( string additional textual information \(ISO-10646 UTF-8 [RFC2279]\)) s -5 393 M -( string language tag \(as defined in [RFC3066]\)) s -5 371 M -( If the recipient of the SSH_MSG_CHANNEL_OPEN message does not support) s -5 360 M -( the specified channel type, it simply responds with) s -5 349 M -( SSH_MSG_CHANNEL_OPEN_FAILURE. The client MAY show the additional) s -5 338 M -( information to the user. If this is done, the client software should) s -5 327 M -( take the precautions discussed in [SSH-ARCH].) s -5 305 M -( The following reason codes are defined:) s -5 283 M -( #define SSH_OPEN_ADMINISTRATIVELY_PROHIBITED 1) s -5 272 M -( #define SSH_OPEN_CONNECT_FAILED 2) s -5 261 M -( #define SSH_OPEN_UNKNOWN_CHANNEL_TYPE 3) s -5 250 M -( #define SSH_OPEN_RESOURCE_SHORTAGE 4) s -5 217 M -(5.2 Data Transfer) s -5 195 M -( The window size specifies how many bytes the other party can send) s -5 184 M -( before it must wait for the window to be adjusted. Both parties use) s -5 173 M -( the following message to adjust the window.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 5]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 6 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( byte SSH_MSG_CHANNEL_WINDOW_ADJUST) s -5 679 M -( uint32 recipient channel) s -5 668 M -( uint32 bytes to add) s -5 646 M -( After receiving this message, the recipient MAY send the given number) s -5 635 M -( of bytes more than it was previously allowed to send; the window size) s -5 624 M -( is incremented.) s -5 602 M -( Data transfer is done with messages of the following type.) s -5 580 M -( byte SSH_MSG_CHANNEL_DATA) s -5 569 M -( uint32 recipient channel) s -5 558 M -( string data) s -5 536 M -( The maximum amount of data allowed is the current window size. The) s -5 525 M -( window size is decremented by the amount of data sent. Both parties) s -5 514 M -( MAY ignore all extra data sent after the allowed window is empty.) s -5 492 M -( Additionally, some channels can transfer several types of data. An) s -5 481 M -( example of this is stderr data from interactive sessions. Such data) s -5 470 M -( can be passed with SSH_MSG_CHANNEL_EXTENDED_DATA messages, where a) s -5 459 M -( separate integer specifies the type of the data. The available types) s -5 448 M -( and their interpretation depend on the type of the channel.) s -5 426 M -( byte SSH_MSG_CHANNEL_EXTENDED_DATA) s -5 415 M -( uint32 recipient_channel) s -5 404 M -( uint32 data_type_code) s -5 393 M -( string data) s -5 371 M -( Data sent with these messages consumes the same window as ordinary) s -5 360 M -( data.) s -5 338 M -( Currently, only the following type is defined.) s -5 316 M -( #define SSH_EXTENDED_DATA_STDERR 1) s -5 283 M -(5.3 Closing a Channel) s -5 261 M -( When a party will no longer send more data to a channel, it SHOULD) s -5 250 M -( send SSH_MSG_CHANNEL_EOF.) s -5 228 M -( byte SSH_MSG_CHANNEL_EOF) s -5 217 M -( uint32 recipient_channel) s -5 195 M -( No explicit response is sent to this message; however, the) s -5 184 M -( application may send EOF to whatever is at the other end of the) s -5 173 M -( channel. Note that the channel remains open after this message, and) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 6]) s -_R -S -PStoPSsaved restore -%%Page: (6,7) 4 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 7 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( more data may still be sent in the other direction. This message) s -5 679 M -( does not consume window space and can be sent even if no window space) s -5 668 M -( is available.) s -5 646 M -( When either party wishes to terminate the channel, it sends) s -5 635 M -( SSH_MSG_CHANNEL_CLOSE. Upon receiving this message, a party MUST) s -5 624 M -( send back a SSH_MSG_CHANNEL_CLOSE unless it has already sent this) s -5 613 M -( message for the channel. The channel is considered closed for a) s -5 602 M -( party when it has both sent and received SSH_MSG_CHANNEL_CLOSE, and) s -5 591 M -( the party may then reuse the channel number. A party MAY send) s -5 580 M -( SSH_MSG_CHANNEL_CLOSE without having sent or received) s -5 569 M -( SSH_MSG_CHANNEL_EOF.) s -5 547 M -( byte SSH_MSG_CHANNEL_CLOSE) s -5 536 M -( uint32 recipient_channel) s -5 514 M -( This message does not consume window space and can be sent even if no) s -5 503 M -( window space is available.) s -5 481 M -( It is recommended that any data sent before this message is delivered) s -5 470 M -( to the actual destination, if possible.) s -5 448 M -(5.4 Channel-Specific Requests) s -5 426 M -( Many channel types have extensions that are specific to that) s -5 415 M -( particular channel type. An example is requesting a pty \(pseudo) s -5 404 M -( terminal\) for an interactive session.) s -5 382 M -( All channel-specific requests use the following format.) s -5 360 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 349 M -( uint32 recipient channel) s -5 338 M -( string request type \(restricted to US-ASCII\)) s -5 327 M -( boolean want reply) s -5 316 M -( ... type-specific data) s -5 294 M -( If want reply is FALSE, no response will be sent to the request.) s -5 283 M -( Otherwise, the recipient responds with either SSH_MSG_CHANNEL_SUCCESS) s -5 272 M -( or SSH_MSG_CHANNEL_FAILURE, or request-specific continuation) s -5 261 M -( messages. If the request is not recognized or is not supported for) s -5 250 M -( the channel, SSH_MSG_CHANNEL_FAILURE is returned.) s -5 228 M -( This message does not consume window space and can be sent even if no) s -5 217 M -( window space is available. Request types are local to each channel) s -5 206 M -( type.) s -5 184 M -( The client is allowed to send further messages without waiting for) s -5 173 M -( the response to the request.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 7]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 8 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( request type names follow the DNS extensibility naming convention) s -5 679 M -( outlined in [SSH-ARCH]) s -5 657 M -( byte SSH_MSG_CHANNEL_SUCCESS) s -5 646 M -( uint32 recipient_channel) s -5 613 M -( byte SSH_MSG_CHANNEL_FAILURE) s -5 602 M -( uint32 recipient_channel) s -5 580 M -( These messages do not consume window space and can be sent even if no) s -5 569 M -( window space is available.) s -5 547 M -(6. Interactive Sessions) s -5 525 M -( A session is a remote execution of a program. The program may be a) s -5 514 M -( shell, an application, a system command, or some built-in subsystem.) s -5 503 M -( It may or may not have a tty, and may or may not involve X11) s -5 492 M -( forwarding. Multiple sessions can be active simultaneously.) s -5 470 M -(6.1 Opening a Session) s -5 448 M -( A session is started by sending the following message.) s -5 426 M -( byte SSH_MSG_CHANNEL_OPEN) s -5 415 M -( string "session") s -5 404 M -( uint32 sender channel) s -5 393 M -( uint32 initial window size) s -5 382 M -( uint32 maximum packet size) s -5 360 M -( Client implementations SHOULD reject any session channel open) s -5 349 M -( requests to make it more difficult for a corrupt server to attack the) s -5 338 M -( client.) s -5 316 M -(6.2 Requesting a Pseudo-Terminal) s -5 294 M -( A pseudo-terminal can be allocated for the session by sending the) s -5 283 M -( following message.) s -5 261 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 250 M -( uint32 recipient_channel) s -5 239 M -( string "pty-req") s -5 228 M -( boolean want_reply) s -5 217 M -( string TERM environment variable value \(e.g., vt100\)) s -5 206 M -( uint32 terminal width, characters \(e.g., 80\)) s -5 195 M -( uint32 terminal height, rows \(e.g., 24\)) s -5 184 M -( uint32 terminal width, pixels \(e.g., 640\)) s -5 173 M -( uint32 terminal height, pixels \(e.g., 480\)) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 8]) s -_R -S -PStoPSsaved restore -%%Page: (8,9) 5 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 9 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( string encoded terminal modes) s -5 668 M -( The encoding of terminal modes is described in Section Encoding of) s -5 657 M -( Terminal Modes \(Section 8\). Zero dimension parameters MUST be) s -5 646 M -( ignored. The character/row dimensions override the pixel dimensions) s -5 635 M -( \(when nonzero\). Pixel dimensions refer to the drawable area of the) s -5 624 M -( window.) s -5 602 M -( The dimension parameters are only informational.) s -5 580 M -( The client SHOULD ignore pty requests.) s -5 558 M -(6.3 X11 Forwarding) s -5 536 M -(6.3.1 Requesting X11 Forwarding) s -5 514 M -( X11 forwarding may be requested for a session by sending) s -5 492 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 481 M -( uint32 recipient channel) s -5 470 M -( string "x11-req") s -5 459 M -( boolean want reply) s -5 448 M -( boolean single connection) s -5 437 M -( string x11 authentication protocol) s -5 426 M -( string x11 authentication cookie) s -5 415 M -( uint32 x11 screen number) s -5 393 M -( It is recommended that the authentication cookie that is sent be a) s -5 382 M -( fake, random cookie, and that the cookie is checked and replaced by) s -5 371 M -( the real cookie when a connection request is received.) s -5 349 M -( X11 connection forwarding should stop when the session channel is) s -5 338 M -( closed; however, already opened forwardings should not be) s -5 327 M -( automatically closed when the session channel is closed.) s -5 305 M -( If `single connection' is TRUE, only a single connection should be) s -5 294 M -( forwarded. No more connections will be forwarded after the first, or) s -5 283 M -( after the session channel has been closed.) s -5 261 M -( The "x11 authentication protocol" is the name of the X11) s -5 250 M -( authentication method used, e.g. "MIT-MAGIC-COOKIE-1".) s -5 228 M -( The x11 authentication cookie MUST be hexadecimal encoded.) s -5 206 M -( X Protocol is documented in [SCHEIFLER].) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 9]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 10 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -(6.3.2 X11 Channels) s -5 668 M -( X11 channels are opened with a channel open request. The resulting) s -5 657 M -( channels are independent of the session, and closing the session) s -5 646 M -( channel does not close the forwarded X11 channels.) s -5 624 M -( byte SSH_MSG_CHANNEL_OPEN) s -5 613 M -( string "x11") s -5 602 M -( uint32 sender channel) s -5 591 M -( uint32 initial window size) s -5 580 M -( uint32 maximum packet size) s -5 569 M -( string originator address \(e.g. "192.168.7.38"\)) s -5 558 M -( uint32 originator port) s -5 536 M -( The recipient should respond with SSH_MSG_CHANNEL_OPEN_CONFIRMATION) s -5 525 M -( or SSH_MSG_CHANNEL_OPEN_FAILURE.) s -5 503 M -( Implementations MUST reject any X11 channel open requests if they) s -5 492 M -( have not requested X11 forwarding.) s -5 470 M -(6.4 Environment Variable Passing) s -5 448 M -( Environment variables may be passed to the shell/command to be) s -5 437 M -( started later. Uncontrolled setting of environment variables in a) s -5 426 M -( privileged process can be a security hazard. It is recommended that) s -5 415 M -( implementations either maintain a list of allowable variable names or) s -5 404 M -( only set environment variables after the server process has dropped) s -5 393 M -( sufficient privileges.) s -5 371 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 360 M -( uint32 recipient channel) s -5 349 M -( string "env") s -5 338 M -( boolean want reply) s -5 327 M -( string variable name) s -5 316 M -( string variable value) s -5 283 M -(6.5 Starting a Shell or a Command) s -5 261 M -( Once the session has been set up, a program is started at the remote) s -5 250 M -( end. The program can be a shell, an application program or a) s -5 239 M -( subsystem with a host-independent name. Only one of these requests) s -5 228 M -( can succeed per channel.) s -5 206 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 195 M -( uint32 recipient channel) s -5 184 M -( string "shell") s -5 173 M -( boolean want reply) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 10]) s -_R -S -PStoPSsaved restore -%%Page: (10,11) 6 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 11 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( This message will request the user's default shell \(typically defined) s -5 679 M -( in /etc/passwd in UNIX systems\) to be started at the other end.) s -5 657 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 646 M -( uint32 recipient channel) s -5 635 M -( string "exec") s -5 624 M -( boolean want reply) s -5 613 M -( string command) s -5 591 M -( This message will request the server to start the execution of the) s -5 580 M -( given command. The command string may contain a path. Normal) s -5 569 M -( precautions MUST be taken to prevent the execution of unauthorized) s -5 558 M -( commands.) s -5 536 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 525 M -( uint32 recipient channel) s -5 514 M -( string "subsystem") s -5 503 M -( boolean want reply) s -5 492 M -( string subsystem name) s -5 470 M -( This last form executes a predefined subsystem. It is expected that) s -5 459 M -( these will include a general file transfer mechanism, and possibly) s -5 448 M -( other features. Implementations may also allow configuring more such) s -5 437 M -( mechanisms. As the user's shell is usually used to execute the) s -5 426 M -( subsystem, it is advisable for the subsystem protocol to have a) s -5 415 M -( "magic cookie" at the beginning of the protocol transaction to) s -5 404 M -( distinguish it from arbitrary output generated by shell) s -5 393 M -( initialization scripts etc. This spurious output from the shell may) s -5 382 M -( be filtered out either at the server or at the client.) s -5 360 M -( The server SHOULD not halt the execution of the protocol stack when) s -5 349 M -( starting a shell or a program. All input and output from these SHOULD) s -5 338 M -( be redirected to the channel or to the encrypted tunnel.) s -5 316 M -( It is RECOMMENDED to request and check the reply for these messages.) s -5 305 M -( The client SHOULD ignore these messages.) s -5 283 M -( Subsystem names follow the DNS extensibility naming convention) s -5 272 M -( outlined in [SSH-ARCH].) s -5 250 M -(6.6 Session Data Transfer) s -5 228 M -( Data transfer for a session is done using SSH_MSG_CHANNEL_DATA and) s -5 217 M -( SSH_MSG_CHANNEL_EXTENDED_DATA packets and the window mechanism. The) s -5 206 M -( extended data type SSH_EXTENDED_DATA_STDERR has been defined for) s -5 195 M -( stderr data.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 11]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 12 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -(6.7 Window Dimension Change Message) s -5 668 M -( When the window \(terminal\) size changes on the client side, it MAY) s -5 657 M -( send a message to the other side to inform it of the new dimensions.) s -5 635 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 624 M -( uint32 recipient_channel) s -5 613 M -( string "window-change") s -5 602 M -( boolean FALSE) s -5 591 M -( uint32 terminal width, columns) s -5 580 M -( uint32 terminal height, rows) s -5 569 M -( uint32 terminal width, pixels) s -5 558 M -( uint32 terminal height, pixels) s -5 536 M -( No response SHOULD be sent to this message.) s -5 514 M -(6.8 Local Flow Control) s -5 492 M -( On many systems, it is possible to determine if a pseudo-terminal is) s -5 481 M -( using control-S/control-Q flow control. When flow control is) s -5 470 M -( allowed, it is often desirable to do the flow control at the client) s -5 459 M -( end to speed up responses to user requests. This is facilitated by) s -5 448 M -( the following notification. Initially, the server is responsible for) s -5 437 M -( flow control. \(Here, again, client means the side originating the) s -5 426 M -( session, and server means the other side.\)) s -5 404 M -( The message below is used by the server to inform the client when it) s -5 393 M -( can or cannot perform flow control \(control-S/control-Q processing\).) s -5 382 M -( If `client can do' is TRUE, the client is allowed to do flow control) s -5 371 M -( using control-S and control-Q. The client MAY ignore this message.) s -5 349 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 338 M -( uint32 recipient channel) s -5 327 M -( string "xon-xoff") s -5 316 M -( boolean FALSE) s -5 305 M -( boolean client can do) s -5 283 M -( No response is sent to this message.) s -5 261 M -(6.9 Signals) s -5 239 M -( A signal can be delivered to the remote process/service using the) s -5 228 M -( following message. Some systems may not implement signals, in which) s -5 217 M -( case they SHOULD ignore this message.) s -5 195 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 184 M -( uint32 recipient channel) s -5 173 M -( string "signal") s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 12]) s -_R -S -PStoPSsaved restore -%%Page: (12,13) 7 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 13 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( boolean FALSE) s -5 679 M -( string signal name without the "SIG" prefix.) s -5 657 M -( Signal names will be encoded as discussed in the "exit-signal") s -5 646 M -( SSH_MSG_CHANNEL_REQUEST.) s -5 624 M -(6.10 Returning Exit Status) s -5 602 M -( When the command running at the other end terminates, the following) s -5 591 M -( message can be sent to return the exit status of the command.) s -5 580 M -( Returning the status is RECOMMENDED. No acknowledgment is sent for) s -5 569 M -( this message. The channel needs to be closed with) s -5 558 M -( SSH_MSG_CHANNEL_CLOSE after this message.) s -5 536 M -( The client MAY ignore these messages.) s -5 514 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 503 M -( uint32 recipient_channel) s -5 492 M -( string "exit-status") s -5 481 M -( boolean FALSE) s -5 470 M -( uint32 exit_status) s -5 448 M -( The remote command may also terminate violently due to a signal.) s -5 437 M -( Such a condition can be indicated by the following message. A zero) s -5 426 M -( exit_status usually means that the command terminated successfully.) s -5 404 M -( byte SSH_MSG_CHANNEL_REQUEST) s -5 393 M -( uint32 recipient channel) s -5 382 M -( string "exit-signal") s -5 371 M -( boolean FALSE) s -5 360 M -( string signal name without the "SIG" prefix.) s -5 349 M -( boolean core dumped) s -5 338 M -( string error message \(ISO-10646 UTF-8\)) s -5 327 M -( string language tag \(as defined in [RFC3066]\)) s -5 305 M -( The signal name is one of the following \(these are from [POSIX]\)) s -5 283 M -( ABRT) s -5 272 M -( ALRM) s -5 261 M -( FPE) s -5 250 M -( HUP) s -5 239 M -( ILL) s -5 228 M -( INT) s -5 217 M -( KILL) s -5 206 M -( PIPE) s -5 195 M -( QUIT) s -5 184 M -( SEGV) s -5 173 M -( TERM) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 13]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 14 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( USR1) s -5 679 M -( USR2) s -5 657 M -( Additional signal names MAY be sent in the format "sig-name@xyz",) s -5 646 M -( where `sig-name' and `xyz' may be anything a particular implementor) s -5 635 M -( wants \(except the `@' sign\). However, it is suggested that if a) s -5 624 M -( `configure' script is used, the non-standard signal names it finds be) s -5 613 M -( encoded as "[email protected]", where `SIG' is the signal name) s -5 602 M -( without the "SIG" prefix, and `xyz' be the host type, as determined) s -5 591 M -( by `config.guess'.) s -5 569 M -( The `error message' contains an additional explanation of the error) s -5 558 M -( message. The message may consist of multiple lines. The client) s -5 547 M -( software MAY display this message to the user. If this is done, the) s -5 536 M -( client software should take the precautions discussed in [SSH-ARCH].) s -5 514 M -(7. TCP/IP Port Forwarding) s -5 492 M -(7.1 Requesting Port Forwarding) s -5 470 M -( A party need not explicitly request forwardings from its own end to) s -5 459 M -( the other direction. However, if it wishes that connections to a) s -5 448 M -( port on the other side be forwarded to the local side, it must) s -5 437 M -( explicitly request this.) s -5 404 M -( byte SSH_MSG_GLOBAL_REQUEST) s -5 393 M -( string "tcpip-forward") s -5 382 M -( boolean want reply) s -5 371 M -( string address to bind \(e.g. "0.0.0.0"\)) s -5 360 M -( uint32 port number to bind) s -5 338 M -( `Address to bind' and `port number to bind' specify the IP address) s -5 327 M -( and port to which the socket to be listened is bound. The address) s -5 316 M -( should be "0.0.0.0" if connections are allowed from anywhere. \(Note) s -5 305 M -( that the client can still filter connections based on information) s -5 294 M -( passed in the open request.\)) s -5 272 M -( Implementations should only allow forwarding privileged ports if the) s -5 261 M -( user has been authenticated as a privileged user.) s -5 239 M -( Client implementations SHOULD reject these messages; they are) s -5 228 M -( normally only sent by the client.) s -5 195 M -( If a client passes 0 as port number to bind and has want reply TRUE) s -5 184 M -( then the server allocates the next available unprivileged port number) s -5 173 M -( and replies with the following message, otherwise there is no) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 14]) s -_R -S -PStoPSsaved restore -%%Page: (14,15) 8 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 15 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( response specific data.) s -5 657 M -( byte SSH_MSG_GLOBAL_REQUEST_SUCCESS) s -5 646 M -( uint32 port that was bound on the server) s -5 624 M -( A port forwarding can be cancelled with the following message. Note) s -5 613 M -( that channel open requests may be received until a reply to this) s -5 602 M -( message is received.) s -5 580 M -( byte SSH_MSG_GLOBAL_REQUEST) s -5 569 M -( string "cancel-tcpip-forward") s -5 558 M -( boolean want reply) s -5 547 M -( string address_to_bind \(e.g. "127.0.0.1"\)) s -5 536 M -( uint32 port number to bind) s -5 514 M -( Client implementations SHOULD reject these messages; they are) s -5 503 M -( normally only sent by the client.) s -5 481 M -(7.2 TCP/IP Forwarding Channels) s -5 459 M -( When a connection comes to a port for which remote forwarding has) s -5 448 M -( been requested, a channel is opened to forward the port to the other) s -5 437 M -( side.) s -5 415 M -( byte SSH_MSG_CHANNEL_OPEN) s -5 404 M -( string "forwarded-tcpip") s -5 393 M -( uint32 sender channel) s -5 382 M -( uint32 initial window size) s -5 371 M -( uint32 maximum packet size) s -5 360 M -( string address that was connected) s -5 349 M -( uint32 port that was connected) s -5 338 M -( string originator IP address) s -5 327 M -( uint32 originator port) s -5 305 M -( Implementations MUST reject these messages unless they have) s -5 294 M -( previously requested a remote TCP/IP port forwarding with the given) s -5 283 M -( port number.) s -5 261 M -( When a connection comes to a locally forwarded TCP/IP port, the) s -5 250 M -( following packet is sent to the other side. Note that these messages) s -5 239 M -( MAY be sent also for ports for which no forwarding has been) s -5 228 M -( explicitly requested. The receiving side must decide whether to) s -5 217 M -( allow the forwarding.) s -5 195 M -( byte SSH_MSG_CHANNEL_OPEN) s -5 184 M -( string "direct-tcpip") s -5 173 M -( uint32 sender channel) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 15]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 16 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( uint32 initial window size) s -5 679 M -( uint32 maximum packet size) s -5 668 M -( string host to connect) s -5 657 M -( uint32 port to connect) s -5 646 M -( string originator IP address) s -5 635 M -( uint32 originator port) s -5 613 M -( `Host to connect' and `port to connect' specify the TCP/IP host and) s -5 602 M -( port where the recipient should connect the channel. `Host to) s -5 591 M -( connect' may be either a domain name or a numeric IP address.) s -5 569 M -( `Originator IP address' is the numeric IP address of the machine) s -5 558 M -( where the connection request comes from, and `originator port' is the) s -5 547 M -( port on the originator host from where the connection came from.) s -5 525 M -( Forwarded TCP/IP channels are independent of any sessions, and) s -5 514 M -( closing a session channel does not in any way imply that forwarded) s -5 503 M -( connections should be closed.) s -5 481 M -( Client implementations SHOULD reject direct TCP/IP open requests for) s -5 470 M -( security reasons.) s -5 448 M -(8. Encoding of Terminal Modes) s -5 426 M -( Terminal modes \(as passed in a pty request\) are encoded into a byte) s -5 415 M -( stream. It is intended that the coding be portable across different) s -5 404 M -( environments.) s -5 382 M -( The tty mode description is a stream of bytes. The stream consists) s -5 371 M -( of opcode-argument pairs. It is terminated by opcode TTY_OP_END \(0\).) s -5 360 M -( Opcodes 1 to 159 have a single uint32 argument. Opcodes 160 to 255) s -5 349 M -( are not yet defined, and cause parsing to stop \(they should only be) s -5 338 M -( used after any other data\).) s -5 316 M -( The client SHOULD put in the stream any modes it knows about, and the) s -5 305 M -( server MAY ignore any modes it does not know about. This allows some) s -5 294 M -( degree of machine-independence, at least between systems that use a) s -5 283 M -( POSIX-like tty interface. The protocol can support other systems as) s -5 272 M -( well, but the client may need to fill reasonable values for a number) s -5 261 M -( of parameters so the server pty gets set to a reasonable mode \(the) s -5 250 M -( server leaves all unspecified mode bits in their default values, and) s -5 239 M -( only some combinations make sense\).) s -5 217 M -( The following opcodes have been defined. The naming of opcodes) s -5 206 M -( mostly follows the POSIX terminal mode flags.) s -5 184 M -( 0 TTY_OP_END Indicates end of options.) s -5 173 M -( 1 VINTR Interrupt character; 255 if none. Similarly for the) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 16]) s -_R -S -PStoPSsaved restore -%%Page: (16,17) 9 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 17 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( other characters. Not all of these characters are) s -5 679 M -( supported on all systems.) s -5 668 M -( 2 VQUIT The quit character \(sends SIGQUIT signal on POSIX) s -5 657 M -( systems\).) s -5 646 M -( 3 VERASE Erase the character to left of the cursor.) s -5 635 M -( 4 VKILL Kill the current input line.) s -5 624 M -( 5 VEOF End-of-file character \(sends EOF from the terminal\).) s -5 613 M -( 6 VEOL End-of-line character in addition to carriage return) s -5 602 M -( and/or linefeed.) s -5 591 M -( 7 VEOL2 Additional end-of-line character.) s -5 580 M -( 8 VSTART Continues paused output \(normally control-Q\).) s -5 569 M -( 9 VSTOP Pauses output \(normally control-S\).) s -5 558 M -( 10 VSUSP Suspends the current program.) s -5 547 M -( 11 VDSUSP Another suspend character.) s -5 536 M -( 12 VREPRINT Reprints the current input line.) s -5 525 M -( 13 VWERASE Erases a word left of cursor.) s -5 514 M -( 14 VLNEXT Enter the next character typed literally, even if it) s -5 503 M -( is a special character) s -5 492 M -( 15 VFLUSH Character to flush output.) s -5 481 M -( 16 VSWTCH Switch to a different shell layer.) s -5 470 M -( 17 VSTATUS Prints system status line \(load, command, pid etc\).) s -5 459 M -( 18 VDISCARD Toggles the flushing of terminal output.) s -5 448 M -( 30 IGNPAR The ignore parity flag. The parameter SHOULD be 0 if) s -5 437 M -( this flag is FALSE set, and 1 if it is TRUE.) s -5 426 M -( 31 PARMRK Mark parity and framing errors.) s -5 415 M -( 32 INPCK Enable checking of parity errors.) s -5 404 M -( 33 ISTRIP Strip 8th bit off characters.) s -5 393 M -( 34 INLCR Map NL into CR on input.) s -5 382 M -( 35 IGNCR Ignore CR on input.) s -5 371 M -( 36 ICRNL Map CR to NL on input.) s -5 360 M -( 37 IUCLC Translate uppercase characters to lowercase.) s -5 349 M -( 38 IXON Enable output flow control.) s -5 338 M -( 39 IXANY Any char will restart after stop.) s -5 327 M -( 40 IXOFF Enable input flow control.) s -5 316 M -( 41 IMAXBEL Ring bell on input queue full.) s -5 305 M -( 50 ISIG Enable signals INTR, QUIT, [D]SUSP.) s -5 294 M -( 51 ICANON Canonicalize input lines.) s -5 283 M -( 52 XCASE Enable input and output of uppercase characters by) s -5 272 M -( preceding their lowercase equivalents with `\\'.) s -5 261 M -( 53 ECHO Enable echoing.) s -5 250 M -( 54 ECHOE Visually erase chars.) s -5 239 M -( 55 ECHOK Kill character discards current line.) s -5 228 M -( 56 ECHONL Echo NL even if ECHO is off.) s -5 217 M -( 57 NOFLSH Don't flush after interrupt.) s -5 206 M -( 58 TOSTOP Stop background jobs from output.) s -5 195 M -( 59 IEXTEN Enable extensions.) s -5 184 M -( 60 ECHOCTL Echo control characters as ^\(Char\).) s -5 173 M -( 61 ECHOKE Visual erase for line kill.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 17]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 18 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( 62 PENDIN Retype pending input.) s -5 679 M -( 70 OPOST Enable output processing.) s -5 668 M -( 71 OLCUC Convert lowercase to uppercase.) s -5 657 M -( 72 ONLCR Map NL to CR-NL.) s -5 646 M -( 73 OCRNL Translate carriage return to newline \(output\).) s -5 635 M -( 74 ONOCR Translate newline to carriage return-newline) s -5 624 M -( \(output\).) s -5 613 M -( 75 ONLRET Newline performs a carriage return \(output\).) s -5 602 M -( 90 CS7 7 bit mode.) s -5 591 M -( 91 CS8 8 bit mode.) s -5 580 M -( 92 PARENB Parity enable.) s -5 569 M -( 93 PARODD Odd parity, else even.) s -5 547 M -( 128 TTY_OP_ISPEED Specifies the input baud rate in bits per second.) s -5 536 M -( 129 TTY_OP_OSPEED Specifies the output baud rate in bits per second.) s -5 503 M -(9. Summary of Message Numbers) s -5 481 M -( #define SSH_MSG_GLOBAL_REQUEST 80) s -5 470 M -( #define SSH_MSG_REQUEST_SUCCESS 81) s -5 459 M -( #define SSH_MSG_REQUEST_FAILURE 82) s -5 448 M -( #define SSH_MSG_CHANNEL_OPEN 90) s -5 437 M -( #define SSH_MSG_CHANNEL_OPEN_CONFIRMATION 91) s -5 426 M -( #define SSH_MSG_CHANNEL_OPEN_FAILURE 92) s -5 415 M -( #define SSH_MSG_CHANNEL_WINDOW_ADJUST 93) s -5 404 M -( #define SSH_MSG_CHANNEL_DATA 94) s -5 393 M -( #define SSH_MSG_CHANNEL_EXTENDED_DATA 95) s -5 382 M -( #define SSH_MSG_CHANNEL_EOF 96) s -5 371 M -( #define SSH_MSG_CHANNEL_CLOSE 97) s -5 360 M -( #define SSH_MSG_CHANNEL_REQUEST 98) s -5 349 M -( #define SSH_MSG_CHANNEL_SUCCESS 99) s -5 338 M -( #define SSH_MSG_CHANNEL_FAILURE 100) s -5 305 M -(10. Security Considerations) s -5 283 M -( This protocol is assumed to run on top of a secure, authenticated) s -5 272 M -( transport. User authentication and protection against network-level) s -5 261 M -( attacks are assumed to be provided by the underlying protocols.) s -5 239 M -( It is RECOMMENDED that implementations disable all the potentially) s -5 228 M -( dangerous features \(e.g. agent forwarding, X11 forwarding, and TCP/IP) s -5 217 M -( forwarding\) if the host key has changed.) s -5 195 M -( Full security considerations for this protocol are provided in) s -5 184 M -( Section 8 of [SSH-ARCH]) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 18]) s -_R -S -PStoPSsaved restore -%%Page: (18,19) 10 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 19 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -(11. iana cONSiderations) s -5 668 M -( This document is part of a set, the IANA considerations for the SSH) s -5 657 M -( protocol as defined in [SSH-ARCH], [SSH-TRANS], [SSH-USERAUTH],) s -5 646 M -( [SSH-CONNECT] are detailed in [SSH-NUMBERS].) s -5 624 M -(12. Intellectual Property) s -5 602 M -( The IETF takes no position regarding the validity or scope of any) s -5 591 M -( intellectual property or other rights that might be claimed to) s -5 580 M -( pertain to the implementation or use of the technology described in) s -5 569 M -( this document or the extent to which any license under such rights) s -5 558 M -( might or might not be available; neither does it represent that it) s -5 547 M -( has made any effort to identify any such rights. Information on the) s -5 536 M -( IETF's procedures with respect to rights in standards-track and) s -5 525 M -( standards-related documentation can be found in BCP-11. Copies of) s -5 514 M -( claims of rights made available for publication and any assurances of) s -5 503 M -( licenses to be made available, or the result of an attempt made to) s -5 492 M -( obtain a general license or permission for the use of such) s -5 481 M -( proprietary rights by implementers or users of this specification can) s -5 470 M -( be obtained from the IETF Secretariat.) s -5 448 M -( The IETF has been notified of intellectual property rights claimed in) s -5 437 M -( regard to some or all of the specification contained in this) s -5 426 M -( document. For more information consult the online list of claimed) s -5 415 M -( rights.) s -5 393 M -(Normative References) s -5 371 M -( [SSH-ARCH]) s -5 360 M -( Ylonen, T., "SSH Protocol Architecture", I-D) s -5 349 M -( draft-ietf-architecture-15.txt, Oct 2003.) s -5 327 M -( [SSH-TRANS]) s -5 316 M -( Ylonen, T., "SSH Transport Layer Protocol", I-D) s -5 305 M -( draft-ietf-transport-17.txt, Oct 2003.) s -5 283 M -( [SSH-USERAUTH]) s -5 272 M -( Ylonen, T., "SSH Authentication Protocol", I-D) s -5 261 M -( draft-ietf-userauth-18.txt, Oct 2003.) s -5 239 M -( [SSH-CONNECT]) s -5 228 M -( Ylonen, T., "SSH Connection Protocol", I-D) s -5 217 M -( draft-ietf-connect-18.txt, Oct 2003.) s -5 195 M -( [SSH-NUMBERS]) s -5 184 M -( Lehtinen, S. and D. Moffat, "SSH Protocol Assigned) s -5 173 M -( Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 19]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 20 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( 2003.) s -5 668 M -( [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate) s -5 657 M -( Requirement Levels", BCP 14, RFC 2119, March 1997.) s -5 635 M -(Informative References) s -5 613 M -( [RFC3066] Alvestrand, H., "Tags for the Identification of) s -5 602 M -( Languages", BCP 47, RFC 3066, January 2001.) s -5 580 M -( [RFC1884] Hinden, R. and S. Deering, "IP Version 6 Addressing) s -5 569 M -( Architecture", RFC 1884, December 1995.) s -5 547 M -( [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO) s -5 536 M -( 10646", RFC 2279, January 1998.) s -5 514 M -( [SCHEIFLER]) s -5 503 M -( Scheifler, R., "X Window System : The Complete Reference) s -5 492 M -( to Xlib, X Protocol, Icccm, Xlfd, 3rd edition.", Digital) s -5 481 M -( Press ISBN 1555580882, Feburary 1992.) s -5 459 M -( [POSIX] ISO/IEC, 9945-1., "Information technology -- Portable) s -5 448 M -( Operating System Interface \(POSIX\)-Part 1: System) s -5 437 M -( Application Program Interface \(API\) C Language", ANSI/IEE) s -5 426 M -( Std 1003.1, July 1996.) s -5 393 M -(Authors' Addresses) s -5 371 M -( Tatu Ylonen) s -5 360 M -( SSH Communications Security Corp) s -5 349 M -( Fredrikinkatu 42) s -5 338 M -( HELSINKI FIN-00100) s -5 327 M -( Finland) s -5 305 M -( EMail: [email protected]) s -5 272 M -( Darren J. Moffat \(editor\)) s -5 261 M -( Sun Microsystems, Inc) s -5 250 M -( 17 Network Circle) s -5 239 M -( Menlo Park CA 94025) s -5 228 M -( USA) s -5 206 M -( EMail: [email protected]) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 20]) s -_R -S -PStoPSsaved restore -%%Page: (20,21) 11 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 21 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -(Intellectual Property Statement) s -5 668 M -( The IETF takes no position regarding the validity or scope of any) s -5 657 M -( intellectual property or other rights that might be claimed to) s -5 646 M -( pertain to the implementation or use of the technology described in) s -5 635 M -( this document or the extent to which any license under such rights) s -5 624 M -( might or might not be available; neither does it represent that it) s -5 613 M -( has made any effort to identify any such rights. Information on the) s -5 602 M -( IETF's procedures with respect to rights in standards-track and) s -5 591 M -( standards-related documentation can be found in BCP-11. Copies of) s -5 580 M -( claims of rights made available for publication and any assurances of) s -5 569 M -( licenses to be made available, or the result of an attempt made to) s -5 558 M -( obtain a general license or permission for the use of such) s -5 547 M -( proprietary rights by implementors or users of this specification can) s -5 536 M -( be obtained from the IETF Secretariat.) s -5 514 M -( The IETF invites any interested party to bring to its attention any) s -5 503 M -( copyrights, patents or patent applications, or other proprietary) s -5 492 M -( rights which may cover technology that may be required to practice) s -5 481 M -( this standard. Please address the information to the IETF Executive) s -5 470 M -( Director.) s -5 448 M -( The IETF has been notified of intellectual property rights claimed in) s -5 437 M -( regard to some or all of the specification contained in this) s -5 426 M -( document. For more information consult the online list of claimed) s -5 415 M -( rights.) s -5 382 M -(Full Copyright Statement) s -5 360 M -( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s -5 338 M -( This document and translations of it may be copied and furnished to) s -5 327 M -( others, and derivative works that comment on or otherwise explain it) s -5 316 M -( or assist in its implementation may be prepared, copied, published) s -5 305 M -( and distributed, in whole or in part, without restriction of any) s -5 294 M -( kind, provided that the above copyright notice and this paragraph are) s -5 283 M -( included on all such copies and derivative works. However, this) s -5 272 M -( document itself may not be modified in any way, such as by removing) s -5 261 M -( the copyright notice or references to the Internet Society or other) s -5 250 M -( Internet organizations, except as needed for the purpose of) s -5 239 M -( developing Internet standards in which case the procedures for) s -5 228 M -( copyrights defined in the Internet Standards process must be) s -5 217 M -( followed, or as required to translate it into languages other than) s -5 206 M -( English.) s -5 184 M -( The limited permissions granted above are perpetual and will not be) s -5 173 M -( revoked by the Internet Society or its successors or assignees.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 21]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 22 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Connection Protocol Oct 2003) s -5 690 M -( This document and the information contained herein is provided on an) s -5 679 M -( "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING) s -5 668 M -( TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING) s -5 657 M -( BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION) s -5 646 M -( HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF) s -5 635 M -( MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.) s -5 602 M -(Acknowledgment) s -5 580 M -( Funding for the RFC Editor function is currently provided by the) s -5 569 M -( Internet Society.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 22]) s -_R -S -PStoPSsaved restore -%%Trailer -%%Pages: 22 -%%DocumentNeededResources: font Courier-Bold Courier -%%EOF diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-connect-18.txt b/lib/ssh/doc/standard/draft-ietf-secsh-connect-18.txt deleted file mode 100644 index 1cb8ad6409..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-connect-18.txt +++ /dev/null @@ -1,1232 +0,0 @@ - - - -Network Working Group T. Ylonen -Internet-Draft SSH Communications Security Corp -Expires: March 31, 2004 D. Moffat, Editor, Ed. - Sun Microsystems, Inc - Oct 2003 - - - SSH Connection Protocol - draft-ietf-secsh-connect-18.txt - -Status of this Memo - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that other - groups may also distribute working documents as Internet-Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at http:// - www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on March 31, 2004. - -Copyright Notice - - Copyright (C) The Internet Society (2003). All Rights Reserved. - -Abstract - - SSH is a protocol for secure remote login and other secure network - services over an insecure network. - - This document describes the SSH Connection Protocol. It provides - interactive login sessions, remote execution of commands, forwarded - TCP/IP connections, and forwarded X11 connections. All of these - channels are multiplexed into a single encrypted tunnel. - - The SSH Connection Protocol has been designed to run on top of the - SSH transport layer and user authentication protocols. - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 1] - -Internet-Draft SSH Connection Protocol Oct 2003 - - -Table of Contents - - 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3. Conventions Used in This Document . . . . . . . . . . . . . 3 - 4. Global Requests . . . . . . . . . . . . . . . . . . . . . . 3 - 5. Channel Mechanism . . . . . . . . . . . . . . . . . . . . . 4 - 5.1 Opening a Channel . . . . . . . . . . . . . . . . . . . . . 4 - 5.2 Data Transfer . . . . . . . . . . . . . . . . . . . . . . . 5 - 5.3 Closing a Channel . . . . . . . . . . . . . . . . . . . . . 6 - 5.4 Channel-Specific Requests . . . . . . . . . . . . . . . . . 7 - 6. Interactive Sessions . . . . . . . . . . . . . . . . . . . . 8 - 6.1 Opening a Session . . . . . . . . . . . . . . . . . . . . . 8 - 6.2 Requesting a Pseudo-Terminal . . . . . . . . . . . . . . . . 8 - 6.3 X11 Forwarding . . . . . . . . . . . . . . . . . . . . . . . 9 - 6.3.1 Requesting X11 Forwarding . . . . . . . . . . . . . . . . . 9 - 6.3.2 X11 Channels . . . . . . . . . . . . . . . . . . . . . . . . 10 - 6.4 Environment Variable Passing . . . . . . . . . . . . . . . . 10 - 6.5 Starting a Shell or a Command . . . . . . . . . . . . . . . 10 - 6.6 Session Data Transfer . . . . . . . . . . . . . . . . . . . 11 - 6.7 Window Dimension Change Message . . . . . . . . . . . . . . 12 - 6.8 Local Flow Control . . . . . . . . . . . . . . . . . . . . . 12 - 6.9 Signals . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 6.10 Returning Exit Status . . . . . . . . . . . . . . . . . . . 13 - 7. TCP/IP Port Forwarding . . . . . . . . . . . . . . . . . . . 14 - 7.1 Requesting Port Forwarding . . . . . . . . . . . . . . . . . 14 - 7.2 TCP/IP Forwarding Channels . . . . . . . . . . . . . . . . . 15 - 8. Encoding of Terminal Modes . . . . . . . . . . . . . . . . . 16 - 9. Summary of Message Numbers . . . . . . . . . . . . . . . . . 18 - 10. Security Considerations . . . . . . . . . . . . . . . . . . 18 - 11. iana cONSiderations . . . . . . . . . . . . . . . . . . . . 19 - 12. Intellectual Property . . . . . . . . . . . . . . . . . . . 19 - Normative References . . . . . . . . . . . . . . . . . . . . 19 - Informative References . . . . . . . . . . . . . . . . . . . 20 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 20 - Intellectual Property and Copyright Statements . . . . . . . 21 - - - - - - - - - - - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 2] - -Internet-Draft SSH Connection Protocol Oct 2003 - - -1. Contributors - - The major original contributors of this document were: Tatu Ylonen, - Tero Kivinen, Timo J. Rinne, Sami Lehtinen (all of SSH Communications - Security Corp), and Markku-Juhani O. Saarinen (University of - Jyvaskyla) - - The document editor is: [email protected]. Comments on this - internet draft should be sent to the IETF SECSH working group, - details at: http://ietf.org/html.charters/secsh-charter.html - -2. Introduction - - The SSH Connection Protocol has been designed to run on top of the - SSH transport layer and user authentication protocols. It provides - interactive login sessions, remote execution of commands, forwarded - TCP/IP connections, and forwarded X11 connections. The service name - for this protocol is "ssh-connection". - - This document should be read only after reading the SSH architecture - document [SSH-ARCH]. This document freely uses terminology and - notation from the architecture document without reference or further - explanation. - -3. Conventions Used in This Document - - The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", - and "MAY" that appear in this document are to be interpreted as - described in [RFC2119]. - - The used data types and terminology are specified in the architecture - document [SSH-ARCH]. - - The architecture document also discusses the algorithm naming - conventions that MUST be used with the SSH protocols. - -4. Global Requests - - There are several kinds of requests that affect the state of the - remote end "globally", independent of any channels. An example is a - request to start TCP/IP forwarding for a specific port. All such - requests use the following format. - - byte SSH_MSG_GLOBAL_REQUEST - string request name (restricted to US-ASCII) - boolean want reply - ... request-specific data follows - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 3] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - Request names follow the DNS extensibility naming convention outlined - in [SSH-ARCH]. - - The recipient will respond to this message with - SSH_MSG_REQUEST_SUCCESS or SSH_MSG_REQUEST_FAILURE if `want reply' is - TRUE. - - byte SSH_MSG_REQUEST_SUCCESS - ..... response specific data - - Usually the response specific data is non-existent. - - If the recipient does not recognize or support the request, it simply - responds with SSH_MSG_REQUEST_FAILURE. - - byte SSH_MSG_REQUEST_FAILURE - - -5. Channel Mechanism - - All terminal sessions, forwarded connections, etc. are channels. - Either side may open a channel. Multiple channels are multiplexed - into a single connection. - - Channels are identified by numbers at each end. The number referring - to a channel may be different on each side. Requests to open a - channel contain the sender's channel number. Any other - channel-related messages contain the recipient's channel number for - the channel. - - Channels are flow-controlled. No data may be sent to a channel until - a message is received to indicate that window space is available. - -5.1 Opening a Channel - - When either side wishes to open a new channel, it allocates a local - number for the channel. It then sends the following message to the - other side, and includes the local channel number and initial window - size in the message. - - byte SSH_MSG_CHANNEL_OPEN - string channel type (restricted to US-ASCII) - uint32 sender channel - uint32 initial window size - uint32 maximum packet size - ... channel type specific data follows - - The channel type is a name as described in the SSH architecture - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 4] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - document, with similar extension mechanisms. `sender channel' is a - local identifier for the channel used by the sender of this message. - `initial window size' specifies how many bytes of channel data can be - sent to the sender of this message without adjusting the window. - `Maximum packet size' specifies the maximum size of an individual - data packet that can be sent to the sender (for example, one might - want to use smaller packets for interactive connections to get better - interactive response on slow links). - - The remote side then decides whether it can open the channel, and - responds with either - - byte SSH_MSG_CHANNEL_OPEN_CONFIRMATION - uint32 recipient channel - uint32 sender channel - uint32 initial window size - uint32 maximum packet size - ... channel type specific data follows - - where `recipient channel' is the channel number given in the original - open request, and `sender channel' is the channel number allocated by - the other side, or - - byte SSH_MSG_CHANNEL_OPEN_FAILURE - uint32 recipient channel - uint32 reason code - string additional textual information (ISO-10646 UTF-8 [RFC2279]) - string language tag (as defined in [RFC3066]) - - If the recipient of the SSH_MSG_CHANNEL_OPEN message does not support - the specified channel type, it simply responds with - SSH_MSG_CHANNEL_OPEN_FAILURE. The client MAY show the additional - information to the user. If this is done, the client software should - take the precautions discussed in [SSH-ARCH]. - - The following reason codes are defined: - - #define SSH_OPEN_ADMINISTRATIVELY_PROHIBITED 1 - #define SSH_OPEN_CONNECT_FAILED 2 - #define SSH_OPEN_UNKNOWN_CHANNEL_TYPE 3 - #define SSH_OPEN_RESOURCE_SHORTAGE 4 - - -5.2 Data Transfer - - The window size specifies how many bytes the other party can send - before it must wait for the window to be adjusted. Both parties use - the following message to adjust the window. - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 5] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - byte SSH_MSG_CHANNEL_WINDOW_ADJUST - uint32 recipient channel - uint32 bytes to add - - After receiving this message, the recipient MAY send the given number - of bytes more than it was previously allowed to send; the window size - is incremented. - - Data transfer is done with messages of the following type. - - byte SSH_MSG_CHANNEL_DATA - uint32 recipient channel - string data - - The maximum amount of data allowed is the current window size. The - window size is decremented by the amount of data sent. Both parties - MAY ignore all extra data sent after the allowed window is empty. - - Additionally, some channels can transfer several types of data. An - example of this is stderr data from interactive sessions. Such data - can be passed with SSH_MSG_CHANNEL_EXTENDED_DATA messages, where a - separate integer specifies the type of the data. The available types - and their interpretation depend on the type of the channel. - - byte SSH_MSG_CHANNEL_EXTENDED_DATA - uint32 recipient_channel - uint32 data_type_code - string data - - Data sent with these messages consumes the same window as ordinary - data. - - Currently, only the following type is defined. - - #define SSH_EXTENDED_DATA_STDERR 1 - - -5.3 Closing a Channel - - When a party will no longer send more data to a channel, it SHOULD - send SSH_MSG_CHANNEL_EOF. - - byte SSH_MSG_CHANNEL_EOF - uint32 recipient_channel - - No explicit response is sent to this message; however, the - application may send EOF to whatever is at the other end of the - channel. Note that the channel remains open after this message, and - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 6] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - more data may still be sent in the other direction. This message - does not consume window space and can be sent even if no window space - is available. - - When either party wishes to terminate the channel, it sends - SSH_MSG_CHANNEL_CLOSE. Upon receiving this message, a party MUST - send back a SSH_MSG_CHANNEL_CLOSE unless it has already sent this - message for the channel. The channel is considered closed for a - party when it has both sent and received SSH_MSG_CHANNEL_CLOSE, and - the party may then reuse the channel number. A party MAY send - SSH_MSG_CHANNEL_CLOSE without having sent or received - SSH_MSG_CHANNEL_EOF. - - byte SSH_MSG_CHANNEL_CLOSE - uint32 recipient_channel - - This message does not consume window space and can be sent even if no - window space is available. - - It is recommended that any data sent before this message is delivered - to the actual destination, if possible. - -5.4 Channel-Specific Requests - - Many channel types have extensions that are specific to that - particular channel type. An example is requesting a pty (pseudo - terminal) for an interactive session. - - All channel-specific requests use the following format. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string request type (restricted to US-ASCII) - boolean want reply - ... type-specific data - - If want reply is FALSE, no response will be sent to the request. - Otherwise, the recipient responds with either SSH_MSG_CHANNEL_SUCCESS - or SSH_MSG_CHANNEL_FAILURE, or request-specific continuation - messages. If the request is not recognized or is not supported for - the channel, SSH_MSG_CHANNEL_FAILURE is returned. - - This message does not consume window space and can be sent even if no - window space is available. Request types are local to each channel - type. - - The client is allowed to send further messages without waiting for - the response to the request. - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 7] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - request type names follow the DNS extensibility naming convention - outlined in [SSH-ARCH] - - byte SSH_MSG_CHANNEL_SUCCESS - uint32 recipient_channel - - - byte SSH_MSG_CHANNEL_FAILURE - uint32 recipient_channel - - These messages do not consume window space and can be sent even if no - window space is available. - -6. Interactive Sessions - - A session is a remote execution of a program. The program may be a - shell, an application, a system command, or some built-in subsystem. - It may or may not have a tty, and may or may not involve X11 - forwarding. Multiple sessions can be active simultaneously. - -6.1 Opening a Session - - A session is started by sending the following message. - - byte SSH_MSG_CHANNEL_OPEN - string "session" - uint32 sender channel - uint32 initial window size - uint32 maximum packet size - - Client implementations SHOULD reject any session channel open - requests to make it more difficult for a corrupt server to attack the - client. - -6.2 Requesting a Pseudo-Terminal - - A pseudo-terminal can be allocated for the session by sending the - following message. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient_channel - string "pty-req" - boolean want_reply - string TERM environment variable value (e.g., vt100) - uint32 terminal width, characters (e.g., 80) - uint32 terminal height, rows (e.g., 24) - uint32 terminal width, pixels (e.g., 640) - uint32 terminal height, pixels (e.g., 480) - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 8] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - string encoded terminal modes - - The encoding of terminal modes is described in Section Encoding of - Terminal Modes (Section 8). Zero dimension parameters MUST be - ignored. The character/row dimensions override the pixel dimensions - (when nonzero). Pixel dimensions refer to the drawable area of the - window. - - The dimension parameters are only informational. - - The client SHOULD ignore pty requests. - -6.3 X11 Forwarding - -6.3.1 Requesting X11 Forwarding - - X11 forwarding may be requested for a session by sending - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string "x11-req" - boolean want reply - boolean single connection - string x11 authentication protocol - string x11 authentication cookie - uint32 x11 screen number - - It is recommended that the authentication cookie that is sent be a - fake, random cookie, and that the cookie is checked and replaced by - the real cookie when a connection request is received. - - X11 connection forwarding should stop when the session channel is - closed; however, already opened forwardings should not be - automatically closed when the session channel is closed. - - If `single connection' is TRUE, only a single connection should be - forwarded. No more connections will be forwarded after the first, or - after the session channel has been closed. - - The "x11 authentication protocol" is the name of the X11 - authentication method used, e.g. "MIT-MAGIC-COOKIE-1". - - The x11 authentication cookie MUST be hexadecimal encoded. - - X Protocol is documented in [SCHEIFLER]. - - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 9] - -Internet-Draft SSH Connection Protocol Oct 2003 - - -6.3.2 X11 Channels - - X11 channels are opened with a channel open request. The resulting - channels are independent of the session, and closing the session - channel does not close the forwarded X11 channels. - - byte SSH_MSG_CHANNEL_OPEN - string "x11" - uint32 sender channel - uint32 initial window size - uint32 maximum packet size - string originator address (e.g. "192.168.7.38") - uint32 originator port - - The recipient should respond with SSH_MSG_CHANNEL_OPEN_CONFIRMATION - or SSH_MSG_CHANNEL_OPEN_FAILURE. - - Implementations MUST reject any X11 channel open requests if they - have not requested X11 forwarding. - -6.4 Environment Variable Passing - - Environment variables may be passed to the shell/command to be - started later. Uncontrolled setting of environment variables in a - privileged process can be a security hazard. It is recommended that - implementations either maintain a list of allowable variable names or - only set environment variables after the server process has dropped - sufficient privileges. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string "env" - boolean want reply - string variable name - string variable value - - -6.5 Starting a Shell or a Command - - Once the session has been set up, a program is started at the remote - end. The program can be a shell, an application program or a - subsystem with a host-independent name. Only one of these requests - can succeed per channel. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string "shell" - boolean want reply - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 10] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - This message will request the user's default shell (typically defined - in /etc/passwd in UNIX systems) to be started at the other end. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string "exec" - boolean want reply - string command - - This message will request the server to start the execution of the - given command. The command string may contain a path. Normal - precautions MUST be taken to prevent the execution of unauthorized - commands. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string "subsystem" - boolean want reply - string subsystem name - - This last form executes a predefined subsystem. It is expected that - these will include a general file transfer mechanism, and possibly - other features. Implementations may also allow configuring more such - mechanisms. As the user's shell is usually used to execute the - subsystem, it is advisable for the subsystem protocol to have a - "magic cookie" at the beginning of the protocol transaction to - distinguish it from arbitrary output generated by shell - initialization scripts etc. This spurious output from the shell may - be filtered out either at the server or at the client. - - The server SHOULD not halt the execution of the protocol stack when - starting a shell or a program. All input and output from these SHOULD - be redirected to the channel or to the encrypted tunnel. - - It is RECOMMENDED to request and check the reply for these messages. - The client SHOULD ignore these messages. - - Subsystem names follow the DNS extensibility naming convention - outlined in [SSH-ARCH]. - -6.6 Session Data Transfer - - Data transfer for a session is done using SSH_MSG_CHANNEL_DATA and - SSH_MSG_CHANNEL_EXTENDED_DATA packets and the window mechanism. The - extended data type SSH_EXTENDED_DATA_STDERR has been defined for - stderr data. - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 11] - -Internet-Draft SSH Connection Protocol Oct 2003 - - -6.7 Window Dimension Change Message - - When the window (terminal) size changes on the client side, it MAY - send a message to the other side to inform it of the new dimensions. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient_channel - string "window-change" - boolean FALSE - uint32 terminal width, columns - uint32 terminal height, rows - uint32 terminal width, pixels - uint32 terminal height, pixels - - No response SHOULD be sent to this message. - -6.8 Local Flow Control - - On many systems, it is possible to determine if a pseudo-terminal is - using control-S/control-Q flow control. When flow control is - allowed, it is often desirable to do the flow control at the client - end to speed up responses to user requests. This is facilitated by - the following notification. Initially, the server is responsible for - flow control. (Here, again, client means the side originating the - session, and server means the other side.) - - The message below is used by the server to inform the client when it - can or cannot perform flow control (control-S/control-Q processing). - If `client can do' is TRUE, the client is allowed to do flow control - using control-S and control-Q. The client MAY ignore this message. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string "xon-xoff" - boolean FALSE - boolean client can do - - No response is sent to this message. - -6.9 Signals - - A signal can be delivered to the remote process/service using the - following message. Some systems may not implement signals, in which - case they SHOULD ignore this message. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string "signal" - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 12] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - boolean FALSE - string signal name without the "SIG" prefix. - - Signal names will be encoded as discussed in the "exit-signal" - SSH_MSG_CHANNEL_REQUEST. - -6.10 Returning Exit Status - - When the command running at the other end terminates, the following - message can be sent to return the exit status of the command. - Returning the status is RECOMMENDED. No acknowledgment is sent for - this message. The channel needs to be closed with - SSH_MSG_CHANNEL_CLOSE after this message. - - The client MAY ignore these messages. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient_channel - string "exit-status" - boolean FALSE - uint32 exit_status - - The remote command may also terminate violently due to a signal. - Such a condition can be indicated by the following message. A zero - exit_status usually means that the command terminated successfully. - - byte SSH_MSG_CHANNEL_REQUEST - uint32 recipient channel - string "exit-signal" - boolean FALSE - string signal name without the "SIG" prefix. - boolean core dumped - string error message (ISO-10646 UTF-8) - string language tag (as defined in [RFC3066]) - - The signal name is one of the following (these are from [POSIX]) - - ABRT - ALRM - FPE - HUP - ILL - INT - KILL - PIPE - QUIT - SEGV - TERM - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 13] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - USR1 - USR2 - - Additional signal names MAY be sent in the format "sig-name@xyz", - where `sig-name' and `xyz' may be anything a particular implementor - wants (except the `@' sign). However, it is suggested that if a - `configure' script is used, the non-standard signal names it finds be - encoded as "[email protected]", where `SIG' is the signal name - without the "SIG" prefix, and `xyz' be the host type, as determined - by `config.guess'. - - The `error message' contains an additional explanation of the error - message. The message may consist of multiple lines. The client - software MAY display this message to the user. If this is done, the - client software should take the precautions discussed in [SSH-ARCH]. - -7. TCP/IP Port Forwarding - -7.1 Requesting Port Forwarding - - A party need not explicitly request forwardings from its own end to - the other direction. However, if it wishes that connections to a - port on the other side be forwarded to the local side, it must - explicitly request this. - - - byte SSH_MSG_GLOBAL_REQUEST - string "tcpip-forward" - boolean want reply - string address to bind (e.g. "0.0.0.0") - uint32 port number to bind - - `Address to bind' and `port number to bind' specify the IP address - and port to which the socket to be listened is bound. The address - should be "0.0.0.0" if connections are allowed from anywhere. (Note - that the client can still filter connections based on information - passed in the open request.) - - Implementations should only allow forwarding privileged ports if the - user has been authenticated as a privileged user. - - Client implementations SHOULD reject these messages; they are - normally only sent by the client. - - - If a client passes 0 as port number to bind and has want reply TRUE - then the server allocates the next available unprivileged port number - and replies with the following message, otherwise there is no - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 14] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - response specific data. - - - byte SSH_MSG_GLOBAL_REQUEST_SUCCESS - uint32 port that was bound on the server - - A port forwarding can be cancelled with the following message. Note - that channel open requests may be received until a reply to this - message is received. - - byte SSH_MSG_GLOBAL_REQUEST - string "cancel-tcpip-forward" - boolean want reply - string address_to_bind (e.g. "127.0.0.1") - uint32 port number to bind - - Client implementations SHOULD reject these messages; they are - normally only sent by the client. - -7.2 TCP/IP Forwarding Channels - - When a connection comes to a port for which remote forwarding has - been requested, a channel is opened to forward the port to the other - side. - - byte SSH_MSG_CHANNEL_OPEN - string "forwarded-tcpip" - uint32 sender channel - uint32 initial window size - uint32 maximum packet size - string address that was connected - uint32 port that was connected - string originator IP address - uint32 originator port - - Implementations MUST reject these messages unless they have - previously requested a remote TCP/IP port forwarding with the given - port number. - - When a connection comes to a locally forwarded TCP/IP port, the - following packet is sent to the other side. Note that these messages - MAY be sent also for ports for which no forwarding has been - explicitly requested. The receiving side must decide whether to - allow the forwarding. - - byte SSH_MSG_CHANNEL_OPEN - string "direct-tcpip" - uint32 sender channel - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 15] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - uint32 initial window size - uint32 maximum packet size - string host to connect - uint32 port to connect - string originator IP address - uint32 originator port - - `Host to connect' and `port to connect' specify the TCP/IP host and - port where the recipient should connect the channel. `Host to - connect' may be either a domain name or a numeric IP address. - - `Originator IP address' is the numeric IP address of the machine - where the connection request comes from, and `originator port' is the - port on the originator host from where the connection came from. - - Forwarded TCP/IP channels are independent of any sessions, and - closing a session channel does not in any way imply that forwarded - connections should be closed. - - Client implementations SHOULD reject direct TCP/IP open requests for - security reasons. - -8. Encoding of Terminal Modes - - Terminal modes (as passed in a pty request) are encoded into a byte - stream. It is intended that the coding be portable across different - environments. - - The tty mode description is a stream of bytes. The stream consists - of opcode-argument pairs. It is terminated by opcode TTY_OP_END (0). - Opcodes 1 to 159 have a single uint32 argument. Opcodes 160 to 255 - are not yet defined, and cause parsing to stop (they should only be - used after any other data). - - The client SHOULD put in the stream any modes it knows about, and the - server MAY ignore any modes it does not know about. This allows some - degree of machine-independence, at least between systems that use a - POSIX-like tty interface. The protocol can support other systems as - well, but the client may need to fill reasonable values for a number - of parameters so the server pty gets set to a reasonable mode (the - server leaves all unspecified mode bits in their default values, and - only some combinations make sense). - - The following opcodes have been defined. The naming of opcodes - mostly follows the POSIX terminal mode flags. - - 0 TTY_OP_END Indicates end of options. - 1 VINTR Interrupt character; 255 if none. Similarly for the - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 16] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - other characters. Not all of these characters are - supported on all systems. - 2 VQUIT The quit character (sends SIGQUIT signal on POSIX - systems). - 3 VERASE Erase the character to left of the cursor. - 4 VKILL Kill the current input line. - 5 VEOF End-of-file character (sends EOF from the terminal). - 6 VEOL End-of-line character in addition to carriage return - and/or linefeed. - 7 VEOL2 Additional end-of-line character. - 8 VSTART Continues paused output (normally control-Q). - 9 VSTOP Pauses output (normally control-S). - 10 VSUSP Suspends the current program. - 11 VDSUSP Another suspend character. - 12 VREPRINT Reprints the current input line. - 13 VWERASE Erases a word left of cursor. - 14 VLNEXT Enter the next character typed literally, even if it - is a special character - 15 VFLUSH Character to flush output. - 16 VSWTCH Switch to a different shell layer. - 17 VSTATUS Prints system status line (load, command, pid etc). - 18 VDISCARD Toggles the flushing of terminal output. - 30 IGNPAR The ignore parity flag. The parameter SHOULD be 0 if - this flag is FALSE set, and 1 if it is TRUE. - 31 PARMRK Mark parity and framing errors. - 32 INPCK Enable checking of parity errors. - 33 ISTRIP Strip 8th bit off characters. - 34 INLCR Map NL into CR on input. - 35 IGNCR Ignore CR on input. - 36 ICRNL Map CR to NL on input. - 37 IUCLC Translate uppercase characters to lowercase. - 38 IXON Enable output flow control. - 39 IXANY Any char will restart after stop. - 40 IXOFF Enable input flow control. - 41 IMAXBEL Ring bell on input queue full. - 50 ISIG Enable signals INTR, QUIT, [D]SUSP. - 51 ICANON Canonicalize input lines. - 52 XCASE Enable input and output of uppercase characters by - preceding their lowercase equivalents with `\'. - 53 ECHO Enable echoing. - 54 ECHOE Visually erase chars. - 55 ECHOK Kill character discards current line. - 56 ECHONL Echo NL even if ECHO is off. - 57 NOFLSH Don't flush after interrupt. - 58 TOSTOP Stop background jobs from output. - 59 IEXTEN Enable extensions. - 60 ECHOCTL Echo control characters as ^(Char). - 61 ECHOKE Visual erase for line kill. - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 17] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - 62 PENDIN Retype pending input. - 70 OPOST Enable output processing. - 71 OLCUC Convert lowercase to uppercase. - 72 ONLCR Map NL to CR-NL. - 73 OCRNL Translate carriage return to newline (output). - 74 ONOCR Translate newline to carriage return-newline - (output). - 75 ONLRET Newline performs a carriage return (output). - 90 CS7 7 bit mode. - 91 CS8 8 bit mode. - 92 PARENB Parity enable. - 93 PARODD Odd parity, else even. - - 128 TTY_OP_ISPEED Specifies the input baud rate in bits per second. - 129 TTY_OP_OSPEED Specifies the output baud rate in bits per second. - - -9. Summary of Message Numbers - - #define SSH_MSG_GLOBAL_REQUEST 80 - #define SSH_MSG_REQUEST_SUCCESS 81 - #define SSH_MSG_REQUEST_FAILURE 82 - #define SSH_MSG_CHANNEL_OPEN 90 - #define SSH_MSG_CHANNEL_OPEN_CONFIRMATION 91 - #define SSH_MSG_CHANNEL_OPEN_FAILURE 92 - #define SSH_MSG_CHANNEL_WINDOW_ADJUST 93 - #define SSH_MSG_CHANNEL_DATA 94 - #define SSH_MSG_CHANNEL_EXTENDED_DATA 95 - #define SSH_MSG_CHANNEL_EOF 96 - #define SSH_MSG_CHANNEL_CLOSE 97 - #define SSH_MSG_CHANNEL_REQUEST 98 - #define SSH_MSG_CHANNEL_SUCCESS 99 - #define SSH_MSG_CHANNEL_FAILURE 100 - - -10. Security Considerations - - This protocol is assumed to run on top of a secure, authenticated - transport. User authentication and protection against network-level - attacks are assumed to be provided by the underlying protocols. - - It is RECOMMENDED that implementations disable all the potentially - dangerous features (e.g. agent forwarding, X11 forwarding, and TCP/IP - forwarding) if the host key has changed. - - Full security considerations for this protocol are provided in - Section 8 of [SSH-ARCH] - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 18] - -Internet-Draft SSH Connection Protocol Oct 2003 - - -11. iana cONSiderations - - This document is part of a set, the IANA considerations for the SSH - protocol as defined in [SSH-ARCH], [SSH-TRANS], [SSH-USERAUTH], - [SSH-CONNECT] are detailed in [SSH-NUMBERS]. - -12. Intellectual Property - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementers or users of this specification can - be obtained from the IETF Secretariat. - - The IETF has been notified of intellectual property rights claimed in - regard to some or all of the specification contained in this - document. For more information consult the online list of claimed - rights. - -Normative References - - [SSH-ARCH] - Ylonen, T., "SSH Protocol Architecture", I-D - draft-ietf-architecture-15.txt, Oct 2003. - - [SSH-TRANS] - Ylonen, T., "SSH Transport Layer Protocol", I-D - draft-ietf-transport-17.txt, Oct 2003. - - [SSH-USERAUTH] - Ylonen, T., "SSH Authentication Protocol", I-D - draft-ietf-userauth-18.txt, Oct 2003. - - [SSH-CONNECT] - Ylonen, T., "SSH Connection Protocol", I-D - draft-ietf-connect-18.txt, Oct 2003. - - [SSH-NUMBERS] - Lehtinen, S. and D. Moffat, "SSH Protocol Assigned - Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 19] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - 2003. - - [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate - Requirement Levels", BCP 14, RFC 2119, March 1997. - -Informative References - - [RFC3066] Alvestrand, H., "Tags for the Identification of - Languages", BCP 47, RFC 3066, January 2001. - - [RFC1884] Hinden, R. and S. Deering, "IP Version 6 Addressing - Architecture", RFC 1884, December 1995. - - [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO - 10646", RFC 2279, January 1998. - - [SCHEIFLER] - Scheifler, R., "X Window System : The Complete Reference - to Xlib, X Protocol, Icccm, Xlfd, 3rd edition.", Digital - Press ISBN 1555580882, Feburary 1992. - - [POSIX] ISO/IEC, 9945-1., "Information technology -- Portable - Operating System Interface (POSIX)-Part 1: System - Application Program Interface (API) C Language", ANSI/IEE - Std 1003.1, July 1996. - - -Authors' Addresses - - Tatu Ylonen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - Darren J. Moffat (editor) - Sun Microsystems, Inc - 17 Network Circle - Menlo Park CA 94025 - USA - - EMail: [email protected] - - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 20] - -Internet-Draft SSH Connection Protocol Oct 2003 - - -Intellectual Property Statement - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementors or users of this specification can - be obtained from the IETF Secretariat. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights which may cover technology that may be required to practice - this standard. Please address the information to the IETF Executive - Director. - - The IETF has been notified of intellectual property rights claimed in - regard to some or all of the specification contained in this - document. For more information consult the online list of claimed - rights. - - -Full Copyright Statement - - Copyright (C) The Internet Society (2003). All Rights Reserved. - - This document and translations of it may be copied and furnished to - others, and derivative works that comment on or otherwise explain it - or assist in its implementation may be prepared, copied, published - and distributed, in whole or in part, without restriction of any - kind, provided that the above copyright notice and this paragraph are - included on all such copies and derivative works. However, this - document itself may not be modified in any way, such as by removing - the copyright notice or references to the Internet Society or other - Internet organizations, except as needed for the purpose of - developing Internet standards in which case the procedures for - copyrights defined in the Internet Standards process must be - followed, or as required to translate it into languages other than - English. - - The limited permissions granted above are perpetual and will not be - revoked by the Internet Society or its successors or assignees. - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 21] - -Internet-Draft SSH Connection Protocol Oct 2003 - - - This document and the information contained herein is provided on an - "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING - TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING - BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION - HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF - MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - -Acknowledgment - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 22]
\ No newline at end of file diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-02.2.ps b/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-02.2.ps deleted file mode 100644 index 06c91bf8cd..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-02.2.ps +++ /dev/null @@ -1,2853 +0,0 @@ -%!PS-Adobe-3.0 -%%BoundingBox: 75 0 595 747 -%%Title: Enscript Output -%%For: Magnus Thoang -%%Creator: GNU enscript 1.6.1 -%%CreationDate: Wed Nov 12 12:26:07 2003 -%%Orientation: Portrait -%%Pages: 15 0 -%%DocumentMedia: A4 595 842 0 () () -%%DocumentNeededResources: (atend) -%%EndComments -%%BeginProlog -%%BeginProcSet: PStoPS 1 15 -userdict begin -[/showpage/erasepage/copypage]{dup where{pop dup load - type/operatortype eq{1 array cvx dup 0 3 index cvx put - bind def}{pop}ifelse}{pop}ifelse}forall -[/letter/legal/executivepage/a4/a4small/b5/com10envelope - /monarchenvelope/c5envelope/dlenvelope/lettersmall/note - /folio/quarto/a5]{dup where{dup wcheck{exch{}put} - {pop{}def}ifelse}{pop}ifelse}forall -/setpagedevice {pop}bind 1 index where{dup wcheck{3 1 roll put} - 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matrix invertmatrix matrix concatmatrix - matrix invertmatrix put -%%EndSetup -%%Page: (0,1) 1 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 1 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 701 M -(Network Working Group T. Ylonen) s -5 690 M -(Internet-Draft S. Lehtinen) s -5 679 M -(Expires: April 1, 2002 SSH Communications Security Corp) s -5 668 M -( October 2001) s -5 635 M -( SSH File Transfer Protocol) s -5 624 M -( draft-ietf-secsh-filexfer-02.txt) s -5 602 M -(Status of this Memo) s -5 580 M -( This document is an Internet-Draft and is in full conformance with) s -5 569 M -( all provisions of Section 10 of RFC2026.) s -5 547 M -( Internet-Drafts are working documents of the Internet Engineering) s -5 536 M -( Task Force \(IETF\), its areas, and its working groups. Note that) s -5 525 M -( other groups may also distribute working documents as Internet-) s -5 514 M -( Drafts.) s -5 492 M -( Internet-Drafts are draft documents valid for a maximum of six months) s -5 481 M -( and may be updated, replaced, or obsoleted by other documents at any) s -5 470 M -( time. It is inappropriate to use Internet-Drafts as reference) s -5 459 M -( material or to cite them other than as "work in progress.") s -5 437 M -( The list of current Internet-Drafts can be accessed at http://) s -5 426 M -( www.ietf.org/ietf/1id-abstracts.txt.) s -5 404 M -( The list of Internet-Draft Shadow Directories can be accessed at) s -5 393 M -( http://www.ietf.org/shadow.html.) s -5 371 M -( This Internet-Draft will expire on April 1, 2002.) s -5 349 M -(Copyright Notice) s -5 327 M -( Copyright \(C\) The Internet Society \(2001\). All Rights Reserved.) s -5 305 M -(Abstract) s -5 283 M -( The SSH File Transfer Protocol provides secure file transfer) s -5 272 M -( functionality over any reliable data stream. It is the standard file) s -5 261 M -( transfer protocol for use with the SSH2 protocol. This document) s -5 250 M -( describes the file transfer protocol and its interface to the SSH2) s -5 239 M -( protocol suite.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 1]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 2 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(Table of Contents) s -5 668 M -( 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 657 M -( 2. Use with the SSH Connection Protocol . . . . . . . . . . . . 4) s -5 646 M -( 3. General Packet Format . . . . . . . . . . . . . . . . . . . 5) s -5 635 M -( 4. Protocol Initialization . . . . . . . . . . . . . . . . . . 7) s -5 624 M -( 5. File Attributes . . . . . . . . . . . . . . . . . . . . . . 8) s -5 613 M -( 6. Requests From the Client to the Server . . . . . . . . . . . 10) s -5 602 M -( 6.1 Request Synchronization and Reordering . . . . . . . . . . . 10) s -5 591 M -( 6.2 File Names . . . . . . . . . . . . . . . . . . . . . . . . . 11) s -5 580 M -( 6.3 Opening, Creating, and Closing Files . . . . . . . . . . . . 11) s -5 569 M -( 6.4 Reading and Writing . . . . . . . . . . . . . . . . . . . . 13) s -5 558 M -( 6.5 Removing and Renaming Files . . . . . . . . . . . . . . . . 14) s -5 547 M -( 6.6 Creating and Deleting Directories . . . . . . . . . . . . . 15) s -5 536 M -( 6.7 Scanning Directories . . . . . . . . . . . . . . . . . . . . 15) s -5 525 M -( 6.8 Retrieving File Attributes . . . . . . . . . . . . . . . . . 16) s -5 514 M -( 6.9 Setting File Attributes . . . . . . . . . . . . . . . . . . 17) s -5 503 M -( 6.10 Dealing with Symbolic links . . . . . . . . . . . . . . . . 18) s -5 492 M -( 6.11 Canonicalizing the Server-Side Path Name . . . . . . . . . . 18) s -5 481 M -( 7. Responses from the Server to the Client . . . . . . . . . . 20) s -5 470 M -( 8. Vendor-Specific Extensions . . . . . . . . . . . . . . . . . 24) s -5 459 M -( 9. Security Considerations . . . . . . . . . . . . . . . . . . 25) s -5 448 M -( 10. Changes from previous protocol versions . . . . . . . . . . 26) s -5 437 M -( 10.1 Changes between versions 3 and 2 . . . . . . . . . . . . . . 26) s -5 426 M -( 10.2 Changes between versions 2 and 1 . . . . . . . . . . . . . . 26) s -5 415 M -( 10.3 Changes between versions 1 and 0 . . . . . . . . . . . . . . 26) s -5 404 M -( 11. Trademark Issues . . . . . . . . . . . . . . . . . . . . . . 27) s -5 393 M -( References . . . . . . . . . . . . . . . . . . . . . . . . . 28) s -5 382 M -( Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 28) s -5 371 M -( Full Copyright Statement . . . . . . . . . . . . . . . . . . 29) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 2]) s -_R -S -PStoPSsaved restore -%%Page: (2,3) 2 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 3 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(1. Introduction) s -5 668 M -( This protocol provides secure file transfer \(and more generally file) s -5 657 M -( system access\) functionality over a reliable data stream, such as a) s -5 646 M -( channel in the SSH2 protocol [3].) s -5 624 M -( This protocol is designed so that it could be used to implement a) s -5 613 M -( secure remote file system service, as well as a secure file transfer) s -5 602 M -( service.) s -5 580 M -( This protocol assumes that it runs over a secure channel, and that) s -5 569 M -( the server has already authenticated the user at the client end, and) s -5 558 M -( that the identity of the client user is externally available to the) s -5 547 M -( server implementation.) s -5 525 M -( In general, this protocol follows a simple request-response model.) s -5 514 M -( Each request and response contains a sequence number and multiple) s -5 503 M -( requests may be pending simultaneously. There are a relatively large) s -5 492 M -( number of different request messages, but a small number of possible) s -5 481 M -( response messages. Each request has one or more response messages) s -5 470 M -( that may be returned in result \(e.g., a read either returns data or) s -5 459 M -( reports error status\).) s -5 437 M -( The packet format descriptions in this specification follow the) s -5 426 M -( notation presented in the secsh architecture draft.[3].) s -5 404 M -( Even though this protocol is described in the context of the SSH2) s -5 393 M -( protocol, this protocol is general and independent of the rest of the) s -5 382 M -( SSH2 protocol suite. It could be used in a number of different) s -5 371 M -( applications, such as secure file transfer over TLS RFC 2246 [1] and) s -5 360 M -( transfer of management information in VPN applications.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 3]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 4 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(2. Use with the SSH Connection Protocol) s -5 668 M -( When used with the SSH2 Protocol suite, this protocol is intended to) s -5 657 M -( be used from the SSH Connection Protocol [5] as a subsystem, as) s -5 646 M -( described in section ``Starting a Shell or a Command''. The) s -5 635 M -( subsystem name used with this protocol is "sftp".) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 4]) s -_R -S -PStoPSsaved restore -%%Page: (4,5) 3 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 5 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(3. General Packet Format) s -5 668 M -( All packets transmitted over the secure connection are of the) s -5 657 M -( following format:) s -5 635 M -( uint32 length) s -5 624 M -( byte type) s -5 613 M -( byte[length - 1] data payload) s -5 591 M -( That is, they are just data preceded by 32-bit length and 8-bit type) s -5 580 M -( fields. The `length' is the length of the data area, and does not) s -5 569 M -( include the `length' field itself. The format and interpretation of) s -5 558 M -( the data area depends on the packet type.) s -5 536 M -( All packet descriptions below only specify the packet type and the) s -5 525 M -( data that goes into the data field. Thus, they should be prefixed by) s -5 514 M -( the `length' and `type' fields.) s -5 492 M -( The maximum size of a packet is in practice determined by the client) s -5 481 M -( \(the maximum size of read or write requests that it sends, plus a few) s -5 470 M -( bytes of packet overhead\). All servers SHOULD support packets of at) s -5 459 M -( least 34000 bytes \(where the packet size refers to the full length,) s -5 448 M -( including the header above\). This should allow for reads and writes) s -5 437 M -( of at most 32768 bytes.) s -5 415 M -( There is no limit on the number of outstanding \(non-acknowledged\)) s -5 404 M -( requests that the client may send to the server. In practice this is) s -5 393 M -( limited by the buffering available on the data stream and the queuing) s -5 382 M -( performed by the server. If the server's queues are full, it should) s -5 371 M -( not read any more data from the stream, and flow control will prevent) s -5 360 M -( the client from sending more requests. Note, however, that while) s -5 349 M -( there is no restriction on the protocol level, the client's API may) s -5 338 M -( provide a limit in order to prevent infinite queuing of outgoing) s -5 327 M -( requests at the client.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 5]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 6 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( The following values are defined for packet types.) s -5 668 M -( #define SSH_FXP_INIT 1) s -5 657 M -( #define SSH_FXP_VERSION 2) s -5 646 M -( #define SSH_FXP_OPEN 3) s -5 635 M -( #define SSH_FXP_CLOSE 4) s -5 624 M -( #define SSH_FXP_READ 5) s -5 613 M -( #define SSH_FXP_WRITE 6) s -5 602 M -( #define SSH_FXP_LSTAT 7) s -5 591 M -( #define SSH_FXP_FSTAT 8) s -5 580 M -( #define SSH_FXP_SETSTAT 9) s -5 569 M -( #define SSH_FXP_FSETSTAT 10) s -5 558 M -( #define SSH_FXP_OPENDIR 11) s -5 547 M -( #define SSH_FXP_READDIR 12) s -5 536 M -( #define SSH_FXP_REMOVE 13) s -5 525 M -( #define SSH_FXP_MKDIR 14) s -5 514 M -( #define SSH_FXP_RMDIR 15) s -5 503 M -( #define SSH_FXP_REALPATH 16) s -5 492 M -( #define SSH_FXP_STAT 17) s -5 481 M -( #define SSH_FXP_RENAME 18) s -5 470 M -( #define SSH_FXP_READLINK 19) s -5 459 M -( #define SSH_FXP_SYMLINK 20) s -5 448 M -( #define SSH_FXP_STATUS 101) s -5 437 M -( #define SSH_FXP_HANDLE 102) s -5 426 M -( #define SSH_FXP_DATA 103) s -5 415 M -( #define SSH_FXP_NAME 104) s -5 404 M -( #define SSH_FXP_ATTRS 105) s -5 393 M -( #define SSH_FXP_EXTENDED 200) s -5 382 M -( #define SSH_FXP_EXTENDED_REPLY 201) s -5 360 M -( Additional packet types should only be defined if the protocol) s -5 349 M -( version number \(see Section ``Protocol Initialization''\) is) s -5 338 M -( incremented, and their use MUST be negotiated using the version) s -5 327 M -( number. However, the SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY) s -5 316 M -( packets can be used to implement vendor-specific extensions. See) s -5 305 M -( Section ``Vendor-Specific-Extensions'' for more details.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 6]) s -_R -S -PStoPSsaved restore -%%Page: (6,7) 4 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 7 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(4. Protocol Initialization) s -5 668 M -( When the file transfer protocol starts, it first sends a SSH_FXP_INIT) s -5 657 M -( \(including its version number\) packet to the server. The server) s -5 646 M -( responds with a SSH_FXP_VERSION packet, supplying the lowest of its) s -5 635 M -( own and the client's version number. Both parties should from then) s -5 624 M -( on adhere to particular version of the protocol.) s -5 602 M -( The SSH_FXP_INIT packet \(from client to server\) has the following) s -5 591 M -( data:) s -5 569 M -( uint32 version) s -5 558 M -( <extension data>) s -5 536 M -( The SSH_FXP_VERSION packet \(from server to client\) has the following) s -5 525 M -( data:) s -5 503 M -( uint32 version) s -5 492 M -( <extension data>) s -5 470 M -( The version number of the protocol specified in this document is 3.) s -5 459 M -( The version number should be incremented for each incompatible) s -5 448 M -( revision of this protocol.) s -5 426 M -( The extension data in the above packets may be empty, or may be a) s -5 415 M -( sequence of) s -5 393 M -( string extension_name) s -5 382 M -( string extension_data) s -5 360 M -( pairs \(both strings MUST always be present if one is, but the) s -5 349 M -( `extension_data' string may be of zero length\). If present, these) s -5 338 M -( strings indicate extensions to the baseline protocol. The) s -5 327 M -( `extension_name' field\(s\) identify the name of the extension. The) s -5 316 M -( name should be of the form "name@domain", where the domain is the DNS) s -5 305 M -( domain name of the organization defining the extension. Additional) s -5 294 M -( names that are not of this format may be defined later by the IETF.) s -5 283 M -( Implementations MUST silently ignore any extensions whose name they) s -5 272 M -( do not recognize.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 7]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 8 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(5. File Attributes) s -5 668 M -( A new compound data type is defined for encoding file attributes. It) s -5 657 M -( is basically just a combination of elementary types, but is defined) s -5 646 M -( once because of the non-trivial description of the fields and to) s -5 635 M -( ensure maintainability.) s -5 613 M -( The same encoding is used both when returning file attributes from) s -5 602 M -( the server and when sending file attributes to the server. When) s -5 591 M -( sending it to the server, the flags field specifies which attributes) s -5 580 M -( are included, and the server will use default values for the) s -5 569 M -( remaining attributes \(or will not modify the values of remaining) s -5 558 M -( attributes\). When receiving attributes from the server, the flags) s -5 547 M -( specify which attributes are included in the returned data. The) s -5 536 M -( server normally returns all attributes it knows about.) s -5 514 M -( uint32 flags) s -5 503 M -( uint64 size present only if flag SSH_FILEXFER_ATTR_SIZE) s -5 492 M -( uint32 uid present only if flag SSH_FILEXFER_ATTR_UIDGID) s -5 481 M -( uint32 gid present only if flag SSH_FILEXFER_ATTR_UIDGID) s -5 470 M -( uint32 permissions present only if flag SSH_FILEXFER_ATTR_PERMISSIONS) s -5 459 M -( uint32 atime present only if flag SSH_FILEXFER_ACMODTIME) s -5 448 M -( uint32 mtime present only if flag SSH_FILEXFER_ACMODTIME) s -5 437 M -( uint32 extended_count present only if flag SSH_FILEXFER_ATTR_EXTENDED) s -5 426 M -( string extended_type) s -5 415 M -( string extended_data) s -5 404 M -( ... more extended data \(extended_type - extended_data pairs\),) s -5 393 M -( so that number of pairs equals extended_count) s -5 371 M -( The `flags' specify which of the fields are present. Those fields) s -5 360 M -( for which the corresponding flag is not set are not present \(not) s -5 349 M -( included in the packet\). New flags can only be added by incrementing) s -5 338 M -( the protocol version number \(or by using the extension mechanism) s -5 327 M -( described below\).) s -5 305 M -( The `size' field specifies the size of the file in bytes.) s -5 283 M -( The `uid' and `gid' fields contain numeric Unix-like user and group) s -5 272 M -( identifiers, respectively.) s -5 250 M -( The `permissions' field contains a bit mask of file permissions as) s -5 239 M -( defined by posix [1].) s -5 217 M -( The `atime' and `mtime' contain the access and modification times of) s -5 206 M -( the files, respectively. They are represented as seconds from Jan 1,) s -5 195 M -( 1970 in UTC.) s -5 173 M -( The SSH_FILEXFER_ATTR_EXTENDED flag provides a general extension) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 8]) s -_R -S -PStoPSsaved restore -%%Page: (8,9) 5 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 9 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( mechanism for vendor-specific extensions. If the flag is specified,) s -5 679 M -( then the `extended_count' field is present. It specifies the number) s -5 668 M -( of extended_type-extended_data pairs that follow. Each of these) s -5 657 M -( pairs specifies an extended attribute. For each of the attributes,) s -5 646 M -( the extended_type field should be a string of the format) s -5 635 M -( "name@domain", where "domain" is a valid, registered domain name and) s -5 624 M -( "name" identifies the method. The IETF may later standardize certain) s -5 613 M -( names that deviate from this format \(e.g., that do not contain the) s -5 602 M -( "@" sign\). The interpretation of `extended_data' depends on the) s -5 591 M -( type. Implementations SHOULD ignore extended data fields that they) s -5 580 M -( do not understand.) s -5 558 M -( Additional fields can be added to the attributes by either defining) s -5 547 M -( additional bits to the flags field to indicate their presence, or by) s -5 536 M -( defining extended attributes for them. The extended attributes) s -5 525 M -( mechanism is recommended for most purposes; additional flags bits) s -5 514 M -( should only be defined by an IETF standards action that also) s -5 503 M -( increments the protocol version number. The use of such new fields) s -5 492 M -( MUST be negotiated by the version number in the protocol exchange.) s -5 481 M -( It is a protocol error if a packet with unsupported protocol bits is) s -5 470 M -( received.) s -5 448 M -( The flags bits are defined to have the following values:) s -5 426 M -( #define SSH_FILEXFER_ATTR_SIZE 0x00000001) s -5 415 M -( #define SSH_FILEXFER_ATTR_UIDGID 0x00000002) s -5 404 M -( #define SSH_FILEXFER_ATTR_PERMISSIONS 0x00000004) s -5 393 M -( #define SSH_FILEXFER_ATTR_ACMODTIME 0x00000008) s -5 382 M -( #define SSH_FILEXFER_ATTR_EXTENDED 0x80000000) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 9]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 10 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(6. Requests From the Client to the Server) s -5 668 M -( Requests from the client to the server represent the various file) s -5 657 M -( system operations. Each request begins with an `id' field, which is) s -5 646 M -( a 32-bit identifier identifying the request \(selected by the client\).) s -5 635 M -( The same identifier will be returned in the response to the request.) s -5 624 M -( One possible implementation of it is a monotonically increasing) s -5 613 M -( request sequence number \(modulo 2^32\).) s -5 591 M -( Many operations in the protocol operate on open files. The) s -5 580 M -( SSH_FXP_OPEN request can return a file handle \(which is an opaque) s -5 569 M -( variable-length string\) which may be used to access the file later) s -5 558 M -( \(e.g. in a read operation\). The client MUST NOT send requests the) s -5 547 M -( server with bogus or closed handles. However, the server MUST) s -5 536 M -( perform adequate checks on the handle in order to avoid security) s -5 525 M -( risks due to fabricated handles.) s -5 503 M -( This design allows either stateful and stateless server) s -5 492 M -( implementation, as well as an implementation which caches state) s -5 481 M -( between requests but may also flush it. The contents of the file) s -5 470 M -( handle string are entirely up to the server and its design. The) s -5 459 M -( client should not modify or attempt to interpret the file handle) s -5 448 M -( strings.) s -5 426 M -( The file handle strings MUST NOT be longer than 256 bytes.) s -5 404 M -(6.1 Request Synchronization and Reordering) s -5 382 M -( The protocol and implementations MUST process requests relating to) s -5 371 M -( the same file in the order in which they are received. In other) s -5 360 M -( words, if an application submits multiple requests to the server, the) s -5 349 M -( results in the responses will be the same as if it had sent the) s -5 338 M -( requests one at a time and waited for the response in each case. For) s -5 327 M -( example, the server may process non-overlapping read/write requests) s -5 316 M -( to the same file in parallel, but overlapping reads and writes cannot) s -5 305 M -( be reordered or parallelized. However, there are no ordering) s -5 294 M -( restrictions on the server for processing requests from two different) s -5 283 M -( file transfer connections. The server may interleave and parallelize) s -5 272 M -( them at will.) s -5 250 M -( There are no restrictions on the order in which responses to) s -5 239 M -( outstanding requests are delivered to the client, except that the) s -5 228 M -( server must ensure fairness in the sense that processing of no) s -5 217 M -( request will be indefinitely delayed even if the client is sending) s -5 206 M -( other requests so that there are multiple outstanding requests all) s -5 195 M -( the time.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 10]) s -_R -S -PStoPSsaved restore -%%Page: (10,11) 6 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 11 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(6.2 File Names) s -5 668 M -( This protocol represents file names as strings. File names are) s -5 657 M -( assumed to use the slash \('/'\) character as a directory separator.) s -5 635 M -( File names starting with a slash are "absolute", and are relative to) s -5 624 M -( the root of the file system. Names starting with any other character) s -5 613 M -( are relative to the user's default directory \(home directory\). Note) s -5 602 M -( that identifying the user is assumed to take place outside of this) s -5 591 M -( protocol.) s -5 569 M -( Servers SHOULD interpret a path name component ".." as referring to) s -5 558 M -( the parent directory, and "." as referring to the current directory.) s -5 547 M -( If the server implementation limits access to certain parts of the) s -5 536 M -( file system, it must be extra careful in parsing file names when) s -5 525 M -( enforcing such restrictions. There have been numerous reported) s -5 514 M -( security bugs where a ".." in a path name has allowed access outside) s -5 503 M -( the intended area.) s -5 481 M -( An empty path name is valid, and it refers to the user's default) s -5 470 M -( directory \(usually the user's home directory\).) s -5 448 M -( Otherwise, no syntax is defined for file names by this specification.) s -5 437 M -( Clients should not make any other assumptions; however, they can) s -5 426 M -( splice path name components returned by SSH_FXP_READDIR together) s -5 415 M -( using a slash \('/'\) as the separator, and that will work as expected.) s -5 393 M -( It is understood that the lack of well-defined semantics for file) s -5 382 M -( names may cause interoperability problems between clients and servers) s -5 371 M -( using radically different operating systems. However, this approach) s -5 360 M -( is known to work acceptably with most systems, and alternative) s -5 349 M -( approaches that e.g. treat file names as sequences of structured) s -5 338 M -( components are quite complicated.) s -5 316 M -(6.3 Opening, Creating, and Closing Files) s -5 294 M -( Files are opened and created using the SSH_FXP_OPEN message, whose) s -5 283 M -( data part is as follows:) s -5 261 M -( uint32 id) s -5 250 M -( string filename) s -5 239 M -( uint32 pflags) s -5 228 M -( ATTRS attrs) s -5 206 M -( The `id' field is the request identifier as for all requests.) s -5 184 M -( The `filename' field specifies the file name. See Section ``File) s -5 173 M -( Names'' for more information.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 11]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 12 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( The `pflags' field is a bitmask. The following bits have been) s -5 679 M -( defined.) s -5 657 M -( #define SSH_FXF_READ 0x00000001) s -5 646 M -( #define SSH_FXF_WRITE 0x00000002) s -5 635 M -( #define SSH_FXF_APPEND 0x00000004) s -5 624 M -( #define SSH_FXF_CREAT 0x00000008) s -5 613 M -( #define SSH_FXF_TRUNC 0x00000010) s -5 602 M -( #define SSH_FXF_EXCL 0x00000020) s -5 580 M -( These have the following meanings:) s -5 558 M -( SSH_FXF_READ) s -5 547 M -( Open the file for reading.) s -5 525 M -( SSH_FXF_WRITE) s -5 514 M -( Open the file for writing. If both this and SSH_FXF_READ are) s -5 503 M -( specified, the file is opened for both reading and writing.) s -5 481 M -( SSH_FXF_APPEND) s -5 470 M -( Force all writes to append data at the end of the file.) s -5 448 M -( SSH_FXF_CREAT) s -5 437 M -( If this flag is specified, then a new file will be created if one) s -5 426 M -( does not already exist \(if O_TRUNC is specified, the new file will) s -5 415 M -( be truncated to zero length if it previously exists\).) s -5 393 M -( SSH_FXF_TRUNC) s -5 382 M -( Forces an existing file with the same name to be truncated to zero) s -5 371 M -( length when creating a file by specifying SSH_FXF_CREAT.) s -5 360 M -( SSH_FXF_CREAT MUST also be specified if this flag is used.) s -5 338 M -( SSH_FXF_EXCL) s -5 327 M -( Causes the request to fail if the named file already exists.) s -5 316 M -( SSH_FXF_CREAT MUST also be specified if this flag is used.) s -5 294 M -( The `attrs' field specifies the initial attributes for the file.) s -5 283 M -( Default values will be used for those attributes that are not) s -5 272 M -( specified. See Section ``File Attributes'' for more information.) s -5 250 M -( Regardless the server operating system, the file will always be) s -5 239 M -( opened in "binary" mode \(i.e., no translations between different) s -5 228 M -( character sets and newline encodings\).) s -5 206 M -( The response to this message will be either SSH_FXP_HANDLE \(if the) s -5 195 M -( operation is successful\) or SSH_FXP_STATUS \(if the operation fails\).) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 12]) s -_R -S -PStoPSsaved restore -%%Page: (12,13) 7 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 13 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( A file is closed by using the SSH_FXP_CLOSE request. Its data field) s -5 679 M -( has the following format:) s -5 657 M -( uint32 id) s -5 646 M -( string handle) s -5 624 M -( where `id' is the request identifier, and `handle' is a handle) s -5 613 M -( previously returned in the response to SSH_FXP_OPEN or) s -5 602 M -( SSH_FXP_OPENDIR. The handle becomes invalid immediately after this) s -5 591 M -( request has been sent.) s -5 569 M -( The response to this request will be a SSH_FXP_STATUS message. One) s -5 558 M -( should note that on some server platforms even a close can fail.) s -5 547 M -( This can happen e.g. if the server operating system caches writes,) s -5 536 M -( and an error occurs while flushing cached writes during the close.) s -5 514 M -(6.4 Reading and Writing) s -5 492 M -( Once a file has been opened, it can be read using the SSH_FXP_READ) s -5 481 M -( message, which has the following format:) s -5 459 M -( uint32 id) s -5 448 M -( string handle) s -5 437 M -( uint64 offset) s -5 426 M -( uint32 len) s -5 404 M -( where `id' is the request identifier, `handle' is an open file handle) s -5 393 M -( returned by SSH_FXP_OPEN, `offset' is the offset \(in bytes\) relative) s -5 382 M -( to the beginning of the file from where to start reading, and `len') s -5 371 M -( is the maximum number of bytes to read.) s -5 349 M -( In response to this request, the server will read as many bytes as it) s -5 338 M -( can from the file \(up to `len'\), and return them in a SSH_FXP_DATA) s -5 327 M -( message. If an error occurs or EOF is encountered before reading any) s -5 316 M -( data, the server will respond with SSH_FXP_STATUS. For normal disk) s -5 305 M -( files, it is guaranteed that this will read the specified number of) s -5 294 M -( bytes, or up to end of file. For e.g. device files this may return) s -5 283 M -( fewer bytes than requested.) s -5 261 M -( Writing to a file is achieved using the SSH_FXP_WRITE message, which) s -5 250 M -( has the following format:) s -5 228 M -( uint32 id) s -5 217 M -( string handle) s -5 206 M -( uint64 offset) s -5 195 M -( string data) s -5 173 M -( where `id' is a request identifier, `handle' is a file handle) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 13]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 14 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( returned by SSH_FXP_OPEN, `offset' is the offset \(in bytes\) from the) s -5 679 M -( beginning of the file where to start writing, and `data' is the data) s -5 668 M -( to be written.) s -5 646 M -( The write will extend the file if writing beyond the end of the file.) s -5 635 M -( It is legal to write way beyond the end of the file; the semantics) s -5 624 M -( are to write zeroes from the end of the file to the specified offset) s -5 613 M -( and then the data. On most operating systems, such writes do not) s -5 602 M -( allocate disk space but instead leave "holes" in the file.) s -5 580 M -( The server responds to a write request with a SSH_FXP_STATUS message.) s -5 558 M -(6.5 Removing and Renaming Files) s -5 536 M -( Files can be removed using the SSH_FXP_REMOVE message. It has the) s -5 525 M -( following format:) s -5 503 M -( uint32 id) s -5 492 M -( string filename) s -5 470 M -( where `id' is the request identifier and `filename' is the name of) s -5 459 M -( the file to be removed. See Section ``File Names'' for more) s -5 448 M -( information. This request cannot be used to remove directories.) s -5 426 M -( The server will respond to this request with a SSH_FXP_STATUS) s -5 415 M -( message.) s -5 393 M -( Files \(and directories\) can be renamed using the SSH_FXP_RENAME) s -5 382 M -( message. Its data is as follows:) s -5 360 M -( uint32 id) s -5 349 M -( string oldpath) s -5 338 M -( string newpath) s -5 316 M -( where `id' is the request identifier, `oldpath' is the name of an) s -5 305 M -( existing file or directory, and `newpath' is the new name for the) s -5 294 M -( file or directory. It is an error if there already exists a file) s -5 283 M -( with the name specified by newpath. The server may also fail rename) s -5 272 M -( requests in other situations, for example if `oldpath' and `newpath') s -5 261 M -( point to different file systems on the server.) s -5 239 M -( The server will respond to this request with a SSH_FXP_STATUS) s -5 228 M -( message.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 14]) s -_R -S -PStoPSsaved restore -%%Page: (14,15) 8 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 15 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(6.6 Creating and Deleting Directories) s -5 668 M -( New directories can be created using the SSH_FXP_MKDIR request. It) s -5 657 M -( has the following format:) s -5 635 M -( uint32 id) s -5 624 M -( string path) s -5 613 M -( ATTRS attrs) s -5 591 M -( where `id' is the request identifier, `path' and `attrs' specifies) s -5 580 M -( the modifications to be made to its attributes. See Section ``File) s -5 569 M -( Names'' for more information on file names. Attributes are discussed) s -5 558 M -( in more detail in Section ``File Attributes''. specifies the) s -5 547 M -( directory to be created. An error will be returned if a file or) s -5 536 M -( directory with the specified path already exists. The server will) s -5 525 M -( respond to this request with a SSH_FXP_STATUS message.) s -5 503 M -( Directories can be removed using the SSH_FXP_RMDIR request, which) s -5 492 M -( has the following format:) s -5 470 M -( uint32 id) s -5 459 M -( string path) s -5 437 M -( where `id' is the request identifier, and `path' specifies the) s -5 426 M -( directory to be removed. See Section ``File Names'' for more) s -5 415 M -( information on file names. An error will be returned if no directory) s -5 404 M -( with the specified path exists, or if the specified directory is not) s -5 393 M -( empty, or if the path specified a file system object other than a) s -5 382 M -( directory. The server responds to this request with a SSH_FXP_STATUS) s -5 371 M -( message.) s -5 349 M -(6.7 Scanning Directories) s -5 327 M -( The files in a directory can be listed using the SSH_FXP_OPENDIR and) s -5 316 M -( SSH_FXP_READDIR requests. Each SSH_FXP_READDIR request returns one) s -5 305 M -( or more file names with full file attributes for each file. The) s -5 294 M -( client should call SSH_FXP_READDIR repeatedly until it has found the) s -5 283 M -( file it is looking for or until the server responds with a) s -5 272 M -( SSH_FXP_STATUS message indicating an error \(normally SSH_FX_EOF if) s -5 261 M -( there are no more files in the directory\). The client should then) s -5 250 M -( close the handle using the SSH_FXP_CLOSE request.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 15]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 16 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( The SSH_FXP_OPENDIR opens a directory for reading. It has the) s -5 679 M -( following format:) s -5 657 M -( uint32 id) s -5 646 M -( string path) s -5 624 M -( where `id' is the request identifier and `path' is the path name of) s -5 613 M -( the directory to be listed \(without any trailing slash\). See Section) s -5 602 M -( ``File Names'' for more information on file names. This will return) s -5 591 M -( an error if the path does not specify a directory or if the directory) s -5 580 M -( is not readable. The server will respond to this request with either) s -5 569 M -( a SSH_FXP_HANDLE or a SSH_FXP_STATUS message.) s -5 547 M -( Once the directory has been successfully opened, files \(and) s -5 536 M -( directories\) contained in it can be listed using SSH_FXP_READDIR) s -5 525 M -( requests. These are of the format) s -5 503 M -( uint32 id) s -5 492 M -( string handle) s -5 470 M -( where `id' is the request identifier, and `handle' is a handle) s -5 459 M -( returned by SSH_FXP_OPENDIR. \(It is a protocol error to attempt to) s -5 448 M -( use an ordinary file handle returned by SSH_FXP_OPEN.\)) s -5 426 M -( The server responds to this request with either a SSH_FXP_NAME or a) s -5 415 M -( SSH_FXP_STATUS message. One or more names may be returned at a time.) s -5 404 M -( Full status information is returned for each name in order to speed) s -5 393 M -( up typical directory listings.) s -5 371 M -( When the client no longer wishes to read more names from the) s -5 360 M -( directory, it SHOULD call SSH_FXP_CLOSE for the handle. The handle) s -5 349 M -( should be closed regardless of whether an error has occurred or not.) s -5 327 M -(6.8 Retrieving File Attributes) s -5 305 M -( Very often, file attributes are automatically returned by) s -5 294 M -( SSH_FXP_READDIR. However, sometimes there is need to specifically) s -5 283 M -( retrieve the attributes for a named file. This can be done using the) s -5 272 M -( SSH_FXP_STAT, SSH_FXP_LSTAT and SSH_FXP_FSTAT requests.) s -5 250 M -( SSH_FXP_STAT and SSH_FXP_LSTAT only differ in that SSH_FXP_STAT) s -5 239 M -( follows symbolic links on the server, whereas SSH_FXP_LSTAT does not) s -5 228 M -( follow symbolic links. Both have the same format:) s -5 206 M -( uint32 id) s -5 195 M -( string path) s -5 173 M -( where `id' is the request identifier, and `path' specifies the file) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 16]) s -_R -S -PStoPSsaved restore -%%Page: (16,17) 9 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 17 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( system object for which status is to be returned. The server) s -5 679 M -( responds to this request with either SSH_FXP_ATTRS or SSH_FXP_STATUS.) s -5 657 M -( SSH_FXP_FSTAT differs from the others in that it returns status) s -5 646 M -( information for an open file \(identified by the file handle\). Its) s -5 635 M -( format is as follows:) s -5 613 M -( uint32 id) s -5 602 M -( string handle) s -5 580 M -( where `id' is the request identifier and `handle' is a file handle) s -5 569 M -( returned by SSH_FXP_OPEN. The server responds to this request with) s -5 558 M -( SSH_FXP_ATTRS or SSH_FXP_STATUS.) s -5 536 M -(6.9 Setting File Attributes) s -5 514 M -( File attributes may be modified using the SSH_FXP_SETSTAT and) s -5 503 M -( SSH_FXP_FSETSTAT requests. These requests are used for operations) s -5 492 M -( such as changing the ownership, permissions or access times, as well) s -5 481 M -( as for truncating a file.) s -5 459 M -( The SSH_FXP_SETSTAT request is of the following format:) s -5 437 M -( uint32 id) s -5 426 M -( string path) s -5 415 M -( ATTRS attrs) s -5 393 M -( where `id' is the request identifier, `path' specifies the file) s -5 382 M -( system object \(e.g. file or directory\) whose attributes are to be) s -5 371 M -( modified, and `attrs' specifies the modifications to be made to its) s -5 360 M -( attributes. Attributes are discussed in more detail in Section) s -5 349 M -( ``File Attributes''.) s -5 327 M -( An error will be returned if the specified file system object does) s -5 316 M -( not exist or the user does not have sufficient rights to modify the) s -5 305 M -( specified attributes. The server responds to this request with a) s -5 294 M -( SSH_FXP_STATUS message.) s -5 272 M -( The SSH_FXP_FSETSTAT request modifies the attributes of a file which) s -5 261 M -( is already open. It has the following format:) s -5 239 M -( uint32 id) s -5 228 M -( string handle) s -5 217 M -( ATTRS attrs) s -5 195 M -( where `id' is the request identifier, `handle' \(MUST be returned by) s -5 184 M -( SSH_FXP_OPEN\) identifies the file whose attributes are to be) s -5 173 M -( modified, and `attrs' specifies the modifications to be made to its) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 17]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 18 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( attributes. Attributes are discussed in more detail in Section) s -5 679 M -( ``File Attributes''. The server will respond to this request with) s -5 668 M -( SSH_FXP_STATUS.) s -5 646 M -(6.10 Dealing with Symbolic links) s -5 624 M -( The SSH_FXP_READLINK request may be used to read the target of a) s -5 613 M -( symbolic link. It would have a data part as follows:) s -5 591 M -( uint32 id) s -5 580 M -( string path) s -5 558 M -( where `id' is the request identifier and `path' specifies the path) s -5 547 M -( name of the symlink to be read.) s -5 525 M -( The server will respond with a SSH_FXP_NAME packet containing only) s -5 514 M -( one name and a dummy attributes value. The name in the returned) s -5 503 M -( packet contains the target of the link. If an error occurs, the) s -5 492 M -( server may respond with SSH_FXP_STATUS.) s -5 470 M -( The SSH_FXP_SYMLINK request will create a symbolic link on the) s -5 459 M -( server. It is of the following format) s -5 437 M -( uint32 id) s -5 426 M -( string linkpath) s -5 415 M -( string targetpath) s -5 393 M -( where `id' is the request identifier, `linkpath' specifies the path) s -5 382 M -( name of the symlink to be created and `targetpath' specifies the) s -5 371 M -( target of the symlink. The server shall respond with a) s -5 360 M -( SSH_FXP_STATUS indicating either success \(SSH_FX_OK\) or an error) s -5 349 M -( condition.) s -5 327 M -(6.11 Canonicalizing the Server-Side Path Name) s -5 305 M -( The SSH_FXP_REALPATH request can be used to have the server) s -5 294 M -( canonicalize any given path name to an absolute path. This is useful) s -5 283 M -( for converting path names containing ".." components or relative) s -5 272 M -( pathnames without a leading slash into absolute paths. The format of) s -5 261 M -( the request is as follows:) s -5 239 M -( uint32 id) s -5 228 M -( string path) s -5 206 M -( where `id' is the request identifier and `path' specifies the path) s -5 195 M -( name to be canonicalized. The server will respond with a) s -5 184 M -( SSH_FXP_NAME packet containing only one name and a dummy attributes) s -5 173 M -( value. The name is the returned packet will be in canonical form.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 18]) s -_R -S -PStoPSsaved restore -%%Page: (18,19) 10 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 19 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( If an error occurs, the server may also respond with SSH_FXP_STATUS.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 19]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 20 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(7. Responses from the Server to the Client) s -5 668 M -( The server responds to the client using one of a few response) s -5 657 M -( packets. All requests can return a SSH_FXP_STATUS response upon) s -5 646 M -( failure. When the operation is successful, any of the responses may) s -5 635 M -( be returned \(depending on the operation\). If no data needs to be) s -5 624 M -( returned to the client, the SSH_FXP_STATUS response with SSH_FX_OK) s -5 613 M -( status is appropriate. Otherwise, the SSH_FXP_HANDLE message is used) s -5 602 M -( to return a file handle \(for SSH_FXP_OPEN and SSH_FXP_OPENDIR) s -5 591 M -( requests\), SSH_FXP_DATA is used to return data from SSH_FXP_READ,) s -5 580 M -( SSH_FXP_NAME is used to return one or more file names from a) s -5 569 M -( SSH_FXP_READDIR or SSH_FXP_REALPATH request, and SSH_FXP_ATTRS is) s -5 558 M -( used to return file attributes from SSH_FXP_STAT, SSH_FXP_LSTAT, and) s -5 547 M -( SSH_FXP_FSTAT requests.) s -5 525 M -( Exactly one response will be returned for each request. Each) s -5 514 M -( response packet contains a request identifier which can be used to) s -5 503 M -( match each response with the corresponding request. Note that it is) s -5 492 M -( legal to have several requests outstanding simultaneously, and the) s -5 481 M -( server is allowed to send responses to them in a different order from) s -5 470 M -( the order in which the requests were sent \(the result of their) s -5 459 M -( execution, however, is guaranteed to be as if they had been processed) s -5 448 M -( one at a time in the order in which the requests were sent\).) s -5 426 M -( Response packets are of the same general format as request packets.) s -5 415 M -( Each response packet begins with the request identifier.) s -5 393 M -( The format of the data portion of the SSH_FXP_STATUS response is as) s -5 382 M -( follows:) s -5 360 M -( uint32 id) s -5 349 M -( uint32 error/status code) s -5 338 M -( string error message \(ISO-10646 UTF-8 [RFC-2279]\)) s -5 327 M -( string language tag \(as defined in [RFC-1766]\)) s -5 305 M -( where `id' is the request identifier, and `error/status code') s -5 294 M -( indicates the result of the requested operation. The value SSH_FX_OK) s -5 283 M -( indicates success, and all other values indicate failure.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 20]) s -_R -S -PStoPSsaved restore -%%Page: (20,21) 11 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 21 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( Currently, the following values are defined \(other values may be) s -5 679 M -( defined by future versions of this protocol\):) s -5 657 M -( #define SSH_FX_OK 0) s -5 646 M -( #define SSH_FX_EOF 1) s -5 635 M -( #define SSH_FX_NO_SUCH_FILE 2) s -5 624 M -( #define SSH_FX_PERMISSION_DENIED 3) s -5 613 M -( #define SSH_FX_FAILURE 4) s -5 602 M -( #define SSH_FX_BAD_MESSAGE 5) s -5 591 M -( #define SSH_FX_NO_CONNECTION 6) s -5 580 M -( #define SSH_FX_CONNECTION_LOST 7) s -5 569 M -( #define SSH_FX_OP_UNSUPPORTED 8) s -5 547 M -( SSH_FX_OK) s -5 536 M -( Indicates successful completion of the operation.) s -5 514 M -( SSH_FX_EOF) s -5 503 M -( indicates end-of-file condition; for SSH_FX_READ it means that no) s -5 492 M -( more data is available in the file, and for SSH_FX_READDIR it) s -5 481 M -( indicates that no more files are contained in the directory.) s -5 459 M -( SSH_FX_NO_SUCH_FILE) s -5 448 M -( is returned when a reference is made to a file which should exist) s -5 437 M -( but doesn't.) s -5 415 M -( SSH_FX_PERMISSION_DENIED) s -5 404 M -( is returned when the authenticated user does not have sufficient) s -5 393 M -( permissions to perform the operation.) s -5 371 M -( SSH_FX_FAILURE) s -5 360 M -( is a generic catch-all error message; it should be returned if an) s -5 349 M -( error occurs for which there is no more specific error code) s -5 338 M -( defined.) s -5 316 M -( SSH_FX_BAD_MESSAGE) s -5 305 M -( may be returned if a badly formatted packet or protocol) s -5 294 M -( incompatibility is detected.) s -5 272 M -( SSH_FX_NO_CONNECTION) s -5 261 M -( is a pseudo-error which indicates that the client has no) s -5 250 M -( connection to the server \(it can only be generated locally by the) s -5 239 M -( client, and MUST NOT be returned by servers\).) s -5 217 M -( SSH_FX_CONNECTION_LOST) s -5 206 M -( is a pseudo-error which indicates that the connection to the) s -5 195 M -( server has been lost \(it can only be generated locally by the) s -5 184 M -( client, and MUST NOT be returned by servers\).) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 21]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 22 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( SSH_FX_OP_UNSUPPORTED) s -5 679 M -( indicates that an attempt was made to perform an operation which) s -5 668 M -( is not supported for the server \(it may be generated locally by) s -5 657 M -( the client if e.g. the version number exchange indicates that a) s -5 646 M -( required feature is not supported by the server, or it may be) s -5 635 M -( returned by the server if the server does not implement an) s -5 624 M -( operation\).) s -5 602 M -( The SSH_FXP_HANDLE response has the following format:) s -5 580 M -( uint32 id) s -5 569 M -( string handle) s -5 547 M -( where `id' is the request identifier, and `handle' is an arbitrary) s -5 536 M -( string that identifies an open file or directory on the server. The) s -5 525 M -( handle is opaque to the client; the client MUST NOT attempt to) s -5 514 M -( interpret or modify it in any way. The length of the handle string) s -5 503 M -( MUST NOT exceed 256 data bytes.) s -5 481 M -( The SSH_FXP_DATA response has the following format:) s -5 459 M -( uint32 id) s -5 448 M -( string data) s -5 426 M -( where `id' is the request identifier, and `data' is an arbitrary byte) s -5 415 M -( string containing the requested data. The data string may be at most) s -5 404 M -( the number of bytes requested in a SSH_FXP_READ request, but may also) s -5 393 M -( be shorter if end of file is reached or if the read is from something) s -5 382 M -( other than a regular file.) s -5 360 M -( The SSH_FXP_NAME response has the following format:) s -5 338 M -( uint32 id) s -5 327 M -( uint32 count) s -5 316 M -( repeats count times:) s -5 305 M -( string filename) s -5 294 M -( string longname) s -5 283 M -( ATTRS attrs) s -5 261 M -( where `id' is the request identifier, `count' is the number of names) s -5 250 M -( returned in this response, and the remaining fields repeat `count') s -5 239 M -( times \(so that all three fields are first included for the first) s -5 228 M -( file, then for the second file, etc\). In the repeated part,) s -5 217 M -( `filename' is a file name being returned \(for SSH_FXP_READDIR, it) s -5 206 M -( will be a relative name within the directory, without any path) s -5 195 M -( components; for SSH_FXP_REALPATH it will be an absolute path name\),) s -5 184 M -( `longname' is an expanded format for the file name, similar to what) s -5 173 M -( is returned by "ls -l" on Unix systems, and `attrs' is the attributes) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 22]) s -_R -S -PStoPSsaved restore -%%Page: (22,23) 12 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 23 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -( of the file as described in Section ``File Attributes''.) s -5 668 M -( The format of the `longname' field is unspecified by this protocol.) s -5 657 M -( It MUST be suitable for use in the output of a directory listing) s -5 646 M -( command \(in fact, the recommended operation for a directory listing) s -5 635 M -( command is to simply display this data\). However, clients SHOULD NOT) s -5 624 M -( attempt to parse the longname field for file attributes; they SHOULD) s -5 613 M -( use the attrs field instead.) s -5 591 M -( The recommended format for the longname field is as follows:) s -5 569 M -( -rwxr-xr-x 1 mjos staff 348911 Mar 25 14:29 t-filexfer) s -5 558 M -( 1234567890 123 12345678 12345678 12345678 123456789012) s -5 536 M -( Here, the first line is sample output, and the second field indicates) s -5 525 M -( widths of the various fields. Fields are separated by spaces. The) s -5 514 M -( first field lists file permissions for user, group, and others; the) s -5 503 M -( second field is link count; the third field is the name of the user) s -5 492 M -( who owns the file; the fourth field is the name of the group that) s -5 481 M -( owns the file; the fifth field is the size of the file in bytes; the) s -5 470 M -( sixth field \(which actually may contain spaces, but is fixed to 12) s -5 459 M -( characters\) is the file modification time, and the seventh field is) s -5 448 M -( the file name. Each field is specified to be a minimum of certain) s -5 437 M -( number of character positions \(indicated by the second line above\),) s -5 426 M -( but may also be longer if the data does not fit in the specified) s -5 415 M -( length.) s -5 393 M -( The SSH_FXP_ATTRS response has the following format:) s -5 371 M -( uint32 id) s -5 360 M -( ATTRS attrs) s -5 338 M -( where `id' is the request identifier, and `attrs' is the returned) s -5 327 M -( file attributes as described in Section ``File Attributes''.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 23]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 24 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(8. Vendor-Specific Extensions) s -5 668 M -( The SSH_FXP_EXTENDED request provides a generic extension mechanism) s -5 657 M -( for adding vendor-specific commands. The request has the following) s -5 646 M -( format:) s -5 624 M -( uint32 id) s -5 613 M -( string extended-request) s -5 602 M -( ... any request-specific data ...) s -5 580 M -( where `id' is the request identifier, and `extended-request' is a) s -5 569 M -( string of the format "name@domain", where domain is an internet) s -5 558 M -( domain name of the vendor defining the request. The rest of the) s -5 547 M -( request is completely vendor-specific, and servers should only) s -5 536 M -( attempt to interpret it if they recognize the `extended-request') s -5 525 M -( name.) s -5 503 M -( The server may respond to such requests using any of the response) s -5 492 M -( packets defined in Section ``Responses from the Server to the) s -5 481 M -( Client''. Additionally, the server may also respond with a) s -5 470 M -( SSH_FXP_EXTENDED_REPLY packet, as defined below. If the server does) s -5 459 M -( not recognize the `extended-request' name, then the server MUST) s -5 448 M -( respond with SSH_FXP_STATUS with error/status set to) s -5 437 M -( SSH_FX_OP_UNSUPPORTED.) s -5 415 M -( The SSH_FXP_EXTENDED_REPLY packet can be used to carry arbitrary) s -5 404 M -( extension-specific data from the server to the client. It is of the) s -5 393 M -( following format:) s -5 371 M -( uint32 id) s -5 360 M -( ... any request-specific data ...) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 24]) s -_R -S -PStoPSsaved restore -%%Page: (24,25) 13 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 25 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(9. Security Considerations) s -5 668 M -( This protocol assumes that it is run over a secure channel and that) s -5 657 M -( the endpoints of the channel have been authenticated. Thus, this) s -5 646 M -( protocol assumes that it is externally protected from network-level) s -5 635 M -( attacks.) s -5 613 M -( This protocol provides file system access to arbitrary files on the) s -5 602 M -( server \(only constrained by the server implementation\). It is the) s -5 591 M -( responsibility of the server implementation to enforce any access) s -5 580 M -( controls that may be required to limit the access allowed for any) s -5 569 M -( particular user \(the user being authenticated externally to this) s -5 558 M -( protocol, typically using the SSH User Authentication Protocol [6].) s -5 536 M -( Care must be taken in the server implementation to check the validity) s -5 525 M -( of received file handle strings. The server should not rely on them) s -5 514 M -( directly; it MUST check the validity of each handle before relying on) s -5 503 M -( it.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 25]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 26 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(10. Changes from previous protocol versions) s -5 668 M -( The SSH File Transfer Protocol has changed over time, before it's) s -5 657 M -( standardization. The following is a description of the incompatible) s -5 646 M -( changes between different versions.) s -5 624 M -(10.1 Changes between versions 3 and 2) s -5 602 M -( o The SSH_FXP_READLINK and SSH_FXP_SYMLINK messages were added.) s -5 580 M -( o The SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY messages were) s -5 569 M -( added.) s -5 547 M -( o The SSH_FXP_STATUS message was changed to include fields `error) s -5 536 M -( message' and `language tag'.) s -5 503 M -(10.2 Changes between versions 2 and 1) s -5 481 M -( o The SSH_FXP_RENAME message was added.) s -5 448 M -(10.3 Changes between versions 1 and 0) s -5 426 M -( o Implementation changes, no actual protocol changes.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 26]) s -_R -S -PStoPSsaved restore -%%Page: (26,27) 14 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 27 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(11. Trademark Issues) s -5 668 M -( "ssh" is a registered trademark of SSH Communications Security Corp) s -5 657 M -( in the United States and/or other countries.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 27]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 28 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(References) s -5 668 M -( [1] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and) s -5 657 M -( P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January) s -5 646 M -( 1999.) s -5 624 M -( [2] Institute of Electrical and Electronics Engineers, "Information) s -5 613 M -( Technology - Portable Operating System Interface \(POSIX\) - Part) s -5 602 M -( 1: System Application Program Interface \(API\) [C Language]",) s -5 591 M -( IEEE Standard 1003.2, 1996.) s -5 569 M -( [3] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.) s -5 558 M -( Lehtinen, "SSH Protocol Architecture", draft-ietf-secsh-) s -5 547 M -( architecture-09 \(work in progress\), July 2001.) s -5 525 M -( [4] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.) s -5 514 M -( Lehtinen, "SSH Protocol Transport Protocol", draft-ietf-secsh-) s -5 503 M -( architecture-09 \(work in progress\), July 2001.) s -5 481 M -( [5] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.) s -5 470 M -( Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-11) s -5 459 M -( \(work in progress\), July 2001.) s -5 437 M -( [6] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.) s -5 426 M -( Lehtinen, "SSH Authentication Protocol", draft-ietf-secsh-) s -5 415 M -( userauth-11 \(work in progress\), July 2001.) s -5 382 M -(Authors' Addresses) s -5 360 M -( Tatu Ylonen) s -5 349 M -( SSH Communications Security Corp) s -5 338 M -( Fredrikinkatu 42) s -5 327 M -( HELSINKI FIN-00100) s -5 316 M -( Finland) s -5 294 M -( EMail: [email protected]) s -5 261 M -( Sami Lehtinen) s -5 250 M -( SSH Communications Security Corp) s -5 239 M -( Fredrikinkatu 42) s -5 228 M -( HELSINKI FIN-00100) s -5 217 M -( Finland) s -5 195 M -( EMail: [email protected]) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 28]) s -_R -S -PStoPSsaved restore -%%Page: (28,29) 15 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 29 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2001) s -5 690 M -(Full Copyright Statement) s -5 668 M -( Copyright \(C\) The Internet Society \(2001\). All Rights Reserved.) s -5 646 M -( This document and translations of it may be copied and furnished to) s -5 635 M -( others, and derivative works that comment on or otherwise explain it) s -5 624 M -( or assist in its implementation may be prepared, copied, published) s -5 613 M -( and distributed, in whole or in part, without restriction of any) s -5 602 M -( kind, provided that the above copyright notice and this paragraph are) s -5 591 M -( included on all such copies and derivative works. However, this) s -5 580 M -( document itself may not be modified in any way, such as by removing) s -5 569 M -( the copyright notice or references to the Internet Society or other) s -5 558 M -( Internet organizations, except as needed for the purpose of) s -5 547 M -( developing Internet standards in which case the procedures for) s -5 536 M -( copyrights defined in the Internet Standards process must be) s -5 525 M -( followed, or as required to translate it into languages other than) s -5 514 M -( English.) s -5 492 M -( The limited permissions granted above are perpetual and will not be) s -5 481 M -( revoked by the Internet Society or its successors or assigns.) s -5 459 M -( This document and the information contained herein is provided on an) s -5 448 M -( "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING) s -5 437 M -( TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING) s -5 426 M -( BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION) s -5 415 M -( HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF) s -5 404 M -( MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.) s -5 382 M -(Acknowledgement) s -5 360 M -( Funding for the RFC Editor function is currently provided by the) s -5 349 M -( Internet Society.) s -5 129 M -(Ylonen & Lehtinen Expires April 1, 2002 [Page 29]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 30 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -_R -S -PStoPSsaved restore -%%Trailer -%%Pages: 30 -%%DocumentNeededResources: font Courier-Bold Courier -%%EOF diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-02.txt b/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-02.txt deleted file mode 100644 index c4ec8c1125..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-02.txt +++ /dev/null @@ -1,1627 +0,0 @@ - - - -Network Working Group T. Ylonen -Internet-Draft S. Lehtinen -Expires: April 1, 2002 SSH Communications Security Corp - October 2001 - - - SSH File Transfer Protocol - draft-ietf-secsh-filexfer-02.txt - -Status of this Memo - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that - other groups may also distribute working documents as Internet- - Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at http:// - www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on April 1, 2002. - -Copyright Notice - - Copyright (C) The Internet Society (2001). All Rights Reserved. - -Abstract - - The SSH File Transfer Protocol provides secure file transfer - functionality over any reliable data stream. It is the standard file - transfer protocol for use with the SSH2 protocol. This document - describes the file transfer protocol and its interface to the SSH2 - protocol suite. - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 1] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -Table of Contents - - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Use with the SSH Connection Protocol . . . . . . . . . . . . 4 - 3. General Packet Format . . . . . . . . . . . . . . . . . . . 5 - 4. Protocol Initialization . . . . . . . . . . . . . . . . . . 7 - 5. File Attributes . . . . . . . . . . . . . . . . . . . . . . 8 - 6. Requests From the Client to the Server . . . . . . . . . . . 10 - 6.1 Request Synchronization and Reordering . . . . . . . . . . . 10 - 6.2 File Names . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 6.3 Opening, Creating, and Closing Files . . . . . . . . . . . . 11 - 6.4 Reading and Writing . . . . . . . . . . . . . . . . . . . . 13 - 6.5 Removing and Renaming Files . . . . . . . . . . . . . . . . 14 - 6.6 Creating and Deleting Directories . . . . . . . . . . . . . 15 - 6.7 Scanning Directories . . . . . . . . . . . . . . . . . . . . 15 - 6.8 Retrieving File Attributes . . . . . . . . . . . . . . . . . 16 - 6.9 Setting File Attributes . . . . . . . . . . . . . . . . . . 17 - 6.10 Dealing with Symbolic links . . . . . . . . . . . . . . . . 18 - 6.11 Canonicalizing the Server-Side Path Name . . . . . . . . . . 18 - 7. Responses from the Server to the Client . . . . . . . . . . 20 - 8. Vendor-Specific Extensions . . . . . . . . . . . . . . . . . 24 - 9. Security Considerations . . . . . . . . . . . . . . . . . . 25 - 10. Changes from previous protocol versions . . . . . . . . . . 26 - 10.1 Changes between versions 3 and 2 . . . . . . . . . . . . . . 26 - 10.2 Changes between versions 2 and 1 . . . . . . . . . . . . . . 26 - 10.3 Changes between versions 1 and 0 . . . . . . . . . . . . . . 26 - 11. Trademark Issues . . . . . . . . . . . . . . . . . . . . . . 27 - References . . . . . . . . . . . . . . . . . . . . . . . . . 28 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 28 - Full Copyright Statement . . . . . . . . . . . . . . . . . . 29 - - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 2] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -1. Introduction - - This protocol provides secure file transfer (and more generally file - system access) functionality over a reliable data stream, such as a - channel in the SSH2 protocol [3]. - - This protocol is designed so that it could be used to implement a - secure remote file system service, as well as a secure file transfer - service. - - This protocol assumes that it runs over a secure channel, and that - the server has already authenticated the user at the client end, and - that the identity of the client user is externally available to the - server implementation. - - In general, this protocol follows a simple request-response model. - Each request and response contains a sequence number and multiple - requests may be pending simultaneously. There are a relatively large - number of different request messages, but a small number of possible - response messages. Each request has one or more response messages - that may be returned in result (e.g., a read either returns data or - reports error status). - - The packet format descriptions in this specification follow the - notation presented in the secsh architecture draft.[3]. - - Even though this protocol is described in the context of the SSH2 - protocol, this protocol is general and independent of the rest of the - SSH2 protocol suite. It could be used in a number of different - applications, such as secure file transfer over TLS RFC 2246 [1] and - transfer of management information in VPN applications. - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 3] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -2. Use with the SSH Connection Protocol - - When used with the SSH2 Protocol suite, this protocol is intended to - be used from the SSH Connection Protocol [5] as a subsystem, as - described in section ``Starting a Shell or a Command''. The - subsystem name used with this protocol is "sftp". - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 4] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -3. General Packet Format - - All packets transmitted over the secure connection are of the - following format: - - uint32 length - byte type - byte[length - 1] data payload - - That is, they are just data preceded by 32-bit length and 8-bit type - fields. The `length' is the length of the data area, and does not - include the `length' field itself. The format and interpretation of - the data area depends on the packet type. - - All packet descriptions below only specify the packet type and the - data that goes into the data field. Thus, they should be prefixed by - the `length' and `type' fields. - - The maximum size of a packet is in practice determined by the client - (the maximum size of read or write requests that it sends, plus a few - bytes of packet overhead). All servers SHOULD support packets of at - least 34000 bytes (where the packet size refers to the full length, - including the header above). This should allow for reads and writes - of at most 32768 bytes. - - There is no limit on the number of outstanding (non-acknowledged) - requests that the client may send to the server. In practice this is - limited by the buffering available on the data stream and the queuing - performed by the server. If the server's queues are full, it should - not read any more data from the stream, and flow control will prevent - the client from sending more requests. Note, however, that while - there is no restriction on the protocol level, the client's API may - provide a limit in order to prevent infinite queuing of outgoing - requests at the client. - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 5] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - The following values are defined for packet types. - - #define SSH_FXP_INIT 1 - #define SSH_FXP_VERSION 2 - #define SSH_FXP_OPEN 3 - #define SSH_FXP_CLOSE 4 - #define SSH_FXP_READ 5 - #define SSH_FXP_WRITE 6 - #define SSH_FXP_LSTAT 7 - #define SSH_FXP_FSTAT 8 - #define SSH_FXP_SETSTAT 9 - #define SSH_FXP_FSETSTAT 10 - #define SSH_FXP_OPENDIR 11 - #define SSH_FXP_READDIR 12 - #define SSH_FXP_REMOVE 13 - #define SSH_FXP_MKDIR 14 - #define SSH_FXP_RMDIR 15 - #define SSH_FXP_REALPATH 16 - #define SSH_FXP_STAT 17 - #define SSH_FXP_RENAME 18 - #define SSH_FXP_READLINK 19 - #define SSH_FXP_SYMLINK 20 - #define SSH_FXP_STATUS 101 - #define SSH_FXP_HANDLE 102 - #define SSH_FXP_DATA 103 - #define SSH_FXP_NAME 104 - #define SSH_FXP_ATTRS 105 - #define SSH_FXP_EXTENDED 200 - #define SSH_FXP_EXTENDED_REPLY 201 - - Additional packet types should only be defined if the protocol - version number (see Section ``Protocol Initialization'') is - incremented, and their use MUST be negotiated using the version - number. However, the SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY - packets can be used to implement vendor-specific extensions. See - Section ``Vendor-Specific-Extensions'' for more details. - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 6] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -4. Protocol Initialization - - When the file transfer protocol starts, it first sends a SSH_FXP_INIT - (including its version number) packet to the server. The server - responds with a SSH_FXP_VERSION packet, supplying the lowest of its - own and the client's version number. Both parties should from then - on adhere to particular version of the protocol. - - The SSH_FXP_INIT packet (from client to server) has the following - data: - - uint32 version - <extension data> - - The SSH_FXP_VERSION packet (from server to client) has the following - data: - - uint32 version - <extension data> - - The version number of the protocol specified in this document is 3. - The version number should be incremented for each incompatible - revision of this protocol. - - The extension data in the above packets may be empty, or may be a - sequence of - - string extension_name - string extension_data - - pairs (both strings MUST always be present if one is, but the - `extension_data' string may be of zero length). If present, these - strings indicate extensions to the baseline protocol. The - `extension_name' field(s) identify the name of the extension. The - name should be of the form "name@domain", where the domain is the DNS - domain name of the organization defining the extension. Additional - names that are not of this format may be defined later by the IETF. - Implementations MUST silently ignore any extensions whose name they - do not recognize. - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 7] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -5. File Attributes - - A new compound data type is defined for encoding file attributes. It - is basically just a combination of elementary types, but is defined - once because of the non-trivial description of the fields and to - ensure maintainability. - - The same encoding is used both when returning file attributes from - the server and when sending file attributes to the server. When - sending it to the server, the flags field specifies which attributes - are included, and the server will use default values for the - remaining attributes (or will not modify the values of remaining - attributes). When receiving attributes from the server, the flags - specify which attributes are included in the returned data. The - server normally returns all attributes it knows about. - - uint32 flags - uint64 size present only if flag SSH_FILEXFER_ATTR_SIZE - uint32 uid present only if flag SSH_FILEXFER_ATTR_UIDGID - uint32 gid present only if flag SSH_FILEXFER_ATTR_UIDGID - uint32 permissions present only if flag SSH_FILEXFER_ATTR_PERMISSIONS - uint32 atime present only if flag SSH_FILEXFER_ACMODTIME - uint32 mtime present only if flag SSH_FILEXFER_ACMODTIME - uint32 extended_count present only if flag SSH_FILEXFER_ATTR_EXTENDED - string extended_type - string extended_data - ... more extended data (extended_type - extended_data pairs), - so that number of pairs equals extended_count - - The `flags' specify which of the fields are present. Those fields - for which the corresponding flag is not set are not present (not - included in the packet). New flags can only be added by incrementing - the protocol version number (or by using the extension mechanism - described below). - - The `size' field specifies the size of the file in bytes. - - The `uid' and `gid' fields contain numeric Unix-like user and group - identifiers, respectively. - - The `permissions' field contains a bit mask of file permissions as - defined by posix [1]. - - The `atime' and `mtime' contain the access and modification times of - the files, respectively. They are represented as seconds from Jan 1, - 1970 in UTC. - - The SSH_FILEXFER_ATTR_EXTENDED flag provides a general extension - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 8] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - mechanism for vendor-specific extensions. If the flag is specified, - then the `extended_count' field is present. It specifies the number - of extended_type-extended_data pairs that follow. Each of these - pairs specifies an extended attribute. For each of the attributes, - the extended_type field should be a string of the format - "name@domain", where "domain" is a valid, registered domain name and - "name" identifies the method. The IETF may later standardize certain - names that deviate from this format (e.g., that do not contain the - "@" sign). The interpretation of `extended_data' depends on the - type. Implementations SHOULD ignore extended data fields that they - do not understand. - - Additional fields can be added to the attributes by either defining - additional bits to the flags field to indicate their presence, or by - defining extended attributes for them. The extended attributes - mechanism is recommended for most purposes; additional flags bits - should only be defined by an IETF standards action that also - increments the protocol version number. The use of such new fields - MUST be negotiated by the version number in the protocol exchange. - It is a protocol error if a packet with unsupported protocol bits is - received. - - The flags bits are defined to have the following values: - - #define SSH_FILEXFER_ATTR_SIZE 0x00000001 - #define SSH_FILEXFER_ATTR_UIDGID 0x00000002 - #define SSH_FILEXFER_ATTR_PERMISSIONS 0x00000004 - #define SSH_FILEXFER_ATTR_ACMODTIME 0x00000008 - #define SSH_FILEXFER_ATTR_EXTENDED 0x80000000 - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 9] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -6. Requests From the Client to the Server - - Requests from the client to the server represent the various file - system operations. Each request begins with an `id' field, which is - a 32-bit identifier identifying the request (selected by the client). - The same identifier will be returned in the response to the request. - One possible implementation of it is a monotonically increasing - request sequence number (modulo 2^32). - - Many operations in the protocol operate on open files. The - SSH_FXP_OPEN request can return a file handle (which is an opaque - variable-length string) which may be used to access the file later - (e.g. in a read operation). The client MUST NOT send requests the - server with bogus or closed handles. However, the server MUST - perform adequate checks on the handle in order to avoid security - risks due to fabricated handles. - - This design allows either stateful and stateless server - implementation, as well as an implementation which caches state - between requests but may also flush it. The contents of the file - handle string are entirely up to the server and its design. The - client should not modify or attempt to interpret the file handle - strings. - - The file handle strings MUST NOT be longer than 256 bytes. - -6.1 Request Synchronization and Reordering - - The protocol and implementations MUST process requests relating to - the same file in the order in which they are received. In other - words, if an application submits multiple requests to the server, the - results in the responses will be the same as if it had sent the - requests one at a time and waited for the response in each case. For - example, the server may process non-overlapping read/write requests - to the same file in parallel, but overlapping reads and writes cannot - be reordered or parallelized. However, there are no ordering - restrictions on the server for processing requests from two different - file transfer connections. The server may interleave and parallelize - them at will. - - There are no restrictions on the order in which responses to - outstanding requests are delivered to the client, except that the - server must ensure fairness in the sense that processing of no - request will be indefinitely delayed even if the client is sending - other requests so that there are multiple outstanding requests all - the time. - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 10] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -6.2 File Names - - This protocol represents file names as strings. File names are - assumed to use the slash ('/') character as a directory separator. - - File names starting with a slash are "absolute", and are relative to - the root of the file system. Names starting with any other character - are relative to the user's default directory (home directory). Note - that identifying the user is assumed to take place outside of this - protocol. - - Servers SHOULD interpret a path name component ".." as referring to - the parent directory, and "." as referring to the current directory. - If the server implementation limits access to certain parts of the - file system, it must be extra careful in parsing file names when - enforcing such restrictions. There have been numerous reported - security bugs where a ".." in a path name has allowed access outside - the intended area. - - An empty path name is valid, and it refers to the user's default - directory (usually the user's home directory). - - Otherwise, no syntax is defined for file names by this specification. - Clients should not make any other assumptions; however, they can - splice path name components returned by SSH_FXP_READDIR together - using a slash ('/') as the separator, and that will work as expected. - - It is understood that the lack of well-defined semantics for file - names may cause interoperability problems between clients and servers - using radically different operating systems. However, this approach - is known to work acceptably with most systems, and alternative - approaches that e.g. treat file names as sequences of structured - components are quite complicated. - -6.3 Opening, Creating, and Closing Files - - Files are opened and created using the SSH_FXP_OPEN message, whose - data part is as follows: - - uint32 id - string filename - uint32 pflags - ATTRS attrs - - The `id' field is the request identifier as for all requests. - - The `filename' field specifies the file name. See Section ``File - Names'' for more information. - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 11] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - The `pflags' field is a bitmask. The following bits have been - defined. - - #define SSH_FXF_READ 0x00000001 - #define SSH_FXF_WRITE 0x00000002 - #define SSH_FXF_APPEND 0x00000004 - #define SSH_FXF_CREAT 0x00000008 - #define SSH_FXF_TRUNC 0x00000010 - #define SSH_FXF_EXCL 0x00000020 - - These have the following meanings: - - SSH_FXF_READ - Open the file for reading. - - SSH_FXF_WRITE - Open the file for writing. If both this and SSH_FXF_READ are - specified, the file is opened for both reading and writing. - - SSH_FXF_APPEND - Force all writes to append data at the end of the file. - - SSH_FXF_CREAT - If this flag is specified, then a new file will be created if one - does not already exist (if O_TRUNC is specified, the new file will - be truncated to zero length if it previously exists). - - SSH_FXF_TRUNC - Forces an existing file with the same name to be truncated to zero - length when creating a file by specifying SSH_FXF_CREAT. - SSH_FXF_CREAT MUST also be specified if this flag is used. - - SSH_FXF_EXCL - Causes the request to fail if the named file already exists. - SSH_FXF_CREAT MUST also be specified if this flag is used. - - The `attrs' field specifies the initial attributes for the file. - Default values will be used for those attributes that are not - specified. See Section ``File Attributes'' for more information. - - Regardless the server operating system, the file will always be - opened in "binary" mode (i.e., no translations between different - character sets and newline encodings). - - The response to this message will be either SSH_FXP_HANDLE (if the - operation is successful) or SSH_FXP_STATUS (if the operation fails). - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 12] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - A file is closed by using the SSH_FXP_CLOSE request. Its data field - has the following format: - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is a handle - previously returned in the response to SSH_FXP_OPEN or - SSH_FXP_OPENDIR. The handle becomes invalid immediately after this - request has been sent. - - The response to this request will be a SSH_FXP_STATUS message. One - should note that on some server platforms even a close can fail. - This can happen e.g. if the server operating system caches writes, - and an error occurs while flushing cached writes during the close. - -6.4 Reading and Writing - - Once a file has been opened, it can be read using the SSH_FXP_READ - message, which has the following format: - - uint32 id - string handle - uint64 offset - uint32 len - - where `id' is the request identifier, `handle' is an open file handle - returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) relative - to the beginning of the file from where to start reading, and `len' - is the maximum number of bytes to read. - - In response to this request, the server will read as many bytes as it - can from the file (up to `len'), and return them in a SSH_FXP_DATA - message. If an error occurs or EOF is encountered before reading any - data, the server will respond with SSH_FXP_STATUS. For normal disk - files, it is guaranteed that this will read the specified number of - bytes, or up to end of file. For e.g. device files this may return - fewer bytes than requested. - - Writing to a file is achieved using the SSH_FXP_WRITE message, which - has the following format: - - uint32 id - string handle - uint64 offset - string data - - where `id' is a request identifier, `handle' is a file handle - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 13] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) from the - beginning of the file where to start writing, and `data' is the data - to be written. - - The write will extend the file if writing beyond the end of the file. - It is legal to write way beyond the end of the file; the semantics - are to write zeroes from the end of the file to the specified offset - and then the data. On most operating systems, such writes do not - allocate disk space but instead leave "holes" in the file. - - The server responds to a write request with a SSH_FXP_STATUS message. - -6.5 Removing and Renaming Files - - Files can be removed using the SSH_FXP_REMOVE message. It has the - following format: - - uint32 id - string filename - - where `id' is the request identifier and `filename' is the name of - the file to be removed. See Section ``File Names'' for more - information. This request cannot be used to remove directories. - - The server will respond to this request with a SSH_FXP_STATUS - message. - - Files (and directories) can be renamed using the SSH_FXP_RENAME - message. Its data is as follows: - - uint32 id - string oldpath - string newpath - - where `id' is the request identifier, `oldpath' is the name of an - existing file or directory, and `newpath' is the new name for the - file or directory. It is an error if there already exists a file - with the name specified by newpath. The server may also fail rename - requests in other situations, for example if `oldpath' and `newpath' - point to different file systems on the server. - - The server will respond to this request with a SSH_FXP_STATUS - message. - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 14] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -6.6 Creating and Deleting Directories - - New directories can be created using the SSH_FXP_MKDIR request. It - has the following format: - - uint32 id - string path - ATTRS attrs - - where `id' is the request identifier, `path' and `attrs' specifies - the modifications to be made to its attributes. See Section ``File - Names'' for more information on file names. Attributes are discussed - in more detail in Section ``File Attributes''. specifies the - directory to be created. An error will be returned if a file or - directory with the specified path already exists. The server will - respond to this request with a SSH_FXP_STATUS message. - - Directories can be removed using the SSH_FXP_RMDIR request, which - has the following format: - - uint32 id - string path - - where `id' is the request identifier, and `path' specifies the - directory to be removed. See Section ``File Names'' for more - information on file names. An error will be returned if no directory - with the specified path exists, or if the specified directory is not - empty, or if the path specified a file system object other than a - directory. The server responds to this request with a SSH_FXP_STATUS - message. - -6.7 Scanning Directories - - The files in a directory can be listed using the SSH_FXP_OPENDIR and - SSH_FXP_READDIR requests. Each SSH_FXP_READDIR request returns one - or more file names with full file attributes for each file. The - client should call SSH_FXP_READDIR repeatedly until it has found the - file it is looking for or until the server responds with a - SSH_FXP_STATUS message indicating an error (normally SSH_FX_EOF if - there are no more files in the directory). The client should then - close the handle using the SSH_FXP_CLOSE request. - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 15] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - The SSH_FXP_OPENDIR opens a directory for reading. It has the - following format: - - uint32 id - string path - - where `id' is the request identifier and `path' is the path name of - the directory to be listed (without any trailing slash). See Section - ``File Names'' for more information on file names. This will return - an error if the path does not specify a directory or if the directory - is not readable. The server will respond to this request with either - a SSH_FXP_HANDLE or a SSH_FXP_STATUS message. - - Once the directory has been successfully opened, files (and - directories) contained in it can be listed using SSH_FXP_READDIR - requests. These are of the format - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is a handle - returned by SSH_FXP_OPENDIR. (It is a protocol error to attempt to - use an ordinary file handle returned by SSH_FXP_OPEN.) - - The server responds to this request with either a SSH_FXP_NAME or a - SSH_FXP_STATUS message. One or more names may be returned at a time. - Full status information is returned for each name in order to speed - up typical directory listings. - - When the client no longer wishes to read more names from the - directory, it SHOULD call SSH_FXP_CLOSE for the handle. The handle - should be closed regardless of whether an error has occurred or not. - -6.8 Retrieving File Attributes - - Very often, file attributes are automatically returned by - SSH_FXP_READDIR. However, sometimes there is need to specifically - retrieve the attributes for a named file. This can be done using the - SSH_FXP_STAT, SSH_FXP_LSTAT and SSH_FXP_FSTAT requests. - - SSH_FXP_STAT and SSH_FXP_LSTAT only differ in that SSH_FXP_STAT - follows symbolic links on the server, whereas SSH_FXP_LSTAT does not - follow symbolic links. Both have the same format: - - uint32 id - string path - - where `id' is the request identifier, and `path' specifies the file - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 16] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - system object for which status is to be returned. The server - responds to this request with either SSH_FXP_ATTRS or SSH_FXP_STATUS. - - SSH_FXP_FSTAT differs from the others in that it returns status - information for an open file (identified by the file handle). Its - format is as follows: - - uint32 id - string handle - - where `id' is the request identifier and `handle' is a file handle - returned by SSH_FXP_OPEN. The server responds to this request with - SSH_FXP_ATTRS or SSH_FXP_STATUS. - -6.9 Setting File Attributes - - File attributes may be modified using the SSH_FXP_SETSTAT and - SSH_FXP_FSETSTAT requests. These requests are used for operations - such as changing the ownership, permissions or access times, as well - as for truncating a file. - - The SSH_FXP_SETSTAT request is of the following format: - - uint32 id - string path - ATTRS attrs - - where `id' is the request identifier, `path' specifies the file - system object (e.g. file or directory) whose attributes are to be - modified, and `attrs' specifies the modifications to be made to its - attributes. Attributes are discussed in more detail in Section - ``File Attributes''. - - An error will be returned if the specified file system object does - not exist or the user does not have sufficient rights to modify the - specified attributes. The server responds to this request with a - SSH_FXP_STATUS message. - - The SSH_FXP_FSETSTAT request modifies the attributes of a file which - is already open. It has the following format: - - uint32 id - string handle - ATTRS attrs - - where `id' is the request identifier, `handle' (MUST be returned by - SSH_FXP_OPEN) identifies the file whose attributes are to be - modified, and `attrs' specifies the modifications to be made to its - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 17] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - attributes. Attributes are discussed in more detail in Section - ``File Attributes''. The server will respond to this request with - SSH_FXP_STATUS. - -6.10 Dealing with Symbolic links - - The SSH_FXP_READLINK request may be used to read the target of a - symbolic link. It would have a data part as follows: - - uint32 id - string path - - where `id' is the request identifier and `path' specifies the path - name of the symlink to be read. - - The server will respond with a SSH_FXP_NAME packet containing only - one name and a dummy attributes value. The name in the returned - packet contains the target of the link. If an error occurs, the - server may respond with SSH_FXP_STATUS. - - The SSH_FXP_SYMLINK request will create a symbolic link on the - server. It is of the following format - - uint32 id - string linkpath - string targetpath - - where `id' is the request identifier, `linkpath' specifies the path - name of the symlink to be created and `targetpath' specifies the - target of the symlink. The server shall respond with a - SSH_FXP_STATUS indicating either success (SSH_FX_OK) or an error - condition. - -6.11 Canonicalizing the Server-Side Path Name - - The SSH_FXP_REALPATH request can be used to have the server - canonicalize any given path name to an absolute path. This is useful - for converting path names containing ".." components or relative - pathnames without a leading slash into absolute paths. The format of - the request is as follows: - - uint32 id - string path - - where `id' is the request identifier and `path' specifies the path - name to be canonicalized. The server will respond with a - SSH_FXP_NAME packet containing only one name and a dummy attributes - value. The name is the returned packet will be in canonical form. - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 18] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - If an error occurs, the server may also respond with SSH_FXP_STATUS. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 19] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -7. Responses from the Server to the Client - - The server responds to the client using one of a few response - packets. All requests can return a SSH_FXP_STATUS response upon - failure. When the operation is successful, any of the responses may - be returned (depending on the operation). If no data needs to be - returned to the client, the SSH_FXP_STATUS response with SSH_FX_OK - status is appropriate. Otherwise, the SSH_FXP_HANDLE message is used - to return a file handle (for SSH_FXP_OPEN and SSH_FXP_OPENDIR - requests), SSH_FXP_DATA is used to return data from SSH_FXP_READ, - SSH_FXP_NAME is used to return one or more file names from a - SSH_FXP_READDIR or SSH_FXP_REALPATH request, and SSH_FXP_ATTRS is - used to return file attributes from SSH_FXP_STAT, SSH_FXP_LSTAT, and - SSH_FXP_FSTAT requests. - - Exactly one response will be returned for each request. Each - response packet contains a request identifier which can be used to - match each response with the corresponding request. Note that it is - legal to have several requests outstanding simultaneously, and the - server is allowed to send responses to them in a different order from - the order in which the requests were sent (the result of their - execution, however, is guaranteed to be as if they had been processed - one at a time in the order in which the requests were sent). - - Response packets are of the same general format as request packets. - Each response packet begins with the request identifier. - - The format of the data portion of the SSH_FXP_STATUS response is as - follows: - - uint32 id - uint32 error/status code - string error message (ISO-10646 UTF-8 [RFC-2279]) - string language tag (as defined in [RFC-1766]) - - where `id' is the request identifier, and `error/status code' - indicates the result of the requested operation. The value SSH_FX_OK - indicates success, and all other values indicate failure. - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 20] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - Currently, the following values are defined (other values may be - defined by future versions of this protocol): - - #define SSH_FX_OK 0 - #define SSH_FX_EOF 1 - #define SSH_FX_NO_SUCH_FILE 2 - #define SSH_FX_PERMISSION_DENIED 3 - #define SSH_FX_FAILURE 4 - #define SSH_FX_BAD_MESSAGE 5 - #define SSH_FX_NO_CONNECTION 6 - #define SSH_FX_CONNECTION_LOST 7 - #define SSH_FX_OP_UNSUPPORTED 8 - - SSH_FX_OK - Indicates successful completion of the operation. - - SSH_FX_EOF - indicates end-of-file condition; for SSH_FX_READ it means that no - more data is available in the file, and for SSH_FX_READDIR it - indicates that no more files are contained in the directory. - - SSH_FX_NO_SUCH_FILE - is returned when a reference is made to a file which should exist - but doesn't. - - SSH_FX_PERMISSION_DENIED - is returned when the authenticated user does not have sufficient - permissions to perform the operation. - - SSH_FX_FAILURE - is a generic catch-all error message; it should be returned if an - error occurs for which there is no more specific error code - defined. - - SSH_FX_BAD_MESSAGE - may be returned if a badly formatted packet or protocol - incompatibility is detected. - - SSH_FX_NO_CONNECTION - is a pseudo-error which indicates that the client has no - connection to the server (it can only be generated locally by the - client, and MUST NOT be returned by servers). - - SSH_FX_CONNECTION_LOST - is a pseudo-error which indicates that the connection to the - server has been lost (it can only be generated locally by the - client, and MUST NOT be returned by servers). - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 21] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - SSH_FX_OP_UNSUPPORTED - indicates that an attempt was made to perform an operation which - is not supported for the server (it may be generated locally by - the client if e.g. the version number exchange indicates that a - required feature is not supported by the server, or it may be - returned by the server if the server does not implement an - operation). - - The SSH_FXP_HANDLE response has the following format: - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is an arbitrary - string that identifies an open file or directory on the server. The - handle is opaque to the client; the client MUST NOT attempt to - interpret or modify it in any way. The length of the handle string - MUST NOT exceed 256 data bytes. - - The SSH_FXP_DATA response has the following format: - - uint32 id - string data - - where `id' is the request identifier, and `data' is an arbitrary byte - string containing the requested data. The data string may be at most - the number of bytes requested in a SSH_FXP_READ request, but may also - be shorter if end of file is reached or if the read is from something - other than a regular file. - - The SSH_FXP_NAME response has the following format: - - uint32 id - uint32 count - repeats count times: - string filename - string longname - ATTRS attrs - - where `id' is the request identifier, `count' is the number of names - returned in this response, and the remaining fields repeat `count' - times (so that all three fields are first included for the first - file, then for the second file, etc). In the repeated part, - `filename' is a file name being returned (for SSH_FXP_READDIR, it - will be a relative name within the directory, without any path - components; for SSH_FXP_REALPATH it will be an absolute path name), - `longname' is an expanded format for the file name, similar to what - is returned by "ls -l" on Unix systems, and `attrs' is the attributes - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 22] - -Internet-Draft SSH File Transfer Protocol October 2001 - - - of the file as described in Section ``File Attributes''. - - The format of the `longname' field is unspecified by this protocol. - It MUST be suitable for use in the output of a directory listing - command (in fact, the recommended operation for a directory listing - command is to simply display this data). However, clients SHOULD NOT - attempt to parse the longname field for file attributes; they SHOULD - use the attrs field instead. - - The recommended format for the longname field is as follows: - - -rwxr-xr-x 1 mjos staff 348911 Mar 25 14:29 t-filexfer - 1234567890 123 12345678 12345678 12345678 123456789012 - - Here, the first line is sample output, and the second field indicates - widths of the various fields. Fields are separated by spaces. The - first field lists file permissions for user, group, and others; the - second field is link count; the third field is the name of the user - who owns the file; the fourth field is the name of the group that - owns the file; the fifth field is the size of the file in bytes; the - sixth field (which actually may contain spaces, but is fixed to 12 - characters) is the file modification time, and the seventh field is - the file name. Each field is specified to be a minimum of certain - number of character positions (indicated by the second line above), - but may also be longer if the data does not fit in the specified - length. - - The SSH_FXP_ATTRS response has the following format: - - uint32 id - ATTRS attrs - - where `id' is the request identifier, and `attrs' is the returned - file attributes as described in Section ``File Attributes''. - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 23] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -8. Vendor-Specific Extensions - - The SSH_FXP_EXTENDED request provides a generic extension mechanism - for adding vendor-specific commands. The request has the following - format: - - uint32 id - string extended-request - ... any request-specific data ... - - where `id' is the request identifier, and `extended-request' is a - string of the format "name@domain", where domain is an internet - domain name of the vendor defining the request. The rest of the - request is completely vendor-specific, and servers should only - attempt to interpret it if they recognize the `extended-request' - name. - - The server may respond to such requests using any of the response - packets defined in Section ``Responses from the Server to the - Client''. Additionally, the server may also respond with a - SSH_FXP_EXTENDED_REPLY packet, as defined below. If the server does - not recognize the `extended-request' name, then the server MUST - respond with SSH_FXP_STATUS with error/status set to - SSH_FX_OP_UNSUPPORTED. - - The SSH_FXP_EXTENDED_REPLY packet can be used to carry arbitrary - extension-specific data from the server to the client. It is of the - following format: - - uint32 id - ... any request-specific data ... - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 24] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -9. Security Considerations - - This protocol assumes that it is run over a secure channel and that - the endpoints of the channel have been authenticated. Thus, this - protocol assumes that it is externally protected from network-level - attacks. - - This protocol provides file system access to arbitrary files on the - server (only constrained by the server implementation). It is the - responsibility of the server implementation to enforce any access - controls that may be required to limit the access allowed for any - particular user (the user being authenticated externally to this - protocol, typically using the SSH User Authentication Protocol [6]. - - Care must be taken in the server implementation to check the validity - of received file handle strings. The server should not rely on them - directly; it MUST check the validity of each handle before relying on - it. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 25] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -10. Changes from previous protocol versions - - The SSH File Transfer Protocol has changed over time, before it's - standardization. The following is a description of the incompatible - changes between different versions. - -10.1 Changes between versions 3 and 2 - - o The SSH_FXP_READLINK and SSH_FXP_SYMLINK messages were added. - - o The SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY messages were - added. - - o The SSH_FXP_STATUS message was changed to include fields `error - message' and `language tag'. - - -10.2 Changes between versions 2 and 1 - - o The SSH_FXP_RENAME message was added. - - -10.3 Changes between versions 1 and 0 - - o Implementation changes, no actual protocol changes. - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 26] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -11. Trademark Issues - - "ssh" is a registered trademark of SSH Communications Security Corp - in the United States and/or other countries. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 27] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -References - - [1] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and - P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January - 1999. - - [2] Institute of Electrical and Electronics Engineers, "Information - Technology - Portable Operating System Interface (POSIX) - Part - 1: System Application Program Interface (API) [C Language]", - IEEE Standard 1003.2, 1996. - - [3] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Protocol Architecture", draft-ietf-secsh- - architecture-09 (work in progress), July 2001. - - [4] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Protocol Transport Protocol", draft-ietf-secsh- - architecture-09 (work in progress), July 2001. - - [5] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-11 - (work in progress), July 2001. - - [6] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Authentication Protocol", draft-ietf-secsh- - userauth-11 (work in progress), July 2001. - - -Authors' Addresses - - Tatu Ylonen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - Sami Lehtinen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 28] - -Internet-Draft SSH File Transfer Protocol October 2001 - - -Full Copyright Statement - - Copyright (C) The Internet Society (2001). All Rights Reserved. - - This document and translations of it may be copied and furnished to - others, and derivative works that comment on or otherwise explain it - or assist in its implementation may be prepared, copied, published - and distributed, in whole or in part, without restriction of any - kind, provided that the above copyright notice and this paragraph are - included on all such copies and derivative works. However, this - document itself may not be modified in any way, such as by removing - the copyright notice or references to the Internet Society or other - Internet organizations, except as needed for the purpose of - developing Internet standards in which case the procedures for - copyrights defined in the Internet Standards process must be - followed, or as required to translate it into languages other than - English. - - The limited permissions granted above are perpetual and will not be - revoked by the Internet Society or its successors or assigns. - - This document and the information contained herein is provided on an - "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING - TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING - BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION - HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF - MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - -Acknowledgement - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - -Ylonen & Lehtinen Expires April 1, 2002 [Page 29] - - - diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-03.2.ps b/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-03.2.ps deleted file mode 100644 index 6a40cd6067..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-03.2.ps +++ /dev/null @@ -1,3511 +0,0 @@ -%!PS-Adobe-3.0 -%%BoundingBox: 75 0 595 747 -%%Title: Enscript Output -%%For: Magnus Thoang -%%Creator: GNU enscript 1.6.1 -%%CreationDate: Wed Nov 12 12:18:50 2003 -%%Orientation: Portrait -%%Pages: 18 0 -%%DocumentMedia: A4 595 842 0 () () -%%DocumentNeededResources: (atend) -%%EndComments -%%BeginProlog -%%BeginProcSet: PStoPS 1 15 -userdict begin -[/showpage/erasepage/copypage]{dup where{pop dup load - type/operatortype eq{1 array cvx dup 0 3 index cvx put - bind def}{pop}ifelse}{pop}ifelse}forall -[/letter/legal/executivepage/a4/a4small/b5/com10envelope - /monarchenvelope/c5envelope/dlenvelope/lettersmall/note - 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matrix invertmatrix matrix concatmatrix - matrix invertmatrix put -%%EndSetup -%%Page: (0,1) 1 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 1 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 701 M -(Secure Shell Working Group J. Galbraith) s -5 690 M -(Internet-Draft VanDyke Software) s -5 679 M -(Expires: April 16, 2003 T. Ylonen) s -5 668 M -( S. Lehtinen) s -5 657 M -( SSH Communications Security Corp) s -5 646 M -( October 16, 2002) s -5 613 M -( SSH File Transfer Protocol) s -5 602 M -( draft-ietf-secsh-filexfer-03.txt) s -5 580 M -(Status of this Memo) s -5 558 M -( This document is an Internet-Draft and is in full conformance with) s -5 547 M -( all provisions of Section 10 of RFC2026.) s -5 525 M -( Internet-Drafts are working documents of the Internet Engineering) s -5 514 M -( Task Force \(IETF\), its areas, and its working groups. Note that) s -5 503 M -( other groups may also distribute working documents as Internet-) s -5 492 M -( Drafts.) s -5 470 M -( Internet-Drafts are draft documents valid for a maximum of six months) s -5 459 M -( and may be updated, replaced, or obsoleted by other documents at any) s -5 448 M -( time. It is inappropriate to use Internet-Drafts as reference) s -5 437 M -( material or to cite them other than as "work in progress.") s -5 415 M -( The list of current Internet-Drafts can be accessed at http://) s -5 404 M -( www.ietf.org/ietf/1id-abstracts.txt.) s -5 382 M -( The list of Internet-Draft Shadow Directories can be accessed at) s -5 371 M -( http://www.ietf.org/shadow.html.) s -5 349 M -( This Internet-Draft will expire on April 16, 2003.) s -5 327 M -(Copyright Notice) s -5 305 M -( Copyright \(C\) The Internet Society \(2002\). All Rights Reserved.) s -5 283 M -(Abstract) s -5 261 M -( The SSH File Transfer Protocol provides secure file transfer) s -5 250 M -( functionality over any reliable data stream. It is the standard file) s -5 239 M -( transfer protocol for use with the SSH2 protocol. This document) s -5 228 M -( describes the file transfer protocol and its interface to the SSH2) s -5 217 M -( protocol suite.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 1]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 2 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(Table of Contents) s -5 668 M -( 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 657 M -( 2. Use with the SSH Connection Protocol . . . . . . . . . . . 4) s -5 646 M -( 3. General Packet Format . . . . . . . . . . . . . . . . . . 5) s -5 635 M -( 4. Protocol Initialization . . . . . . . . . . . . . . . . . 7) s -5 624 M -( 4.1 Client Initialization . . . . . . . . . . . . . . . . . . 7) s -5 613 M -( 4.2 Server Initialization . . . . . . . . . . . . . . . . . . 7) s -5 602 M -( 4.3 Determining Server Newline Convention . . . . . . . . . . 8) s -5 591 M -( 5. File Attributes . . . . . . . . . . . . . . . . . . . . . 9) s -5 580 M -( 5.1 Flags . . . . . . . . . . . . . . . . . . . . . . . . . . 9) s -5 569 M -( 5.2 Type . . . . . . . . . . . . . . . . . . . . . . . . . . . 10) s -5 558 M -( 5.3 Size . . . . . . . . . . . . . . . . . . . . . . . . . . . 10) s -5 547 M -( 5.4 Owner and Group . . . . . . . . . . . . . . . . . . . . . 10) s -5 536 M -( 5.5 Permissions . . . . . . . . . . . . . . . . . . . . . . . 11) s -5 525 M -( 5.6 Times . . . . . . . . . . . . . . . . . . . . . . . . . . 11) s -5 514 M -( 5.7 ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 11) s -5 503 M -( 5.8 Extended attributes . . . . . . . . . . . . . . . . . . . 12) s -5 492 M -( 6. Requests From the Client to the Server . . . . . . . . . . 13) s -5 481 M -( 6.1 Request Synchronization and Reordering . . . . . . . . . . 13) s -5 470 M -( 6.2 File Names . . . . . . . . . . . . . . . . . . . . . . . . 14) s -5 459 M -( 6.3 Opening, Creating, and Closing Files . . . . . . . . . . . 14) s -5 448 M -( 6.4 Reading and Writing . . . . . . . . . . . . . . . . . . . 17) s -5 437 M -( 6.5 Removing and Renaming Files . . . . . . . . . . . . . . . 18) s -5 426 M -( 6.6 Creating and Deleting Directories . . . . . . . . . . . . 19) s -5 415 M -( 6.7 Scanning Directories . . . . . . . . . . . . . . . . . . . 19) s -5 404 M -( 6.8 Retrieving File Attributes . . . . . . . . . . . . . . . . 20) s -5 393 M -( 6.9 Setting File Attributes . . . . . . . . . . . . . . . . . 21) s -5 382 M -( 6.10 Dealing with Symbolic links . . . . . . . . . . . . . . . 22) s -5 371 M -( 6.11 Canonicalizing the Server-Side Path Name . . . . . . . . . 23) s -5 360 M -( 6.11.1 Best practice for dealing with paths . . . . . . . . . . . 23) s -5 349 M -( 7. Responses from the Server to the Client . . . . . . . . . 24) s -5 338 M -( 8. Vendor-Specific Extensions . . . . . . . . . . . . . . . . 28) s -5 327 M -( 9. Security Considerations . . . . . . . . . . . . . . . . . 29) s -5 316 M -( 10. Changes from previous protocol versions . . . . . . . . . 30) s -5 305 M -( 10.1 Changes between versions 4 and 3 . . . . . . . . . . . . . 30) s -5 294 M -( 10.2 Changes between versions 3 and 2 . . . . . . . . . . . . . 31) s -5 283 M -( 10.3 Changes between versions 2 and 1 . . . . . . . . . . . . . 31) s -5 272 M -( 10.4 Changes between versions 1 and 0 . . . . . . . . . . . . . 31) s -5 261 M -( 11. Trademark Issues . . . . . . . . . . . . . . . . . . . . . 32) s -5 250 M -( References . . . . . . . . . . . . . . . . . . . . . . . . 33) s -5 239 M -( Authors' Addresses . . . . . . . . . . . . . . . . . . . . 33) s -5 228 M -( Full Copyright Statement . . . . . . . . . . . . . . . . . 35) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 2]) s -_R -S -PStoPSsaved restore -%%Page: (2,3) 2 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 3 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(1. Introduction) s -5 668 M -( This protocol provides secure file transfer \(and more generally file) s -5 657 M -( system access\) functionality over a reliable data stream, such as a) s -5 646 M -( channel in the SSH2 protocol [5].) s -5 624 M -( This protocol is designed so that it could be used to implement a) s -5 613 M -( secure remote file system service, as well as a secure file transfer) s -5 602 M -( service.) s -5 580 M -( This protocol assumes that it runs over a secure channel, and that) s -5 569 M -( the server has already authenticated the user at the client end, and) s -5 558 M -( that the identity of the client user is externally available to the) s -5 547 M -( server implementation.) s -5 525 M -( In general, this protocol follows a simple request-response model.) s -5 514 M -( Each request and response contains a sequence number and multiple) s -5 503 M -( requests may be pending simultaneously. There are a relatively large) s -5 492 M -( number of different request messages, but a small number of possible) s -5 481 M -( response messages. Each request has one or more response messages) s -5 470 M -( that may be returned in result \(e.g., a read either returns data or) s -5 459 M -( reports error status\).) s -5 437 M -( The packet format descriptions in this specification follow the) s -5 426 M -( notation presented in the secsh architecture draft. [5]) s -5 404 M -( Even though this protocol is described in the context of the SSH2) s -5 393 M -( protocol, this protocol is general and independent of the rest of the) s -5 382 M -( SSH2 protocol suite. It could be used in a number of different) s -5 371 M -( applications, such as secure file transfer over TLS RFC 2246 [1] and) s -5 360 M -( transfer of management information in VPN applications.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 3]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 4 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(2. Use with the SSH Connection Protocol) s -5 668 M -( When used with the SSH2 Protocol suite, this protocol is intended to) s -5 657 M -( be used from the SSH Connection Protocol [7] as a subsystem, as) s -5 646 M -( described in section ``Starting a Shell or a Command''. The) s -5 635 M -( subsystem name used with this protocol is "sftp".) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 4]) s -_R -S -PStoPSsaved restore -%%Page: (4,5) 3 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 5 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(3. General Packet Format) s -5 668 M -( All packets transmitted over the secure connection are of the) s -5 657 M -( following format:) s -5 635 M -( uint32 length) s -5 624 M -( byte type) s -5 613 M -( byte[length - 1] data payload) s -5 591 M -( That is, they are just data preceded by 32-bit length and 8-bit type) s -5 580 M -( fields. The `length' is the length of the data area, and does not) s -5 569 M -( include the `length' field itself. The format and interpretation of) s -5 558 M -( the data area depends on the packet type.) s -5 536 M -( All packet descriptions below only specify the packet type and the) s -5 525 M -( data that goes into the data field. Thus, they should be prefixed by) s -5 514 M -( the `length' and `type' fields.) s -5 492 M -( The maximum size of a packet is in practice determined by the client) s -5 481 M -( \(the maximum size of read or write requests that it sends, plus a few) s -5 470 M -( bytes of packet overhead\). All servers SHOULD support packets of at) s -5 459 M -( least 34000 bytes \(where the packet size refers to the full length,) s -5 448 M -( including the header above\). This should allow for reads and writes) s -5 437 M -( of at most 32768 bytes.) s -5 415 M -( There is no limit on the number of outstanding \(non-acknowledged\)) s -5 404 M -( requests that the client may send to the server. In practice this is) s -5 393 M -( limited by the buffering available on the data stream and the queuing) s -5 382 M -( performed by the server. If the server's queues are full, it should) s -5 371 M -( not read any more data from the stream, and flow control will prevent) s -5 360 M -( the client from sending more requests. Note, however, that while) s -5 349 M -( there is no restriction on the protocol level, the client's API may) s -5 338 M -( provide a limit in order to prevent infinite queuing of outgoing) s -5 327 M -( requests at the client.) s -5 305 M -( The following values are defined for packet types.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 5]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 6 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( #define SSH_FXP_INIT 1) s -5 679 M -( #define SSH_FXP_VERSION 2) s -5 668 M -( #define SSH_FXP_OPEN 3) s -5 657 M -( #define SSH_FXP_CLOSE 4) s -5 646 M -( #define SSH_FXP_READ 5) s -5 635 M -( #define SSH_FXP_WRITE 6) s -5 624 M -( #define SSH_FXP_LSTAT 7) s -5 613 M -( #define SSH_FXP_FSTAT 8) s -5 602 M -( #define SSH_FXP_SETSTAT 9) s -5 591 M -( #define SSH_FXP_FSETSTAT 10) s -5 580 M -( #define SSH_FXP_OPENDIR 11) s -5 569 M -( #define SSH_FXP_READDIR 12) s -5 558 M -( #define SSH_FXP_REMOVE 13) s -5 547 M -( #define SSH_FXP_MKDIR 14) s -5 536 M -( #define SSH_FXP_RMDIR 15) s -5 525 M -( #define SSH_FXP_REALPATH 16) s -5 514 M -( #define SSH_FXP_STAT 17) s -5 503 M -( #define SSH_FXP_RENAME 18) s -5 492 M -( #define SSH_FXP_READLINK 19) s -5 481 M -( #define SSH_FXP_SYMLINK 20) s -5 459 M -( #define SSH_FXP_STATUS 101) s -5 448 M -( #define SSH_FXP_HANDLE 102) s -5 437 M -( #define SSH_FXP_DATA 103) s -5 426 M -( #define SSH_FXP_NAME 104) s -5 415 M -( #define SSH_FXP_ATTRS 105) s -5 393 M -( #define SSH_FXP_EXTENDED 200) s -5 382 M -( #define SSH_FXP_EXTENDED_REPLY 201) s -5 360 M -( RESERVED_FOR_EXTENSIONS 210-255) s -5 338 M -( Additional packet types should only be defined if the protocol) s -5 327 M -( version number \(see Section ``Protocol Initialization''\) is) s -5 316 M -( incremented, and their use MUST be negotiated using the version) s -5 305 M -( number. However, the SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY) s -5 294 M -( packets can be used to implement vendor-specific extensions. See) s -5 283 M -( Section ``Vendor-Specific-Extensions'' for more details.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 6]) s -_R -S -PStoPSsaved restore -%%Page: (6,7) 4 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 7 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(4. Protocol Initialization) s -5 668 M -( When the file transfer protocol starts, the client first sends a) s -5 657 M -( SSH_FXP_INIT \(including its version number\) packet to the server.) s -5 646 M -( The server responds with a SSH_FXP_VERSION packet, supplying the) s -5 635 M -( lowest of its own and the client's version number. Both parties) s -5 624 M -( should from then on adhere to particular version of the protocol.) s -5 602 M -( The version number of the protocol specified in this document is 4.) s -5 591 M -( The version number should be incremented for each incompatible) s -5 580 M -( revision of this protocol.) s -5 558 M -(4.1 Client Initialization) s -5 536 M -( The SSH_FXP_INIT packet \(from client to server\) has the following) s -5 525 M -( data:) s -5 503 M -( uint32 version) s -5 481 M -( Version 3 of this protocol allowed clients to include extensions in) s -5 470 M -( the SSH_FXP_INIT packet; however, this can cause interoperability) s -5 459 M -( problems with version 1 and version 2 servers because the client must) s -5 448 M -( send this packet before knowing the servers version.) s -5 426 M -( In this version of the protocol, clients MUST use the) s -5 415 M -( SSH_FXP_EXTENDED packet to send extensions to the server after) s -5 404 M -( version exchange has completed. Clients MUST NOT include extensions) s -5 393 M -( in the version packet. This will prevent interoperability problems) s -5 382 M -( with older servers) s -5 360 M -(4.2 Server Initialization) s -5 338 M -( The SSH_FXP_VERSION packet \(from server to client\) has the following) s -5 327 M -( data:) s -5 305 M -( uint32 version) s -5 294 M -( <extension data>) s -5 272 M -( 'version' is the lower of the protocol version supported by the) s -5 261 M -( server and the version number received from the client.) s -5 239 M -( The extension data may be empty, or may be a sequence of) s -5 217 M -( string extension_name) s -5 206 M -( string extension_data) s -5 184 M -( pairs \(both strings MUST always be present if one is, but the) s -5 173 M -( `extension_data' string may be of zero length\). If present, these) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 7]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 8 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( strings indicate extensions to the baseline protocol. The) s -5 679 M -( `extension_name' field\(s\) identify the name of the extension. The) s -5 668 M -( name should be of the form "name@domain", where the domain is the DNS) s -5 657 M -( domain name of the organization defining the extension. Additional) s -5 646 M -( names that are not of this format may be defined later by the IETF.) s -5 635 M -( Implementations MUST silently ignore any extensions whose name they) s -5 624 M -( do not recognize.) s -5 602 M -(4.3 Determining Server Newline Convention) s -5 580 M -( In order to correctly process text files in a cross platform) s -5 569 M -( compatible way, the newline convention must be converted from that of) s -5 558 M -( the server to that of the client, or, during an upload, from that of) s -5 547 M -( the client to that of the server.) s -5 525 M -( Versions 3 and prior of this protocol made no provisions for) s -5 514 M -( processing text files. Many clients implemented some sort of) s -5 503 M -( conversion algorithm, but without either a 'canonical' on the wire) s -5 492 M -( format or knowledge of the servers newline convention, correct) s -5 481 M -( conversion was not always possible.) s -5 459 M -( Starting with Version 4, the SSH_FXF_TEXT file open flag \(Section) s -5 448 M -( 6.3\) makes it possible to request that the server translate a file to) s -5 437 M -( a 'canonical' on the wire format. This format uses \\r\\n as the line) s -5 426 M -( separator.) s -5 404 M -( Servers for systems using multiple newline characters \(for example,) s -5 393 M -( Mac OS X or VMS\) or systems using counted records, MUST translate to) s -5 382 M -( the canonical form.) s -5 360 M -( However, to ease the burden of implementation on servers that use a) s -5 349 M -( single, simple separator sequence, the following extension allows the) s -5 338 M -( canonical format to be changed.) s -5 316 M -( string "newline") s -5 305 M -( string new-canonical-separator \(usually "\\r" or "\\n" or "\\r\\n"\)) s -5 283 M -( All clients MUST support this extension.) s -5 261 M -( When processing text files, clients SHOULD NOT translate any) s -5 250 M -( character or sequence that is not an exact match of the servers) s -5 239 M -( newline separator.) s -5 217 M -( In particular, if the newline sequence being used is the canonical) s -5 206 M -( "\\r\\n" sequence, a lone \\r or a lone \\n SHOULD be written through) s -5 195 M -( without change.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 8]) s -_R -S -PStoPSsaved restore -%%Page: (8,9) 5 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 9 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(5. File Attributes) s -5 668 M -( A new compound data type is defined for encoding file attributes.) s -5 657 M -( The same encoding is used both when returning file attributes from) s -5 646 M -( the server and when sending file attributes to the server. When) s -5 635 M -( sending it to the server, the flags field specifies which attributes) s -5 624 M -( are included, and the server will use default values for the) s -5 613 M -( remaining attributes \(or will not modify the values of remaining) s -5 602 M -( attributes\). When receiving attributes from the server, the flags) s -5 591 M -( specify which attributes are included in the returned data. The) s -5 580 M -( server normally returns all attributes it knows about.) s -5 558 M -( uint32 flags) s -5 547 M -( byte type always present) s -5 536 M -( uint64 size present only if flag SSH_FILEXFER_ATTR_SIZE) s -5 525 M -( string owner present only if flag SSH_FILEXFER_ATTR_OWNERGROUP) s -5 514 M -( string group present only if flag SSH_FILEXFER_ATTR_OWNERGROUP) s -5 503 M -( uint32 permissions present only if flag SSH_FILEXFER_ATTR_PERMISSIONS) s -5 492 M -( uint32 atime present only if flag SSH_FILEXFER_ATTR_ACCESSTIME) s -5 481 M -( uint32 createtime present only if flag SSH_FILEXFER_ATTR_CREATETIME) s -5 470 M -( uint32 mtime present only if flag SSH_FILEXFER_ATTR_MODIFYTIME) s -5 459 M -( string acl present only if flag SSH_FILEXFER_ATTR_ACL) s -5 448 M -( uint32 extended_count present only if flag SSH_FILEXFER_ATTR_EXTENDED) s -5 437 M -( string extended_type) s -5 426 M -( string extended_data) s -5 415 M -( ... more extended data \(extended_type - extended_data pairs\),) s -5 404 M -( so that number of pairs equals extended_count) s -5 371 M -(5.1 Flags) s -5 349 M -( The `flags' specify which of the fields are present. Those fields) s -5 338 M -( for which the corresponding flag is not set are not present \(not) s -5 327 M -( included in the packet\). New flags can only be added by incrementing) s -5 316 M -( the protocol version number \(or by using the extension mechanism) s -5 305 M -( described below\).) s -5 283 M -( The flags bits are defined to have the following values:) s -5 261 M -( #define SSH_FILEXFER_ATTR_SIZE 0x00000001) s -5 250 M -( #define SSH_FILEXFER_ATTR_PERMISSIONS 0x00000004) s -5 239 M -( #define SSH_FILEXFER_ATTR_ACCESSTIME 0x00000008) s -5 228 M -( #define SSH_FILEXFER_ATTR_CREATETIME 0x00000010) s -5 217 M -( #define SSH_FILEXFER_ATTR_MODIFYTIME 0x00000020) s -5 206 M -( #define SSH_FILEXFER_ATTR_ACL 0x00000040) s -5 195 M -( #define SSH_FILEXFER_ATTR_OWNERGROUP 0x00000080) s -5 184 M -( #define SSH_FILEXFER_ATTR_EXTENDED 0x80000000) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 9]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 10 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( In previous versions of this protocol flags value 0x00000002 was) s -5 679 M -( SSH_FILEXFER_ATTR_UIDGID. This value is now unused, and OWNERGROUP) s -5 668 M -( was given a new value in order to ease implementation burden.) s -5 657 M -( 0x00000002 MUST NOT appear in the mask. Some future version of this) s -5 646 M -( protocol may reuse flag 0x00000002.) s -5 624 M -(5.2 Type) s -5 602 M -( The type field is always present. The following types are defined:) s -5 580 M -( #define SSH_FILEXFER_TYPE_REGULAR 1) s -5 569 M -( #define SSH_FILEXFER_TYPE_DIRECTORY 2) s -5 558 M -( #define SSH_FILEXFER_TYPE_SYMLINK 3) s -5 547 M -( #define SSH_FILEXFER_TYPE_SPECIAL 4) s -5 536 M -( #define SSH_FILEXFER_TYPE_UNKNOWN 5) s -5 514 M -( On a POSIX system, these values would be derived from the permission) s -5 503 M -( field.) s -5 481 M -(5.3 Size) s -5 459 M -( The `size' field specifies the size of the file on disk, in bytes.) s -5 448 M -( If it is present during file creation, it should be considered a hint) s -5 437 M -( as to the files eventual size.) s -5 415 M -( Files opened with the SSH_FXF_TEXT flag may have a size that is) s -5 404 M -( greater or less than the value of the size field.) s -5 382 M -(5.4 Owner and Group) s -5 360 M -( The `owner' and `group' fields are represented as UTF-8 strings; this) s -5 349 M -( is the form used by NFS v4. See NFS version 4 Protocol. [3] The) s -5 338 M -( following text is selected quotations from section 5.6.) s -5 316 M -( To avoid a representation that is tied to a particular underlying) s -5 305 M -( implementation at the client or server, the use of UTF-8 strings has) s -5 294 M -( been chosen. The string should be of the form user@dns_domain".) s -5 283 M -( This will allow for a client and server that do not use the same) s -5 272 M -( local representation the ability to translate to a common syntax that) s -5 261 M -( can be interpreted by both. In the case where there is no) s -5 250 M -( translation available to the client or server, the attribute value) s -5 239 M -( must be constructed without the "@". Therefore, the absence of the @) s -5 228 M -( from the owner or owner_group attribute signifies that no translation) s -5 217 M -( was available and the receiver of the attribute should not place any) s -5 206 M -( special meaning with the attribute value. Even though the attribute) s -5 195 M -( value can not be translated, it may still be useful. In the case of) s -5 184 M -( a client, the attribute string may be used for local display of) s -5 173 M -( ownership.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 10]) s -_R -S -PStoPSsaved restore -%%Page: (10,11) 6 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 11 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(5.5 Permissions) s -5 668 M -( The `permissions' field contains a bit mask of file permissions as) s -5 657 M -( defined by POSIX [1].) s -5 635 M -(5.6 Times) s -5 613 M -( The 'atime', 'createtime', and 'mtime' contain the access, creation,) s -5 602 M -( and modification times of the files, respectively. They are) s -5 591 M -( represented as seconds from Jan 1, 1970 in UTC.) s -5 569 M -(5.7 ACL) s -5 547 M -( The 'ACL' field contains an ACL similar to that defined in section) s -5 536 M -( 5.9 of NFS version 4 Protocol [3].) s -5 514 M -( uint32 ace-count) s -5 492 M -( repeated ace-count time:) s -5 481 M -( uint32 ace-type) s -5 470 M -( uint32 ace-flag) s -5 459 M -( uint32 ace-mask) s -5 448 M -( string who [UTF-8]) s -5 426 M -( ace-type is one of the following four values \(taken from NFS Version) s -5 415 M -( 4 Protocol [3]:) s -5 393 M -( const ACE4_ACCESS_ALLOWED_ACE_TYPE = 0x00000000;) s -5 382 M -( const ACE4_ACCESS_DENIED_ACE_TYPE = 0x00000001;) s -5 371 M -( const ACE4_SYSTEM_AUDIT_ACE_TYPE = 0x00000002;) s -5 360 M -( const ACE4_SYSTEM_ALARM_ACE_TYPE = 0x00000003;) s -5 338 M -( ace-flag is a combination of the following flag values. See NFS) s -5 327 M -( Version 4 Protocol [3] section 5.9.2:) s -5 305 M -( const ACE4_FILE_INHERIT_ACE = 0x00000001;) s -5 294 M -( const ACE4_DIRECTORY_INHERIT_ACE = 0x00000002;) s -5 283 M -( const ACE4_NO_PROPAGATE_INHERIT_ACE = 0x00000004;) s -5 272 M -( const ACE4_INHERIT_ONLY_ACE = 0x00000008;) s -5 261 M -( const ACE4_SUCCESSFUL_ACCESS_ACE_FLAG = 0x00000010;) s -5 250 M -( const ACE4_FAILED_ACCESS_ACE_FLAG = 0x00000020;) s -5 239 M -( const ACE4_IDENTIFIER_GROUP = 0x00000040;) s -5 217 M -( ace-mask is any combination of the following flags \(taken from NFS) s -5 206 M -( Version 4 Protocol [3] section 5.9.3:) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 11]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 12 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( const ACE4_READ_DATA = 0x00000001;) s -5 679 M -( const ACE4_LIST_DIRECTORY = 0x00000001;) s -5 668 M -( const ACE4_WRITE_DATA = 0x00000002;) s -5 657 M -( const ACE4_ADD_FILE = 0x00000002;) s -5 646 M -( const ACE4_APPEND_DATA = 0x00000004;) s -5 635 M -( const ACE4_ADD_SUBDIRECTORY = 0x00000004;) s -5 624 M -( const ACE4_READ_NAMED_ATTRS = 0x00000008;) s -5 613 M -( const ACE4_WRITE_NAMED_ATTRS = 0x00000010;) s -5 602 M -( const ACE4_EXECUTE = 0x00000020;) s -5 591 M -( const ACE4_DELETE_CHILD = 0x00000040;) s -5 580 M -( const ACE4_READ_ATTRIBUTES = 0x00000080;) s -5 569 M -( const ACE4_WRITE_ATTRIBUTES = 0x00000100;) s -5 558 M -( const ACE4_DELETE = 0x00010000;) s -5 547 M -( const ACE4_READ_ACL = 0x00020000;) s -5 536 M -( const ACE4_WRITE_ACL = 0x00040000;) s -5 525 M -( const ACE4_WRITE_OWNER = 0x00080000;) s -5 514 M -( const ACE4_SYNCHRONIZE = 0x00100000;) s -5 492 M -( who is a UTF-8 string of the form described in 'Owner and Group') s -5 481 M -( \(Section 5.4\)) s -5 459 M -(5.8 Extended attributes) s -5 437 M -( The SSH_FILEXFER_ATTR_EXTENDED flag provides a general extension) s -5 426 M -( mechanism for vendor-specific extensions. If the flag is specified,) s -5 415 M -( then the `extended_count' field is present. It specifies the number) s -5 404 M -( of extended_type-extended_data pairs that follow. Each of these) s -5 393 M -( pairs specifies an extended attribute. For each of the attributes,) s -5 382 M -( the extended_type field should be a string of the format) s -5 371 M -( "name@domain", where "domain" is a valid, registered domain name and) s -5 360 M -( "name" identifies the method. The IETF may later standardize certain) s -5 349 M -( names that deviate from this format \(e.g., that do not contain the) s -5 338 M -( "@" sign\). The interpretation of `extended_data' depends on the) s -5 327 M -( type. Implementations SHOULD ignore extended data fields that they) s -5 316 M -( do not understand.) s -5 294 M -( Additional fields can be added to the attributes by either defining) s -5 283 M -( additional bits to the flags field to indicate their presence, or by) s -5 272 M -( defining extended attributes for them. The extended attributes) s -5 261 M -( mechanism is recommended for most purposes; additional flags bits) s -5 250 M -( should only be defined by an IETF standards action that also) s -5 239 M -( increments the protocol version number. The use of such new fields) s -5 228 M -( MUST be negotiated by the version number in the protocol exchange.) s -5 217 M -( It is a protocol error if a packet with unsupported protocol bits is) s -5 206 M -( received.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 12]) s -_R -S -PStoPSsaved restore -%%Page: (12,13) 7 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 13 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(6. Requests From the Client to the Server) s -5 668 M -( Requests from the client to the server represent the various file) s -5 657 M -( system operations. Each request begins with an `id' field, which is) s -5 646 M -( a 32-bit identifier identifying the request \(selected by the client\).) s -5 635 M -( The same identifier will be returned in the response to the request.) s -5 624 M -( One possible implementation is a monotonically increasing request) s -5 613 M -( sequence number \(modulo 2^32\).) s -5 591 M -( Many operations in the protocol operate on open files. The) s -5 580 M -( SSH_FXP_OPEN request can return a file handle \(which is an opaque) s -5 569 M -( variable-length string\) which may be used to access the file later) s -5 558 M -( \(e.g. in a read operation\). The client MUST NOT send requests the) s -5 547 M -( server with bogus or closed handles. However, the server MUST) s -5 536 M -( perform adequate checks on the handle in order to avoid security) s -5 525 M -( risks due to fabricated handles.) s -5 503 M -( This design allows either stateful and stateless server) s -5 492 M -( implementation, as well as an implementation which caches state) s -5 481 M -( between requests but may also flush it. The contents of the file) s -5 470 M -( handle string are entirely up to the server and its design. The) s -5 459 M -( client should not modify or attempt to interpret the file handle) s -5 448 M -( strings.) s -5 426 M -( The file handle strings MUST NOT be longer than 256 bytes.) s -5 404 M -(6.1 Request Synchronization and Reordering) s -5 382 M -( The protocol and implementations MUST process requests relating to) s -5 371 M -( the same file in the order in which they are received. In other) s -5 360 M -( words, if an application submits multiple requests to the server, the) s -5 349 M -( results in the responses will be the same as if it had sent the) s -5 338 M -( requests one at a time and waited for the response in each case. For) s -5 327 M -( example, the server may process non-overlapping read/write requests) s -5 316 M -( to the same file in parallel, but overlapping reads and writes cannot) s -5 305 M -( be reordered or parallelized. However, there are no ordering) s -5 294 M -( restrictions on the server for processing requests from two different) s -5 283 M -( file transfer connections. The server may interleave and parallelize) s -5 272 M -( them at will.) s -5 250 M -( There are no restrictions on the order in which responses to) s -5 239 M -( outstanding requests are delivered to the client, except that the) s -5 228 M -( server must ensure fairness in the sense that processing of no) s -5 217 M -( request will be indefinitely delayed even if the client is sending) s -5 206 M -( other requests so that there are multiple outstanding requests all) s -5 195 M -( the time.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 13]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 14 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(6.2 File Names) s -5 668 M -( This protocol represents file names as strings. File names are) s -5 657 M -( assumed to use the slash \('/'\) character as a directory separator.) s -5 635 M -( File names starting with a slash are "absolute", and are relative to) s -5 624 M -( the root of the file system. Names starting with any other character) s -5 613 M -( are relative to the user's default directory \(home directory\). Note) s -5 602 M -( that identifying the user is assumed to take place outside of this) s -5 591 M -( protocol.) s -5 569 M -( Servers SHOULD interpret a path name component ".." as referring to) s -5 558 M -( the parent directory, and "." as referring to the current directory.) s -5 547 M -( If the server implementation limits access to certain parts of the) s -5 536 M -( file system, it must be extra careful in parsing file names when) s -5 525 M -( enforcing such restrictions. There have been numerous reported) s -5 514 M -( security bugs where a ".." in a path name has allowed access outside) s -5 503 M -( the intended area.) s -5 481 M -( An empty path name is valid, and it refers to the user's default) s -5 470 M -( directory \(usually the user's home directory\).) s -5 448 M -( Otherwise, no syntax is defined for file names by this specification.) s -5 437 M -( Clients should not make any other assumptions; however, they can) s -5 426 M -( splice path name components returned by SSH_FXP_READDIR together) s -5 415 M -( using a slash \('/'\) as the separator, and that will work as expected.) s -5 393 M -( In order to comply with IETF Policy on Character Sets and Languages) s -5 382 M -( [2], all filenames are to be encoded in UTF-8. The shortest valid) s -5 371 M -( UTF-8 encoding of the UNICODE data MUST be used. The server is) s -5 360 M -( responsible for converting the UNICODE data to whatever canonical) s -5 349 M -( form it requires.) s -5 327 M -( For example, if the server requires that precomposed characters) s -5 316 M -( always be used, the server MUST NOT assume the filename as sent by) s -5 305 M -( the client has this attribute, but must do this normalization itself.) s -5 283 M -( It is understood that the lack of well-defined semantics for file) s -5 272 M -( names may cause interoperability problems between clients and servers) s -5 261 M -( using radically different operating systems. However, this approach) s -5 250 M -( is known to work acceptably with most systems, and alternative) s -5 239 M -( approaches that e.g. treat file names as sequences of structured) s -5 228 M -( components are quite complicated.) s -5 206 M -(6.3 Opening, Creating, and Closing Files) s -5 184 M -( Files are opened and created using the SSH_FXP_OPEN message, whose) s -5 173 M -( data part is as follows:) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 14]) s -_R -S -PStoPSsaved restore -%%Page: (14,15) 8 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 15 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( uint32 id) s -5 679 M -( string filename [UTF-8]) s -5 668 M -( uint32 pflags) s -5 657 M -( ATTRS attrs) s -5 635 M -( The `id' field is the request identifier as for all requests.) s -5 613 M -( The `filename' field specifies the file name. See Section ``File) s -5 602 M -( Names'' for more information.) s -5 580 M -( The `pflags' field is a bitmask. The following bits have been) s -5 569 M -( defined.) s -5 547 M -( #define SSH_FXF_READ 0x00000001) s -5 536 M -( #define SSH_FXF_WRITE 0x00000002) s -5 525 M -( #define SSH_FXF_APPEND 0x00000004) s -5 514 M -( #define SSH_FXF_CREAT 0x00000008) s -5 503 M -( #define SSH_FXF_TRUNC 0x00000010) s -5 492 M -( #define SSH_FXF_EXCL 0x00000020) s -5 481 M -( #define SSH_FXF_TEXT 0x00000040) s -5 459 M -( These have the following meanings:) s -5 437 M -( SSH_FXF_READ) s -5 426 M -( Open the file for reading.) s -5 404 M -( SSH_FXF_WRITE) s -5 393 M -( Open the file for writing. If both this and SSH_FXF_READ are) s -5 382 M -( specified, the file is opened for both reading and writing.) s -5 360 M -( SSH_FXF_APPEND) s -5 349 M -( Force all writes to append data at the end of the file. The) s -5 338 M -( offset parameter to write will be ignored.) s -5 316 M -( SSH_FXF_CREAT) s -5 305 M -( If this flag is specified, then a new file will be created if one) s -5 294 M -( does not already exist \(if O_TRUNC is specified, the new file will) s -5 283 M -( be truncated to zero length if it previously exists\).) s -5 261 M -( SSH_FXF_TRUNC) s -5 250 M -( Forces an existing file with the same name to be truncated to zero) s -5 239 M -( length when creating a file by specifying SSH_FXF_CREAT.) s -5 228 M -( SSH_FXF_CREAT MUST also be specified if this flag is used.) s -5 206 M -( SSH_FXF_EXCL) s -5 195 M -( Causes the request to fail if the named file already exists.) s -5 184 M -( SSH_FXF_CREAT MUST also be specified if this flag is used.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 15]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 16 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( SSH_FXF_TEXT) s -5 679 M -( Indicates that the server should treat the file as text and) s -5 668 M -( convert it to the canonical newline convention in use. \(See) s -5 657 M -( Determining Server Newline Convention. \(Section 4.3\)) s -5 635 M -( When a file is opened with the FXF_TEXT flag, the offset field in) s -5 624 M -( both the read and write function are ignored.) s -5 602 M -( Servers MUST correctly process multiple parallel reads and writes) s -5 591 M -( correctly in this mode. Naturally, it is permissible for them to) s -5 580 M -( do this by serializing the requests. It would not be possible for) s -5 569 M -( a client to reliably detect a server that does not implement) s -5 558 M -( parallel writes in time to prevent damage.) s -5 536 M -( Clients SHOULD use the SSH_FXF_APPEND flag to append data to a) s -5 525 M -( text file rather then using write with a calculated offset.) s -5 503 M -( To support seeks on text file the following SSH_FXP_EXTENDED) s -5 492 M -( packet is defined.) s -5 448 M -( string "text-seek") s -5 437 M -( string file-handle) s -5 426 M -( uint64 line-number) s -5 404 M -( line-number is the index of the line number to seek to, where byte) s -5 393 M -( 0 in the file is line number 0, and the byte directly following) s -5 382 M -( the first newline sequence in the file is line number 1 and so on.) s -5 360 M -( The response to a "text-seek" request is an SSH_FXP_STATUS) s -5 349 M -( message.) s -5 327 M -( An attempt to seek past the end-of-file should result in a) s -5 316 M -( SSH_FX_EOF status.) s -5 294 M -( Servers SHOULD support at least one "text-seek" in order to) s -5 283 M -( support resume. However, a client MUST be prepared to receive) s -5 272 M -( SSH_FX_OP_UNSUPPORTED when attempting a "text-seek" operation.) s -5 261 M -( The client can then try a fall-back strategy, if it has one.) s -5 239 M -( Clients MUST be prepared to handle SSH_FX_OP_UNSUPPORTED returned) s -5 228 M -( for read or write operations that are not sequential.) s -5 206 M -( The `attrs' field specifies the initial attributes for the file.) s -5 195 M -( Default values will be used for those attributes that are not) s -5 184 M -( specified. See Section ``File Attributes'' for more information.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 16]) s -_R -S -PStoPSsaved restore -%%Page: (16,17) 9 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 17 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( The response to this message will be either SSH_FXP_HANDLE \(if the) s -5 679 M -( operation is successful\) or SSH_FXP_STATUS \(if the operation fails\).) s -5 657 M -( A file is closed by using the SSH_FXP_CLOSE request. Its data field) s -5 646 M -( has the following format:) s -5 624 M -( uint32 id) s -5 613 M -( string handle) s -5 591 M -( where `id' is the request identifier, and `handle' is a handle) s -5 580 M -( previously returned in the response to SSH_FXP_OPEN or) s -5 569 M -( SSH_FXP_OPENDIR. The handle becomes invalid immediately after this) s -5 558 M -( request has been sent.) s -5 536 M -( The response to this request will be a SSH_FXP_STATUS message. One) s -5 525 M -( should note that on some server platforms even a close can fail.) s -5 514 M -( This can happen e.g. if the server operating system caches writes,) s -5 503 M -( and an error occurs while flushing cached writes during the close.) s -5 481 M -(6.4 Reading and Writing) s -5 459 M -( Once a file has been opened, it can be read using the SSH_FXP_READ) s -5 448 M -( message, which has the following format:) s -5 426 M -( uint32 id) s -5 415 M -( string handle) s -5 404 M -( uint64 offset) s -5 393 M -( uint32 len) s -5 371 M -( where `id' is the request identifier, `handle' is an open file handle) s -5 360 M -( returned by SSH_FXP_OPEN, `offset' is the offset \(in bytes\) relative) s -5 349 M -( to the beginning of the file from where to start reading, and `len') s -5 338 M -( is the maximum number of bytes to read.) s -5 316 M -( In response to this request, the server will read as many bytes as it) s -5 305 M -( can from the file \(up to `len'\), and return them in a SSH_FXP_DATA) s -5 294 M -( message. If an error occurs or EOF is encountered before reading any) s -5 283 M -( data, the server will respond with SSH_FXP_STATUS. For normal disk) s -5 272 M -( files, it is guaranteed that this will read the specified number of) s -5 261 M -( bytes, or up to end of file. For e.g. device files this may return) s -5 250 M -( fewer bytes than requested.) s -5 228 M -( Writing to a file is achieved using the SSH_FXP_WRITE message, which) s -5 217 M -( has the following format:) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 17]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 18 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( uint32 id) s -5 679 M -( string handle) s -5 668 M -( uint64 offset) s -5 657 M -( string data) s -5 635 M -( where `id' is a request identifier, `handle' is a file handle) s -5 624 M -( returned by SSH_FXP_OPEN, `offset' is the offset \(in bytes\) from the) s -5 613 M -( beginning of the file where to start writing, and `data' is the data) s -5 602 M -( to be written.) s -5 580 M -( The write will extend the file if writing beyond the end of the file.) s -5 569 M -( It is legal to write way beyond the end of the file; the semantics) s -5 558 M -( are to write zeroes from the end of the file to the specified offset) s -5 547 M -( and then the data. On most operating systems, such writes do not) s -5 536 M -( allocate disk space but instead leave "holes" in the file.) s -5 514 M -( The server responds to a write request with a SSH_FXP_STATUS message.) s -5 492 M -(6.5 Removing and Renaming Files) s -5 470 M -( Files can be removed using the SSH_FXP_REMOVE message. It has the) s -5 459 M -( following format:) s -5 437 M -( uint32 id) s -5 426 M -( string filename [UTF-8]) s -5 404 M -( where `id' is the request identifier and `filename' is the name of) s -5 393 M -( the file to be removed. See Section ``File Names'' for more) s -5 382 M -( information. This request cannot be used to remove directories.) s -5 360 M -( The server will respond to this request with a SSH_FXP_STATUS) s -5 349 M -( message.) s -5 327 M -( Files \(and directories\) can be renamed using the SSH_FXP_RENAME) s -5 316 M -( message. Its data is as follows:) s -5 294 M -( uint32 id) s -5 283 M -( string oldpath [UTF-8]) s -5 272 M -( string newpath [UTF-8]) s -5 250 M -( where `id' is the request identifier, `oldpath' is the name of an) s -5 239 M -( existing file or directory, and `newpath' is the new name for the) s -5 228 M -( file or directory. It is an error if there already exists a file) s -5 217 M -( with the name specified by newpath. The server may also fail rename) s -5 206 M -( requests in other situations, for example if `oldpath' and `newpath') s -5 195 M -( point to different file systems on the server.) s -5 173 M -( The server will respond to this request with a SSH_FXP_STATUS) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 18]) s -_R -S -PStoPSsaved restore -%%Page: (18,19) 10 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 19 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( message.) s -5 668 M -(6.6 Creating and Deleting Directories) s -5 646 M -( New directories can be created using the SSH_FXP_MKDIR request. It) s -5 635 M -( has the following format:) s -5 613 M -( uint32 id) s -5 602 M -( string path [UTF-8]) s -5 591 M -( ATTRS attrs) s -5 569 M -( where `id' is the request identifier.) s -5 547 M -( `path' specifies the directory to be created. See Section ``File) s -5 536 M -( Names'' for more information on file names.) s -5 514 M -( `attrs' specifies the attributes that should be applied to it upon) s -5 503 M -( creation. Attributes are discussed in more detail in Section ``File) s -5 492 M -( Attributes''.) s -5 470 M -( The server will respond to this request with a SSH_FXP_STATUS) s -5 459 M -( message. If a file or directory with the specified path already) s -5 448 M -( exists, an error will be returned.) s -5 426 M -( Directories can be removed using the SSH_FXP_RMDIR request, which has) s -5 415 M -( the following format:) s -5 393 M -( uint32 id) s -5 382 M -( string path [UTF-8]) s -5 360 M -( where `id' is the request identifier, and `path' specifies the) s -5 349 M -( directory to be removed. See Section ``File Names'' for more) s -5 338 M -( information on file names.) s -5 316 M -( The server responds to this request with a SSH_FXP_STATUS message.) s -5 305 M -( Errors may be returned from this operation for various reasons,) s -5 294 M -( including, but not limited to, the path does not exist, the path does) s -5 283 M -( not refer to a directory object, the directory is not empty, or the) s -5 272 M -( user has insufficient access or permission to perform the requested) s -5 261 M -( operation.) s -5 239 M -(6.7 Scanning Directories) s -5 217 M -( The files in a directory can be listed using the SSH_FXP_OPENDIR and) s -5 206 M -( SSH_FXP_READDIR requests. Each SSH_FXP_READDIR request returns one) s -5 195 M -( or more file names with full file attributes for each file. The) s -5 184 M -( client should call SSH_FXP_READDIR repeatedly until it has found the) s -5 173 M -( file it is looking for or until the server responds with a) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 19]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 20 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( SSH_FXP_STATUS message indicating an error \(normally SSH_FX_EOF if) s -5 679 M -( there are no more files in the directory\). The client should then) s -5 668 M -( close the handle using the SSH_FXP_CLOSE request.) s -5 646 M -( The SSH_FXP_OPENDIR opens a directory for reading. It has the) s -5 635 M -( following format:) s -5 613 M -( uint32 id) s -5 602 M -( string path [UTF-8]) s -5 580 M -( where `id' is the request identifier and `path' is the path name of) s -5 569 M -( the directory to be listed \(without any trailing slash\). See Section) s -5 558 M -( ``File Names'' for more information on file names. This will return) s -5 547 M -( an error if the path does not specify a directory or if the directory) s -5 536 M -( is not readable. The server will respond to this request with either) s -5 525 M -( a SSH_FXP_HANDLE or a SSH_FXP_STATUS message.) s -5 503 M -( Once the directory has been successfully opened, files \(and) s -5 492 M -( directories\) contained in it can be listed using SSH_FXP_READDIR) s -5 481 M -( requests. These are of the format) s -5 459 M -( uint32 id) s -5 448 M -( string handle) s -5 426 M -( where `id' is the request identifier, and `handle' is a handle) s -5 415 M -( returned by SSH_FXP_OPENDIR. \(It is a protocol error to attempt to) s -5 404 M -( use an ordinary file handle returned by SSH_FXP_OPEN.\)) s -5 382 M -( The server responds to this request with either a SSH_FXP_NAME or a) s -5 371 M -( SSH_FXP_STATUS message. One or more names may be returned at a time.) s -5 360 M -( Full status information is returned for each name in order to speed) s -5 349 M -( up typical directory listings.) s -5 327 M -( If there are no more names available to be read, the server MUST) s -5 316 M -( respond with a SSH_FXP_STATUS message with error code of SSH_FX_EOF.) s -5 294 M -( When the client no longer wishes to read more names from the) s -5 283 M -( directory, it SHOULD call SSH_FXP_CLOSE for the handle. The handle) s -5 272 M -( should be closed regardless of whether an error has occurred or not.) s -5 250 M -(6.8 Retrieving File Attributes) s -5 228 M -( Very often, file attributes are automatically returned by) s -5 217 M -( SSH_FXP_READDIR. However, sometimes there is need to specifically) s -5 206 M -( retrieve the attributes for a named file. This can be done using the) s -5 195 M -( SSH_FXP_STAT, SSH_FXP_LSTAT and SSH_FXP_FSTAT requests.) s -5 173 M -( SSH_FXP_STAT and SSH_FXP_LSTAT only differ in that SSH_FXP_STAT) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 20]) s -_R -S -PStoPSsaved restore -%%Page: (20,21) 11 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 21 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( follows symbolic links on the server, whereas SSH_FXP_LSTAT does not) s -5 679 M -( follow symbolic links. Both have the same format:) s -5 657 M -( uint32 id) s -5 646 M -( string path [UTF-8]) s -5 635 M -( uint32 flags) s -5 613 M -( where `id' is the request identifier, and `path' specifies the file) s -5 602 M -( system object for which status is to be returned. The server) s -5 591 M -( responds to this request with either SSH_FXP_ATTRS or SSH_FXP_STATUS.) s -5 569 M -( The flags field specify the attribute flags in which the client has) s -5 558 M -( particular interest. This is a hint to the server. For example,) s -5 547 M -( because retrieving owner / group and acl information can be an) s -5 536 M -( expensive operation under some operating systems, the server may) s -5 525 M -( choose not to retrieve this information unless the client expresses a) s -5 514 M -( specific interest in it.) s -5 492 M -( The client has no guarantee the server will provide all the fields) s -5 481 M -( that it has expressed an interest in.) s -5 459 M -( SSH_FXP_FSTAT differs from the others in that it returns status) s -5 448 M -( information for an open file \(identified by the file handle\). Its) s -5 437 M -( format is as follows:) s -5 415 M -( uint32 id) s -5 404 M -( string handle) s -5 393 M -( uint32 flags) s -5 371 M -( where `id' is the request identifier and `handle' is a file handle) s -5 360 M -( returned by SSH_FXP_OPEN. The server responds to this request with) s -5 349 M -( SSH_FXP_ATTRS or SSH_FXP_STATUS.) s -5 327 M -(6.9 Setting File Attributes) s -5 305 M -( File attributes may be modified using the SSH_FXP_SETSTAT and) s -5 294 M -( SSH_FXP_FSETSTAT requests. These requests are used for operations) s -5 283 M -( such as changing the ownership, permissions or access times, as well) s -5 272 M -( as for truncating a file.) s -5 250 M -( The SSH_FXP_SETSTAT request is of the following format:) s -5 228 M -( uint32 id) s -5 217 M -( string path [UTF-8]) s -5 206 M -( ATTRS attrs) s -5 184 M -( where `id' is the request identifier, `path' specifies the file) s -5 173 M -( system object \(e.g. file or directory\) whose attributes are to be) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 21]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 22 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( modified, and `attrs' specifies the modifications to be made to its) s -5 679 M -( attributes. Attributes are discussed in more detail in Section) s -5 668 M -( ``File Attributes''.) s -5 646 M -( An error will be returned if the specified file system object does) s -5 635 M -( not exist or the user does not have sufficient rights to modify the) s -5 624 M -( specified attributes. The server responds to this request with a) s -5 613 M -( SSH_FXP_STATUS message.) s -5 591 M -( The SSH_FXP_FSETSTAT request modifies the attributes of a file which) s -5 580 M -( is already open. It has the following format:) s -5 558 M -( uint32 id) s -5 547 M -( string handle) s -5 536 M -( ATTRS attrs) s -5 514 M -( where `id' is the request identifier, `handle' \(MUST be returned by) s -5 503 M -( SSH_FXP_OPEN\) identifies the file whose attributes are to be) s -5 492 M -( modified, and `attrs' specifies the modifications to be made to its) s -5 481 M -( attributes. Attributes are discussed in more detail in Section) s -5 470 M -( ``File Attributes''. The server will respond to this request with) s -5 459 M -( SSH_FXP_STATUS.) s -5 437 M -(6.10 Dealing with Symbolic links) s -5 415 M -( The SSH_FXP_READLINK request may be used to read the target of a) s -5 404 M -( symbolic link. It would have a data part as follows:) s -5 382 M -( uint32 id) s -5 371 M -( string path [UTF-8]) s -5 349 M -( where `id' is the request identifier and `path' specifies the path) s -5 338 M -( name of the symlink to be read.) s -5 316 M -( The server will respond with a SSH_FXP_NAME packet containing only) s -5 305 M -( one name and a dummy attributes value. The name in the returned) s -5 294 M -( packet contains the target of the link. If an error occurs, the) s -5 283 M -( server may respond with SSH_FXP_STATUS.) s -5 261 M -( The SSH_FXP_SYMLINK request will create a symbolic link on the) s -5 250 M -( server. It is of the following format) s -5 228 M -( uint32 id) s -5 217 M -( string linkpath [UTF-8]) s -5 206 M -( string targetpath [UTF-8]) s -5 184 M -( where `id' is the request identifier, `linkpath' specifies the path) s -5 173 M -( name of the symlink to be created and `targetpath' specifies the) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 22]) s -_R -S -PStoPSsaved restore -%%Page: (22,23) 12 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 23 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( target of the symlink. The server shall respond with a) s -5 679 M -( SSH_FXP_STATUS indicating either success \(SSH_FX_OK\) or an error) s -5 668 M -( condition.) s -5 646 M -(6.11 Canonicalizing the Server-Side Path Name) s -5 624 M -( The SSH_FXP_REALPATH request can be used to have the server) s -5 613 M -( canonicalize any given path name to an absolute path. This is useful) s -5 602 M -( for converting path names containing ".." components or relative) s -5 591 M -( pathnames without a leading slash into absolute paths. The format of) s -5 580 M -( the request is as follows:) s -5 558 M -( uint32 id) s -5 547 M -( string path [UTF-8]) s -5 525 M -( where `id' is the request identifier and `path' specifies the path) s -5 514 M -( name to be canonicalized. The server will respond with a) s -5 503 M -( SSH_FXP_NAME packet containing the name in canonical form and a dummy) s -5 492 M -( attributes value. If an error occurs, the server may also respond) s -5 481 M -( with SSH_FXP_STATUS.) s -5 459 M -(6.11.1 Best practice for dealing with paths) s -5 437 M -( The client SHOULD treat the results of SSH_FXP_REALPATH as a) s -5 426 M -( canonical absolute path, even if the path does not appear to be) s -5 415 M -( absolute. A client that use REALPATH\("."\) and treats the result as) s -5 404 M -( absolute, even if there is no leading slash, will continue to) s -5 393 M -( function correctly, even when talking to a Windows NT or VMS style) s -5 382 M -( system, where absolute paths may not begin with a slash.) s -5 360 M -( For example, if the client wishes to change directory up, and the) s -5 349 M -( server has returned "c:/x/y/z" from REALPATH, the client SHOULD use) s -5 338 M -( "c:/x/y/z/..".) s -5 316 M -( As a second example, if the client wishes to open the file "x.txt" in) s -5 305 M -( the current directory, and server has returned "dka100:/x/y/z" as the) s -5 294 M -( canonical path of the directory, the client SHOULD open "dka100:/x/y/) s -5 283 M -( z/x.txt") s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 23]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 24 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(7. Responses from the Server to the Client) s -5 668 M -( The server responds to the client using one of a few response) s -5 657 M -( packets. All requests can return a SSH_FXP_STATUS response upon) s -5 646 M -( failure. When the operation is successful, any of the responses may) s -5 635 M -( be returned \(depending on the operation\). If no data needs to be) s -5 624 M -( returned to the client, the SSH_FXP_STATUS response with SSH_FX_OK) s -5 613 M -( status is appropriate. Otherwise, the SSH_FXP_HANDLE message is used) s -5 602 M -( to return a file handle \(for SSH_FXP_OPEN and SSH_FXP_OPENDIR) s -5 591 M -( requests\), SSH_FXP_DATA is used to return data from SSH_FXP_READ,) s -5 580 M -( SSH_FXP_NAME is used to return one or more file names from a) s -5 569 M -( SSH_FXP_READDIR or SSH_FXP_REALPATH request, and SSH_FXP_ATTRS is) s -5 558 M -( used to return file attributes from SSH_FXP_STAT, SSH_FXP_LSTAT, and) s -5 547 M -( SSH_FXP_FSTAT requests.) s -5 525 M -( Exactly one response will be returned for each request. Each) s -5 514 M -( response packet contains a request identifier which can be used to) s -5 503 M -( match each response with the corresponding request. Note that it is) s -5 492 M -( legal to have several requests outstanding simultaneously, and the) s -5 481 M -( server is allowed to send responses to them in a different order from) s -5 470 M -( the order in which the requests were sent \(the result of their) s -5 459 M -( execution, however, is guaranteed to be as if they had been processed) s -5 448 M -( one at a time in the order in which the requests were sent\).) s -5 426 M -( Response packets are of the same general format as request packets.) s -5 415 M -( Each response packet begins with the request identifier.) s -5 393 M -( The format of the data portion of the SSH_FXP_STATUS response is as) s -5 382 M -( follows:) s -5 360 M -( uint32 id) s -5 349 M -( uint32 error/status code) s -5 338 M -( string error message \(ISO-10646 UTF-8 [RFC-2279]\)) s -5 327 M -( string language tag \(as defined in [RFC-1766]\)) s -5 305 M -( where `id' is the request identifier, and `error/status code') s -5 294 M -( indicates the result of the requested operation. The value SSH_FX_OK) s -5 283 M -( indicates success, and all other values indicate failure.) s -5 261 M -( Currently, the following values are defined \(other values may be) s -5 250 M -( defined by future versions of this protocol\):) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 24]) s -_R -S -PStoPSsaved restore -%%Page: (24,25) 13 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 25 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( #define SSH_FX_OK 0) s -5 679 M -( #define SSH_FX_EOF 1) s -5 668 M -( #define SSH_FX_NO_SUCH_FILE 2) s -5 657 M -( #define SSH_FX_PERMISSION_DENIED 3) s -5 646 M -( #define SSH_FX_FAILURE 4) s -5 635 M -( #define SSH_FX_BAD_MESSAGE 5) s -5 624 M -( #define SSH_FX_NO_CONNECTION 6) s -5 613 M -( #define SSH_FX_CONNECTION_LOST 7) s -5 602 M -( #define SSH_FX_OP_UNSUPPORTED 8) s -5 591 M -( #define SSH_FX_INVALID_HANDLE 9) s -5 580 M -( #define SSH_FX_NO_SUCH_PATH 10) s -5 569 M -( #define SSH_FX_FILE_ALREADY_EXISTS 11) s -5 558 M -( #define SSH_FX_WRITE_PROTECT 12) s -5 536 M -( SSH_FX_OK) s -5 525 M -( Indicates successful completion of the operation.) s -5 503 M -( SSH_FX_EOF) s -5 492 M -( indicates end-of-file condition; for SSH_FX_READ it means that no) s -5 481 M -( more data is available in the file, and for SSH_FX_READDIR it) s -5 470 M -( indicates that no more files are contained in the directory.) s -5 448 M -( SSH_FX_NO_SUCH_FILE) s -5 437 M -( is returned when a reference is made to a file which does not) s -5 426 M -( exist.) s -5 404 M -( SSH_FX_PERMISSION_DENIED) s -5 393 M -( is returned when the authenticated user does not have sufficient) s -5 382 M -( permissions to perform the operation.) s -5 360 M -( SSH_FX_FAILURE) s -5 349 M -( is a generic catch-all error message; it should be returned if an) s -5 338 M -( error occurs for which there is no more specific error code) s -5 327 M -( defined.) s -5 305 M -( SSH_FX_BAD_MESSAGE) s -5 294 M -( may be returned if a badly formatted packet or protocol) s -5 283 M -( incompatibility is detected.) s -5 261 M -( SSH_FX_NO_CONNECTION) s -5 250 M -( is a pseudo-error which indicates that the client has no) s -5 239 M -( connection to the server \(it can only be generated locally by the) s -5 228 M -( client, and MUST NOT be returned by servers\).) s -5 206 M -( SSH_FX_CONNECTION_LOST) s -5 195 M -( is a pseudo-error which indicates that the connection to the) s -5 184 M -( server has been lost \(it can only be generated locally by the) s -5 173 M -( client, and MUST NOT be returned by servers\).) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 25]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 26 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( SSH_FX_OP_UNSUPPORTED) s -5 679 M -( indicates that an attempt was made to perform an operation which) s -5 668 M -( is not supported for the server \(it may be generated locally by) s -5 657 M -( the client if e.g. the version number exchange indicates that a) s -5 646 M -( required feature is not supported by the server, or it may be) s -5 635 M -( returned by the server if the server does not implement an) s -5 624 M -( operation\).) s -5 602 M -( SSH_FX_INVALID_HANDLE) s -5 591 M -( The handle value was invalid.) s -5 569 M -( SSH_FX_NO_SUCH_PATH) s -5 558 M -( The file path does not exist or is invalid.) s -5 536 M -( SSH_FX_FILE_ALREADY_EXISTS) s -5 525 M -( The file already exists.) s -5 503 M -( SSH_FX_WRITE_PROTECT) s -5 492 M -( The file is on read only media, or the media is write protected.) s -5 470 M -( The SSH_FXP_HANDLE response has the following format:) s -5 448 M -( uint32 id) s -5 437 M -( string handle) s -5 415 M -( where `id' is the request identifier, and `handle' is an arbitrary) s -5 404 M -( string that identifies an open file or directory on the server. The) s -5 393 M -( handle is opaque to the client; the client MUST NOT attempt to) s -5 382 M -( interpret or modify it in any way. The length of the handle string) s -5 371 M -( MUST NOT exceed 256 data bytes.) s -5 349 M -( The SSH_FXP_DATA response has the following format:) s -5 327 M -( uint32 id) s -5 316 M -( string data) s -5 294 M -( where `id' is the request identifier, and `data' is an arbitrary byte) s -5 283 M -( string containing the requested data. The data string may be at most) s -5 272 M -( the number of bytes requested in a SSH_FXP_READ request, but may also) s -5 261 M -( be shorter if end of file is reached or if the read is from something) s -5 250 M -( other than a regular file.) s -5 228 M -( The SSH_FXP_NAME response has the following format:) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 26]) s -_R -S -PStoPSsaved restore -%%Page: (26,27) 14 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 27 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( uint32 id) s -5 679 M -( uint32 count) s -5 668 M -( repeats count times:) s -5 657 M -( string filename [UTF-8]) s -5 646 M -( ATTRS attrs) s -5 624 M -( where `id' is the request identifier, `count' is the number of names) s -5 613 M -( returned in this response, and the remaining fields repeat `count') s -5 602 M -( times \(so that all three fields are first included for the first) s -5 591 M -( file, then for the second file, etc\). In the repeated part,) s -5 580 M -( `filename' is a file name being returned \(for SSH_FXP_READDIR, it) s -5 569 M -( will be a relative name within the directory, without any path) s -5 558 M -( components; for SSH_FXP_REALPATH it will be an absolute path name\),) s -5 547 M -( and `attrs' is the attributes of the file as described in Section) s -5 536 M -( ``File Attributes''.) s -5 514 M -( The SSH_FXP_ATTRS response has the following format:) s -5 492 M -( uint32 id) s -5 481 M -( ATTRS attrs) s -5 459 M -( where `id' is the request identifier, and `attrs' is the returned) s -5 448 M -( file attributes as described in Section ``File Attributes''.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 27]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 28 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(8. Vendor-Specific Extensions) s -5 668 M -( The SSH_FXP_EXTENDED request provides a generic extension mechanism) s -5 657 M -( for adding vendor-specific commands. The request has the following) s -5 646 M -( format:) s -5 624 M -( uint32 id) s -5 613 M -( string extended-request) s -5 602 M -( ... any request-specific data ...) s -5 580 M -( where `id' is the request identifier, and `extended-request' is a) s -5 569 M -( string of the format "name@domain", where domain is an internet) s -5 558 M -( domain name of the vendor defining the request. The rest of the) s -5 547 M -( request is completely vendor-specific, and servers should only) s -5 536 M -( attempt to interpret it if they recognize the `extended-request') s -5 525 M -( name.) s -5 503 M -( The server may respond to such requests using any of the response) s -5 492 M -( packets defined in Section ``Responses from the Server to the) s -5 481 M -( Client''. Additionally, the server may also respond with a) s -5 470 M -( SSH_FXP_EXTENDED_REPLY packet, as defined below. If the server does) s -5 459 M -( not recognize the `extended-request' name, then the server MUST) s -5 448 M -( respond with SSH_FXP_STATUS with error/status set to) s -5 437 M -( SSH_FX_OP_UNSUPPORTED.) s -5 415 M -( The SSH_FXP_EXTENDED_REPLY packet can be used to carry arbitrary) s -5 404 M -( extension-specific data from the server to the client. It is of the) s -5 393 M -( following format:) s -5 371 M -( uint32 id) s -5 360 M -( ... any request-specific data ...) s -5 338 M -( There is a range of packet types reserved for use by extensions. In) s -5 327 M -( order to avoid collision, extensions that turn on the use of) s -5 316 M -( additional packet types should determine those numbers dynamically.) s -5 294 M -( The suggested way of doing this is have an extension request from the) s -5 283 M -( client to the server that enables the extension; the extension) s -5 272 M -( response from the server to the client would specify the actual type) s -5 261 M -( values to use, in additional to any other data.) s -5 239 M -( Extension authors should be mindful of the limited range of packet) s -5 228 M -( types available \(there are only 45 values available\) and avoid) s -5 217 M -( requiring a new packet type where possible.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 28]) s -_R -S -PStoPSsaved restore -%%Page: (28,29) 15 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 29 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(9. Security Considerations) s -5 668 M -( This protocol assumes that it is run over a secure channel and that) s -5 657 M -( the endpoints of the channel have been authenticated. Thus, this) s -5 646 M -( protocol assumes that it is externally protected from network-level) s -5 635 M -( attacks.) s -5 613 M -( This protocol provides file system access to arbitrary files on the) s -5 602 M -( server \(only constrained by the server implementation\). It is the) s -5 591 M -( responsibility of the server implementation to enforce any access) s -5 580 M -( controls that may be required to limit the access allowed for any) s -5 569 M -( particular user \(the user being authenticated externally to this) s -5 558 M -( protocol, typically using the SSH User Authentication Protocol [8].) s -5 536 M -( Care must be taken in the server implementation to check the validity) s -5 525 M -( of received file handle strings. The server should not rely on them) s -5 514 M -( directly; it MUST check the validity of each handle before relying on) s -5 503 M -( it.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 29]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 30 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(10. Changes from previous protocol versions) s -5 668 M -( The SSH File Transfer Protocol has changed over time, before it's) s -5 657 M -( standardization. The following is a description of the incompatible) s -5 646 M -( changes between different versions.) s -5 624 M -(10.1 Changes between versions 4 and 3) s -5 602 M -( Many of the changes between version 4 and version 3 are to the) s -5 591 M -( attribute structure to make it more flexible for non-unix platforms.) s -5 569 M -( o Make all filenames UTF-8.) s -5 547 M -( o Added 'newline' extension.) s -5 525 M -( o Made file attribute owner and group strings so they can actually) s -5 514 M -( be used on disparate systems.) s -5 492 M -( o Added createtime field, and added separate flags for atime,) s -5 481 M -( createtime, and mtime so they can be set separately.) s -5 459 M -( o Split the file type out of the permissions field and into it's own) s -5 448 M -( field \(which is always present.\)) s -5 426 M -( o Added acl attribute.) s -5 404 M -( o Added SSH_FXF_TEXT file open flag.) s -5 382 M -( o Added flags field to the get stat commands so that the client can) s -5 371 M -( specifically request information the server might not normally) s -5 360 M -( included for performance reasons.) s -5 338 M -( o Removed the long filename from the names structure-- it can now be) s -5 327 M -( built from information available in the attrs structure.) s -5 305 M -( o Added reserved range of packet numbers for extensions.) s -5 283 M -( o Added several additional error codes.) s -5 261 M -( o Change the way version negotiate works slightly. Previously, if) s -5 250 M -( the client version were higher than the server version, the server) s -5 239 M -( was supposed to 'echo back' the clients version. The server now) s -5 228 M -( sends it's own version and the lower of the two is considered to) s -5 217 M -( be the one in use.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 30]) s -_R -S -PStoPSsaved restore -%%Page: (30,31) 16 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 31 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(10.2 Changes between versions 3 and 2) s -5 668 M -( o The SSH_FXP_READLINK and SSH_FXP_SYMLINK messages were added.) s -5 646 M -( o The SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY messages were) s -5 635 M -( added.) s -5 613 M -( o The SSH_FXP_STATUS message was changed to include fields `error) s -5 602 M -( message' and `language tag'.) s -5 569 M -(10.3 Changes between versions 2 and 1) s -5 547 M -( o The SSH_FXP_RENAME message was added.) s -5 514 M -(10.4 Changes between versions 1 and 0) s -5 492 M -( o Implementation changes, no actual protocol changes.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 31]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 32 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(11. Trademark Issues) s -5 668 M -( "ssh" is a registered trademark of SSH Communications Security Corp) s -5 657 M -( in the United States and/or other countries.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 32]) s -_R -S -PStoPSsaved restore -%%Page: (32,33) 17 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 33 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(References) s -5 668 M -( [1] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and) s -5 657 M -( P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January) s -5 646 M -( 1999.) s -5 624 M -( [2] Alvestrand, H., "IETF Policy on Character Sets and Languages",) s -5 613 M -( BCP 18, RFC 2277, January 1998.) s -5 591 M -( [3] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., Beame,) s -5 580 M -( C., Eisler, M. and D. Noveck, "NFS version 4 Protocol", RFC) s -5 569 M -( 3010, December 2000.) s -5 547 M -( [4] Institute of Electrical and Electronics Engineers, "Information) s -5 536 M -( Technology - Portable Operating System Interface \(POSIX\) - Part) s -5 525 M -( 1: System Application Program Interface \(API\) [C Language]",) s -5 514 M -( IEEE Standard 1003.2, 1996.) s -5 492 M -( [5] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.) s -5 481 M -( Lehtinen, "SSH Protocol Architecture", draft-ietf-secsh-) s -5 470 M -( architecture-13 \(work in progress\), September 2002.) s -5 448 M -( [6] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.) s -5 437 M -( Lehtinen, "SSH Protocol Transport Protocol", draft-ietf-secsh-) s -5 426 M -( transport-15 \(work in progress\), September 2002.) s -5 404 M -( [7] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.) s -5 393 M -( Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-16) s -5 382 M -( \(work in progress\), September 2002.) s -5 360 M -( [8] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.) s -5 349 M -( Lehtinen, "SSH Authentication Protocol", draft-ietf-secsh-) s -5 338 M -( userauth-16 \(work in progress\), September 2002.) s -5 305 M -(Authors' Addresses) s -5 283 M -( Joseph Galbraith) s -5 272 M -( VanDyke Software) s -5 261 M -( 4848 Tramway Ridge Blvd) s -5 250 M -( Suite 101) s -5 239 M -( Albuquerque, NM 87111) s -5 228 M -( US) s -5 206 M -( Phone: +1 505 332 5700) s -5 195 M -( EMail: [email protected]) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 33]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 34 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -( Tatu Ylonen) s -5 679 M -( SSH Communications Security Corp) s -5 668 M -( Fredrikinkatu 42) s -5 657 M -( HELSINKI FIN-00100) s -5 646 M -( Finland) s -5 624 M -( EMail: [email protected]) s -5 591 M -( Sami Lehtinen) s -5 580 M -( SSH Communications Security Corp) s -5 569 M -( Fredrikinkatu 42) s -5 558 M -( HELSINKI FIN-00100) s -5 547 M -( Finland) s -5 525 M -( EMail: [email protected]) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 34]) s -_R -S -PStoPSsaved restore -%%Page: (34,35) 18 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 35 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH File Transfer Protocol October 2002) s -5 690 M -(Full Copyright Statement) s -5 668 M -( Copyright \(C\) The Internet Society \(2002\). All Rights Reserved.) s -5 646 M -( This document and translations of it may be copied and furnished to) s -5 635 M -( others, and derivative works that comment on or otherwise explain it) s -5 624 M -( or assist in its implementation may be prepared, copied, published) s -5 613 M -( and distributed, in whole or in part, without restriction of any) s -5 602 M -( kind, provided that the above copyright notice and this paragraph are) s -5 591 M -( included on all such copies and derivative works. However, this) s -5 580 M -( document itself may not be modified in any way, such as by removing) s -5 569 M -( the copyright notice or references to the Internet Society or other) s -5 558 M -( Internet organizations, except as needed for the purpose of) s -5 547 M -( developing Internet standards in which case the procedures for) s -5 536 M -( copyrights defined in the Internet Standards process must be) s -5 525 M -( followed, or as required to translate it into languages other than) s -5 514 M -( English.) s -5 492 M -( The limited permissions granted above are perpetual and will not be) s -5 481 M -( revoked by the Internet Society or its successors or assigns.) s -5 459 M -( This document and the information contained herein is provided on an) s -5 448 M -( "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING) s -5 437 M -( TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING) s -5 426 M -( BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION) s -5 415 M -( HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF) s -5 404 M -( MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.) s -5 382 M -(Acknowledgement) s -5 360 M -( Funding for the RFC Editor function is currently provided by the) s -5 349 M -( Internet Society.) s -5 129 M -(Galbraith, et al. Expires April 16, 2003 [Page 35]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 36 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -_R -S -PStoPSsaved restore -%%Trailer -%%Pages: 36 -%%DocumentNeededResources: font Courier-Bold Courier -%%EOF diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-03.txt b/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-03.txt deleted file mode 100644 index 83960ae976..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-03.txt +++ /dev/null @@ -1,1962 +0,0 @@ - - - -Secure Shell Working Group J. Galbraith -Internet-Draft VanDyke Software -Expires: April 16, 2003 T. Ylonen - S. Lehtinen - SSH Communications Security Corp - October 16, 2002 - - - SSH File Transfer Protocol - draft-ietf-secsh-filexfer-03.txt - -Status of this Memo - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that - other groups may also distribute working documents as Internet- - Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at http:// - www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on April 16, 2003. - -Copyright Notice - - Copyright (C) The Internet Society (2002). All Rights Reserved. - -Abstract - - The SSH File Transfer Protocol provides secure file transfer - functionality over any reliable data stream. It is the standard file - transfer protocol for use with the SSH2 protocol. This document - describes the file transfer protocol and its interface to the SSH2 - protocol suite. - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 1] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -Table of Contents - - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Use with the SSH Connection Protocol . . . . . . . . . . . 4 - 3. General Packet Format . . . . . . . . . . . . . . . . . . 5 - 4. Protocol Initialization . . . . . . . . . . . . . . . . . 7 - 4.1 Client Initialization . . . . . . . . . . . . . . . . . . 7 - 4.2 Server Initialization . . . . . . . . . . . . . . . . . . 7 - 4.3 Determining Server Newline Convention . . . . . . . . . . 8 - 5. File Attributes . . . . . . . . . . . . . . . . . . . . . 9 - 5.1 Flags . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 5.2 Type . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 5.3 Size . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 5.4 Owner and Group . . . . . . . . . . . . . . . . . . . . . 10 - 5.5 Permissions . . . . . . . . . . . . . . . . . . . . . . . 11 - 5.6 Times . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 5.7 ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 5.8 Extended attributes . . . . . . . . . . . . . . . . . . . 12 - 6. Requests From the Client to the Server . . . . . . . . . . 13 - 6.1 Request Synchronization and Reordering . . . . . . . . . . 13 - 6.2 File Names . . . . . . . . . . . . . . . . . . . . . . . . 14 - 6.3 Opening, Creating, and Closing Files . . . . . . . . . . . 14 - 6.4 Reading and Writing . . . . . . . . . . . . . . . . . . . 17 - 6.5 Removing and Renaming Files . . . . . . . . . . . . . . . 18 - 6.6 Creating and Deleting Directories . . . . . . . . . . . . 19 - 6.7 Scanning Directories . . . . . . . . . . . . . . . . . . . 19 - 6.8 Retrieving File Attributes . . . . . . . . . . . . . . . . 20 - 6.9 Setting File Attributes . . . . . . . . . . . . . . . . . 21 - 6.10 Dealing with Symbolic links . . . . . . . . . . . . . . . 22 - 6.11 Canonicalizing the Server-Side Path Name . . . . . . . . . 23 - 6.11.1 Best practice for dealing with paths . . . . . . . . . . . 23 - 7. Responses from the Server to the Client . . . . . . . . . 24 - 8. Vendor-Specific Extensions . . . . . . . . . . . . . . . . 28 - 9. Security Considerations . . . . . . . . . . . . . . . . . 29 - 10. Changes from previous protocol versions . . . . . . . . . 30 - 10.1 Changes between versions 4 and 3 . . . . . . . . . . . . . 30 - 10.2 Changes between versions 3 and 2 . . . . . . . . . . . . . 31 - 10.3 Changes between versions 2 and 1 . . . . . . . . . . . . . 31 - 10.4 Changes between versions 1 and 0 . . . . . . . . . . . . . 31 - 11. Trademark Issues . . . . . . . . . . . . . . . . . . . . . 32 - References . . . . . . . . . . . . . . . . . . . . . . . . 33 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . 33 - Full Copyright Statement . . . . . . . . . . . . . . . . . 35 - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 2] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -1. Introduction - - This protocol provides secure file transfer (and more generally file - system access) functionality over a reliable data stream, such as a - channel in the SSH2 protocol [5]. - - This protocol is designed so that it could be used to implement a - secure remote file system service, as well as a secure file transfer - service. - - This protocol assumes that it runs over a secure channel, and that - the server has already authenticated the user at the client end, and - that the identity of the client user is externally available to the - server implementation. - - In general, this protocol follows a simple request-response model. - Each request and response contains a sequence number and multiple - requests may be pending simultaneously. There are a relatively large - number of different request messages, but a small number of possible - response messages. Each request has one or more response messages - that may be returned in result (e.g., a read either returns data or - reports error status). - - The packet format descriptions in this specification follow the - notation presented in the secsh architecture draft. [5] - - Even though this protocol is described in the context of the SSH2 - protocol, this protocol is general and independent of the rest of the - SSH2 protocol suite. It could be used in a number of different - applications, such as secure file transfer over TLS RFC 2246 [1] and - transfer of management information in VPN applications. - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 3] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -2. Use with the SSH Connection Protocol - - When used with the SSH2 Protocol suite, this protocol is intended to - be used from the SSH Connection Protocol [7] as a subsystem, as - described in section ``Starting a Shell or a Command''. The - subsystem name used with this protocol is "sftp". - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 4] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -3. General Packet Format - - All packets transmitted over the secure connection are of the - following format: - - uint32 length - byte type - byte[length - 1] data payload - - That is, they are just data preceded by 32-bit length and 8-bit type - fields. The `length' is the length of the data area, and does not - include the `length' field itself. The format and interpretation of - the data area depends on the packet type. - - All packet descriptions below only specify the packet type and the - data that goes into the data field. Thus, they should be prefixed by - the `length' and `type' fields. - - The maximum size of a packet is in practice determined by the client - (the maximum size of read or write requests that it sends, plus a few - bytes of packet overhead). All servers SHOULD support packets of at - least 34000 bytes (where the packet size refers to the full length, - including the header above). This should allow for reads and writes - of at most 32768 bytes. - - There is no limit on the number of outstanding (non-acknowledged) - requests that the client may send to the server. In practice this is - limited by the buffering available on the data stream and the queuing - performed by the server. If the server's queues are full, it should - not read any more data from the stream, and flow control will prevent - the client from sending more requests. Note, however, that while - there is no restriction on the protocol level, the client's API may - provide a limit in order to prevent infinite queuing of outgoing - requests at the client. - - The following values are defined for packet types. - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 5] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - #define SSH_FXP_INIT 1 - #define SSH_FXP_VERSION 2 - #define SSH_FXP_OPEN 3 - #define SSH_FXP_CLOSE 4 - #define SSH_FXP_READ 5 - #define SSH_FXP_WRITE 6 - #define SSH_FXP_LSTAT 7 - #define SSH_FXP_FSTAT 8 - #define SSH_FXP_SETSTAT 9 - #define SSH_FXP_FSETSTAT 10 - #define SSH_FXP_OPENDIR 11 - #define SSH_FXP_READDIR 12 - #define SSH_FXP_REMOVE 13 - #define SSH_FXP_MKDIR 14 - #define SSH_FXP_RMDIR 15 - #define SSH_FXP_REALPATH 16 - #define SSH_FXP_STAT 17 - #define SSH_FXP_RENAME 18 - #define SSH_FXP_READLINK 19 - #define SSH_FXP_SYMLINK 20 - - #define SSH_FXP_STATUS 101 - #define SSH_FXP_HANDLE 102 - #define SSH_FXP_DATA 103 - #define SSH_FXP_NAME 104 - #define SSH_FXP_ATTRS 105 - - #define SSH_FXP_EXTENDED 200 - #define SSH_FXP_EXTENDED_REPLY 201 - - RESERVED_FOR_EXTENSIONS 210-255 - - Additional packet types should only be defined if the protocol - version number (see Section ``Protocol Initialization'') is - incremented, and their use MUST be negotiated using the version - number. However, the SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY - packets can be used to implement vendor-specific extensions. See - Section ``Vendor-Specific-Extensions'' for more details. - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 6] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -4. Protocol Initialization - - When the file transfer protocol starts, the client first sends a - SSH_FXP_INIT (including its version number) packet to the server. - The server responds with a SSH_FXP_VERSION packet, supplying the - lowest of its own and the client's version number. Both parties - should from then on adhere to particular version of the protocol. - - The version number of the protocol specified in this document is 4. - The version number should be incremented for each incompatible - revision of this protocol. - -4.1 Client Initialization - - The SSH_FXP_INIT packet (from client to server) has the following - data: - - uint32 version - - Version 3 of this protocol allowed clients to include extensions in - the SSH_FXP_INIT packet; however, this can cause interoperability - problems with version 1 and version 2 servers because the client must - send this packet before knowing the servers version. - - In this version of the protocol, clients MUST use the - SSH_FXP_EXTENDED packet to send extensions to the server after - version exchange has completed. Clients MUST NOT include extensions - in the version packet. This will prevent interoperability problems - with older servers - -4.2 Server Initialization - - The SSH_FXP_VERSION packet (from server to client) has the following - data: - - uint32 version - <extension data> - - 'version' is the lower of the protocol version supported by the - server and the version number received from the client. - - The extension data may be empty, or may be a sequence of - - string extension_name - string extension_data - - pairs (both strings MUST always be present if one is, but the - `extension_data' string may be of zero length). If present, these - - - -Galbraith, et al. Expires April 16, 2003 [Page 7] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - strings indicate extensions to the baseline protocol. The - `extension_name' field(s) identify the name of the extension. The - name should be of the form "name@domain", where the domain is the DNS - domain name of the organization defining the extension. Additional - names that are not of this format may be defined later by the IETF. - Implementations MUST silently ignore any extensions whose name they - do not recognize. - -4.3 Determining Server Newline Convention - - In order to correctly process text files in a cross platform - compatible way, the newline convention must be converted from that of - the server to that of the client, or, during an upload, from that of - the client to that of the server. - - Versions 3 and prior of this protocol made no provisions for - processing text files. Many clients implemented some sort of - conversion algorithm, but without either a 'canonical' on the wire - format or knowledge of the servers newline convention, correct - conversion was not always possible. - - Starting with Version 4, the SSH_FXF_TEXT file open flag (Section - 6.3) makes it possible to request that the server translate a file to - a 'canonical' on the wire format. This format uses \r\n as the line - separator. - - Servers for systems using multiple newline characters (for example, - Mac OS X or VMS) or systems using counted records, MUST translate to - the canonical form. - - However, to ease the burden of implementation on servers that use a - single, simple separator sequence, the following extension allows the - canonical format to be changed. - - string "newline" - string new-canonical-separator (usually "\r" or "\n" or "\r\n") - - All clients MUST support this extension. - - When processing text files, clients SHOULD NOT translate any - character or sequence that is not an exact match of the servers - newline separator. - - In particular, if the newline sequence being used is the canonical - "\r\n" sequence, a lone \r or a lone \n SHOULD be written through - without change. - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 8] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -5. File Attributes - - A new compound data type is defined for encoding file attributes. - The same encoding is used both when returning file attributes from - the server and when sending file attributes to the server. When - sending it to the server, the flags field specifies which attributes - are included, and the server will use default values for the - remaining attributes (or will not modify the values of remaining - attributes). When receiving attributes from the server, the flags - specify which attributes are included in the returned data. The - server normally returns all attributes it knows about. - - uint32 flags - byte type always present - uint64 size present only if flag SSH_FILEXFER_ATTR_SIZE - string owner present only if flag SSH_FILEXFER_ATTR_OWNERGROUP - string group present only if flag SSH_FILEXFER_ATTR_OWNERGROUP - uint32 permissions present only if flag SSH_FILEXFER_ATTR_PERMISSIONS - uint32 atime present only if flag SSH_FILEXFER_ATTR_ACCESSTIME - uint32 createtime present only if flag SSH_FILEXFER_ATTR_CREATETIME - uint32 mtime present only if flag SSH_FILEXFER_ATTR_MODIFYTIME - string acl present only if flag SSH_FILEXFER_ATTR_ACL - uint32 extended_count present only if flag SSH_FILEXFER_ATTR_EXTENDED - string extended_type - string extended_data - ... more extended data (extended_type - extended_data pairs), - so that number of pairs equals extended_count - - -5.1 Flags - - The `flags' specify which of the fields are present. Those fields - for which the corresponding flag is not set are not present (not - included in the packet). New flags can only be added by incrementing - the protocol version number (or by using the extension mechanism - described below). - - The flags bits are defined to have the following values: - - #define SSH_FILEXFER_ATTR_SIZE 0x00000001 - #define SSH_FILEXFER_ATTR_PERMISSIONS 0x00000004 - #define SSH_FILEXFER_ATTR_ACCESSTIME 0x00000008 - #define SSH_FILEXFER_ATTR_CREATETIME 0x00000010 - #define SSH_FILEXFER_ATTR_MODIFYTIME 0x00000020 - #define SSH_FILEXFER_ATTR_ACL 0x00000040 - #define SSH_FILEXFER_ATTR_OWNERGROUP 0x00000080 - #define SSH_FILEXFER_ATTR_EXTENDED 0x80000000 - - - - -Galbraith, et al. Expires April 16, 2003 [Page 9] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - In previous versions of this protocol flags value 0x00000002 was - SSH_FILEXFER_ATTR_UIDGID. This value is now unused, and OWNERGROUP - was given a new value in order to ease implementation burden. - 0x00000002 MUST NOT appear in the mask. Some future version of this - protocol may reuse flag 0x00000002. - -5.2 Type - - The type field is always present. The following types are defined: - - #define SSH_FILEXFER_TYPE_REGULAR 1 - #define SSH_FILEXFER_TYPE_DIRECTORY 2 - #define SSH_FILEXFER_TYPE_SYMLINK 3 - #define SSH_FILEXFER_TYPE_SPECIAL 4 - #define SSH_FILEXFER_TYPE_UNKNOWN 5 - - On a POSIX system, these values would be derived from the permission - field. - -5.3 Size - - The `size' field specifies the size of the file on disk, in bytes. - If it is present during file creation, it should be considered a hint - as to the files eventual size. - - Files opened with the SSH_FXF_TEXT flag may have a size that is - greater or less than the value of the size field. - -5.4 Owner and Group - - The `owner' and `group' fields are represented as UTF-8 strings; this - is the form used by NFS v4. See NFS version 4 Protocol. [3] The - following text is selected quotations from section 5.6. - - To avoid a representation that is tied to a particular underlying - implementation at the client or server, the use of UTF-8 strings has - been chosen. The string should be of the form user@dns_domain". - This will allow for a client and server that do not use the same - local representation the ability to translate to a common syntax that - can be interpreted by both. In the case where there is no - translation available to the client or server, the attribute value - must be constructed without the "@". Therefore, the absence of the @ - from the owner or owner_group attribute signifies that no translation - was available and the receiver of the attribute should not place any - special meaning with the attribute value. Even though the attribute - value can not be translated, it may still be useful. In the case of - a client, the attribute string may be used for local display of - ownership. - - - -Galbraith, et al. Expires April 16, 2003 [Page 10] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -5.5 Permissions - - The `permissions' field contains a bit mask of file permissions as - defined by POSIX [1]. - -5.6 Times - - The 'atime', 'createtime', and 'mtime' contain the access, creation, - and modification times of the files, respectively. They are - represented as seconds from Jan 1, 1970 in UTC. - -5.7 ACL - - The 'ACL' field contains an ACL similar to that defined in section - 5.9 of NFS version 4 Protocol [3]. - - uint32 ace-count - - repeated ace-count time: - uint32 ace-type - uint32 ace-flag - uint32 ace-mask - string who [UTF-8] - - ace-type is one of the following four values (taken from NFS Version - 4 Protocol [3]: - - const ACE4_ACCESS_ALLOWED_ACE_TYPE = 0x00000000; - const ACE4_ACCESS_DENIED_ACE_TYPE = 0x00000001; - const ACE4_SYSTEM_AUDIT_ACE_TYPE = 0x00000002; - const ACE4_SYSTEM_ALARM_ACE_TYPE = 0x00000003; - - ace-flag is a combination of the following flag values. See NFS - Version 4 Protocol [3] section 5.9.2: - - const ACE4_FILE_INHERIT_ACE = 0x00000001; - const ACE4_DIRECTORY_INHERIT_ACE = 0x00000002; - const ACE4_NO_PROPAGATE_INHERIT_ACE = 0x00000004; - const ACE4_INHERIT_ONLY_ACE = 0x00000008; - const ACE4_SUCCESSFUL_ACCESS_ACE_FLAG = 0x00000010; - const ACE4_FAILED_ACCESS_ACE_FLAG = 0x00000020; - const ACE4_IDENTIFIER_GROUP = 0x00000040; - - ace-mask is any combination of the following flags (taken from NFS - Version 4 Protocol [3] section 5.9.3: - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 11] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - const ACE4_READ_DATA = 0x00000001; - const ACE4_LIST_DIRECTORY = 0x00000001; - const ACE4_WRITE_DATA = 0x00000002; - const ACE4_ADD_FILE = 0x00000002; - const ACE4_APPEND_DATA = 0x00000004; - const ACE4_ADD_SUBDIRECTORY = 0x00000004; - const ACE4_READ_NAMED_ATTRS = 0x00000008; - const ACE4_WRITE_NAMED_ATTRS = 0x00000010; - const ACE4_EXECUTE = 0x00000020; - const ACE4_DELETE_CHILD = 0x00000040; - const ACE4_READ_ATTRIBUTES = 0x00000080; - const ACE4_WRITE_ATTRIBUTES = 0x00000100; - const ACE4_DELETE = 0x00010000; - const ACE4_READ_ACL = 0x00020000; - const ACE4_WRITE_ACL = 0x00040000; - const ACE4_WRITE_OWNER = 0x00080000; - const ACE4_SYNCHRONIZE = 0x00100000; - - who is a UTF-8 string of the form described in 'Owner and Group' - (Section 5.4) - -5.8 Extended attributes - - The SSH_FILEXFER_ATTR_EXTENDED flag provides a general extension - mechanism for vendor-specific extensions. If the flag is specified, - then the `extended_count' field is present. It specifies the number - of extended_type-extended_data pairs that follow. Each of these - pairs specifies an extended attribute. For each of the attributes, - the extended_type field should be a string of the format - "name@domain", where "domain" is a valid, registered domain name and - "name" identifies the method. The IETF may later standardize certain - names that deviate from this format (e.g., that do not contain the - "@" sign). The interpretation of `extended_data' depends on the - type. Implementations SHOULD ignore extended data fields that they - do not understand. - - Additional fields can be added to the attributes by either defining - additional bits to the flags field to indicate their presence, or by - defining extended attributes for them. The extended attributes - mechanism is recommended for most purposes; additional flags bits - should only be defined by an IETF standards action that also - increments the protocol version number. The use of such new fields - MUST be negotiated by the version number in the protocol exchange. - It is a protocol error if a packet with unsupported protocol bits is - received. - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 12] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -6. Requests From the Client to the Server - - Requests from the client to the server represent the various file - system operations. Each request begins with an `id' field, which is - a 32-bit identifier identifying the request (selected by the client). - The same identifier will be returned in the response to the request. - One possible implementation is a monotonically increasing request - sequence number (modulo 2^32). - - Many operations in the protocol operate on open files. The - SSH_FXP_OPEN request can return a file handle (which is an opaque - variable-length string) which may be used to access the file later - (e.g. in a read operation). The client MUST NOT send requests the - server with bogus or closed handles. However, the server MUST - perform adequate checks on the handle in order to avoid security - risks due to fabricated handles. - - This design allows either stateful and stateless server - implementation, as well as an implementation which caches state - between requests but may also flush it. The contents of the file - handle string are entirely up to the server and its design. The - client should not modify or attempt to interpret the file handle - strings. - - The file handle strings MUST NOT be longer than 256 bytes. - -6.1 Request Synchronization and Reordering - - The protocol and implementations MUST process requests relating to - the same file in the order in which they are received. In other - words, if an application submits multiple requests to the server, the - results in the responses will be the same as if it had sent the - requests one at a time and waited for the response in each case. For - example, the server may process non-overlapping read/write requests - to the same file in parallel, but overlapping reads and writes cannot - be reordered or parallelized. However, there are no ordering - restrictions on the server for processing requests from two different - file transfer connections. The server may interleave and parallelize - them at will. - - There are no restrictions on the order in which responses to - outstanding requests are delivered to the client, except that the - server must ensure fairness in the sense that processing of no - request will be indefinitely delayed even if the client is sending - other requests so that there are multiple outstanding requests all - the time. - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 13] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -6.2 File Names - - This protocol represents file names as strings. File names are - assumed to use the slash ('/') character as a directory separator. - - File names starting with a slash are "absolute", and are relative to - the root of the file system. Names starting with any other character - are relative to the user's default directory (home directory). Note - that identifying the user is assumed to take place outside of this - protocol. - - Servers SHOULD interpret a path name component ".." as referring to - the parent directory, and "." as referring to the current directory. - If the server implementation limits access to certain parts of the - file system, it must be extra careful in parsing file names when - enforcing such restrictions. There have been numerous reported - security bugs where a ".." in a path name has allowed access outside - the intended area. - - An empty path name is valid, and it refers to the user's default - directory (usually the user's home directory). - - Otherwise, no syntax is defined for file names by this specification. - Clients should not make any other assumptions; however, they can - splice path name components returned by SSH_FXP_READDIR together - using a slash ('/') as the separator, and that will work as expected. - - In order to comply with IETF Policy on Character Sets and Languages - [2], all filenames are to be encoded in UTF-8. The shortest valid - UTF-8 encoding of the UNICODE data MUST be used. The server is - responsible for converting the UNICODE data to whatever canonical - form it requires. - - For example, if the server requires that precomposed characters - always be used, the server MUST NOT assume the filename as sent by - the client has this attribute, but must do this normalization itself. - - It is understood that the lack of well-defined semantics for file - names may cause interoperability problems between clients and servers - using radically different operating systems. However, this approach - is known to work acceptably with most systems, and alternative - approaches that e.g. treat file names as sequences of structured - components are quite complicated. - -6.3 Opening, Creating, and Closing Files - - Files are opened and created using the SSH_FXP_OPEN message, whose - data part is as follows: - - - -Galbraith, et al. Expires April 16, 2003 [Page 14] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - uint32 id - string filename [UTF-8] - uint32 pflags - ATTRS attrs - - The `id' field is the request identifier as for all requests. - - The `filename' field specifies the file name. See Section ``File - Names'' for more information. - - The `pflags' field is a bitmask. The following bits have been - defined. - - #define SSH_FXF_READ 0x00000001 - #define SSH_FXF_WRITE 0x00000002 - #define SSH_FXF_APPEND 0x00000004 - #define SSH_FXF_CREAT 0x00000008 - #define SSH_FXF_TRUNC 0x00000010 - #define SSH_FXF_EXCL 0x00000020 - #define SSH_FXF_TEXT 0x00000040 - - These have the following meanings: - - SSH_FXF_READ - Open the file for reading. - - SSH_FXF_WRITE - Open the file for writing. If both this and SSH_FXF_READ are - specified, the file is opened for both reading and writing. - - SSH_FXF_APPEND - Force all writes to append data at the end of the file. The - offset parameter to write will be ignored. - - SSH_FXF_CREAT - If this flag is specified, then a new file will be created if one - does not already exist (if O_TRUNC is specified, the new file will - be truncated to zero length if it previously exists). - - SSH_FXF_TRUNC - Forces an existing file with the same name to be truncated to zero - length when creating a file by specifying SSH_FXF_CREAT. - SSH_FXF_CREAT MUST also be specified if this flag is used. - - SSH_FXF_EXCL - Causes the request to fail if the named file already exists. - SSH_FXF_CREAT MUST also be specified if this flag is used. - - - - -Galbraith, et al. Expires April 16, 2003 [Page 15] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - SSH_FXF_TEXT - Indicates that the server should treat the file as text and - convert it to the canonical newline convention in use. (See - Determining Server Newline Convention. (Section 4.3) - - When a file is opened with the FXF_TEXT flag, the offset field in - both the read and write function are ignored. - - Servers MUST correctly process multiple parallel reads and writes - correctly in this mode. Naturally, it is permissible for them to - do this by serializing the requests. It would not be possible for - a client to reliably detect a server that does not implement - parallel writes in time to prevent damage. - - Clients SHOULD use the SSH_FXF_APPEND flag to append data to a - text file rather then using write with a calculated offset. - - To support seeks on text file the following SSH_FXP_EXTENDED - packet is defined. - - - - string "text-seek" - string file-handle - uint64 line-number - - line-number is the index of the line number to seek to, where byte - 0 in the file is line number 0, and the byte directly following - the first newline sequence in the file is line number 1 and so on. - - The response to a "text-seek" request is an SSH_FXP_STATUS - message. - - An attempt to seek past the end-of-file should result in a - SSH_FX_EOF status. - - Servers SHOULD support at least one "text-seek" in order to - support resume. However, a client MUST be prepared to receive - SSH_FX_OP_UNSUPPORTED when attempting a "text-seek" operation. - The client can then try a fall-back strategy, if it has one. - - Clients MUST be prepared to handle SSH_FX_OP_UNSUPPORTED returned - for read or write operations that are not sequential. - - The `attrs' field specifies the initial attributes for the file. - Default values will be used for those attributes that are not - specified. See Section ``File Attributes'' for more information. - - - - -Galbraith, et al. Expires April 16, 2003 [Page 16] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - The response to this message will be either SSH_FXP_HANDLE (if the - operation is successful) or SSH_FXP_STATUS (if the operation fails). - - A file is closed by using the SSH_FXP_CLOSE request. Its data field - has the following format: - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is a handle - previously returned in the response to SSH_FXP_OPEN or - SSH_FXP_OPENDIR. The handle becomes invalid immediately after this - request has been sent. - - The response to this request will be a SSH_FXP_STATUS message. One - should note that on some server platforms even a close can fail. - This can happen e.g. if the server operating system caches writes, - and an error occurs while flushing cached writes during the close. - -6.4 Reading and Writing - - Once a file has been opened, it can be read using the SSH_FXP_READ - message, which has the following format: - - uint32 id - string handle - uint64 offset - uint32 len - - where `id' is the request identifier, `handle' is an open file handle - returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) relative - to the beginning of the file from where to start reading, and `len' - is the maximum number of bytes to read. - - In response to this request, the server will read as many bytes as it - can from the file (up to `len'), and return them in a SSH_FXP_DATA - message. If an error occurs or EOF is encountered before reading any - data, the server will respond with SSH_FXP_STATUS. For normal disk - files, it is guaranteed that this will read the specified number of - bytes, or up to end of file. For e.g. device files this may return - fewer bytes than requested. - - Writing to a file is achieved using the SSH_FXP_WRITE message, which - has the following format: - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 17] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - uint32 id - string handle - uint64 offset - string data - - where `id' is a request identifier, `handle' is a file handle - returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) from the - beginning of the file where to start writing, and `data' is the data - to be written. - - The write will extend the file if writing beyond the end of the file. - It is legal to write way beyond the end of the file; the semantics - are to write zeroes from the end of the file to the specified offset - and then the data. On most operating systems, such writes do not - allocate disk space but instead leave "holes" in the file. - - The server responds to a write request with a SSH_FXP_STATUS message. - -6.5 Removing and Renaming Files - - Files can be removed using the SSH_FXP_REMOVE message. It has the - following format: - - uint32 id - string filename [UTF-8] - - where `id' is the request identifier and `filename' is the name of - the file to be removed. See Section ``File Names'' for more - information. This request cannot be used to remove directories. - - The server will respond to this request with a SSH_FXP_STATUS - message. - - Files (and directories) can be renamed using the SSH_FXP_RENAME - message. Its data is as follows: - - uint32 id - string oldpath [UTF-8] - string newpath [UTF-8] - - where `id' is the request identifier, `oldpath' is the name of an - existing file or directory, and `newpath' is the new name for the - file or directory. It is an error if there already exists a file - with the name specified by newpath. The server may also fail rename - requests in other situations, for example if `oldpath' and `newpath' - point to different file systems on the server. - - The server will respond to this request with a SSH_FXP_STATUS - - - -Galbraith, et al. Expires April 16, 2003 [Page 18] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - message. - -6.6 Creating and Deleting Directories - - New directories can be created using the SSH_FXP_MKDIR request. It - has the following format: - - uint32 id - string path [UTF-8] - ATTRS attrs - - where `id' is the request identifier. - - `path' specifies the directory to be created. See Section ``File - Names'' for more information on file names. - - `attrs' specifies the attributes that should be applied to it upon - creation. Attributes are discussed in more detail in Section ``File - Attributes''. - - The server will respond to this request with a SSH_FXP_STATUS - message. If a file or directory with the specified path already - exists, an error will be returned. - - Directories can be removed using the SSH_FXP_RMDIR request, which has - the following format: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier, and `path' specifies the - directory to be removed. See Section ``File Names'' for more - information on file names. - - The server responds to this request with a SSH_FXP_STATUS message. - Errors may be returned from this operation for various reasons, - including, but not limited to, the path does not exist, the path does - not refer to a directory object, the directory is not empty, or the - user has insufficient access or permission to perform the requested - operation. - -6.7 Scanning Directories - - The files in a directory can be listed using the SSH_FXP_OPENDIR and - SSH_FXP_READDIR requests. Each SSH_FXP_READDIR request returns one - or more file names with full file attributes for each file. The - client should call SSH_FXP_READDIR repeatedly until it has found the - file it is looking for or until the server responds with a - - - -Galbraith, et al. Expires April 16, 2003 [Page 19] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - SSH_FXP_STATUS message indicating an error (normally SSH_FX_EOF if - there are no more files in the directory). The client should then - close the handle using the SSH_FXP_CLOSE request. - - The SSH_FXP_OPENDIR opens a directory for reading. It has the - following format: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' is the path name of - the directory to be listed (without any trailing slash). See Section - ``File Names'' for more information on file names. This will return - an error if the path does not specify a directory or if the directory - is not readable. The server will respond to this request with either - a SSH_FXP_HANDLE or a SSH_FXP_STATUS message. - - Once the directory has been successfully opened, files (and - directories) contained in it can be listed using SSH_FXP_READDIR - requests. These are of the format - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is a handle - returned by SSH_FXP_OPENDIR. (It is a protocol error to attempt to - use an ordinary file handle returned by SSH_FXP_OPEN.) - - The server responds to this request with either a SSH_FXP_NAME or a - SSH_FXP_STATUS message. One or more names may be returned at a time. - Full status information is returned for each name in order to speed - up typical directory listings. - - If there are no more names available to be read, the server MUST - respond with a SSH_FXP_STATUS message with error code of SSH_FX_EOF. - - When the client no longer wishes to read more names from the - directory, it SHOULD call SSH_FXP_CLOSE for the handle. The handle - should be closed regardless of whether an error has occurred or not. - -6.8 Retrieving File Attributes - - Very often, file attributes are automatically returned by - SSH_FXP_READDIR. However, sometimes there is need to specifically - retrieve the attributes for a named file. This can be done using the - SSH_FXP_STAT, SSH_FXP_LSTAT and SSH_FXP_FSTAT requests. - - SSH_FXP_STAT and SSH_FXP_LSTAT only differ in that SSH_FXP_STAT - - - -Galbraith, et al. Expires April 16, 2003 [Page 20] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - follows symbolic links on the server, whereas SSH_FXP_LSTAT does not - follow symbolic links. Both have the same format: - - uint32 id - string path [UTF-8] - uint32 flags - - where `id' is the request identifier, and `path' specifies the file - system object for which status is to be returned. The server - responds to this request with either SSH_FXP_ATTRS or SSH_FXP_STATUS. - - The flags field specify the attribute flags in which the client has - particular interest. This is a hint to the server. For example, - because retrieving owner / group and acl information can be an - expensive operation under some operating systems, the server may - choose not to retrieve this information unless the client expresses a - specific interest in it. - - The client has no guarantee the server will provide all the fields - that it has expressed an interest in. - - SSH_FXP_FSTAT differs from the others in that it returns status - information for an open file (identified by the file handle). Its - format is as follows: - - uint32 id - string handle - uint32 flags - - where `id' is the request identifier and `handle' is a file handle - returned by SSH_FXP_OPEN. The server responds to this request with - SSH_FXP_ATTRS or SSH_FXP_STATUS. - -6.9 Setting File Attributes - - File attributes may be modified using the SSH_FXP_SETSTAT and - SSH_FXP_FSETSTAT requests. These requests are used for operations - such as changing the ownership, permissions or access times, as well - as for truncating a file. - - The SSH_FXP_SETSTAT request is of the following format: - - uint32 id - string path [UTF-8] - ATTRS attrs - - where `id' is the request identifier, `path' specifies the file - system object (e.g. file or directory) whose attributes are to be - - - -Galbraith, et al. Expires April 16, 2003 [Page 21] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - modified, and `attrs' specifies the modifications to be made to its - attributes. Attributes are discussed in more detail in Section - ``File Attributes''. - - An error will be returned if the specified file system object does - not exist or the user does not have sufficient rights to modify the - specified attributes. The server responds to this request with a - SSH_FXP_STATUS message. - - The SSH_FXP_FSETSTAT request modifies the attributes of a file which - is already open. It has the following format: - - uint32 id - string handle - ATTRS attrs - - where `id' is the request identifier, `handle' (MUST be returned by - SSH_FXP_OPEN) identifies the file whose attributes are to be - modified, and `attrs' specifies the modifications to be made to its - attributes. Attributes are discussed in more detail in Section - ``File Attributes''. The server will respond to this request with - SSH_FXP_STATUS. - -6.10 Dealing with Symbolic links - - The SSH_FXP_READLINK request may be used to read the target of a - symbolic link. It would have a data part as follows: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' specifies the path - name of the symlink to be read. - - The server will respond with a SSH_FXP_NAME packet containing only - one name and a dummy attributes value. The name in the returned - packet contains the target of the link. If an error occurs, the - server may respond with SSH_FXP_STATUS. - - The SSH_FXP_SYMLINK request will create a symbolic link on the - server. It is of the following format - - uint32 id - string linkpath [UTF-8] - string targetpath [UTF-8] - - where `id' is the request identifier, `linkpath' specifies the path - name of the symlink to be created and `targetpath' specifies the - - - -Galbraith, et al. Expires April 16, 2003 [Page 22] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - target of the symlink. The server shall respond with a - SSH_FXP_STATUS indicating either success (SSH_FX_OK) or an error - condition. - -6.11 Canonicalizing the Server-Side Path Name - - The SSH_FXP_REALPATH request can be used to have the server - canonicalize any given path name to an absolute path. This is useful - for converting path names containing ".." components or relative - pathnames without a leading slash into absolute paths. The format of - the request is as follows: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' specifies the path - name to be canonicalized. The server will respond with a - SSH_FXP_NAME packet containing the name in canonical form and a dummy - attributes value. If an error occurs, the server may also respond - with SSH_FXP_STATUS. - -6.11.1 Best practice for dealing with paths - - The client SHOULD treat the results of SSH_FXP_REALPATH as a - canonical absolute path, even if the path does not appear to be - absolute. A client that use REALPATH(".") and treats the result as - absolute, even if there is no leading slash, will continue to - function correctly, even when talking to a Windows NT or VMS style - system, where absolute paths may not begin with a slash. - - For example, if the client wishes to change directory up, and the - server has returned "c:/x/y/z" from REALPATH, the client SHOULD use - "c:/x/y/z/..". - - As a second example, if the client wishes to open the file "x.txt" in - the current directory, and server has returned "dka100:/x/y/z" as the - canonical path of the directory, the client SHOULD open "dka100:/x/y/ - z/x.txt" - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 23] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -7. Responses from the Server to the Client - - The server responds to the client using one of a few response - packets. All requests can return a SSH_FXP_STATUS response upon - failure. When the operation is successful, any of the responses may - be returned (depending on the operation). If no data needs to be - returned to the client, the SSH_FXP_STATUS response with SSH_FX_OK - status is appropriate. Otherwise, the SSH_FXP_HANDLE message is used - to return a file handle (for SSH_FXP_OPEN and SSH_FXP_OPENDIR - requests), SSH_FXP_DATA is used to return data from SSH_FXP_READ, - SSH_FXP_NAME is used to return one or more file names from a - SSH_FXP_READDIR or SSH_FXP_REALPATH request, and SSH_FXP_ATTRS is - used to return file attributes from SSH_FXP_STAT, SSH_FXP_LSTAT, and - SSH_FXP_FSTAT requests. - - Exactly one response will be returned for each request. Each - response packet contains a request identifier which can be used to - match each response with the corresponding request. Note that it is - legal to have several requests outstanding simultaneously, and the - server is allowed to send responses to them in a different order from - the order in which the requests were sent (the result of their - execution, however, is guaranteed to be as if they had been processed - one at a time in the order in which the requests were sent). - - Response packets are of the same general format as request packets. - Each response packet begins with the request identifier. - - The format of the data portion of the SSH_FXP_STATUS response is as - follows: - - uint32 id - uint32 error/status code - string error message (ISO-10646 UTF-8 [RFC-2279]) - string language tag (as defined in [RFC-1766]) - - where `id' is the request identifier, and `error/status code' - indicates the result of the requested operation. The value SSH_FX_OK - indicates success, and all other values indicate failure. - - Currently, the following values are defined (other values may be - defined by future versions of this protocol): - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 24] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - #define SSH_FX_OK 0 - #define SSH_FX_EOF 1 - #define SSH_FX_NO_SUCH_FILE 2 - #define SSH_FX_PERMISSION_DENIED 3 - #define SSH_FX_FAILURE 4 - #define SSH_FX_BAD_MESSAGE 5 - #define SSH_FX_NO_CONNECTION 6 - #define SSH_FX_CONNECTION_LOST 7 - #define SSH_FX_OP_UNSUPPORTED 8 - #define SSH_FX_INVALID_HANDLE 9 - #define SSH_FX_NO_SUCH_PATH 10 - #define SSH_FX_FILE_ALREADY_EXISTS 11 - #define SSH_FX_WRITE_PROTECT 12 - - SSH_FX_OK - Indicates successful completion of the operation. - - SSH_FX_EOF - indicates end-of-file condition; for SSH_FX_READ it means that no - more data is available in the file, and for SSH_FX_READDIR it - indicates that no more files are contained in the directory. - - SSH_FX_NO_SUCH_FILE - is returned when a reference is made to a file which does not - exist. - - SSH_FX_PERMISSION_DENIED - is returned when the authenticated user does not have sufficient - permissions to perform the operation. - - SSH_FX_FAILURE - is a generic catch-all error message; it should be returned if an - error occurs for which there is no more specific error code - defined. - - SSH_FX_BAD_MESSAGE - may be returned if a badly formatted packet or protocol - incompatibility is detected. - - SSH_FX_NO_CONNECTION - is a pseudo-error which indicates that the client has no - connection to the server (it can only be generated locally by the - client, and MUST NOT be returned by servers). - - SSH_FX_CONNECTION_LOST - is a pseudo-error which indicates that the connection to the - server has been lost (it can only be generated locally by the - client, and MUST NOT be returned by servers). - - - -Galbraith, et al. Expires April 16, 2003 [Page 25] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - SSH_FX_OP_UNSUPPORTED - indicates that an attempt was made to perform an operation which - is not supported for the server (it may be generated locally by - the client if e.g. the version number exchange indicates that a - required feature is not supported by the server, or it may be - returned by the server if the server does not implement an - operation). - - SSH_FX_INVALID_HANDLE - The handle value was invalid. - - SSH_FX_NO_SUCH_PATH - The file path does not exist or is invalid. - - SSH_FX_FILE_ALREADY_EXISTS - The file already exists. - - SSH_FX_WRITE_PROTECT - The file is on read only media, or the media is write protected. - - The SSH_FXP_HANDLE response has the following format: - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is an arbitrary - string that identifies an open file or directory on the server. The - handle is opaque to the client; the client MUST NOT attempt to - interpret or modify it in any way. The length of the handle string - MUST NOT exceed 256 data bytes. - - The SSH_FXP_DATA response has the following format: - - uint32 id - string data - - where `id' is the request identifier, and `data' is an arbitrary byte - string containing the requested data. The data string may be at most - the number of bytes requested in a SSH_FXP_READ request, but may also - be shorter if end of file is reached or if the read is from something - other than a regular file. - - The SSH_FXP_NAME response has the following format: - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 26] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - uint32 id - uint32 count - repeats count times: - string filename [UTF-8] - ATTRS attrs - - where `id' is the request identifier, `count' is the number of names - returned in this response, and the remaining fields repeat `count' - times (so that all three fields are first included for the first - file, then for the second file, etc). In the repeated part, - `filename' is a file name being returned (for SSH_FXP_READDIR, it - will be a relative name within the directory, without any path - components; for SSH_FXP_REALPATH it will be an absolute path name), - and `attrs' is the attributes of the file as described in Section - ``File Attributes''. - - The SSH_FXP_ATTRS response has the following format: - - uint32 id - ATTRS attrs - - where `id' is the request identifier, and `attrs' is the returned - file attributes as described in Section ``File Attributes''. - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 27] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -8. Vendor-Specific Extensions - - The SSH_FXP_EXTENDED request provides a generic extension mechanism - for adding vendor-specific commands. The request has the following - format: - - uint32 id - string extended-request - ... any request-specific data ... - - where `id' is the request identifier, and `extended-request' is a - string of the format "name@domain", where domain is an internet - domain name of the vendor defining the request. The rest of the - request is completely vendor-specific, and servers should only - attempt to interpret it if they recognize the `extended-request' - name. - - The server may respond to such requests using any of the response - packets defined in Section ``Responses from the Server to the - Client''. Additionally, the server may also respond with a - SSH_FXP_EXTENDED_REPLY packet, as defined below. If the server does - not recognize the `extended-request' name, then the server MUST - respond with SSH_FXP_STATUS with error/status set to - SSH_FX_OP_UNSUPPORTED. - - The SSH_FXP_EXTENDED_REPLY packet can be used to carry arbitrary - extension-specific data from the server to the client. It is of the - following format: - - uint32 id - ... any request-specific data ... - - There is a range of packet types reserved for use by extensions. In - order to avoid collision, extensions that turn on the use of - additional packet types should determine those numbers dynamically. - - The suggested way of doing this is have an extension request from the - client to the server that enables the extension; the extension - response from the server to the client would specify the actual type - values to use, in additional to any other data. - - Extension authors should be mindful of the limited range of packet - types available (there are only 45 values available) and avoid - requiring a new packet type where possible. - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 28] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -9. Security Considerations - - This protocol assumes that it is run over a secure channel and that - the endpoints of the channel have been authenticated. Thus, this - protocol assumes that it is externally protected from network-level - attacks. - - This protocol provides file system access to arbitrary files on the - server (only constrained by the server implementation). It is the - responsibility of the server implementation to enforce any access - controls that may be required to limit the access allowed for any - particular user (the user being authenticated externally to this - protocol, typically using the SSH User Authentication Protocol [8]. - - Care must be taken in the server implementation to check the validity - of received file handle strings. The server should not rely on them - directly; it MUST check the validity of each handle before relying on - it. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 29] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -10. Changes from previous protocol versions - - The SSH File Transfer Protocol has changed over time, before it's - standardization. The following is a description of the incompatible - changes between different versions. - -10.1 Changes between versions 4 and 3 - - Many of the changes between version 4 and version 3 are to the - attribute structure to make it more flexible for non-unix platforms. - - o Make all filenames UTF-8. - - o Added 'newline' extension. - - o Made file attribute owner and group strings so they can actually - be used on disparate systems. - - o Added createtime field, and added separate flags for atime, - createtime, and mtime so they can be set separately. - - o Split the file type out of the permissions field and into it's own - field (which is always present.) - - o Added acl attribute. - - o Added SSH_FXF_TEXT file open flag. - - o Added flags field to the get stat commands so that the client can - specifically request information the server might not normally - included for performance reasons. - - o Removed the long filename from the names structure-- it can now be - built from information available in the attrs structure. - - o Added reserved range of packet numbers for extensions. - - o Added several additional error codes. - - o Change the way version negotiate works slightly. Previously, if - the client version were higher than the server version, the server - was supposed to 'echo back' the clients version. The server now - sends it's own version and the lower of the two is considered to - be the one in use. - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 30] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -10.2 Changes between versions 3 and 2 - - o The SSH_FXP_READLINK and SSH_FXP_SYMLINK messages were added. - - o The SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY messages were - added. - - o The SSH_FXP_STATUS message was changed to include fields `error - message' and `language tag'. - - -10.3 Changes between versions 2 and 1 - - o The SSH_FXP_RENAME message was added. - - -10.4 Changes between versions 1 and 0 - - o Implementation changes, no actual protocol changes. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 31] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -11. Trademark Issues - - "ssh" is a registered trademark of SSH Communications Security Corp - in the United States and/or other countries. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 32] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -References - - [1] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and - P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January - 1999. - - [2] Alvestrand, H., "IETF Policy on Character Sets and Languages", - BCP 18, RFC 2277, January 1998. - - [3] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., Beame, - C., Eisler, M. and D. Noveck, "NFS version 4 Protocol", RFC - 3010, December 2000. - - [4] Institute of Electrical and Electronics Engineers, "Information - Technology - Portable Operating System Interface (POSIX) - Part - 1: System Application Program Interface (API) [C Language]", - IEEE Standard 1003.2, 1996. - - [5] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Protocol Architecture", draft-ietf-secsh- - architecture-13 (work in progress), September 2002. - - [6] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Protocol Transport Protocol", draft-ietf-secsh- - transport-15 (work in progress), September 2002. - - [7] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-16 - (work in progress), September 2002. - - [8] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Authentication Protocol", draft-ietf-secsh- - userauth-16 (work in progress), September 2002. - - -Authors' Addresses - - Joseph Galbraith - VanDyke Software - 4848 Tramway Ridge Blvd - Suite 101 - Albuquerque, NM 87111 - US - - Phone: +1 505 332 5700 - EMail: [email protected] - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 33] - -Internet-Draft SSH File Transfer Protocol October 2002 - - - Tatu Ylonen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - Sami Lehtinen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 34] - -Internet-Draft SSH File Transfer Protocol October 2002 - - -Full Copyright Statement - - Copyright (C) The Internet Society (2002). All Rights Reserved. - - This document and translations of it may be copied and furnished to - others, and derivative works that comment on or otherwise explain it - or assist in its implementation may be prepared, copied, published - and distributed, in whole or in part, without restriction of any - kind, provided that the above copyright notice and this paragraph are - included on all such copies and derivative works. However, this - document itself may not be modified in any way, such as by removing - the copyright notice or references to the Internet Society or other - Internet organizations, except as needed for the purpose of - developing Internet standards in which case the procedures for - copyrights defined in the Internet Standards process must be - followed, or as required to translate it into languages other than - English. - - The limited permissions granted above are perpetual and will not be - revoked by the Internet Society or its successors or assigns. - - This document and the information contained herein is provided on an - "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING - TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING - BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION - HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF - MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - -Acknowledgement - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires April 16, 2003 [Page 35] - - diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-04.txt b/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-04.txt deleted file mode 100644 index 9f51883cd2..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-04.txt +++ /dev/null @@ -1,2130 +0,0 @@ - - - -Secure Shell Working Group J. Galbraith -Internet-Draft VanDyke Software -Expires: June 18, 2003 T. Ylonen - S. Lehtinen - SSH Communications Security Corp - December 18, 2002 - - - SSH File Transfer Protocol - draft-ietf-secsh-filexfer-04.txt - -Status of this Memo - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that - other groups may also distribute working documents as - Internet-Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at http:// - www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on June 18, 2003. - -Copyright Notice - - Copyright (C) The Internet Society (2002). All Rights Reserved. - -Abstract - - The SSH File Transfer Protocol provides secure file transfer - functionality over any reliable data stream. It is the standard file - transfer protocol for use with the SSH2 protocol. This document - describes the file transfer protocol and its interface to the SSH2 - protocol suite. - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 1] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -Table of Contents - - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Use with the SSH Connection Protocol . . . . . . . . . . . 4 - 3. General Packet Format . . . . . . . . . . . . . . . . . . 5 - 3.1 The use of stderr in the server . . . . . . . . . . . . . 6 - 4. Protocol Initialization . . . . . . . . . . . . . . . . . 8 - 4.1 Client Initialization . . . . . . . . . . . . . . . . . . 8 - 4.2 Server Initialization . . . . . . . . . . . . . . . . . . 8 - 4.3 Determining Server Newline Convention . . . . . . . . . . 9 - 5. File Attributes . . . . . . . . . . . . . . . . . . . . . 10 - 5.1 Flags . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 5.2 Type . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 5.3 Size . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 5.4 Owner and Group . . . . . . . . . . . . . . . . . . . . . 11 - 5.5 Permissions . . . . . . . . . . . . . . . . . . . . . . . 12 - 5.6 Times . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 5.7 ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 5.8 Extended attributes . . . . . . . . . . . . . . . . . . . 14 - 6. Requests From the Client to the Server . . . . . . . . . . 15 - 6.1 Request Synchronization and Reordering . . . . . . . . . . 15 - 6.2 File Names . . . . . . . . . . . . . . . . . . . . . . . . 16 - 6.3 Opening, Creating, and Closing Files . . . . . . . . . . . 16 - 6.4 Reading and Writing . . . . . . . . . . . . . . . . . . . 19 - 6.5 Removing and Renaming Files . . . . . . . . . . . . . . . 20 - 6.6 Creating and Deleting Directories . . . . . . . . . . . . 21 - 6.7 Scanning Directories . . . . . . . . . . . . . . . . . . . 21 - 6.8 Retrieving File Attributes . . . . . . . . . . . . . . . . 22 - 6.9 Setting File Attributes . . . . . . . . . . . . . . . . . 23 - 6.10 Dealing with Symbolic links . . . . . . . . . . . . . . . 24 - 6.11 Canonicalizing the Server-Side Path Name . . . . . . . . . 25 - 6.11.1 Best practice for dealing with paths . . . . . . . . . . . 25 - 7. Responses from the Server to the Client . . . . . . . . . 26 - 8. Vendor-Specific Extensions . . . . . . . . . . . . . . . . 30 - 9. Security Considerations . . . . . . . . . . . . . . . . . 31 - 10. Changes from previous protocol versions . . . . . . . . . 32 - 10.1 Changes between versions 4 and 3 . . . . . . . . . . . . . 32 - 10.2 Changes between versions 3 and 2 . . . . . . . . . . . . . 33 - 10.3 Changes between versions 2 and 1 . . . . . . . . . . . . . 33 - 10.4 Changes between versions 1 and 0 . . . . . . . . . . . . . 33 - 11. Trademark Issues . . . . . . . . . . . . . . . . . . . . . 34 - References . . . . . . . . . . . . . . . . . . . . . . . . 35 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . 35 - Intellectual Property and Copyright Statements . . . . . . 37 - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 2] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -1. Introduction - - This protocol provides secure file transfer (and more generally file - system access) functionality over a reliable data stream, such as a - channel in the SSH2 protocol [5]. - - This protocol is designed so that it could be used to implement a - secure remote file system service, as well as a secure file transfer - service. - - This protocol assumes that it runs over a secure channel, and that - the server has already authenticated the user at the client end, and - that the identity of the client user is externally available to the - server implementation. - - In general, this protocol follows a simple request-response model. - Each request and response contains a sequence number and multiple - requests may be pending simultaneously. There are a relatively large - number of different request messages, but a small number of possible - response messages. Each request has one or more response messages - that may be returned in result (e.g., a read either returns data or - reports error status). - - The packet format descriptions in this specification follow the - notation presented in the secsh architecture draft. [5] - - Even though this protocol is described in the context of the SSH2 - protocol, this protocol is general and independent of the rest of the - SSH2 protocol suite. It could be used in a number of different - applications, such as secure file transfer over TLS RFC 2246 [1] and - transfer of management information in VPN applications. - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 3] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -2. Use with the SSH Connection Protocol - - When used with the SSH2 Protocol suite, this protocol is intended to - be used from the SSH Connection Protocol [7] as a subsystem, as - described in section ``Starting a Shell or a Command''. The - subsystem name used with this protocol is "sftp". - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 4] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -3. General Packet Format - - All packets transmitted over the secure connection are of the - following format: - - uint32 length - byte type - byte[length - 1] data payload - - That is, they are just data preceded by 32-bit length and 8-bit type - fields. The `length' is the length of the data area, and does not - include the `length' field itself. The format and interpretation of - the data area depends on the packet type. - - All packet descriptions below only specify the packet type and the - data that goes into the data field. Thus, they should be prefixed by - the `length' and `type' fields. - - The maximum size of a packet is in practice determined by the client - (the maximum size of read or write requests that it sends, plus a few - bytes of packet overhead). All servers SHOULD support packets of at - least 34000 bytes (where the packet size refers to the full length, - including the header above). This should allow for reads and writes - of at most 32768 bytes. - - There is no limit on the number of outstanding (non-acknowledged) - requests that the client may send to the server. In practice this is - limited by the buffering available on the data stream and the queuing - performed by the server. If the server's queues are full, it should - not read any more data from the stream, and flow control will prevent - the client from sending more requests. Note, however, that while - there is no restriction on the protocol level, the client's API may - provide a limit in order to prevent infinite queuing of outgoing - requests at the client. - - The following values are defined for packet types. - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 5] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - #define SSH_FXP_INIT 1 - #define SSH_FXP_VERSION 2 - #define SSH_FXP_OPEN 3 - #define SSH_FXP_CLOSE 4 - #define SSH_FXP_READ 5 - #define SSH_FXP_WRITE 6 - #define SSH_FXP_LSTAT 7 - #define SSH_FXP_FSTAT 8 - #define SSH_FXP_SETSTAT 9 - #define SSH_FXP_FSETSTAT 10 - #define SSH_FXP_OPENDIR 11 - #define SSH_FXP_READDIR 12 - #define SSH_FXP_REMOVE 13 - #define SSH_FXP_MKDIR 14 - #define SSH_FXP_RMDIR 15 - #define SSH_FXP_REALPATH 16 - #define SSH_FXP_STAT 17 - #define SSH_FXP_RENAME 18 - #define SSH_FXP_READLINK 19 - #define SSH_FXP_SYMLINK 20 - - #define SSH_FXP_STATUS 101 - #define SSH_FXP_HANDLE 102 - #define SSH_FXP_DATA 103 - #define SSH_FXP_NAME 104 - #define SSH_FXP_ATTRS 105 - - #define SSH_FXP_EXTENDED 200 - #define SSH_FXP_EXTENDED_REPLY 201 - - RESERVED_FOR_EXTENSIONS 210-255 - - Additional packet types should only be defined if the protocol - version number (see Section ``Protocol Initialization'') is - incremented, and their use MUST be negotiated using the version - number. However, the SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY - packets can be used to implement vendor-specific extensions. See - Section ``Vendor-Specific-Extensions'' for more details. - -3.1 The use of stderr in the server - - Packets are sent and received on stdout and stdin. Data sent on - stderr by the server SHOULD be considered debug or supplemental error - information, and MAY be displayed to the user. - - For example, during initialization, there is no client request - active, so errors or warning information cannot be sent to the client - as part of the SFTP protocol at this early stage. However, the - - - -Galbraith, et al. Expires June 18, 2003 [Page 6] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - errors or warnings MAY be sent as stderr text. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 7] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -4. Protocol Initialization - - When the file transfer protocol starts, the client first sends a - SSH_FXP_INIT (including its version number) packet to the server. - The server responds with a SSH_FXP_VERSION packet, supplying the - lowest of its own and the client's version number. Both parties - should from then on adhere to particular version of the protocol. - - The version number of the protocol specified in this document is 4. - The version number should be incremented for each incompatible - revision of this protocol. - -4.1 Client Initialization - - The SSH_FXP_INIT packet (from client to server) has the following - data: - - uint32 version - - Version 3 of this protocol allowed clients to include extensions in - the SSH_FXP_INIT packet; however, this can cause interoperability - problems with version 1 and version 2 servers because the client must - send this packet before knowing the servers version. - - In this version of the protocol, clients MUST use the - SSH_FXP_EXTENDED packet to send extensions to the server after - version exchange has completed. Clients MUST NOT include extensions - in the version packet. This will prevent interoperability problems - with older servers - -4.2 Server Initialization - - The SSH_FXP_VERSION packet (from server to client) has the following - data: - - uint32 version - <extension data> - - 'version' is the lower of the protocol version supported by the - server and the version number received from the client. - - The extension data may be empty, or may be a sequence of - - string extension_name - string extension_data - - pairs (both strings MUST always be present if one is, but the - `extension_data' string may be of zero length). If present, these - - - -Galbraith, et al. Expires June 18, 2003 [Page 8] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - strings indicate extensions to the baseline protocol. The - `extension_name' field(s) identify the name of the extension. The - name should be of the form "name@domain", where the domain is the DNS - domain name of the organization defining the extension. Additional - names that are not of this format may be defined later by the IETF. - Implementations MUST silently ignore any extensions whose name they - do not recognize. - -4.3 Determining Server Newline Convention - - In order to correctly process text files in a cross platform - compatible way, the newline convention must be converted from that of - the server to that of the client, or, during an upload, from that of - the client to that of the server. - - Versions 3 and prior of this protocol made no provisions for - processing text files. Many clients implemented some sort of - conversion algorithm, but without either a 'canonical' on the wire - format or knowledge of the servers newline convention, correct - conversion was not always possible. - - Starting with Version 4, the SSH_FXF_TEXT file open flag (Section - 6.3) makes it possible to request that the server translate a file to - a 'canonical' on the wire format. This format uses \r\n as the line - separator. - - Servers for systems using multiple newline characters (for example, - Mac OS X or VMS) or systems using counted records, MUST translate to - the canonical form. - - However, to ease the burden of implementation on servers that use a - single, simple separator sequence, the following extension allows the - canonical format to be changed. - - string "newline" - string new-canonical-separator (usually "\r" or "\n" or "\r\n") - - All clients MUST support this extension. - - When processing text files, clients SHOULD NOT translate any - character or sequence that is not an exact match of the servers - newline separator. - - In particular, if the newline sequence being used is the canonical - "\r\n" sequence, a lone \r or a lone \n SHOULD be written through - without change. - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 9] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -5. File Attributes - - A new compound data type is defined for encoding file attributes. - The same encoding is used both when returning file attributes from - the server and when sending file attributes to the server. When - sending it to the server, the flags field specifies which attributes - are included, and the server will use default values for the - remaining attributes (or will not modify the values of remaining - attributes). When receiving attributes from the server, the flags - specify which attributes are included in the returned data. The - server normally returns all attributes it knows about. - - uint32 flags - byte type always present - uint64 size present only if flag SIZE - string owner present only if flag OWNERGROUP - string group present only if flag OWNERGROUP - uint32 permissions present only if flag PERMISSIONS - uint64 atime present only if flag ACCESSTIME - uint32 atime_nseconds present only if flag SUBSECOND_TIMES - uint64 createtime present only if flag CREATETIME - uint32 createtime_nseconds present only if flag SUBSECOND_TIMES - uint64 mtime present only if flag MODIFYTIME - uint32 mtime_nseconds present only if flag SUBSECOND_TIMES - string acl present only if flag ACL - uint32 extended_count present only if flag EXTENDED - string extended_type - string extended_data - ... more extended data (extended_type - extended_data pairs), - so that number of pairs equals extended_count - - -5.1 Flags - - The `flags' specify which of the fields are present. Those fields - for which the corresponding flag is not set are not present (not - included in the packet). New flags can only be added by incrementing - the protocol version number (or by using the extension mechanism - described below). - - The flags bits are defined to have the following values: - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 10] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - #define SSH_FILEXFER_ATTR_SIZE 0x00000001 - #define SSH_FILEXFER_ATTR_PERMISSIONS 0x00000040 - #define SSH_FILEXFER_ATTR_ACCESSTIME 0x00000008 - #define SSH_FILEXFER_ATTR_CREATETIME 0x00000010 - #define SSH_FILEXFER_ATTR_MODIFYTIME 0x00000020 - #define SSH_FILEXFER_ATTR_ACL 0x00000040 - #define SSH_FILEXFER_ATTR_OWNERGROUP 0x00000080 - #define SSH_FILEXFER_ATTR_SUBSECOND_TIMES 0x00000100 - #define SSH_FILEXFER_ATTR_EXTENDED 0x80000000 - - In previous versions of this protocol flags value 0x00000002 was - SSH_FILEXFER_ATTR_UIDGID. This value is now unused, and OWNERGROUP - was given a new value in order to ease implementation burden. - 0x00000002 MUST NOT appear in the mask. Some future version of this - protocol may reuse flag 0x00000002. - -5.2 Type - - The type field is always present. The following types are defined: - - #define SSH_FILEXFER_TYPE_REGULAR 1 - #define SSH_FILEXFER_TYPE_DIRECTORY 2 - #define SSH_FILEXFER_TYPE_SYMLINK 3 - #define SSH_FILEXFER_TYPE_SPECIAL 4 - #define SSH_FILEXFER_TYPE_UNKNOWN 5 - - On a POSIX system, these values would be derived from the permission - field. - -5.3 Size - - The `size' field specifies the size of the file on disk, in bytes. - If it is present during file creation, it should be considered a hint - as to the files eventual size. - - Files opened with the SSH_FXF_TEXT flag may have a size that is - greater or less than the value of the size field. - -5.4 Owner and Group - - The `owner' and `group' fields are represented as UTF-8 strings; this - is the form used by NFS v4. See NFS version 4 Protocol. [3] The - following text is selected quotations from section 5.6. - - To avoid a representation that is tied to a particular underlying - implementation at the client or server, the use of UTF-8 strings has - been chosen. The string should be of the form user@dns_domain". - This will allow for a client and server that do not use the same - - - -Galbraith, et al. Expires June 18, 2003 [Page 11] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - local representation the ability to translate to a common syntax that - can be interpreted by both. In the case where there is no - translation available to the client or server, the attribute value - must be constructed without the "@". Therefore, the absence of the @ - from the owner or owner_group attribute signifies that no translation - was available and the receiver of the attribute should not place any - special meaning with the attribute value. Even though the attribute - value can not be translated, it may still be useful. In the case of - a client, the attribute string may be used for local display of - ownership. - -5.5 Permissions - - The `permissions' field contains a bit mask of file permissions as - defined by POSIX [1]. - -5.6 Times - - The 'atime', 'createtime', and 'mtime' contain the access, creation, - and modification times of the files, respectively. They are - represented as seconds from Jan 1, 1970 in UTC. - - A negative value indicates number of seconds before Jan 1, 1970. In - both cases, if the SSH_FILEXFER_ATTR_SUBSECOND_TIMES flag is set, the - nseconds field is to be added to the seconds field for the final time - representation. For example, if the time to be represented is - one-half second before 0 hour January 1, 1970, the seconds field - would have a value of negative one (-1) and the nseconds fields would - have a value of one-half second (500000000). Values greater than - 999,999,999 for nseconds are considered invalid. - -5.7 ACL - - The 'ACL' field contains an ACL similar to that defined in section - 5.9 of NFS version 4 Protocol [3]. - - uint32 ace-count - - repeated ace-count time: - uint32 ace-type - uint32 ace-flag - uint32 ace-mask - string who [UTF-8] - - ace-type is one of the following four values (taken from NFS Version - 4 Protocol [3]: - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 12] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - const ACE4_ACCESS_ALLOWED_ACE_TYPE = 0x00000000; - const ACE4_ACCESS_DENIED_ACE_TYPE = 0x00000001; - const ACE4_SYSTEM_AUDIT_ACE_TYPE = 0x00000002; - const ACE4_SYSTEM_ALARM_ACE_TYPE = 0x00000003; - - ace-flag is a combination of the following flag values. See NFS - Version 4 Protocol [3] section 5.9.2: - - const ACE4_FILE_INHERIT_ACE = 0x00000001; - const ACE4_DIRECTORY_INHERIT_ACE = 0x00000002; - const ACE4_NO_PROPAGATE_INHERIT_ACE = 0x00000004; - const ACE4_INHERIT_ONLY_ACE = 0x00000008; - const ACE4_SUCCESSFUL_ACCESS_ACE_FLAG = 0x00000010; - const ACE4_FAILED_ACCESS_ACE_FLAG = 0x00000020; - const ACE4_IDENTIFIER_GROUP = 0x00000040; - - ace-mask is any combination of the following flags (taken from NFS - Version 4 Protocol [3] section 5.9.3: - - const ACE4_READ_DATA = 0x00000001; - const ACE4_LIST_DIRECTORY = 0x00000001; - const ACE4_WRITE_DATA = 0x00000002; - const ACE4_ADD_FILE = 0x00000002; - const ACE4_APPEND_DATA = 0x00000004; - const ACE4_ADD_SUBDIRECTORY = 0x00000004; - const ACE4_READ_NAMED_ATTRS = 0x00000008; - const ACE4_WRITE_NAMED_ATTRS = 0x00000010; - const ACE4_EXECUTE = 0x00000020; - const ACE4_DELETE_CHILD = 0x00000040; - const ACE4_READ_ATTRIBUTES = 0x00000080; - const ACE4_WRITE_ATTRIBUTES = 0x00000100; - const ACE4_DELETE = 0x00010000; - const ACE4_READ_ACL = 0x00020000; - const ACE4_WRITE_ACL = 0x00040000; - const ACE4_WRITE_OWNER = 0x00080000; - const ACE4_SYNCHRONIZE = 0x00100000; - - who is a UTF-8 string of the form described in 'Owner and Group' - (Section 5.4) - - Also, as per '5.9.4 ACE who' [3] there are several identifiers that - need to be understood universally. Some of these identifiers cannot - be understood when an client access the server, but have meaning when - a local process accesses the file. The ability to display and modify - these permissions is permitted over SFTP. - - OWNER The owner of the file. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 13] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - GROUP The group associated with the file. - - EVERYONE The world. - - INTERACTIVE Accessed from an interactive terminal. - - NETWORK Accessed via the network. - - DIALUP Accessed as a dialup user to the server. - - BATCH Accessed from a batch job. - - ANONYMOUS Accessed without any authentication. - - AUTHENTICATED Any authenticated user (opposite of ANONYMOUS). - - SERVICE Access from a system service. - - To avoid conflict, these special identifiers are distinguish by an - appended "@" and should appear in the form "xxxx@" (note: no domain - name after the "@"). For example: ANONYMOUS@. - -5.8 Extended attributes - - The SSH_FILEXFER_ATTR_EXTENDED flag provides a general extension - mechanism for vendor-specific extensions. If the flag is specified, - then the `extended_count' field is present. It specifies the number - of extended_type-extended_data pairs that follow. Each of these - pairs specifies an extended attribute. For each of the attributes, - the extended_type field should be a string of the format - "name@domain", where "domain" is a valid, registered domain name and - "name" identifies the method. The IETF may later standardize certain - names that deviate from this format (e.g., that do not contain the - "@" sign). The interpretation of `extended_data' depends on the - type. Implementations SHOULD ignore extended data fields that they - do not understand. - - Additional fields can be added to the attributes by either defining - additional bits to the flags field to indicate their presence, or by - defining extended attributes for them. The extended attributes - mechanism is recommended for most purposes; additional flags bits - should only be defined by an IETF standards action that also - increments the protocol version number. The use of such new fields - MUST be negotiated by the version number in the protocol exchange. - It is a protocol error if a packet with unsupported protocol bits is - received. - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 14] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -6. Requests From the Client to the Server - - Requests from the client to the server represent the various file - system operations. Each request begins with an `id' field, which is - a 32-bit identifier identifying the request (selected by the client). - The same identifier will be returned in the response to the request. - One possible implementation is a monotonically increasing request - sequence number (modulo 2^32). - - Many operations in the protocol operate on open files. The - SSH_FXP_OPEN request can return a file handle (which is an opaque - variable-length string) which may be used to access the file later - (e.g. in a read operation). The client MUST NOT send requests the - server with bogus or closed handles. However, the server MUST - perform adequate checks on the handle in order to avoid security - risks due to fabricated handles. - - This design allows either stateful and stateless server - implementation, as well as an implementation which caches state - between requests but may also flush it. The contents of the file - handle string are entirely up to the server and its design. The - client should not modify or attempt to interpret the file handle - strings. - - The file handle strings MUST NOT be longer than 256 bytes. - -6.1 Request Synchronization and Reordering - - The protocol and implementations MUST process requests relating to - the same file in the order in which they are received. In other - words, if an application submits multiple requests to the server, the - results in the responses will be the same as if it had sent the - requests one at a time and waited for the response in each case. For - example, the server may process non-overlapping read/write requests - to the same file in parallel, but overlapping reads and writes cannot - be reordered or parallelized. However, there are no ordering - restrictions on the server for processing requests from two different - file transfer connections. The server may interleave and parallelize - them at will. - - There are no restrictions on the order in which responses to - outstanding requests are delivered to the client, except that the - server must ensure fairness in the sense that processing of no - request will be indefinitely delayed even if the client is sending - other requests so that there are multiple outstanding requests all - the time. - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 15] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -6.2 File Names - - This protocol represents file names as strings. File names are - assumed to use the slash ('/') character as a directory separator. - - File names starting with a slash are "absolute", and are relative to - the root of the file system. Names starting with any other character - are relative to the user's default directory (home directory). Note - that identifying the user is assumed to take place outside of this - protocol. - - Servers SHOULD interpret a path name component ".." as referring to - the parent directory, and "." as referring to the current directory. - If the server implementation limits access to certain parts of the - file system, it must be extra careful in parsing file names when - enforcing such restrictions. There have been numerous reported - security bugs where a ".." in a path name has allowed access outside - the intended area. - - An empty path name is valid, and it refers to the user's default - directory (usually the user's home directory). - - Otherwise, no syntax is defined for file names by this specification. - Clients should not make any other assumptions; however, they can - splice path name components returned by SSH_FXP_READDIR together - using a slash ('/') as the separator, and that will work as expected. - - In order to comply with IETF Policy on Character Sets and Languages - [2], all filenames are to be encoded in UTF-8. The shortest valid - UTF-8 encoding of the UNICODE data MUST be used. The server is - responsible for converting the UNICODE data to whatever canonical - form it requires. - - For example, if the server requires that precomposed characters - always be used, the server MUST NOT assume the filename as sent by - the client has this attribute, but must do this normalization itself. - - It is understood that the lack of well-defined semantics for file - names may cause interoperability problems between clients and servers - using radically different operating systems. However, this approach - is known to work acceptably with most systems, and alternative - approaches that e.g. treat file names as sequences of structured - components are quite complicated. - -6.3 Opening, Creating, and Closing Files - - Files are opened and created using the SSH_FXP_OPEN message, whose - data part is as follows: - - - -Galbraith, et al. Expires June 18, 2003 [Page 16] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - uint32 id - string filename [UTF-8] - uint32 pflags - ATTRS attrs - - The `id' field is the request identifier as for all requests. - - The `filename' field specifies the file name. See Section ``File - Names'' for more information. - - The `pflags' field is a bitmask. The following bits have been - defined. - - #define SSH_FXF_READ 0x00000001 - #define SSH_FXF_WRITE 0x00000002 - #define SSH_FXF_APPEND 0x00000004 - #define SSH_FXF_CREAT 0x00000008 - #define SSH_FXF_TRUNC 0x00000010 - #define SSH_FXF_EXCL 0x00000020 - #define SSH_FXF_TEXT 0x00000040 - - These have the following meanings: - - SSH_FXF_READ - Open the file for reading. - - SSH_FXF_WRITE - Open the file for writing. If both this and SSH_FXF_READ are - specified, the file is opened for both reading and writing. - - SSH_FXF_APPEND - Force all writes to append data at the end of the file. The - offset parameter to write will be ignored. - - SSH_FXF_CREAT - If this flag is specified, then a new file will be created if one - does not already exist (if O_TRUNC is specified, the new file will - be truncated to zero length if it previously exists). - - SSH_FXF_TRUNC - Forces an existing file with the same name to be truncated to zero - length when creating a file by specifying SSH_FXF_CREAT. - SSH_FXF_CREAT MUST also be specified if this flag is used. - - SSH_FXF_EXCL - Causes the request to fail if the named file already exists. - SSH_FXF_CREAT MUST also be specified if this flag is used. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 17] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - SSH_FXF_TEXT - Indicates that the server should treat the file as text and - convert it to the canonical newline convention in use. (See - Determining Server Newline Convention. (Section 4.3) - - When a file is opened with the FXF_TEXT flag, the offset field in - both the read and write function are ignored. - - Servers MUST correctly process multiple parallel reads and writes - correctly in this mode. Naturally, it is permissible for them to - do this by serializing the requests. It would not be possible for - a client to reliably detect a server that does not implement - parallel writes in time to prevent damage. - - Clients SHOULD use the SSH_FXF_APPEND flag to append data to a - text file rather then using write with a calculated offset. - - To support seeks on text file the following SSH_FXP_EXTENDED - packet is defined. - - - - string "text-seek" - string file-handle - uint64 line-number - - line-number is the index of the line number to seek to, where byte - 0 in the file is line number 0, and the byte directly following - the first newline sequence in the file is line number 1 and so on. - - The response to a "text-seek" request is an SSH_FXP_STATUS - message. - - An attempt to seek past the end-of-file should result in a - SSH_FX_EOF status. - - Servers SHOULD support at least one "text-seek" in order to - support resume. However, a client MUST be prepared to receive - SSH_FX_OP_UNSUPPORTED when attempting a "text-seek" operation. - The client can then try a fall-back strategy, if it has one. - - Clients MUST be prepared to handle SSH_FX_OP_UNSUPPORTED returned - for read or write operations that are not sequential. - - The `attrs' field specifies the initial attributes for the file. - Default values will be used for those attributes that are not - specified. See Section ``File Attributes'' for more information. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 18] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - The response to this message will be either SSH_FXP_HANDLE (if the - operation is successful) or SSH_FXP_STATUS (if the operation fails). - - A file is closed by using the SSH_FXP_CLOSE request. Its data field - has the following format: - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is a handle - previously returned in the response to SSH_FXP_OPEN or - SSH_FXP_OPENDIR. The handle becomes invalid immediately after this - request has been sent. - - The response to this request will be a SSH_FXP_STATUS message. One - should note that on some server platforms even a close can fail. - This can happen e.g. if the server operating system caches writes, - and an error occurs while flushing cached writes during the close. - -6.4 Reading and Writing - - Once a file has been opened, it can be read using the following - message: - - byte SSH_FXP_READ - uint32 id - string handle - uint64 offset - uint32 len - - where `id' is the request identifier, `handle' is an open file handle - returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) relative - to the beginning of the file from where to start reading, and `len' - is the maximum number of bytes to read. - - In response to this request, the server will read as many bytes as it - can from the file (up to `len'), and return them in a SSH_FXP_DATA - message. If an error occurs or EOF is encountered before reading any - data, the server will respond with SSH_FXP_STATUS. - - For normal disk files, it is normally guaranteed that this will read - the specified number of bytes, or up to end of file. However, if the - read length is very long, the server may truncate it if it doesn't - support packets of that length. See General Packet Format (Section - 3). - - For e.g. device files this may return fewer bytes than requested. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 19] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - Writing to a file is achieved using the following message: - - byte SSH_FXP_WRITE - uint32 id - string handle - uint64 offset - string data - - where `id' is a request identifier, `handle' is a file handle - returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) from the - beginning of the file where to start writing, and `data' is the data - to be written. - - The write will extend the file if writing beyond the end of the file. - It is legal to write way beyond the end of the file; the semantics - are to write zeroes from the end of the file to the specified offset - and then the data. On most operating systems, such writes do not - allocate disk space but instead leave "holes" in the file. - - The server responds to a write request with a SSH_FXP_STATUS message. - -6.5 Removing and Renaming Files - - Files can be removed using the SSH_FXP_REMOVE message. It has the - following format: - - uint32 id - string filename [UTF-8] - - where `id' is the request identifier and `filename' is the name of - the file to be removed. See Section ``File Names'' for more - information. This request cannot be used to remove directories. - - The server will respond to this request with a SSH_FXP_STATUS - message. - - Files (and directories) can be renamed using the SSH_FXP_RENAME - message. Its data is as follows: - - uint32 id - string oldpath [UTF-8] - string newpath [UTF-8] - - where `id' is the request identifier, `oldpath' is the name of an - existing file or directory, and `newpath' is the new name for the - file or directory. It is an error if there already exists a file - with the name specified by newpath. The server may also fail rename - requests in other situations, for example if `oldpath' and `newpath' - - - -Galbraith, et al. Expires June 18, 2003 [Page 20] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - point to different file systems on the server. - - The server will respond to this request with a SSH_FXP_STATUS - message. - -6.6 Creating and Deleting Directories - - New directories can be created using the SSH_FXP_MKDIR request. It - has the following format: - - uint32 id - string path [UTF-8] - ATTRS attrs - - where `id' is the request identifier. - - `path' specifies the directory to be created. See Section ``File - Names'' for more information on file names. - - `attrs' specifies the attributes that should be applied to it upon - creation. Attributes are discussed in more detail in Section ``File - Attributes''. - - The server will respond to this request with a SSH_FXP_STATUS - message. If a file or directory with the specified path already - exists, an error will be returned. - - Directories can be removed using the SSH_FXP_RMDIR request, which has - the following format: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier, and `path' specifies the - directory to be removed. See Section ``File Names'' for more - information on file names. - - The server responds to this request with a SSH_FXP_STATUS message. - Errors may be returned from this operation for various reasons, - including, but not limited to, the path does not exist, the path does - not refer to a directory object, the directory is not empty, or the - user has insufficient access or permission to perform the requested - operation. - -6.7 Scanning Directories - - The files in a directory can be listed using the SSH_FXP_OPENDIR and - SSH_FXP_READDIR requests. Each SSH_FXP_READDIR request returns one - - - -Galbraith, et al. Expires June 18, 2003 [Page 21] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - or more file names with full file attributes for each file. The - client should call SSH_FXP_READDIR repeatedly until it has found the - file it is looking for or until the server responds with a - SSH_FXP_STATUS message indicating an error (normally SSH_FX_EOF if - there are no more files in the directory). The client should then - close the handle using the SSH_FXP_CLOSE request. - - The SSH_FXP_OPENDIR opens a directory for reading. It has the - following format: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' is the path name of - the directory to be listed (without any trailing slash). See Section - ``File Names'' for more information on file names. This will return - an error if the path does not specify a directory or if the directory - is not readable. The server will respond to this request with either - a SSH_FXP_HANDLE or a SSH_FXP_STATUS message. - - Once the directory has been successfully opened, files (and - directories) contained in it can be listed using SSH_FXP_READDIR - requests. These are of the format - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is a handle - returned by SSH_FXP_OPENDIR. (It is a protocol error to attempt to - use an ordinary file handle returned by SSH_FXP_OPEN.) - - The server responds to this request with either a SSH_FXP_NAME or a - SSH_FXP_STATUS message. One or more names may be returned at a time. - Full status information is returned for each name in order to speed - up typical directory listings. - - If there are no more names available to be read, the server MUST - respond with a SSH_FXP_STATUS message with error code of SSH_FX_EOF. - - When the client no longer wishes to read more names from the - directory, it SHOULD call SSH_FXP_CLOSE for the handle. The handle - should be closed regardless of whether an error has occurred or not. - -6.8 Retrieving File Attributes - - Very often, file attributes are automatically returned by - SSH_FXP_READDIR. However, sometimes there is need to specifically - retrieve the attributes for a named file. This can be done using the - - - -Galbraith, et al. Expires June 18, 2003 [Page 22] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - SSH_FXP_STAT, SSH_FXP_LSTAT and SSH_FXP_FSTAT requests. - - SSH_FXP_STAT and SSH_FXP_LSTAT only differ in that SSH_FXP_STAT - follows symbolic links on the server, whereas SSH_FXP_LSTAT does not - follow symbolic links. Both have the same format: - - uint32 id - string path [UTF-8] - uint32 flags - - where `id' is the request identifier, and `path' specifies the file - system object for which status is to be returned. The server - responds to this request with either SSH_FXP_ATTRS or SSH_FXP_STATUS. - - The flags field specify the attribute flags in which the client has - particular interest. This is a hint to the server. For example, - because retrieving owner / group and acl information can be an - expensive operation under some operating systems, the server may - choose not to retrieve this information unless the client expresses a - specific interest in it. - - The client has no guarantee the server will provide all the fields - that it has expressed an interest in. - - SSH_FXP_FSTAT differs from the others in that it returns status - information for an open file (identified by the file handle). Its - format is as follows: - - uint32 id - string handle - uint32 flags - - where `id' is the request identifier and `handle' is a file handle - returned by SSH_FXP_OPEN. The server responds to this request with - SSH_FXP_ATTRS or SSH_FXP_STATUS. - -6.9 Setting File Attributes - - File attributes may be modified using the SSH_FXP_SETSTAT and - SSH_FXP_FSETSTAT requests. These requests are used for operations - such as changing the ownership, permissions or access times, as well - as for truncating a file. - - The SSH_FXP_SETSTAT request is of the following format: - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 23] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - uint32 id - string path [UTF-8] - ATTRS attrs - - where `id' is the request identifier, `path' specifies the file - system object (e.g. file or directory) whose attributes are to be - modified, and `attrs' specifies the modifications to be made to its - attributes. Attributes are discussed in more detail in Section - ``File Attributes''. - - An error will be returned if the specified file system object does - not exist or the user does not have sufficient rights to modify the - specified attributes. The server responds to this request with a - SSH_FXP_STATUS message. - - The SSH_FXP_FSETSTAT request modifies the attributes of a file which - is already open. It has the following format: - - uint32 id - string handle - ATTRS attrs - - where `id' is the request identifier, `handle' (MUST be returned by - SSH_FXP_OPEN) identifies the file whose attributes are to be - modified, and `attrs' specifies the modifications to be made to its - attributes. Attributes are discussed in more detail in Section - ``File Attributes''. The server will respond to this request with - SSH_FXP_STATUS. - -6.10 Dealing with Symbolic links - - The SSH_FXP_READLINK request may be used to read the target of a - symbolic link. It would have a data part as follows: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' specifies the path - name of the symlink to be read. - - The server will respond with a SSH_FXP_NAME packet containing only - one name and a dummy attributes value. The name in the returned - packet contains the target of the link. If an error occurs, the - server may respond with SSH_FXP_STATUS. - - The SSH_FXP_SYMLINK request will create a symbolic link on the - server. It is of the following format - - - - -Galbraith, et al. Expires June 18, 2003 [Page 24] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - uint32 id - string linkpath [UTF-8] - string targetpath [UTF-8] - - where `id' is the request identifier, `linkpath' specifies the path - name of the symlink to be created and `targetpath' specifies the - target of the symlink. The server shall respond with a - SSH_FXP_STATUS indicating either success (SSH_FX_OK) or an error - condition. - -6.11 Canonicalizing the Server-Side Path Name - - The SSH_FXP_REALPATH request can be used to have the server - canonicalize any given path name to an absolute path. This is useful - for converting path names containing ".." components or relative - pathnames without a leading slash into absolute paths. The format of - the request is as follows: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' specifies the path - name to be canonicalized. The server will respond with a - SSH_FXP_NAME packet containing the name in canonical form and a dummy - attributes value. If an error occurs, the server may also respond - with SSH_FXP_STATUS. - -6.11.1 Best practice for dealing with paths - - The client SHOULD treat the results of SSH_FXP_REALPATH as a - canonical absolute path, even if the path does not appear to be - absolute. A client that use REALPATH(".") and treats the result as - absolute, even if there is no leading slash, will continue to - function correctly, even when talking to a Windows NT or VMS style - system, where absolute paths may not begin with a slash. - - For example, if the client wishes to change directory up, and the - server has returned "c:/x/y/z" from REALPATH, the client SHOULD use - "c:/x/y/z/..". - - As a second example, if the client wishes to open the file "x.txt" in - the current directory, and server has returned "dka100:/x/y/z" as the - canonical path of the directory, the client SHOULD open "dka100:/x/y/ - z/x.txt" - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 25] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -7. Responses from the Server to the Client - - The server responds to the client using one of a few response - packets. All requests can return a SSH_FXP_STATUS response upon - failure. When the operation is successful, any of the responses may - be returned (depending on the operation). If no data needs to be - returned to the client, the SSH_FXP_STATUS response with SSH_FX_OK - status is appropriate. Otherwise, the SSH_FXP_HANDLE message is used - to return a file handle (for SSH_FXP_OPEN and SSH_FXP_OPENDIR - requests), SSH_FXP_DATA is used to return data from SSH_FXP_READ, - SSH_FXP_NAME is used to return one or more file names from a - SSH_FXP_READDIR or SSH_FXP_REALPATH request, and SSH_FXP_ATTRS is - used to return file attributes from SSH_FXP_STAT, SSH_FXP_LSTAT, and - SSH_FXP_FSTAT requests. - - Exactly one response will be returned for each request. Each - response packet contains a request identifier which can be used to - match each response with the corresponding request. Note that it is - legal to have several requests outstanding simultaneously, and the - server is allowed to send responses to them in a different order from - the order in which the requests were sent (the result of their - execution, however, is guaranteed to be as if they had been processed - one at a time in the order in which the requests were sent). - - Response packets are of the same general format as request packets. - Each response packet begins with the request identifier. - - The format of the data portion of the SSH_FXP_STATUS response is as - follows: - - uint32 id - uint32 error/status code - string error message (ISO-10646 UTF-8 [RFC-2279]) - string language tag (as defined in [RFC-1766]) - - where `id' is the request identifier, and `error/status code' - indicates the result of the requested operation. The value SSH_FX_OK - indicates success, and all other values indicate failure. - - Currently, the following values are defined (other values may be - defined by future versions of this protocol): - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 26] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - #define SSH_FX_OK 0 - #define SSH_FX_EOF 1 - #define SSH_FX_NO_SUCH_FILE 2 - #define SSH_FX_PERMISSION_DENIED 3 - #define SSH_FX_FAILURE 4 - #define SSH_FX_BAD_MESSAGE 5 - #define SSH_FX_NO_CONNECTION 6 - #define SSH_FX_CONNECTION_LOST 7 - #define SSH_FX_OP_UNSUPPORTED 8 - #define SSH_FX_INVALID_HANDLE 9 - #define SSH_FX_NO_SUCH_PATH 10 - #define SSH_FX_FILE_ALREADY_EXISTS 11 - #define SSH_FX_WRITE_PROTECT 12 - #define SSH_FX_NO_MEDIA 13 - - SSH_FX_OK - Indicates successful completion of the operation. - - SSH_FX_EOF - indicates end-of-file condition; for SSH_FX_READ it means that no - more data is available in the file, and for SSH_FX_READDIR it - indicates that no more files are contained in the directory. - - SSH_FX_NO_SUCH_FILE - is returned when a reference is made to a file which does not - exist. - - SSH_FX_PERMISSION_DENIED - is returned when the authenticated user does not have sufficient - permissions to perform the operation. - - SSH_FX_FAILURE - is a generic catch-all error message; it should be returned if an - error occurs for which there is no more specific error code - defined. - - SSH_FX_BAD_MESSAGE - may be returned if a badly formatted packet or protocol - incompatibility is detected. - - SSH_FX_NO_CONNECTION - is a pseudo-error which indicates that the client has no - connection to the server (it can only be generated locally by the - client, and MUST NOT be returned by servers). - - SSH_FX_CONNECTION_LOST - is a pseudo-error which indicates that the connection to the - server has been lost (it can only be generated locally by the - - - -Galbraith, et al. Expires June 18, 2003 [Page 27] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - client, and MUST NOT be returned by servers). - - SSH_FX_OP_UNSUPPORTED - indicates that an attempt was made to perform an operation which - is not supported for the server (it may be generated locally by - the client if e.g. the version number exchange indicates that a - required feature is not supported by the server, or it may be - returned by the server if the server does not implement an - operation). - - SSH_FX_INVALID_HANDLE - The handle value was invalid. - - SSH_FX_NO_SUCH_PATH - The file path does not exist or is invalid. - - SSH_FX_FILE_ALREADY_EXISTS - The file already exists. - - SSH_FX_WRITE_PROTECT - The file is on read only media, or the media is write protected. - - SSH_FX_NO_MEDIA - The requested operation can not be completed because there is no - media available in the drive. - - The SSH_FXP_HANDLE response has the following format: - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is an arbitrary - string that identifies an open file or directory on the server. The - handle is opaque to the client; the client MUST NOT attempt to - interpret or modify it in any way. The length of the handle string - MUST NOT exceed 256 data bytes. - - The SSH_FXP_DATA response has the following format: - - uint32 id - string data - - where `id' is the request identifier, and `data' is an arbitrary byte - string containing the requested data. The data string may be at most - the number of bytes requested in a SSH_FXP_READ request, but may also - be shorter if end of file is reached or if the read is from something - other than a regular file. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 28] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - The SSH_FXP_NAME response has the following format: - - uint32 id - uint32 count - repeats count times: - string filename [UTF-8] - ATTRS attrs - - where `id' is the request identifier, `count' is the number of names - returned in this response, and the remaining fields repeat `count' - times (so that all three fields are first included for the first - file, then for the second file, etc). In the repeated part, - `filename' is a file name being returned (for SSH_FXP_READDIR, it - will be a relative name within the directory, without any path - components; for SSH_FXP_REALPATH it will be an absolute path name), - and `attrs' is the attributes of the file as described in Section - ``File Attributes''. - - The SSH_FXP_ATTRS response has the following format: - - uint32 id - ATTRS attrs - - where `id' is the request identifier, and `attrs' is the returned - file attributes as described in Section ``File Attributes''. - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 29] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -8. Vendor-Specific Extensions - - The SSH_FXP_EXTENDED request provides a generic extension mechanism - for adding vendor-specific commands. The request has the following - format: - - uint32 id - string extended-request - ... any request-specific data ... - - where `id' is the request identifier, and `extended-request' is a - string of the format "name@domain", where domain is an internet - domain name of the vendor defining the request. The rest of the - request is completely vendor-specific, and servers should only - attempt to interpret it if they recognize the `extended-request' - name. - - The server may respond to such requests using any of the response - packets defined in Section ``Responses from the Server to the - Client''. Additionally, the server may also respond with a - SSH_FXP_EXTENDED_REPLY packet, as defined below. If the server does - not recognize the `extended-request' name, then the server MUST - respond with SSH_FXP_STATUS with error/status set to - SSH_FX_OP_UNSUPPORTED. - - The SSH_FXP_EXTENDED_REPLY packet can be used to carry arbitrary - extension-specific data from the server to the client. It is of the - following format: - - uint32 id - ... any request-specific data ... - - There is a range of packet types reserved for use by extensions. In - order to avoid collision, extensions that turn on the use of - additional packet types should determine those numbers dynamically. - - The suggested way of doing this is have an extension request from the - client to the server that enables the extension; the extension - response from the server to the client would specify the actual type - values to use, in additional to any other data. - - Extension authors should be mindful of the limited range of packet - types available (there are only 45 values available) and avoid - requiring a new packet type where possible. - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 30] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -9. Security Considerations - - This protocol assumes that it is run over a secure channel and that - the endpoints of the channel have been authenticated. Thus, this - protocol assumes that it is externally protected from network-level - attacks. - - This protocol provides file system access to arbitrary files on the - server (only constrained by the server implementation). It is the - responsibility of the server implementation to enforce any access - controls that may be required to limit the access allowed for any - particular user (the user being authenticated externally to this - protocol, typically using the SSH User Authentication Protocol [8]. - - Care must be taken in the server implementation to check the validity - of received file handle strings. The server should not rely on them - directly; it MUST check the validity of each handle before relying on - it. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 31] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -10. Changes from previous protocol versions - - The SSH File Transfer Protocol has changed over time, before it's - standardization. The following is a description of the incompatible - changes between different versions. - -10.1 Changes between versions 4 and 3 - - Many of the changes between version 4 and version 3 are to the - attribute structure to make it more flexible for non-unix platforms. - - o Clarify the use of stderr by the server. - - o Clarify handling of very large read requests by the server. - - o Make all filenames UTF-8. - - o Added 'newline' extension. - - o Made time fields 64 bit, and optionally have nanosecond resultion. - - o Made file attribute owner and group strings so they can actually - be used on disparate systems. - - o Added createtime field, and added separate flags for atime, - createtime, and mtime so they can be set separately. - - o Split the file type out of the permissions field and into it's own - field (which is always present.) - - o Added acl attribute. - - o Added SSH_FXF_TEXT file open flag. - - o Added flags field to the get stat commands so that the client can - specifically request information the server might not normally - included for performance reasons. - - o Removed the long filename from the names structure-- it can now be - built from information available in the attrs structure. - - o Added reserved range of packet numbers for extensions. - - o Added several additional error codes. - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 32] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -10.2 Changes between versions 3 and 2 - - o The SSH_FXP_READLINK and SSH_FXP_SYMLINK messages were added. - - o The SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY messages were - added. - - o The SSH_FXP_STATUS message was changed to include fields `error - message' and `language tag'. - - -10.3 Changes between versions 2 and 1 - - o The SSH_FXP_RENAME message was added. - - -10.4 Changes between versions 1 and 0 - - o Implementation changes, no actual protocol changes. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 33] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -11. Trademark Issues - - "ssh" is a registered trademark of SSH Communications Security Corp - in the United States and/or other countries. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 34] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -References - - [1] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and - P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January - 1999. - - [2] Alvestrand, H., "IETF Policy on Character Sets and Languages", - BCP 18, RFC 2277, January 1998. - - [3] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., Beame, - C., Eisler, M. and D. Noveck, "NFS version 4 Protocol", RFC - 3010, December 2000. - - [4] Institute of Electrical and Electronics Engineers, "Information - Technology - Portable Operating System Interface (POSIX) - Part - 1: System Application Program Interface (API) [C Language]", - IEEE Standard 1003.2, 1996. - - [5] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Protocol Architecture", - draft-ietf-secsh-architecture-13 (work in progress), September - 2002. - - [6] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Protocol Transport Protocol", - draft-ietf-secsh-transport-15 (work in progress), September - 2002. - - [7] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-16 - (work in progress), September 2002. - - [8] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Authentication Protocol", - draft-ietf-secsh-userauth-16 (work in progress), September 2002. - - -Authors' Addresses - - Joseph Galbraith - VanDyke Software - 4848 Tramway Ridge Blvd - Suite 101 - Albuquerque, NM 87111 - US - - Phone: +1 505 332 5700 - EMail: [email protected] - - - -Galbraith, et al. Expires June 18, 2003 [Page 35] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - Tatu Ylonen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - Sami Lehtinen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 36] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -Intellectual Property Statement - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementors or users of this specification can - be obtained from the IETF Secretariat. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights which may cover technology that may be required to practice - this standard. Please address the information to the IETF Executive - Director. - - -Full Copyright Statement - - Copyright (C) The Internet Society (2002). All Rights Reserved. - - This document and translations of it may be copied and furnished to - others, and derivative works that comment on or otherwise explain it - or assist in its implementation may be prepared, copied, published - and distributed, in whole or in part, without restriction of any - kind, provided that the above copyright notice and this paragraph are - included on all such copies and derivative works. However, this - document itself may not be modified in any way, such as by removing - the copyright notice or references to the Internet Society or other - Internet organizations, except as needed for the purpose of - developing Internet standards in which case the procedures for - copyrights defined in the Internet Standards process must be - followed, or as required to translate it into languages other than - English. - - The limited permissions granted above are perpetual and will not be - revoked by the Internet Society or its successors or assignees. - - This document and the information contained herein is provided on an - "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING - TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING - BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION - - - -Galbraith, et al. Expires June 18, 2003 [Page 37] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF - MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - -Acknowledgement - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 38] - - diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-transport-17.2.ps b/lib/ssh/doc/standard/draft-ietf-secsh-transport-17.2.ps deleted file mode 100644 index d692285b4e..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-transport-17.2.ps +++ /dev/null @@ -1,3205 +0,0 @@ -%!PS-Adobe-3.0 -%%BoundingBox: 75 0 595 747 -%%Title: Enscript Output -%%For: Magnus Thoang -%%Creator: GNU enscript 1.6.1 -%%CreationDate: Fri Oct 31 13:35:14 2003 -%%Orientation: Portrait -%%Pages: 15 0 -%%DocumentMedia: A4 595 842 0 () () -%%DocumentNeededResources: (atend) -%%EndComments -%%BeginProlog -%%BeginProcSet: PStoPS 1 15 -userdict begin -[/showpage/erasepage/copypage]{dup where{pop dup load - type/operatortype eq{1 array cvx dup 0 3 index cvx put - bind def}{pop}ifelse}{pop}ifelse}forall -[/letter/legal/executivepage/a4/a4small/b5/com10envelope - /monarchenvelope/c5envelope/dlenvelope/lettersmall/note - /folio/quarto/a5]{dup where{dup wcheck{exch{}put} - {pop{}def}ifelse}{pop}ifelse}forall -/setpagedevice {pop}bind 1 index where{dup wcheck{3 1 roll put} - 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matrix invertmatrix matrix concatmatrix - matrix invertmatrix put -%%EndSetup -%%Page: (0,1) 1 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 1 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 701 M -(Network Working Group T. Ylonen) s -5 690 M -(Internet-Draft SSH Communications Security Corp) s -5 679 M -(Expires: March 31, 2004 D. Moffat, Editor, Ed.) s -5 668 M -( Sun Microsystems, Inc) s -5 657 M -( Oct 2003) s -5 624 M -( SSH Transport Layer Protocol) s -5 613 M -( draft-ietf-secsh-transport-17.txt) s -5 591 M -(Status of this Memo) s -5 569 M -( This document is an Internet-Draft and is in full conformance with) s -5 558 M -( all provisions of Section 10 of RFC2026.) s -5 536 M -( Internet-Drafts are working documents of the Internet Engineering) s -5 525 M -( Task Force \(IETF\), its areas, and its working groups. Note that other) s -5 514 M -( groups may also distribute working documents as Internet-Drafts.) s -5 492 M -( Internet-Drafts are draft documents valid for a maximum of six months) s -5 481 M -( and may be updated, replaced, or obsoleted by other documents at any) s -5 470 M -( time. It is inappropriate to use Internet-Drafts as reference) s -5 459 M -( material or to cite them other than as "work in progress.") s -5 437 M -( The list of current Internet-Drafts can be accessed at http://) s -5 426 M -( www.ietf.org/ietf/1id-abstracts.txt.) s -5 404 M -( The list of Internet-Draft Shadow Directories can be accessed at) s -5 393 M -( http://www.ietf.org/shadow.html.) s -5 371 M -( This Internet-Draft will expire on March 31, 2004.) s -5 349 M -(Copyright Notice) s -5 327 M -( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s -5 305 M -(Abstract) s -5 283 M -( SSH is a protocol for secure remote login and other secure network) s -5 272 M -( services over an insecure network.) s -5 250 M -( This document describes the SSH transport layer protocol which) s -5 239 M -( typically runs on top of TCP/IP. The protocol can be used as a basis) s -5 228 M -( for a number of secure network services. It provides strong) s -5 217 M -( encryption, server authentication, and integrity protection. It may) s -5 206 M -( also provide compression.) s -5 184 M -( Key exchange method, public key algorithm, symmetric encryption) s -5 173 M -( algorithm, message authentication algorithm, and hash algorithm are) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 1]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 2 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( all negotiated.) s -5 668 M -( This document also describes the Diffie-Hellman key exchange method) s -5 657 M -( and the minimal set of algorithms that are needed to implement the) s -5 646 M -( SSH transport layer protocol.) s -5 624 M -(Table of Contents) s -5 602 M -( 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 591 M -( 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 580 M -( 3. Conventions Used in This Document . . . . . . . . . . . . . 3) s -5 569 M -( 4. Connection Setup . . . . . . . . . . . . . . . . . . . . . . 3) s -5 558 M -( 4.1 Use over TCP/IP . . . . . . . . . . . . . . . . . . . . . . 4) s -5 547 M -( 4.2 Protocol Version Exchange . . . . . . . . . . . . . . . . . 4) s -5 536 M -( 4.3 Compatibility With Old SSH Versions . . . . . . . . . . . . 4) s -5 525 M -( 4.3.1 Old Client, New Server . . . . . . . . . . . . . . . . . . . 5) s -5 514 M -( 4.3.2 New Client, Old Server . . . . . . . . . . . . . . . . . . . 5) s -5 503 M -( 5. Binary Packet Protocol . . . . . . . . . . . . . . . . . . . 5) s -5 492 M -( 5.1 Maximum Packet Length . . . . . . . . . . . . . . . . . . . 6) s -5 481 M -( 5.2 Compression . . . . . . . . . . . . . . . . . . . . . . . . 7) s -5 470 M -( 5.3 Encryption . . . . . . . . . . . . . . . . . . . . . . . . . 7) s -5 459 M -( 5.4 Data Integrity . . . . . . . . . . . . . . . . . . . . . . . 9) s -5 448 M -( 5.5 Key Exchange Methods . . . . . . . . . . . . . . . . . . . . 10) s -5 437 M -( 5.6 Public Key Algorithms . . . . . . . . . . . . . . . . . . . 11) s -5 426 M -( 6. Key Exchange . . . . . . . . . . . . . . . . . . . . . . . . 13) s -5 415 M -( 6.1 Algorithm Negotiation . . . . . . . . . . . . . . . . . . . 13) s -5 404 M -( 6.2 Output from Key Exchange . . . . . . . . . . . . . . . . . . 16) s -5 393 M -( 6.3 Taking Keys Into Use . . . . . . . . . . . . . . . . . . . . 17) s -5 382 M -( 7. Diffie-Hellman Key Exchange . . . . . . . . . . . . . . . . 18) s -5 371 M -( 7.1 diffie-hellman-group1-sha1 . . . . . . . . . . . . . . . . . 19) s -5 360 M -( 8. Key Re-Exchange . . . . . . . . . . . . . . . . . . . . . . 20) s -5 349 M -( 9. Service Request . . . . . . . . . . . . . . . . . . . . . . 21) s -5 338 M -( 10. Additional Messages . . . . . . . . . . . . . . . . . . . . 21) s -5 327 M -( 10.1 Disconnection Message . . . . . . . . . . . . . . . . . . . 22) s -5 316 M -( 10.2 Ignored Data Message . . . . . . . . . . . . . . . . . . . . 22) s -5 305 M -( 10.3 Debug Message . . . . . . . . . . . . . . . . . . . . . . . 23) s -5 294 M -( 10.4 Reserved Messages . . . . . . . . . . . . . . . . . . . . . 23) s -5 283 M -( 11. Summary of Message Numbers . . . . . . . . . . . . . . . . . 23) s -5 272 M -( 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 24) s -5 261 M -( 13. Security Considerations . . . . . . . . . . . . . . . . . . 24) s -5 250 M -( 14. Intellectual Property . . . . . . . . . . . . . . . . . . . 24) s -5 239 M -( 15. Additional Information . . . . . . . . . . . . . . . . . . . 24) s -5 228 M -( Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 26) s -5 217 M -( Normative . . . . . . . . . . . . . . . . . . . . . . . . . 25) s -5 206 M -( Informative . . . . . . . . . . . . . . . . . . . . . . . . 25) s -5 195 M -( A. Contibutors . . . . . . . . . . . . . . . . . . . . . . . . 27) s -5 184 M -( Intellectual Property and Copyright Statements . . . . . . . 28) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 2]) s -_R -S -PStoPSsaved restore -%%Page: (2,3) 2 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 3 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -(1. Contributors) s -5 668 M -( The major original contributors of this document were: Tatu Ylonen,) s -5 657 M -( Tero Kivinen, Timo J. Rinne, Sami Lehtinen \(all of SSH Communications) s -5 646 M -( Security Corp\), and Markku-Juhani O. Saarinen \(University of) s -5 635 M -( Jyvaskyla\)) s -5 613 M -( The document editor is: [email protected]. Comments on this) s -5 602 M -( internet draft should be sent to the IETF SECSH working group,) s -5 591 M -( details at: http://ietf.org/html.charters/secsh-charter.html) s -5 569 M -(2. Introduction) s -5 547 M -( The SSH transport layer is a secure low level transport protocol. It) s -5 536 M -( provides strong encryption, cryptographic host authentication, and) s -5 525 M -( integrity protection.) s -5 503 M -( Authentication in this protocol level is host-based; this protocol) s -5 492 M -( does not perform user authentication. A higher level protocol for) s -5 481 M -( user authentication can be designed on top of this protocol.) s -5 459 M -( The protocol has been designed to be simple, flexible, to allow) s -5 448 M -( parameter negotiation, and to minimize the number of round-trips.) s -5 437 M -( Key exchange method, public key algorithm, symmetric encryption) s -5 426 M -( algorithm, message authentication algorithm, and hash algorithm are) s -5 415 M -( all negotiated. It is expected that in most environments, only 2) s -5 404 M -( round-trips will be needed for full key exchange, server) s -5 393 M -( authentication, service request, and acceptance notification of) s -5 382 M -( service request. The worst case is 3 round-trips.) s -5 360 M -(3. Conventions Used in This Document) s -5 338 M -( The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",) s -5 327 M -( and "MAY" that appear in this document are to be interpreted as) s -5 316 M -( described in [RFC2119].) s -5 294 M -( The used data types and terminology are specified in the architecture) s -5 283 M -( document [SSH-ARCH].) s -5 261 M -( The architecture document also discusses the algorithm naming) s -5 250 M -( conventions that MUST be used with the SSH protocols.) s -5 228 M -(4. Connection Setup) s -5 206 M -( SSH works over any 8-bit clean, binary-transparent transport. The) s -5 195 M -( underlying transport SHOULD protect against transmission errors as) s -5 184 M -( such errors cause the SSH connection to terminate.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 3]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 4 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( The client initiates the connection.) s -5 668 M -(4.1 Use over TCP/IP) s -5 646 M -( When used over TCP/IP, the server normally listens for connections on) s -5 635 M -( port 22. This port number has been registered with the IANA, and has) s -5 624 M -( been officially assigned for SSH.) s -5 602 M -(4.2 Protocol Version Exchange) s -5 580 M -( When the connection has been established, both sides MUST send an) s -5 569 M -( identification string of the form "SSH-protoversion-softwareversion) s -5 558 M -( comments", followed by carriage return and newline characters \(ASCII) s -5 547 M -( 13 and 10, respectively\). Both sides MUST be able to process) s -5 536 M -( identification strings without carriage return character. No null) s -5 525 M -( character is sent. The maximum length of the string is 255) s -5 514 M -( characters, including the carriage return and newline.) s -5 492 M -( The part of the identification string preceding carriage return and) s -5 481 M -( newline is used in the Diffie-Hellman key exchange \(see Section) s -5 470 M -( Section 7\).) s -5 448 M -( The server MAY send other lines of data before sending the version) s -5 437 M -( string. Each line SHOULD be terminated by a carriage return and) s -5 426 M -( newline. Such lines MUST NOT begin with "SSH-", and SHOULD be) s -5 415 M -( encoded in ISO-10646 UTF-8 [RFC2279] \(language is not specified\).) s -5 404 M -( Clients MUST be able to process such lines; they MAY be silently) s -5 393 M -( ignored, or MAY be displayed to the client user; if they are) s -5 382 M -( displayed, control character filtering discussed in [SSH-ARCH] SHOULD) s -5 371 M -( be used. The primary use of this feature is to allow TCP-wrappers to) s -5 360 M -( display an error message before disconnecting.) s -5 338 M -( Version strings MUST consist of printable US-ASCII characters, not) s -5 327 M -( including whitespaces or a minus sign \(-\). The version string is) s -5 316 M -( primarily used to trigger compatibility extensions and to indicate) s -5 305 M -( the capabilities of an implementation. The comment string should) s -5 294 M -( contain additional information that might be useful in solving user) s -5 283 M -( problems.) s -5 261 M -( The protocol version described in this document is 2.0.) s -5 239 M -( Key exchange will begin immediately after sending this identifier.) s -5 228 M -( All packets following the identification string SHALL use the binary) s -5 217 M -( packet protocol, to be described below.) s -5 195 M -(4.3 Compatibility With Old SSH Versions) s -5 173 M -( During the transition period, it is important to be able to work in a) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 4]) s -_R -S -PStoPSsaved restore -%%Page: (4,5) 3 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 5 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( way that is compatible with the installed SSH clients and servers) s -5 679 M -( that use an older version of the protocol. Information in this) s -5 668 M -( section is only relevant for implementations supporting compatibility) s -5 657 M -( with SSH versions 1.x. There is no standards track or informational) s -5 646 M -( draft available that defines the SSH 1.x protocol. The only known) s -5 635 M -( documentation of the 1.x protocol is contained in README files that) s -5 624 M -( are shipped along with the source code.) s -5 602 M -(4.3.1 Old Client, New Server) s -5 580 M -( Server implementations MAY support a configurable "compatibility") s -5 569 M -( flag that enables compatibility with old versions. When this flag is) s -5 558 M -( on, the server SHOULD identify its protocol version as "1.99".) s -5 547 M -( Clients using protocol 2.0 MUST be able to identify this as identical) s -5 536 M -( to "2.0". In this mode the server SHOULD NOT send the carriage) s -5 525 M -( return character \(ASCII 13\) after the version identification string.) s -5 503 M -( In the compatibility mode the server SHOULD NOT send any further data) s -5 492 M -( after its initialization string until it has received an) s -5 481 M -( identification string from the client. The server can then determine) s -5 470 M -( whether the client is using an old protocol, and can revert to the) s -5 459 M -( old protocol if required. In the compatibility mode, the server MUST) s -5 448 M -( NOT send additional data before the version string.) s -5 426 M -( When compatibility with old clients is not needed, the server MAY) s -5 415 M -( send its initial key exchange data immediately after the) s -5 404 M -( identification string.) s -5 382 M -(4.3.2 New Client, Old Server) s -5 360 M -( Since the new client MAY immediately send additional data after its) s -5 349 M -( identification string \(before receiving server's identification\), the) s -5 338 M -( old protocol may already have been corrupted when the client learns) s -5 327 M -( that the server is old. When this happens, the client SHOULD close) s -5 316 M -( the connection to the server, and reconnect using the old protocol.) s -5 294 M -(5. Binary Packet Protocol) s -5 272 M -( Each packet is in the following format:) s -5 250 M -( uint32 packet_length) s -5 239 M -( byte padding_length) s -5 228 M -( byte[n1] payload; n1 = packet_length - padding_length - 1) s -5 217 M -( byte[n2] random padding; n2 = padding_length) s -5 206 M -( byte[m] mac \(message authentication code\); m = mac_length) s -5 184 M -( packet_length) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 5]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 6 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( The length of the packet \(bytes\), not including MAC or the) s -5 679 M -( packet_length field itself.) s -5 657 M -( padding_length) s -5 646 M -( Length of padding \(bytes\).) s -5 624 M -( payload) s -5 613 M -( The useful contents of the packet. If compression has been) s -5 602 M -( negotiated, this field is compressed. Initially, compression) s -5 591 M -( MUST be "none".) s -5 569 M -( random padding) s -5 558 M -( Arbitrary-length padding, such that the total length of) s -5 547 M -( \(packet_length || padding_length || payload || padding\) is a) s -5 536 M -( multiple of the cipher block size or 8, whichever is larger.) s -5 525 M -( There MUST be at least four bytes of padding. The padding) s -5 514 M -( SHOULD consist of random bytes. The maximum amount of padding) s -5 503 M -( is 255 bytes.) s -5 481 M -( mac) s -5 470 M -( Message authentication code. If message authentication has) s -5 459 M -( been negotiated, this field contains the MAC bytes. Initially,) s -5 448 M -( the MAC algorithm MUST be "none".) s -5 415 M -( Note that length of the concatenation of packet length, padding) s -5 404 M -( length, payload, and padding MUST be a multiple of the cipher block) s -5 393 M -( size or 8, whichever is larger. This constraint MUST be enforced) s -5 382 M -( even when using stream ciphers. Note that the packet length field is) s -5 371 M -( also encrypted, and processing it requires special care when sending) s -5 360 M -( or receiving packets.) s -5 338 M -( The minimum size of a packet is 16 \(or the cipher block size,) s -5 327 M -( whichever is larger\) bytes \(plus MAC\); implementations SHOULD decrypt) s -5 316 M -( the length after receiving the first 8 \(or cipher block size,) s -5 305 M -( whichever is larger\) bytes of a packet.) s -5 283 M -(5.1 Maximum Packet Length) s -5 261 M -( All implementations MUST be able to process packets with uncompressed) s -5 250 M -( payload length of 32768 bytes or less and total packet size of 35000) s -5 239 M -( bytes or less \(including length, padding length, payload, padding,) s -5 228 M -( and MAC.\). The maximum of 35000 bytes is an arbitrary chosen value) s -5 217 M -( larger than uncompressed size. Implementations SHOULD support longer) s -5 206 M -( packets, where they might be needed, e.g. if an implementation wants) s -5 195 M -( to send a very large number of certificates. Such packets MAY be) s -5 184 M -( sent if the version string indicates that the other party is able to) s -5 173 M -( process them. However, implementations SHOULD check that the packet) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 6]) s -_R -S -PStoPSsaved restore -%%Page: (6,7) 4 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 7 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( length is reasonable for the implementation to avoid) s -5 679 M -( denial-of-service and/or buffer overflow attacks.) s -5 657 M -(5.2 Compression) s -5 635 M -( If compression has been negotiated, the payload field \(and only it\)) s -5 624 M -( will be compressed using the negotiated algorithm. The length field) s -5 613 M -( and MAC will be computed from the compressed payload. Encryption will) s -5 602 M -( be done after compression.) s -5 580 M -( Compression MAY be stateful, depending on the method. Compression) s -5 569 M -( MUST be independent for each direction, and implementations MUST) s -5 558 M -( allow independently choosing the algorithm for each direction.) s -5 536 M -( The following compression methods are currently defined:) s -5 514 M -( none REQUIRED no compression) s -5 503 M -( zlib OPTIONAL ZLIB \(LZ77\) compression) s -5 481 M -( The "zlib" compression is described in [RFC1950] and in [RFC1951].) s -5 470 M -( The compression context is initialized after each key exchange, and) s -5 459 M -( is passed from one packet to the next with only a partial flush being) s -5 448 M -( performed at the end of each packet. A partial flush means that the) s -5 437 M -( current compressed block is ended and all data will be output. If the) s -5 426 M -( current block is not a stored block, one or more empty blocks are) s -5 415 M -( added after the current block to ensure that there are at least 8) s -5 404 M -( bits counting from the start of the end-of-block code of the current) s -5 393 M -( block to the end of the packet payload.) s -5 371 M -( Additional methods may be defined as specified in [SSH-ARCH].) s -5 349 M -(5.3 Encryption) s -5 327 M -( An encryption algorithm and a key will be negotiated during the key) s -5 316 M -( exchange. When encryption is in effect, the packet length, padding) s -5 305 M -( length, payload and padding fields of each packet MUST be encrypted) s -5 294 M -( with the given algorithm.) s -5 272 M -( The encrypted data in all packets sent in one direction SHOULD be) s -5 261 M -( considered a single data stream. For example, initialization vectors) s -5 250 M -( SHOULD be passed from the end of one packet to the beginning of the) s -5 239 M -( next packet. All ciphers SHOULD use keys with an effective key length) s -5 228 M -( of 128 bits or more.) s -5 206 M -( The ciphers in each direction MUST run independently of each other,) s -5 195 M -( and implementations MUST allow independently choosing the algorithm) s -5 184 M -( for each direction \(if multiple algorithms are allowed by local) s -5 173 M -( policy\).) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 7]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 8 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( The following ciphers are currently defined:) s -5 668 M -( 3des-cbc REQUIRED three-key 3DES in CBC mode) s -5 657 M -( blowfish-cbc OPTIONALi Blowfish in CBC mode) s -5 646 M -( twofish256-cbc OPTIONAL Twofish in CBC mode,) s -5 635 M -( with 256-bit key) s -5 624 M -( twofish-cbc OPTIONAL alias for "twofish256-cbc" \(this) s -5 613 M -( is being retained for) s -5 602 M -( historical reasons\)) s -5 591 M -( twofish192-cbc OPTIONAL Twofish with 192-bit key) s -5 580 M -( twofish128-cbc OPTIONAL Twofish with 128-bit key) s -5 569 M -( aes256-cbc OPTIONAL AES \(Rijndael\) in CBC mode,) s -5 558 M -( with 256-bit key) s -5 547 M -( aes192-cbc OPTIONAL AES with 192-bit key) s -5 536 M -( aes128-cbc RECOMMENDED AES with 128-bit key) s -5 525 M -( serpent256-cbc OPTIONAL Serpent in CBC mode, with) s -5 514 M -( 256-bit key) s -5 503 M -( serpent192-cbc OPTIONAL Serpent with 192-bit key) s -5 492 M -( serpent128-cbc OPTIONAL Serpent with 128-bit key) s -5 481 M -( arcfour OPTIONAL the ARCFOUR stream cipher) s -5 470 M -( idea-cbc OPTIONAL IDEA in CBC mode) s -5 459 M -( cast128-cbc OPTIONAL CAST-128 in CBC mode) s -5 448 M -( none OPTIONAL no encryption; NOT RECOMMENDED) s -5 426 M -( The "3des-cbc" cipher is three-key triple-DES) s -5 415 M -( \(encrypt-decrypt-encrypt\), where the first 8 bytes of the key are) s -5 404 M -( used for the first encryption, the next 8 bytes for the decryption,) s -5 393 M -( and the following 8 bytes for the final encryption. This requires 24) s -5 382 M -( bytes of key data \(of which 168 bits are actually used\). To) s -5 371 M -( implement CBC mode, outer chaining MUST be used \(i.e., there is only) s -5 360 M -( one initialization vector\). This is a block cipher with 8 byte) s -5 349 M -( blocks. This algorithm is defined in [FIPS-46-3]) s -5 327 M -( The "blowfish-cbc" cipher is Blowfish in CBC mode, with 128 bit keys) s -5 316 M -( [SCHNEIER]. This is a block cipher with 8 byte blocks.) s -5 294 M -( The "twofish-cbc" or "twofish256-cbc" cipher is Twofish in CBC mode,) s -5 283 M -( with 256 bit keys as described [TWOFISH]. This is a block cipher with) s -5 272 M -( 16 byte blocks.) s -5 250 M -( The "twofish192-cbc" cipher. Same as above but with 192-bit key.) s -5 228 M -( The "twofish128-cbc" cipher. Same as above but with 128-bit key.) s -5 206 M -( The "aes256-cbc" cipher is AES \(Advanced Encryption Standard\)) s -5 195 M -( [FIPS-197], formerly Rijndael, in CBC mode. This version uses 256-bit) s -5 184 M -( key.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 8]) s -_R -S -PStoPSsaved restore -%%Page: (8,9) 5 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 9 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( The "aes192-cbc" cipher. Same as above but with 192-bit key.) s -5 668 M -( The "aes128-cbc" cipher. Same as above but with 128-bit key.) s -5 646 M -( The "serpent256-cbc" cipher in CBC mode, with 256-bit key as) s -5 635 M -( described in the Serpent AES submission.) s -5 613 M -( The "serpent192-cbc" cipher. Same as above but with 192-bit key.) s -5 591 M -( The "serpent128-cbc" cipher. Same as above but with 128-bit key.) s -5 569 M -( The "arcfour" is the Arcfour stream cipher with 128 bit keys. The) s -5 558 M -( Arcfour cipher is believed to be compatible with the RC4 cipher) s -5 547 M -( [SCHNEIER]. RC4 is a registered trademark of RSA Data Security Inc.) s -5 536 M -( Arcfour \(and RC4\) has problems with weak keys, and should be used) s -5 525 M -( with caution.) s -5 503 M -( The "idea-cbc" cipher is the IDEA cipher in CBC mode [SCHNEIER].) s -5 481 M -( The "cast128-cbc" cipher is the CAST-128 cipher in CBC mode) s -5 470 M -( [RFC2144].) s -5 448 M -( The "none" algorithm specifies that no encryption is to be done.) s -5 437 M -( Note that this method provides no confidentiality protection, and it) s -5 426 M -( is not recommended. Some functionality \(e.g. password) s -5 415 M -( authentication\) may be disabled for security reasons if this cipher) s -5 404 M -( is chosen.) s -5 382 M -( Additional methods may be defined as specified in [SSH-ARCH].) s -5 360 M -(5.4 Data Integrity) s -5 338 M -( Data integrity is protected by including with each packet a message) s -5 327 M -( authentication code \(MAC\) that is computed from a shared secret,) s -5 316 M -( packet sequence number, and the contents of the packet.) s -5 294 M -( The message authentication algorithm and key are negotiated during) s -5 283 M -( key exchange. Initially, no MAC will be in effect, and its length) s -5 272 M -( MUST be zero. After key exchange, the selected MAC will be computed) s -5 261 M -( before encryption from the concatenation of packet data:) s -5 239 M -( mac = MAC\(key, sequence_number || unencrypted_packet\)) s -5 217 M -( where unencrypted_packet is the entire packet without MAC \(the length) s -5 206 M -( fields, payload and padding\), and sequence_number is an implicit) s -5 195 M -( packet sequence number represented as uint32. The sequence number is) s -5 184 M -( initialized to zero for the first packet, and is incremented after) s -5 173 M -( every packet \(regardless of whether encryption or MAC is in use\). It) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 9]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 10 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( is never reset, even if keys/algorithms are renegotiated later. It) s -5 679 M -( wraps around to zero after every 2^32 packets. The packet sequence) s -5 668 M -( number itself is not included in the packet sent over the wire.) s -5 646 M -( The MAC algorithms for each direction MUST run independently, and) s -5 635 M -( implementations MUST allow choosing the algorithm independently for) s -5 624 M -( both directions.) s -5 602 M -( The MAC bytes resulting from the MAC algorithm MUST be transmitted) s -5 591 M -( without encryption as the last part of the packet. The number of MAC) s -5 580 M -( bytes depends on the algorithm chosen.) s -5 558 M -( The following MAC algorithms are currently defined:) s -5 536 M -( hmac-sha1 REQUIRED HMAC-SHA1 \(digest length = key) s -5 525 M -( length = 20\)) s -5 514 M -( hmac-sha1-96 RECOMMENDED first 96 bits of HMAC-SHA1 \(digest) s -5 503 M -( length = 12, key length = 20\)) s -5 492 M -( hmac-md5 OPTIONAL HMAC-MD5 \(digest length = key) s -5 481 M -( length = 16\)) s -5 470 M -( hmac-md5-96 OPTIONAL first 96 bits of HMAC-MD5 \(digest) s -5 459 M -( length = 12, key length = 16\)) s -5 448 M -( none OPTIONAL no MAC; NOT RECOMMENDED) s -5 426 M -( Figure 1) s -5 404 M -( The "hmac-*" algorithms are described in [RFC2104] The "*-n" MACs use) s -5 393 M -( only the first n bits of the resulting value.) s -5 371 M -( The hash algorithms are described in [SCHNEIER].) s -5 349 M -( Additional methods may be defined as specified in [SSH-ARCH].) s -5 327 M -(5.5 Key Exchange Methods) s -5 305 M -( The key exchange method specifies how one-time session keys are) s -5 294 M -( generated for encryption and for authentication, and how the server) s -5 283 M -( authentication is done.) s -5 261 M -( Only one REQUIRED key exchange method has been defined:) s -5 239 M -( diffie-hellman-group1-sha1 REQUIRED) s -5 217 M -( This method is described later in this document.) s -5 195 M -( Additional methods may be defined as specified in [SSH-ARCH].) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 10]) s -_R -S -PStoPSsaved restore -%%Page: (10,11) 6 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 11 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -(5.6 Public Key Algorithms) s -5 668 M -( This protocol has been designed to be able to operate with almost any) s -5 657 M -( public key format, encoding, and algorithm \(signature and/or) s -5 646 M -( encryption\).) s -5 624 M -( There are several aspects that define a public key type:) s -5 613 M -( o Key format: how is the key encoded and how are certificates) s -5 602 M -( represented. The key blobs in this protocol MAY contain) s -5 591 M -( certificates in addition to keys.) s -5 580 M -( o Signature and/or encryption algorithms. Some key types may not) s -5 569 M -( support both signing and encryption. Key usage may also be) s -5 558 M -( restricted by policy statements in e.g. certificates. In this) s -5 547 M -( case, different key types SHOULD be defined for the different) s -5 536 M -( policy alternatives.) s -5 525 M -( o Encoding of signatures and/or encrypted data. This includes but is) s -5 514 M -( not limited to padding, byte order, and data formats.) s -5 492 M -( The following public key and/or certificate formats are currently defined:) s -5 470 M -( ssh-dss REQUIRED sign Raw DSS Key) s -5 459 M -( ssh-rsa RECOMMENDED sign Raw RSA Key) s -5 448 M -( x509v3-sign-rsa OPTIONAL sign X.509 certificates \(RSA key\)) s -5 437 M -( x509v3-sign-dss OPTIONAL sign X.509 certificates \(DSS key\)) s -5 426 M -( spki-sign-rsa OPTIONAL sign SPKI certificates \(RSA key\)) s -5 415 M -( spki-sign-dss OPTIONAL sign SPKI certificates \(DSS key\)) s -5 404 M -( pgp-sign-rsa OPTIONAL sign OpenPGP certificates \(RSA key\)) s -5 393 M -( pgp-sign-dss OPTIONAL sign OpenPGP certificates \(DSS key\)) s -5 371 M -( Additional key types may be defined as specified in [SSH-ARCH].) s -5 349 M -( The key type MUST always be explicitly known \(from algorithm) s -5 338 M -( negotiation or some other source\). It is not normally included in) s -5 327 M -( the key blob.) s -5 305 M -( Certificates and public keys are encoded as follows:) s -5 283 M -( string certificate or public key format identifier) s -5 272 M -( byte[n] key/certificate data) s -5 250 M -( The certificate part may have be a zero length string, but a public) s -5 239 M -( key is required. This is the public key that will be used for) s -5 228 M -( authentication; the certificate sequence contained in the certificate) s -5 217 M -( blob can be used to provide authorization.) s -5 195 M -( Public key / certifcate formats that do not explicitly specify a) s -5 184 M -( signature format identifier MUST use the public key / certificate) s -5 173 M -( format identifier as the signature identifier.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 11]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 12 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( Signatures are encoded as follows:) s -5 679 M -( string signature format identifier \(as specified by the) s -5 668 M -( public key / cert format\)) s -5 657 M -( byte[n] signature blob in format specific encoding.) s -5 624 M -( The "ssh-dss" key format has the following specific encoding:) s -5 602 M -( string "ssh-dss") s -5 591 M -( mpint p) s -5 580 M -( mpint q) s -5 569 M -( mpint g) s -5 558 M -( mpint y) s -5 536 M -( Here the p, q, g, and y parameters form the signature key blob.) s -5 514 M -( Signing and verifying using this key format is done according to the) s -5 503 M -( Digital Signature Standard [FIPS-186] using the SHA-1 hash. A) s -5 492 M -( description can also be found in [SCHNEIER].) s -5 470 M -( The resulting signature is encoded as follows:) s -5 448 M -( string "ssh-dss") s -5 437 M -( string dss_signature_blob) s -5 415 M -( dss_signature_blob is encoded as a string containing r followed by s) s -5 404 M -( \(which are 160 bits long integers, without lengths or padding,) s -5 393 M -( unsigned and in network byte order\).) s -5 371 M -( The "ssh-rsa" key format has the following specific encoding:) s -5 349 M -( string "ssh-rsa") s -5 338 M -( mpint e) s -5 327 M -( mpint n) s -5 305 M -( Here the e and n parameters form the signature key blob.) s -5 283 M -( Signing and verifying using this key format is done according to) s -5 272 M -( [SCHNEIER] and [PKCS1] using the SHA-1 hash.) s -5 250 M -( The resulting signature is encoded as follows:) s -5 228 M -( string "ssh-rsa") s -5 217 M -( string rsa_signature_blob) s -5 195 M -( rsa_signature_blob is encoded as a string containing s \(which is an) s -5 184 M -( integer, without lengths or padding, unsigned and in network byte) s -5 173 M -( order\).) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 12]) s -_R -S -PStoPSsaved restore -%%Page: (12,13) 7 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 13 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( The "spki-sign-rsa" method indicates that the certificate blob) s -5 679 M -( contains a sequence of SPKI certificates. The format of SPKI) s -5 668 M -( certificates is described in [RFC2693]. This method indicates that) s -5 657 M -( the key \(or one of the keys in the certificate\) is an RSA-key.) s -5 635 M -( The "spki-sign-dss". As above, but indicates that the key \(or one of) s -5 624 M -( the keys in the certificate\) is a DSS-key.) s -5 602 M -( The "pgp-sign-rsa" method indicates the certificates, the public key,) s -5 591 M -( and the signature are in OpenPGP compatible binary format) s -5 580 M -( \([RFC2440]\). This method indicates that the key is an RSA-key.) s -5 558 M -( The "pgp-sign-dss". As above, but indicates that the key is a) s -5 547 M -( DSS-key.) s -5 525 M -(6. Key Exchange) s -5 503 M -( Key exchange begins by each side sending lists of supported) s -5 492 M -( algorithms. Each side has a preferred algorithm in each category, and) s -5 481 M -( it is assumed that most implementations at any given time will use) s -5 470 M -( the same preferred algorithm. Each side MAY guess which algorithm) s -5 459 M -( the other side is using, and MAY send an initial key exchange packet) s -5 448 M -( according to the algorithm if appropriate for the preferred method.) s -5 426 M -( Guess is considered wrong, if:) s -5 415 M -( o the kex algorithm and/or the host key algorithm is guessed wrong) s -5 404 M -( \(server and client have different preferred algorithm\), or) s -5 393 M -( o if any of the other algorithms cannot be agreed upon \(the) s -5 382 M -( procedure is defined below in Section Section 6.1\).) s -5 360 M -( Otherwise, the guess is considered to be right and the optimistically) s -5 349 M -( sent packet MUST be handled as the first key exchange packet.) s -5 327 M -( However, if the guess was wrong, and a packet was optimistically sent) s -5 316 M -( by one or both parties, such packets MUST be ignored \(even if the) s -5 305 M -( error in the guess would not affect the contents of the initial) s -5 294 M -( packet\(s\)\), and the appropriate side MUST send the correct initial) s -5 283 M -( packet.) s -5 261 M -( Server authentication in the key exchange MAY be implicit. After a) s -5 250 M -( key exchange with implicit server authentication, the client MUST) s -5 239 M -( wait for response to its service request message before sending any) s -5 228 M -( further data.) s -5 206 M -(6.1 Algorithm Negotiation) s -5 184 M -( Key exchange begins by each side sending the following packet:) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 13]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 14 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( byte SSH_MSG_KEXINIT) s -5 679 M -( byte[16] cookie \(random bytes\)) s -5 668 M -( string kex_algorithms) s -5 657 M -( string server_host_key_algorithms) s -5 646 M -( string encryption_algorithms_client_to_server) s -5 635 M -( string encryption_algorithms_server_to_client) s -5 624 M -( string mac_algorithms_client_to_server) s -5 613 M -( string mac_algorithms_server_to_client) s -5 602 M -( string compression_algorithms_client_to_server) s -5 591 M -( string compression_algorithms_server_to_client) s -5 580 M -( string languages_client_to_server) s -5 569 M -( string languages_server_to_client) s -5 558 M -( boolean first_kex_packet_follows) s -5 547 M -( uint32 0 \(reserved for future extension\)) s -5 525 M -( Each of the algorithm strings MUST be a comma-separated list of) s -5 514 M -( algorithm names \(see ''Algorithm Naming'' in [SSH-ARCH]\). Each) s -5 503 M -( supported \(allowed\) algorithm MUST be listed in order of preference.) s -5 481 M -( The first algorithm in each list MUST be the preferred \(guessed\)) s -5 470 M -( algorithm. Each string MUST contain at least one algorithm name.) s -5 437 M -( cookie) s -5 426 M -( The cookie MUST be a random value generated by the sender. Its) s -5 415 M -( purpose is to make it impossible for either side to fully) s -5 404 M -( determine the keys and the session identifier.) s -5 382 M -( kex_algorithms) s -5 371 M -( Key exchange algorithms were defined above. The first) s -5 360 M -( algorithm MUST be the preferred \(and guessed\) algorithm. If) s -5 349 M -( both sides make the same guess, that algorithm MUST be used.) s -5 338 M -( Otherwise, the following algorithm MUST be used to choose a key) s -5 327 M -( exchange method: iterate over client's kex algorithms, one at a) s -5 316 M -( time. Choose the first algorithm that satisfies the following) s -5 305 M -( conditions:) s -5 294 M -( + the server also supports the algorithm,) s -5 283 M -( + if the algorithm requires an encryption-capable host key,) s -5 272 M -( there is an encryption-capable algorithm on the server's) s -5 261 M -( server_host_key_algorithms that is also supported by the) s -5 250 M -( client, and) s -5 239 M -( + if the algorithm requires a signature-capable host key,) s -5 228 M -( there is a signature-capable algorithm on the server's) s -5 217 M -( server_host_key_algorithms that is also supported by the) s -5 206 M -( client.) s -5 195 M -( + If no algorithm satisfying all these conditions can be) s -5 184 M -( found, the connection fails, and both sides MUST disconnect.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 14]) s -_R -S -PStoPSsaved restore -%%Page: (14,15) 8 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 15 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( server_host_key_algorithms) s -5 679 M -( List of the algorithms supported for the server host key. The) s -5 668 M -( server lists the algorithms for which it has host keys; the) s -5 657 M -( client lists the algorithms that it is willing to accept.) s -5 646 M -( \(There MAY be multiple host keys for a host, possibly with) s -5 635 M -( different algorithms.\)) s -5 613 M -( Some host keys may not support both signatures and encryption) s -5 602 M -( \(this can be determined from the algorithm\), and thus not all) s -5 591 M -( host keys are valid for all key exchange methods.) s -5 569 M -( Algorithm selection depends on whether the chosen key exchange) s -5 558 M -( algorithm requires a signature or encryption capable host key.) s -5 547 M -( It MUST be possible to determine this from the public key) s -5 536 M -( algorithm name. The first algorithm on the client's list that) s -5 525 M -( satisfies the requirements and is also supported by the server) s -5 514 M -( MUST be chosen. If there is no such algorithm, both sides MUST) s -5 503 M -( disconnect.) s -5 481 M -( encryption_algorithms) s -5 470 M -( Lists the acceptable symmetric encryption algorithms in order) s -5 459 M -( of preference. The chosen encryption algorithm to each) s -5 448 M -( direction MUST be the first algorithm on the client's list) s -5 437 M -( that is also on the server's list. If there is no such) s -5 426 M -( algorithm, both sides MUST disconnect.) s -5 404 M -( Note that "none" must be explicitly listed if it is to be) s -5 393 M -( acceptable. The defined algorithm names are listed in Section) s -5 382 M -( Section 5.3.) s -5 360 M -( mac_algorithms) s -5 349 M -( Lists the acceptable MAC algorithms in order of preference.) s -5 338 M -( The chosen MAC algorithm MUST be the first algorithm on the) s -5 327 M -( client's list that is also on the server's list. If there is) s -5 316 M -( no such algorithm, both sides MUST disconnect.) s -5 294 M -( Note that "none" must be explicitly listed if it is to be) s -5 283 M -( acceptable. The MAC algorithm names are listed in Section) s -5 272 M -( Figure 1.) s -5 250 M -( compression_algorithms) s -5 239 M -( Lists the acceptable compression algorithms in order of) s -5 228 M -( preference. The chosen compression algorithm MUST be the first) s -5 217 M -( algorithm on the client's list that is also on the server's) s -5 206 M -( list. If there is no such algorithm, both sides MUST) s -5 195 M -( disconnect.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 15]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 16 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( Note that "none" must be explicitly listed if it is to be) s -5 679 M -( acceptable. The compression algorithm names are listed in) s -5 668 M -( Section Section 5.2.) s -5 646 M -( languages) s -5 635 M -( This is a comma-separated list of language tags in order of) s -5 624 M -( preference [RFC3066]. Both parties MAY ignore this list. If) s -5 613 M -( there are no language preferences, this list SHOULD be empty.) s -5 602 M -( Language tags SHOULD NOT be present unless they are known to be) s -5 591 M -( needed by the sending party.) s -5 569 M -( first_kex_packet_follows) s -5 558 M -( Indicates whether a guessed key exchange packet follows. If a) s -5 547 M -( guessed packet will be sent, this MUST be TRUE. If no guessed) s -5 536 M -( packet will be sent, this MUST be FALSE.) s -5 514 M -( After receiving the SSH_MSG_KEXINIT packet from the other side,) s -5 503 M -( each party will know whether their guess was right. If the) s -5 492 M -( other party's guess was wrong, and this field was TRUE, the) s -5 481 M -( next packet MUST be silently ignored, and both sides MUST then) s -5 470 M -( act as determined by the negotiated key exchange method. If) s -5 459 M -( the guess was right, key exchange MUST continue using the) s -5 448 M -( guessed packet.) s -5 426 M -( After the KEXINIT packet exchange, the key exchange algorithm is run.) s -5 415 M -( It may involve several packet exchanges, as specified by the key) s -5 404 M -( exchange method.) s -5 382 M -(6.2 Output from Key Exchange) s -5 360 M -( The key exchange produces two values: a shared secret K, and an) s -5 349 M -( exchange hash H. Encryption and authentication keys are derived from) s -5 338 M -( these. The exchange hash H from the first key exchange is) s -5 327 M -( additionally used as the session identifier, which is a unique) s -5 316 M -( identifier for this connection. It is used by authentication methods) s -5 305 M -( as a part of the data that is signed as a proof of possession of a) s -5 294 M -( private key. Once computed, the session identifier is not changed,) s -5 283 M -( even if keys are later re-exchanged.) s -5 250 M -( Each key exchange method specifies a hash function that is used in) s -5 239 M -( the key exchange. The same hash algorithm MUST be used in key) s -5 228 M -( derivation. Here, we'll call it HASH.) s -5 195 M -( Encryption keys MUST be computed as HASH of a known value and K as) s -5 184 M -( follows:) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 16]) s -_R -S -PStoPSsaved restore -%%Page: (16,17) 9 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 17 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( o Initial IV client to server: HASH\(K || H || "A" || session_id\)) s -5 679 M -( \(Here K is encoded as mpint and "A" as byte and session_id as raw) s -5 668 M -( data."A" means the single character A, ASCII 65\).) s -5 657 M -( o Initial IV server to client: HASH\(K || H || "B" || session_id\)) s -5 646 M -( o Encryption key client to server: HASH\(K || H || "C" || session_id\)) s -5 635 M -( o Encryption key server to client: HASH\(K || H || "D" || session_id\)) s -5 624 M -( o Integrity key client to server: HASH\(K || H || "E" || session_id\)) s -5 613 M -( o Integrity key server to client: HASH\(K || H || "F" || session_id\)) s -5 591 M -( Key data MUST be taken from the beginning of the hash output. 128) s -5 580 M -( bits \(16 bytes\) MUST be used for algorithms with variable-length) s -5 569 M -( keys. The only variable key length algorithm defined in this document) s -5 558 M -( is arcfour\). For other algorithms, as many bytes as are needed are) s -5 547 M -( taken from the beginning of the hash value. If the key length needed) s -5 536 M -( is longer than the output of the HASH, the key is extended by) s -5 525 M -( computing HASH of the concatenation of K and H and the entire key so) s -5 514 M -( far, and appending the resulting bytes \(as many as HASH generates\) to) s -5 503 M -( the key. This process is repeated until enough key material is) s -5 492 M -( available; the key is taken from the beginning of this value. In) s -5 481 M -( other words:) s -5 459 M -( K1 = HASH\(K || H || X || session_id\) \(X is e.g. "A"\)) s -5 448 M -( K2 = HASH\(K || H || K1\)) s -5 437 M -( K3 = HASH\(K || H || K1 || K2\)) s -5 426 M -( ...) s -5 415 M -( key = K1 || K2 || K3 || ...) s -5 393 M -( This process will lose entropy if the amount of entropy in K is) s -5 382 M -( larger than the internal state size of HASH.) s -5 360 M -(6.3 Taking Keys Into Use) s -5 338 M -( Key exchange ends by each side sending an SSH_MSG_NEWKEYS message.) s -5 327 M -( This message is sent with the old keys and algorithms. All messages) s -5 316 M -( sent after this message MUST use the new keys and algorithms.) s -5 283 M -( When this message is received, the new keys and algorithms MUST be) s -5 272 M -( taken into use for receiving.) s -5 239 M -( This message is the only valid message after key exchange, in) s -5 228 M -( addition to SSH_MSG_DEBUG, SSH_MSG_DISCONNECT and SSH_MSG_IGNORE) s -5 217 M -( messages. The purpose of this message is to ensure that a party is) s -5 206 M -( able to respond with a disconnect message that the other party can) s -5 195 M -( understand if something goes wrong with the key exchange.) s -5 184 M -( Implementations MUST NOT accept any other messages after key exchange) s -5 173 M -( before receiving SSH_MSG_NEWKEYS.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 17]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 18 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( byte SSH_MSG_NEWKEYS) s -5 657 M -(7. Diffie-Hellman Key Exchange) s -5 635 M -( The Diffie-Hellman key exchange provides a shared secret that can not) s -5 624 M -( be determined by either party alone. The key exchange is combined) s -5 613 M -( with a signature with the host key to provide host authentication.) s -5 580 M -( In the following description \(C is the client, S is the server; p is) s -5 569 M -( a large safe prime, g is a generator for a subgroup of GF\(p\), and q) s -5 558 M -( is the order of the subgroup; V_S is S's version string; V_C is C's) s -5 547 M -( version string; K_S is S's public host key; I_C is C's KEXINIT) s -5 536 M -( message and I_S S's KEXINIT message which have been exchanged before) s -5 525 M -( this part begins\):) s -5 492 M -( 1. C generates a random number x \(1 < x < q\) and computes e = g^x) s -5 481 M -( mod p. C sends "e" to S.) s -5 459 M -( 2. S generates a random number y \(0 < y < q\) and computes f = g^y) s -5 448 M -( mod p. S receives "e". It computes K = e^y mod p, H = hash\(V_C) s -5 437 M -( || V_S || I_C || I_S || K_S || e || f || K\) \(these elements are) s -5 426 M -( encoded according to their types; see below\), and signature s on) s -5 415 M -( H with its private host key. S sends "K_S || f || s" to C. The) s -5 404 M -( signing operation may involve a second hashing operation.) s -5 382 M -( 3. C verifies that K_S really is the host key for S \(e.g. using) s -5 371 M -( certificates or a local database\). C is also allowed to accept) s -5 360 M -( the key without verification; however, doing so will render the) s -5 349 M -( protocol insecure against active attacks \(but may be desirable) s -5 338 M -( for practical reasons in the short term in many environments\). C) s -5 327 M -( then computes K = f^x mod p, H = hash\(V_C || V_S || I_C || I_S ||) s -5 316 M -( K_S || e || f || K\), and verifies the signature s on H.) s -5 294 M -( Either side MUST NOT send or accept e or f values that are not in the) s -5 283 M -( range [1, p-1]. If this condition is violated, the key exchange) s -5 272 M -( fails.) s -5 239 M -( This is implemented with the following messages. The hash algorithm) s -5 228 M -( for computing the exchange hash is defined by the method name, and is) s -5 217 M -( called HASH. The public key algorithm for signing is negotiated with) s -5 206 M -( the KEXINIT messages.) s -5 184 M -( First, the client sends the following:) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 18]) s -_R -S -PStoPSsaved restore -%%Page: (18,19) 10 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 19 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( byte SSH_MSG_KEXDH_INIT) s -5 679 M -( mpint e) s -5 646 M -( The server responds with the following:) s -5 624 M -( byte SSH_MSG_KEXDH_REPLY) s -5 613 M -( string server public host key and certificates \(K_S\)) s -5 602 M -( mpint f) s -5 591 M -( string signature of H) s -5 569 M -( The hash H is computed as the HASH hash of the concatenation of the) s -5 558 M -( following:) s -5 536 M -( string V_C, the client's version string \(CR and NL excluded\)) s -5 525 M -( string V_S, the server's version string \(CR and NL excluded\)) s -5 514 M -( string I_C, the payload of the client's SSH_MSG_KEXINIT) s -5 503 M -( string I_S, the payload of the server's SSH_MSG_KEXINIT) s -5 492 M -( string K_S, the host key) s -5 481 M -( mpint e, exchange value sent by the client) s -5 470 M -( mpint f, exchange value sent by the server) s -5 459 M -( mpint K, the shared secret) s -5 437 M -( This value is called the exchange hash, and it is used to) s -5 426 M -( authenticate the key exchange. The exchange hash SHOULD be kept) s -5 415 M -( secret.) s -5 382 M -( The signature algorithm MUST be applied over H, not the original) s -5 371 M -( data. Most signature algorithms include hashing and additional) s -5 360 M -( padding. For example, "ssh-dss" specifies SHA-1 hashing; in that) s -5 349 M -( case, the data is first hashed with HASH to compute H, and H is then) s -5 338 M -( hashed with SHA-1 as part of the signing operation.) s -5 316 M -(7.1 diffie-hellman-group1-sha1) s -5 294 M -( The "diffie-hellman-group1-sha1" method specifies Diffie-Hellman key) s -5 283 M -( exchange with SHA-1 as HASH, and Oakley group 14 [RFC3526] \(2048-bit) s -5 272 M -( MODP Group\). It is included below in hexadecimal and decimal.) s -5 250 M -( The prime p is equal to 2^1024 - 2^960 - 1 + 2^64 * floor\( 2^894 Pi +) s -5 239 M -( 129093 \). Its hexadecimal value is:) s -5 217 M -( FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1) s -5 206 M -( 29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD) s -5 195 M -( EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245) s -5 184 M -( E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED) s -5 173 M -( EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 19]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 20 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( FFFFFFFF FFFFFFFF.) s -5 668 M -( In decimal, this value is:) s -5 646 M -( 179769313486231590770839156793787453197860296048756011706444) s -5 635 M -( 423684197180216158519368947833795864925541502180565485980503) s -5 624 M -( 646440548199239100050792877003355816639229553136239076508735) s -5 613 M -( 759914822574862575007425302077447712589550957937778424442426) s -5 602 M -( 617334727629299387668709205606050270810842907692932019128194) s -5 591 M -( 467627007.) s -5 569 M -( The generator used with this prime is g = 2. The group order q is \(p) s -5 558 M -( - 1\) / 2.) s -5 536 M -(8. Key Re-Exchange) s -5 514 M -( Key re-exchange is started by sending an SSH_MSG_KEXINIT packet when) s -5 503 M -( not already doing a key exchange \(as described in Section Section) s -5 492 M -( 6.1\). When this message is received, a party MUST respond with its) s -5 481 M -( own SSH_MSG_KEXINIT message except when the received SSH_MSG_KEXINIT) s -5 470 M -( already was a reply. Either party MAY initiate the re-exchange, but) s -5 459 M -( roles MUST NOT be changed \(i.e., the server remains the server, and) s -5 448 M -( the client remains the client\).) s -5 415 M -( Key re-exchange is performed using whatever encryption was in effect) s -5 404 M -( when the exchange was started. Encryption, compression, and MAC) s -5 393 M -( methods are not changed before a new SSH_MSG_NEWKEYS is sent after) s -5 382 M -( the key exchange \(as in the initial key exchange\). Re-exchange is) s -5 371 M -( processed identically to the initial key exchange, except for the) s -5 360 M -( session identifier that will remain unchanged. It is permissible to) s -5 349 M -( change some or all of the algorithms during the re-exchange. Host) s -5 338 M -( keys can also change. All keys and initialization vectors are) s -5 327 M -( recomputed after the exchange. Compression and encryption contexts) s -5 316 M -( are reset.) s -5 283 M -( It is recommended that the keys are changed after each gigabyte of) s -5 272 M -( transmitted data or after each hour of connection time, whichever) s -5 261 M -( comes sooner. However, since the re-exchange is a public key) s -5 250 M -( operation, it requires a fair amount of processing power and should) s -5 239 M -( not be performed too often.) s -5 206 M -( More application data may be sent after the SSH_MSG_NEWKEYS packet) s -5 195 M -( has been sent; key exchange does not affect the protocols that lie) s -5 184 M -( above the SSH transport layer.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 20]) s -_R -S -PStoPSsaved restore -%%Page: (20,21) 11 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 21 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -(9. Service Request) s -5 668 M -( After the key exchange, the client requests a service. The service is) s -5 657 M -( identified by a name. The format of names and procedures for defining) s -5 646 M -( new names are defined in [SSH-ARCH].) s -5 613 M -( Currently, the following names have been reserved:) s -5 591 M -( ssh-userauth) s -5 580 M -( ssh-connection) s -5 558 M -( Similar local naming policy is applied to the service names, as is) s -5 547 M -( applied to the algorithm names; a local service should use the) s -5 536 M -( "servicename@domain" syntax.) s -5 514 M -( byte SSH_MSG_SERVICE_REQUEST) s -5 503 M -( string service name) s -5 481 M -( If the server rejects the service request, it SHOULD send an) s -5 470 M -( appropriate SSH_MSG_DISCONNECT message and MUST disconnect.) s -5 437 M -( When the service starts, it may have access to the session identifier) s -5 426 M -( generated during the key exchange.) s -5 393 M -( If the server supports the service \(and permits the client to use) s -5 382 M -( it\), it MUST respond with the following:) s -5 360 M -( byte SSH_MSG_SERVICE_ACCEPT) s -5 349 M -( string service name) s -5 327 M -( Message numbers used by services should be in the area reserved for) s -5 316 M -( them \(see Section 6 in [SSH-ARCH]\). The transport level will) s -5 305 M -( continue to process its own messages.) s -5 272 M -( Note that after a key exchange with implicit server authentication,) s -5 261 M -( the client MUST wait for response to its service request message) s -5 250 M -( before sending any further data.) s -5 228 M -(10. Additional Messages) s -5 206 M -( Either party may send any of the following messages at any time.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 21]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 22 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -(10.1 Disconnection Message) s -5 668 M -( byte SSH_MSG_DISCONNECT) s -5 657 M -( uint32 reason code) s -5 646 M -( string description [RFC2279]) s -5 635 M -( string language tag [RFC3066]) s -5 613 M -( This message causes immediate termination of the connection. All) s -5 602 M -( implementations MUST be able to process this message; they SHOULD be) s -5 591 M -( able to send this message.) s -5 569 M -( The sender MUST NOT send or receive any data after this message, and) s -5 558 M -( the recipient MUST NOT accept any data after receiving this message.) s -5 547 M -( The description field gives a more specific explanation in a) s -5 536 M -( human-readable form. The error code gives the reason in a more) s -5 525 M -( machine-readable format \(suitable for localization\), and can have the) s -5 514 M -( following values:) s -5 492 M -( #define SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1) s -5 481 M -( #define SSH_DISCONNECT_PROTOCOL_ERROR 2) s -5 470 M -( #define SSH_DISCONNECT_KEY_EXCHANGE_FAILED 3) s -5 459 M -( #define SSH_DISCONNECT_RESERVED 4) s -5 448 M -( #define SSH_DISCONNECT_MAC_ERROR 5) s -5 437 M -( #define SSH_DISCONNECT_COMPRESSION_ERROR 6) s -5 426 M -( #define SSH_DISCONNECT_SERVICE_NOT_AVAILABLE 7) s -5 415 M -( #define SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8) s -5 404 M -( #define SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9) s -5 393 M -( #define SSH_DISCONNECT_CONNECTION_LOST 10) s -5 382 M -( #define SSH_DISCONNECT_BY_APPLICATION 11) s -5 371 M -( #define SSH_DISCONNECT_TOO_MANY_CONNECTIONS 12) s -5 360 M -( #define SSH_DISCONNECT_AUTH_CANCELLED_BY_USER 13) s -5 349 M -( #define SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14) s -5 338 M -( #define SSH_DISCONNECT_ILLEGAL_USER_NAME 15) s -5 316 M -( If the description string is displayed, control character filtering) s -5 305 M -( discussed in [SSH-ARCH] should be used to avoid attacks by sending) s -5 294 M -( terminal control characters.) s -5 272 M -(10.2 Ignored Data Message) s -5 250 M -( byte SSH_MSG_IGNORE) s -5 239 M -( string data) s -5 217 M -( All implementations MUST understand \(and ignore\) this message at any) s -5 206 M -( time \(after receiving the protocol version\). No implementation is) s -5 195 M -( required to send them. This message can be used as an additional) s -5 184 M -( protection measure against advanced traffic analysis techniques.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 22]) s -_R -S -PStoPSsaved restore -%%Page: (22,23) 12 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 23 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -(10.3 Debug Message) s -5 668 M -( byte SSH_MSG_DEBUG) s -5 657 M -( boolean always_display) s -5 646 M -( string message [RFC2279]) s -5 635 M -( string language tag [RFC3066]) s -5 613 M -( All implementations MUST understand this message, but they are) s -5 602 M -( allowed to ignore it. This message is used to pass the other side) s -5 591 M -( information that may help debugging. If always_display is TRUE, the) s -5 580 M -( message SHOULD be displayed. Otherwise, it SHOULD NOT be displayed) s -5 569 M -( unless debugging information has been explicitly requested by the) s -5 558 M -( user.) s -5 525 M -( The message doesn't need to contain a newline. It is, however,) s -5 514 M -( allowed to consist of multiple lines separated by CRLF \(Carriage) s -5 503 M -( Return - Line Feed\) pairs.) s -5 470 M -( If the message string is displayed, terminal control character) s -5 459 M -( filtering discussed in [SSH-ARCH] should be used to avoid attacks by) s -5 448 M -( sending terminal control characters.) s -5 426 M -(10.4 Reserved Messages) s -5 404 M -( An implementation MUST respond to all unrecognized messages with an) s -5 393 M -( SSH_MSG_UNIMPLEMENTED message in the order in which the messages were) s -5 382 M -( received. Such messages MUST be otherwise ignored. Later protocol) s -5 371 M -( versions may define other meanings for these message types.) s -5 349 M -( byte SSH_MSG_UNIMPLEMENTED) s -5 338 M -( uint32 packet sequence number of rejected message) s -5 305 M -(11. Summary of Message Numbers) s -5 283 M -( The following message numbers have been defined in this protocol:) s -5 261 M -( #define SSH_MSG_DISCONNECT 1) s -5 250 M -( #define SSH_MSG_IGNORE 2) s -5 239 M -( #define SSH_MSG_UNIMPLEMENTED 3) s -5 228 M -( #define SSH_MSG_DEBUG 4) s -5 217 M -( #define SSH_MSG_SERVICE_REQUEST 5) s -5 206 M -( #define SSH_MSG_SERVICE_ACCEPT 6) s -5 184 M -( #define SSH_MSG_KEXINIT 20) s -5 173 M -( #define SSH_MSG_NEWKEYS 21) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 23]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 24 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( /* Numbers 30-49 used for kex packets.) s -5 679 M -( Different kex methods may reuse message numbers in) s -5 668 M -( this range. */) s -5 646 M -( #define SSH_MSG_KEXDH_INIT 30) s -5 635 M -( #define SSH_MSG_KEXDH_REPLY 31) s -5 602 M -(12. IANA Considerations) s -5 580 M -( This document is part of a set, the IANA considerations for the SSH) s -5 569 M -( protocol as defined in [SSH-ARCH], [SSH-TRANS], [SSH-USERAUTH],) s -5 558 M -( [SSH-CONNECT] are detailed in [SSH-NUMBERS].) s -5 536 M -(13. Security Considerations) s -5 514 M -( This protocol provides a secure encrypted channel over an insecure) s -5 503 M -( network. It performs server host authentication, key exchange,) s -5 492 M -( encryption, and integrity protection. It also derives a unique) s -5 481 M -( session id that may be used by higher-level protocols.) s -5 459 M -( Full security considerations for this protocol are provided in) s -5 448 M -( Section 8 of [SSH-ARCH]) s -5 426 M -(14. Intellectual Property) s -5 404 M -( The IETF takes no position regarding the validity or scope of any) s -5 393 M -( intellectual property or other rights that might be claimed to) s -5 382 M -( pertain to the implementation or use of the technology described in) s -5 371 M -( this document or the extent to which any license under such rights) s -5 360 M -( might or might not be available; neither does it represent that it) s -5 349 M -( has made any effort to identify any such rights. Information on the) s -5 338 M -( IETF's procedures with respect to rights in standards-track and) s -5 327 M -( standards-related documentation can be found in BCP-11. Copies of) s -5 316 M -( claims of rights made available for publication and any assurances of) s -5 305 M -( licenses to be made available, or the result of an attempt made to) s -5 294 M -( obtain a general license or permission for the use of such) s -5 283 M -( proprietary rights by implementers or users of this specification can) s -5 272 M -( be obtained from the IETF Secretariat.) s -5 250 M -( The IETF has been notified of intellectual property rights claimed in) s -5 239 M -( regard to some or all of the specification contained in this) s -5 228 M -( document. For more information consult the online list of claimed) s -5 217 M -( rights.) s -5 195 M -(15. Additional Information) s -5 173 M -( The current document editor is: [email protected]. Comments on) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 24]) s -_R -S -PStoPSsaved restore -%%Page: (24,25) 13 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 25 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( this internet draft should be sent to the IETF SECSH working group,) s -5 679 M -( details at: http://ietf.org/html.charters/secsh-charter.html) s -5 657 M -(Normative) s -5 635 M -( [SSH-ARCH]) s -5 624 M -( Ylonen, T., "SSH Protocol Architecture", I-D) s -5 613 M -( draft-ietf-architecture-15.txt, Oct 2003.) s -5 591 M -( [SSH-TRANS]) s -5 580 M -( Ylonen, T., "SSH Transport Layer Protocol", I-D) s -5 569 M -( draft-ietf-transport-17.txt, Oct 2003.) s -5 547 M -( [SSH-USERAUTH]) s -5 536 M -( Ylonen, T., "SSH Authentication Protocol", I-D) s -5 525 M -( draft-ietf-userauth-18.txt, Oct 2003.) s -5 503 M -( [SSH-CONNECT]) s -5 492 M -( Ylonen, T., "SSH Connection Protocol", I-D) s -5 481 M -( draft-ietf-connect-18.txt, Oct 2003.) s -5 459 M -( [SSH-NUMBERS]) s -5 448 M -( Lehtinen, S. and D. Moffat, "SSH Protocol Assigned) s -5 437 M -( Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct) s -5 426 M -( 2003.) s -5 404 M -( [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate) s -5 393 M -( Requirement Levels", BCP 14, RFC 2119, March 1997.) s -5 371 M -(Informative) s -5 349 M -( [FIPS-186]) s -5 338 M -( Federal Information Processing Standards Publication,) s -5 327 M -( "FIPS PUB 186, Digital Signature Standard", May 1994.) s -5 305 M -( [FIPS-197]) s -5 294 M -( NIST, "FIPS PUB 197 Advanced Encryption Standard \(AES\)",) s -5 283 M -( November 2001.) s -5 261 M -( [FIPS-46-3]) s -5 250 M -( U.S. Dept. of Commerce, "FIPS PUB 46-3, Data Encryption) s -5 239 M -( Standard \(DES\)", October 1999.) s -5 217 M -( [RFC2459] Housley, R., Ford, W., Polk, T. and D. Solo, "Internet) s -5 206 M -( X.509 Public Key Infrastructure Certificate and CRL) s -5 195 M -( Profile", RFC 2459, January 1999.) s -5 173 M -( [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 25]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 26 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( STD 13, RFC 1034, November 1987.) s -5 668 M -( [RFC3066] Alvestrand, H., "Tags for the Identification of) s -5 657 M -( Languages", BCP 47, RFC 3066, January 2001.) s -5 635 M -( [RFC1950] Deutsch, L. and J-L. Gailly, "ZLIB Compressed Data Format) s -5 624 M -( Specification version 3.3", RFC 1950, May 1996.) s -5 602 M -( [RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification) s -5 591 M -( version 1.3", RFC 1951, May 1996.) s -5 569 M -( [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO) s -5 558 M -( 10646", RFC 2279, January 1998.) s -5 536 M -( [RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC:) s -5 525 M -( Keyed-Hashing for Message Authentication", RFC 2104,) s -5 514 M -( February 1997.) s -5 492 M -( [RFC2144] Adams, C., "The CAST-128 Encryption Algorithm", RFC 2144,) s -5 481 M -( May 1997.) s -5 459 M -( [RFC2440] Callas, J., Donnerhacke, L., Finney, H. and R. Thayer,) s -5 448 M -( "OpenPGP Message Format", RFC 2440, November 1998.) s -5 426 M -( [RFC2693] Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas,) s -5 415 M -( B. and T. Ylonen, "SPKI Certificate Theory", RFC 2693,) s -5 404 M -( September 1999.) s -5 382 M -( [RFC3526] Kivinen, T. and M. Kojo, "More Modular Exponential \(MODP\)) s -5 371 M -( Diffie-Hellman groups for Internet Key Exchange \(IKE\)",) s -5 360 M -( RFC 3526, May 2003.) s -5 338 M -( [SCHNEIER]) s -5 327 M -( Schneier, B., "Applied Cryptography Second Edition:) s -5 316 M -( protocols algorithms and source in code in C", 1996.) s -5 294 M -( [TWOFISH] Schneier, B., "The Twofish Encryptions Algorithm: A) s -5 283 M -( 128-Bit Block Cipher, 1st Edition", March 1999.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 26]) s -_R -S -PStoPSsaved restore -%%Page: (26,27) 14 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 27 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -(Authors' Addresses) s -5 668 M -( Tatu Ylonen) s -5 657 M -( SSH Communications Security Corp) s -5 646 M -( Fredrikinkatu 42) s -5 635 M -( HELSINKI FIN-00100) s -5 624 M -( Finland) s -5 602 M -( EMail: [email protected]) s -5 569 M -( Darren J. Moffat \(editor\)) s -5 558 M -( Sun Microsystems, Inc) s -5 547 M -( 17 Network Circle) s -5 536 M -( Menlo Park 95025) s -5 525 M -( USA) s -5 503 M -( EMail: [email protected]) s -5 481 M -(Appendix A. Contibutors) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 27]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 28 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -(Intellectual Property Statement) s -5 668 M -( The IETF takes no position regarding the validity or scope of any) s -5 657 M -( intellectual property or other rights that might be claimed to) s -5 646 M -( pertain to the implementation or use of the technology described in) s -5 635 M -( this document or the extent to which any license under such rights) s -5 624 M -( might or might not be available; neither does it represent that it) s -5 613 M -( has made any effort to identify any such rights. Information on the) s -5 602 M -( IETF's procedures with respect to rights in standards-track and) s -5 591 M -( standards-related documentation can be found in BCP-11. Copies of) s -5 580 M -( claims of rights made available for publication and any assurances of) s -5 569 M -( licenses to be made available, or the result of an attempt made to) s -5 558 M -( obtain a general license or permission for the use of such) s -5 547 M -( proprietary rights by implementors or users of this specification can) s -5 536 M -( be obtained from the IETF Secretariat.) s -5 514 M -( The IETF invites any interested party to bring to its attention any) s -5 503 M -( copyrights, patents or patent applications, or other proprietary) s -5 492 M -( rights which may cover technology that may be required to practice) s -5 481 M -( this standard. Please address the information to the IETF Executive) s -5 470 M -( Director.) s -5 448 M -( The IETF has been notified of intellectual property rights claimed in) s -5 437 M -( regard to some or all of the specification contained in this) s -5 426 M -( document. For more information consult the online list of claimed) s -5 415 M -( rights.) s -5 382 M -(Full Copyright Statement) s -5 360 M -( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s -5 338 M -( This document and translations of it may be copied and furnished to) s -5 327 M -( others, and derivative works that comment on or otherwise explain it) s -5 316 M -( or assist in its implementation may be prepared, copied, published) s -5 305 M -( and distributed, in whole or in part, without restriction of any) s -5 294 M -( kind, provided that the above copyright notice and this paragraph are) s -5 283 M -( included on all such copies and derivative works. However, this) s -5 272 M -( document itself may not be modified in any way, such as by removing) s -5 261 M -( the copyright notice or references to the Internet Society or other) s -5 250 M -( Internet organizations, except as needed for the purpose of) s -5 239 M -( developing Internet standards in which case the procedures for) s -5 228 M -( copyrights defined in the Internet Standards process must be) s -5 217 M -( followed, or as required to translate it into languages other than) s -5 206 M -( English.) s -5 184 M -( The limited permissions granted above are perpetual and will not be) s -5 173 M -( revoked by the Internet Society or its successors or assignees.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 28]) s -_R -S -PStoPSsaved restore -%%Page: (28,29) 15 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 29 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Transport Layer Protocol Oct 2003) s -5 690 M -( This document and the information contained herein is provided on an) s -5 679 M -( "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING) s -5 668 M -( TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING) s -5 657 M -( BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION) s -5 646 M -( HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF) s -5 635 M -( MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.) s -5 602 M -(Acknowledgment) s -5 580 M -( Funding for the RFC Editor function is currently provided by the) s -5 569 M -( Internet Society.) s -5 129 M -(Ylonen & Moffat, Editor Expires March 31, 2004 [Page 29]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -showpage -PStoPSsaved restore -%%Trailer -%%Pages: 29 -%%DocumentNeededResources: font Courier-Bold Courier -%%EOF diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-transport-17.txt b/lib/ssh/doc/standard/draft-ietf-secsh-transport-17.txt deleted file mode 100644 index 9073ea52b2..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-transport-17.txt +++ /dev/null @@ -1,1624 +0,0 @@ - - - -Network Working Group T. Ylonen -Internet-Draft SSH Communications Security Corp -Expires: March 31, 2004 D. Moffat, Editor, Ed. - Sun Microsystems, Inc - Oct 2003 - - - SSH Transport Layer Protocol - draft-ietf-secsh-transport-17.txt - -Status of this Memo - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that other - groups may also distribute working documents as Internet-Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at http:// - www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on March 31, 2004. - -Copyright Notice - - Copyright (C) The Internet Society (2003). All Rights Reserved. - -Abstract - - SSH is a protocol for secure remote login and other secure network - services over an insecure network. - - This document describes the SSH transport layer protocol which - typically runs on top of TCP/IP. The protocol can be used as a basis - for a number of secure network services. It provides strong - encryption, server authentication, and integrity protection. It may - also provide compression. - - Key exchange method, public key algorithm, symmetric encryption - algorithm, message authentication algorithm, and hash algorithm are - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 1] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - all negotiated. - - This document also describes the Diffie-Hellman key exchange method - and the minimal set of algorithms that are needed to implement the - SSH transport layer protocol. - -Table of Contents - - 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3. Conventions Used in This Document . . . . . . . . . . . . . 3 - 4. Connection Setup . . . . . . . . . . . . . . . . . . . . . . 3 - 4.1 Use over TCP/IP . . . . . . . . . . . . . . . . . . . . . . 4 - 4.2 Protocol Version Exchange . . . . . . . . . . . . . . . . . 4 - 4.3 Compatibility With Old SSH Versions . . . . . . . . . . . . 4 - 4.3.1 Old Client, New Server . . . . . . . . . . . . . . . . . . . 5 - 4.3.2 New Client, Old Server . . . . . . . . . . . . . . . . . . . 5 - 5. Binary Packet Protocol . . . . . . . . . . . . . . . . . . . 5 - 5.1 Maximum Packet Length . . . . . . . . . . . . . . . . . . . 6 - 5.2 Compression . . . . . . . . . . . . . . . . . . . . . . . . 7 - 5.3 Encryption . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 5.4 Data Integrity . . . . . . . . . . . . . . . . . . . . . . . 9 - 5.5 Key Exchange Methods . . . . . . . . . . . . . . . . . . . . 10 - 5.6 Public Key Algorithms . . . . . . . . . . . . . . . . . . . 11 - 6. Key Exchange . . . . . . . . . . . . . . . . . . . . . . . . 13 - 6.1 Algorithm Negotiation . . . . . . . . . . . . . . . . . . . 13 - 6.2 Output from Key Exchange . . . . . . . . . . . . . . . . . . 16 - 6.3 Taking Keys Into Use . . . . . . . . . . . . . . . . . . . . 17 - 7. Diffie-Hellman Key Exchange . . . . . . . . . . . . . . . . 18 - 7.1 diffie-hellman-group1-sha1 . . . . . . . . . . . . . . . . . 19 - 8. Key Re-Exchange . . . . . . . . . . . . . . . . . . . . . . 20 - 9. Service Request . . . . . . . . . . . . . . . . . . . . . . 21 - 10. Additional Messages . . . . . . . . . . . . . . . . . . . . 21 - 10.1 Disconnection Message . . . . . . . . . . . . . . . . . . . 22 - 10.2 Ignored Data Message . . . . . . . . . . . . . . . . . . . . 22 - 10.3 Debug Message . . . . . . . . . . . . . . . . . . . . . . . 23 - 10.4 Reserved Messages . . . . . . . . . . . . . . . . . . . . . 23 - 11. Summary of Message Numbers . . . . . . . . . . . . . . . . . 23 - 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 24 - 13. Security Considerations . . . . . . . . . . . . . . . . . . 24 - 14. Intellectual Property . . . . . . . . . . . . . . . . . . . 24 - 15. Additional Information . . . . . . . . . . . . . . . . . . . 24 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 26 - Normative . . . . . . . . . . . . . . . . . . . . . . . . . 25 - Informative . . . . . . . . . . . . . . . . . . . . . . . . 25 - A. Contibutors . . . . . . . . . . . . . . . . . . . . . . . . 27 - Intellectual Property and Copyright Statements . . . . . . . 28 - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 2] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - -1. Contributors - - The major original contributors of this document were: Tatu Ylonen, - Tero Kivinen, Timo J. Rinne, Sami Lehtinen (all of SSH Communications - Security Corp), and Markku-Juhani O. Saarinen (University of - Jyvaskyla) - - The document editor is: [email protected]. Comments on this - internet draft should be sent to the IETF SECSH working group, - details at: http://ietf.org/html.charters/secsh-charter.html - -2. Introduction - - The SSH transport layer is a secure low level transport protocol. It - provides strong encryption, cryptographic host authentication, and - integrity protection. - - Authentication in this protocol level is host-based; this protocol - does not perform user authentication. A higher level protocol for - user authentication can be designed on top of this protocol. - - The protocol has been designed to be simple, flexible, to allow - parameter negotiation, and to minimize the number of round-trips. - Key exchange method, public key algorithm, symmetric encryption - algorithm, message authentication algorithm, and hash algorithm are - all negotiated. It is expected that in most environments, only 2 - round-trips will be needed for full key exchange, server - authentication, service request, and acceptance notification of - service request. The worst case is 3 round-trips. - -3. Conventions Used in This Document - - The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", - and "MAY" that appear in this document are to be interpreted as - described in [RFC2119]. - - The used data types and terminology are specified in the architecture - document [SSH-ARCH]. - - The architecture document also discusses the algorithm naming - conventions that MUST be used with the SSH protocols. - -4. Connection Setup - - SSH works over any 8-bit clean, binary-transparent transport. The - underlying transport SHOULD protect against transmission errors as - such errors cause the SSH connection to terminate. - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 3] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - The client initiates the connection. - -4.1 Use over TCP/IP - - When used over TCP/IP, the server normally listens for connections on - port 22. This port number has been registered with the IANA, and has - been officially assigned for SSH. - -4.2 Protocol Version Exchange - - When the connection has been established, both sides MUST send an - identification string of the form "SSH-protoversion-softwareversion - comments", followed by carriage return and newline characters (ASCII - 13 and 10, respectively). Both sides MUST be able to process - identification strings without carriage return character. No null - character is sent. The maximum length of the string is 255 - characters, including the carriage return and newline. - - The part of the identification string preceding carriage return and - newline is used in the Diffie-Hellman key exchange (see Section - Section 7). - - The server MAY send other lines of data before sending the version - string. Each line SHOULD be terminated by a carriage return and - newline. Such lines MUST NOT begin with "SSH-", and SHOULD be - encoded in ISO-10646 UTF-8 [RFC2279] (language is not specified). - Clients MUST be able to process such lines; they MAY be silently - ignored, or MAY be displayed to the client user; if they are - displayed, control character filtering discussed in [SSH-ARCH] SHOULD - be used. The primary use of this feature is to allow TCP-wrappers to - display an error message before disconnecting. - - Version strings MUST consist of printable US-ASCII characters, not - including whitespaces or a minus sign (-). The version string is - primarily used to trigger compatibility extensions and to indicate - the capabilities of an implementation. The comment string should - contain additional information that might be useful in solving user - problems. - - The protocol version described in this document is 2.0. - - Key exchange will begin immediately after sending this identifier. - All packets following the identification string SHALL use the binary - packet protocol, to be described below. - -4.3 Compatibility With Old SSH Versions - - During the transition period, it is important to be able to work in a - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 4] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - way that is compatible with the installed SSH clients and servers - that use an older version of the protocol. Information in this - section is only relevant for implementations supporting compatibility - with SSH versions 1.x. There is no standards track or informational - draft available that defines the SSH 1.x protocol. The only known - documentation of the 1.x protocol is contained in README files that - are shipped along with the source code. - -4.3.1 Old Client, New Server - - Server implementations MAY support a configurable "compatibility" - flag that enables compatibility with old versions. When this flag is - on, the server SHOULD identify its protocol version as "1.99". - Clients using protocol 2.0 MUST be able to identify this as identical - to "2.0". In this mode the server SHOULD NOT send the carriage - return character (ASCII 13) after the version identification string. - - In the compatibility mode the server SHOULD NOT send any further data - after its initialization string until it has received an - identification string from the client. The server can then determine - whether the client is using an old protocol, and can revert to the - old protocol if required. In the compatibility mode, the server MUST - NOT send additional data before the version string. - - When compatibility with old clients is not needed, the server MAY - send its initial key exchange data immediately after the - identification string. - -4.3.2 New Client, Old Server - - Since the new client MAY immediately send additional data after its - identification string (before receiving server's identification), the - old protocol may already have been corrupted when the client learns - that the server is old. When this happens, the client SHOULD close - the connection to the server, and reconnect using the old protocol. - -5. Binary Packet Protocol - - Each packet is in the following format: - - uint32 packet_length - byte padding_length - byte[n1] payload; n1 = packet_length - padding_length - 1 - byte[n2] random padding; n2 = padding_length - byte[m] mac (message authentication code); m = mac_length - - packet_length - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 5] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - The length of the packet (bytes), not including MAC or the - packet_length field itself. - - padding_length - Length of padding (bytes). - - payload - The useful contents of the packet. If compression has been - negotiated, this field is compressed. Initially, compression - MUST be "none". - - random padding - Arbitrary-length padding, such that the total length of - (packet_length || padding_length || payload || padding) is a - multiple of the cipher block size or 8, whichever is larger. - There MUST be at least four bytes of padding. The padding - SHOULD consist of random bytes. The maximum amount of padding - is 255 bytes. - - mac - Message authentication code. If message authentication has - been negotiated, this field contains the MAC bytes. Initially, - the MAC algorithm MUST be "none". - - - Note that length of the concatenation of packet length, padding - length, payload, and padding MUST be a multiple of the cipher block - size or 8, whichever is larger. This constraint MUST be enforced - even when using stream ciphers. Note that the packet length field is - also encrypted, and processing it requires special care when sending - or receiving packets. - - The minimum size of a packet is 16 (or the cipher block size, - whichever is larger) bytes (plus MAC); implementations SHOULD decrypt - the length after receiving the first 8 (or cipher block size, - whichever is larger) bytes of a packet. - -5.1 Maximum Packet Length - - All implementations MUST be able to process packets with uncompressed - payload length of 32768 bytes or less and total packet size of 35000 - bytes or less (including length, padding length, payload, padding, - and MAC.). The maximum of 35000 bytes is an arbitrary chosen value - larger than uncompressed size. Implementations SHOULD support longer - packets, where they might be needed, e.g. if an implementation wants - to send a very large number of certificates. Such packets MAY be - sent if the version string indicates that the other party is able to - process them. However, implementations SHOULD check that the packet - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 6] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - length is reasonable for the implementation to avoid - denial-of-service and/or buffer overflow attacks. - -5.2 Compression - - If compression has been negotiated, the payload field (and only it) - will be compressed using the negotiated algorithm. The length field - and MAC will be computed from the compressed payload. Encryption will - be done after compression. - - Compression MAY be stateful, depending on the method. Compression - MUST be independent for each direction, and implementations MUST - allow independently choosing the algorithm for each direction. - - The following compression methods are currently defined: - - none REQUIRED no compression - zlib OPTIONAL ZLIB (LZ77) compression - - The "zlib" compression is described in [RFC1950] and in [RFC1951]. - The compression context is initialized after each key exchange, and - is passed from one packet to the next with only a partial flush being - performed at the end of each packet. A partial flush means that the - current compressed block is ended and all data will be output. If the - current block is not a stored block, one or more empty blocks are - added after the current block to ensure that there are at least 8 - bits counting from the start of the end-of-block code of the current - block to the end of the packet payload. - - Additional methods may be defined as specified in [SSH-ARCH]. - -5.3 Encryption - - An encryption algorithm and a key will be negotiated during the key - exchange. When encryption is in effect, the packet length, padding - length, payload and padding fields of each packet MUST be encrypted - with the given algorithm. - - The encrypted data in all packets sent in one direction SHOULD be - considered a single data stream. For example, initialization vectors - SHOULD be passed from the end of one packet to the beginning of the - next packet. All ciphers SHOULD use keys with an effective key length - of 128 bits or more. - - The ciphers in each direction MUST run independently of each other, - and implementations MUST allow independently choosing the algorithm - for each direction (if multiple algorithms are allowed by local - policy). - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 7] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - The following ciphers are currently defined: - - 3des-cbc REQUIRED three-key 3DES in CBC mode - blowfish-cbc OPTIONALi Blowfish in CBC mode - twofish256-cbc OPTIONAL Twofish in CBC mode, - with 256-bit key - twofish-cbc OPTIONAL alias for "twofish256-cbc" (this - is being retained for - historical reasons) - twofish192-cbc OPTIONAL Twofish with 192-bit key - twofish128-cbc OPTIONAL Twofish with 128-bit key - aes256-cbc OPTIONAL AES (Rijndael) in CBC mode, - with 256-bit key - aes192-cbc OPTIONAL AES with 192-bit key - aes128-cbc RECOMMENDED AES with 128-bit key - serpent256-cbc OPTIONAL Serpent in CBC mode, with - 256-bit key - serpent192-cbc OPTIONAL Serpent with 192-bit key - serpent128-cbc OPTIONAL Serpent with 128-bit key - arcfour OPTIONAL the ARCFOUR stream cipher - idea-cbc OPTIONAL IDEA in CBC mode - cast128-cbc OPTIONAL CAST-128 in CBC mode - none OPTIONAL no encryption; NOT RECOMMENDED - - The "3des-cbc" cipher is three-key triple-DES - (encrypt-decrypt-encrypt), where the first 8 bytes of the key are - used for the first encryption, the next 8 bytes for the decryption, - and the following 8 bytes for the final encryption. This requires 24 - bytes of key data (of which 168 bits are actually used). To - implement CBC mode, outer chaining MUST be used (i.e., there is only - one initialization vector). This is a block cipher with 8 byte - blocks. This algorithm is defined in [FIPS-46-3] - - The "blowfish-cbc" cipher is Blowfish in CBC mode, with 128 bit keys - [SCHNEIER]. This is a block cipher with 8 byte blocks. - - The "twofish-cbc" or "twofish256-cbc" cipher is Twofish in CBC mode, - with 256 bit keys as described [TWOFISH]. This is a block cipher with - 16 byte blocks. - - The "twofish192-cbc" cipher. Same as above but with 192-bit key. - - The "twofish128-cbc" cipher. Same as above but with 128-bit key. - - The "aes256-cbc" cipher is AES (Advanced Encryption Standard) - [FIPS-197], formerly Rijndael, in CBC mode. This version uses 256-bit - key. - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 8] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - The "aes192-cbc" cipher. Same as above but with 192-bit key. - - The "aes128-cbc" cipher. Same as above but with 128-bit key. - - The "serpent256-cbc" cipher in CBC mode, with 256-bit key as - described in the Serpent AES submission. - - The "serpent192-cbc" cipher. Same as above but with 192-bit key. - - The "serpent128-cbc" cipher. Same as above but with 128-bit key. - - The "arcfour" is the Arcfour stream cipher with 128 bit keys. The - Arcfour cipher is believed to be compatible with the RC4 cipher - [SCHNEIER]. RC4 is a registered trademark of RSA Data Security Inc. - Arcfour (and RC4) has problems with weak keys, and should be used - with caution. - - The "idea-cbc" cipher is the IDEA cipher in CBC mode [SCHNEIER]. - - The "cast128-cbc" cipher is the CAST-128 cipher in CBC mode - [RFC2144]. - - The "none" algorithm specifies that no encryption is to be done. - Note that this method provides no confidentiality protection, and it - is not recommended. Some functionality (e.g. password - authentication) may be disabled for security reasons if this cipher - is chosen. - - Additional methods may be defined as specified in [SSH-ARCH]. - -5.4 Data Integrity - - Data integrity is protected by including with each packet a message - authentication code (MAC) that is computed from a shared secret, - packet sequence number, and the contents of the packet. - - The message authentication algorithm and key are negotiated during - key exchange. Initially, no MAC will be in effect, and its length - MUST be zero. After key exchange, the selected MAC will be computed - before encryption from the concatenation of packet data: - - mac = MAC(key, sequence_number || unencrypted_packet) - - where unencrypted_packet is the entire packet without MAC (the length - fields, payload and padding), and sequence_number is an implicit - packet sequence number represented as uint32. The sequence number is - initialized to zero for the first packet, and is incremented after - every packet (regardless of whether encryption or MAC is in use). It - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 9] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - is never reset, even if keys/algorithms are renegotiated later. It - wraps around to zero after every 2^32 packets. The packet sequence - number itself is not included in the packet sent over the wire. - - The MAC algorithms for each direction MUST run independently, and - implementations MUST allow choosing the algorithm independently for - both directions. - - The MAC bytes resulting from the MAC algorithm MUST be transmitted - without encryption as the last part of the packet. The number of MAC - bytes depends on the algorithm chosen. - - The following MAC algorithms are currently defined: - - hmac-sha1 REQUIRED HMAC-SHA1 (digest length = key - length = 20) - hmac-sha1-96 RECOMMENDED first 96 bits of HMAC-SHA1 (digest - length = 12, key length = 20) - hmac-md5 OPTIONAL HMAC-MD5 (digest length = key - length = 16) - hmac-md5-96 OPTIONAL first 96 bits of HMAC-MD5 (digest - length = 12, key length = 16) - none OPTIONAL no MAC; NOT RECOMMENDED - - Figure 1 - - The "hmac-*" algorithms are described in [RFC2104] The "*-n" MACs use - only the first n bits of the resulting value. - - The hash algorithms are described in [SCHNEIER]. - - Additional methods may be defined as specified in [SSH-ARCH]. - -5.5 Key Exchange Methods - - The key exchange method specifies how one-time session keys are - generated for encryption and for authentication, and how the server - authentication is done. - - Only one REQUIRED key exchange method has been defined: - - diffie-hellman-group1-sha1 REQUIRED - - This method is described later in this document. - - Additional methods may be defined as specified in [SSH-ARCH]. - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 10] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - -5.6 Public Key Algorithms - - This protocol has been designed to be able to operate with almost any - public key format, encoding, and algorithm (signature and/or - encryption). - - There are several aspects that define a public key type: - o Key format: how is the key encoded and how are certificates - represented. The key blobs in this protocol MAY contain - certificates in addition to keys. - o Signature and/or encryption algorithms. Some key types may not - support both signing and encryption. Key usage may also be - restricted by policy statements in e.g. certificates. In this - case, different key types SHOULD be defined for the different - policy alternatives. - o Encoding of signatures and/or encrypted data. This includes but is - not limited to padding, byte order, and data formats. - - The following public key and/or certificate formats are currently defined: - - ssh-dss REQUIRED sign Raw DSS Key - ssh-rsa RECOMMENDED sign Raw RSA Key - x509v3-sign-rsa OPTIONAL sign X.509 certificates (RSA key) - x509v3-sign-dss OPTIONAL sign X.509 certificates (DSS key) - spki-sign-rsa OPTIONAL sign SPKI certificates (RSA key) - spki-sign-dss OPTIONAL sign SPKI certificates (DSS key) - pgp-sign-rsa OPTIONAL sign OpenPGP certificates (RSA key) - pgp-sign-dss OPTIONAL sign OpenPGP certificates (DSS key) - - Additional key types may be defined as specified in [SSH-ARCH]. - - The key type MUST always be explicitly known (from algorithm - negotiation or some other source). It is not normally included in - the key blob. - - Certificates and public keys are encoded as follows: - - string certificate or public key format identifier - byte[n] key/certificate data - - The certificate part may have be a zero length string, but a public - key is required. This is the public key that will be used for - authentication; the certificate sequence contained in the certificate - blob can be used to provide authorization. - - Public key / certifcate formats that do not explicitly specify a - signature format identifier MUST use the public key / certificate - format identifier as the signature identifier. - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 11] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - Signatures are encoded as follows: - string signature format identifier (as specified by the - public key / cert format) - byte[n] signature blob in format specific encoding. - - - The "ssh-dss" key format has the following specific encoding: - - string "ssh-dss" - mpint p - mpint q - mpint g - mpint y - - Here the p, q, g, and y parameters form the signature key blob. - - Signing and verifying using this key format is done according to the - Digital Signature Standard [FIPS-186] using the SHA-1 hash. A - description can also be found in [SCHNEIER]. - - The resulting signature is encoded as follows: - - string "ssh-dss" - string dss_signature_blob - - dss_signature_blob is encoded as a string containing r followed by s - (which are 160 bits long integers, without lengths or padding, - unsigned and in network byte order). - - The "ssh-rsa" key format has the following specific encoding: - - string "ssh-rsa" - mpint e - mpint n - - Here the e and n parameters form the signature key blob. - - Signing and verifying using this key format is done according to - [SCHNEIER] and [PKCS1] using the SHA-1 hash. - - The resulting signature is encoded as follows: - - string "ssh-rsa" - string rsa_signature_blob - - rsa_signature_blob is encoded as a string containing s (which is an - integer, without lengths or padding, unsigned and in network byte - order). - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 12] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - The "spki-sign-rsa" method indicates that the certificate blob - contains a sequence of SPKI certificates. The format of SPKI - certificates is described in [RFC2693]. This method indicates that - the key (or one of the keys in the certificate) is an RSA-key. - - The "spki-sign-dss". As above, but indicates that the key (or one of - the keys in the certificate) is a DSS-key. - - The "pgp-sign-rsa" method indicates the certificates, the public key, - and the signature are in OpenPGP compatible binary format - ([RFC2440]). This method indicates that the key is an RSA-key. - - The "pgp-sign-dss". As above, but indicates that the key is a - DSS-key. - -6. Key Exchange - - Key exchange begins by each side sending lists of supported - algorithms. Each side has a preferred algorithm in each category, and - it is assumed that most implementations at any given time will use - the same preferred algorithm. Each side MAY guess which algorithm - the other side is using, and MAY send an initial key exchange packet - according to the algorithm if appropriate for the preferred method. - - Guess is considered wrong, if: - o the kex algorithm and/or the host key algorithm is guessed wrong - (server and client have different preferred algorithm), or - o if any of the other algorithms cannot be agreed upon (the - procedure is defined below in Section Section 6.1). - - Otherwise, the guess is considered to be right and the optimistically - sent packet MUST be handled as the first key exchange packet. - - However, if the guess was wrong, and a packet was optimistically sent - by one or both parties, such packets MUST be ignored (even if the - error in the guess would not affect the contents of the initial - packet(s)), and the appropriate side MUST send the correct initial - packet. - - Server authentication in the key exchange MAY be implicit. After a - key exchange with implicit server authentication, the client MUST - wait for response to its service request message before sending any - further data. - -6.1 Algorithm Negotiation - - Key exchange begins by each side sending the following packet: - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 13] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - byte SSH_MSG_KEXINIT - byte[16] cookie (random bytes) - string kex_algorithms - string server_host_key_algorithms - string encryption_algorithms_client_to_server - string encryption_algorithms_server_to_client - string mac_algorithms_client_to_server - string mac_algorithms_server_to_client - string compression_algorithms_client_to_server - string compression_algorithms_server_to_client - string languages_client_to_server - string languages_server_to_client - boolean first_kex_packet_follows - uint32 0 (reserved for future extension) - - Each of the algorithm strings MUST be a comma-separated list of - algorithm names (see ''Algorithm Naming'' in [SSH-ARCH]). Each - supported (allowed) algorithm MUST be listed in order of preference. - - The first algorithm in each list MUST be the preferred (guessed) - algorithm. Each string MUST contain at least one algorithm name. - - - cookie - The cookie MUST be a random value generated by the sender. Its - purpose is to make it impossible for either side to fully - determine the keys and the session identifier. - - kex_algorithms - Key exchange algorithms were defined above. The first - algorithm MUST be the preferred (and guessed) algorithm. If - both sides make the same guess, that algorithm MUST be used. - Otherwise, the following algorithm MUST be used to choose a key - exchange method: iterate over client's kex algorithms, one at a - time. Choose the first algorithm that satisfies the following - conditions: - + the server also supports the algorithm, - + if the algorithm requires an encryption-capable host key, - there is an encryption-capable algorithm on the server's - server_host_key_algorithms that is also supported by the - client, and - + if the algorithm requires a signature-capable host key, - there is a signature-capable algorithm on the server's - server_host_key_algorithms that is also supported by the - client. - + If no algorithm satisfying all these conditions can be - found, the connection fails, and both sides MUST disconnect. - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 14] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - server_host_key_algorithms - List of the algorithms supported for the server host key. The - server lists the algorithms for which it has host keys; the - client lists the algorithms that it is willing to accept. - (There MAY be multiple host keys for a host, possibly with - different algorithms.) - - Some host keys may not support both signatures and encryption - (this can be determined from the algorithm), and thus not all - host keys are valid for all key exchange methods. - - Algorithm selection depends on whether the chosen key exchange - algorithm requires a signature or encryption capable host key. - It MUST be possible to determine this from the public key - algorithm name. The first algorithm on the client's list that - satisfies the requirements and is also supported by the server - MUST be chosen. If there is no such algorithm, both sides MUST - disconnect. - - encryption_algorithms - Lists the acceptable symmetric encryption algorithms in order - of preference. The chosen encryption algorithm to each - direction MUST be the first algorithm on the client's list - that is also on the server's list. If there is no such - algorithm, both sides MUST disconnect. - - Note that "none" must be explicitly listed if it is to be - acceptable. The defined algorithm names are listed in Section - Section 5.3. - - mac_algorithms - Lists the acceptable MAC algorithms in order of preference. - The chosen MAC algorithm MUST be the first algorithm on the - client's list that is also on the server's list. If there is - no such algorithm, both sides MUST disconnect. - - Note that "none" must be explicitly listed if it is to be - acceptable. The MAC algorithm names are listed in Section - Figure 1. - - compression_algorithms - Lists the acceptable compression algorithms in order of - preference. The chosen compression algorithm MUST be the first - algorithm on the client's list that is also on the server's - list. If there is no such algorithm, both sides MUST - disconnect. - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 15] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - Note that "none" must be explicitly listed if it is to be - acceptable. The compression algorithm names are listed in - Section Section 5.2. - - languages - This is a comma-separated list of language tags in order of - preference [RFC3066]. Both parties MAY ignore this list. If - there are no language preferences, this list SHOULD be empty. - Language tags SHOULD NOT be present unless they are known to be - needed by the sending party. - - first_kex_packet_follows - Indicates whether a guessed key exchange packet follows. If a - guessed packet will be sent, this MUST be TRUE. If no guessed - packet will be sent, this MUST be FALSE. - - After receiving the SSH_MSG_KEXINIT packet from the other side, - each party will know whether their guess was right. If the - other party's guess was wrong, and this field was TRUE, the - next packet MUST be silently ignored, and both sides MUST then - act as determined by the negotiated key exchange method. If - the guess was right, key exchange MUST continue using the - guessed packet. - - After the KEXINIT packet exchange, the key exchange algorithm is run. - It may involve several packet exchanges, as specified by the key - exchange method. - -6.2 Output from Key Exchange - - The key exchange produces two values: a shared secret K, and an - exchange hash H. Encryption and authentication keys are derived from - these. The exchange hash H from the first key exchange is - additionally used as the session identifier, which is a unique - identifier for this connection. It is used by authentication methods - as a part of the data that is signed as a proof of possession of a - private key. Once computed, the session identifier is not changed, - even if keys are later re-exchanged. - - - Each key exchange method specifies a hash function that is used in - the key exchange. The same hash algorithm MUST be used in key - derivation. Here, we'll call it HASH. - - - Encryption keys MUST be computed as HASH of a known value and K as - follows: - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 16] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - o Initial IV client to server: HASH(K || H || "A" || session_id) - (Here K is encoded as mpint and "A" as byte and session_id as raw - data."A" means the single character A, ASCII 65). - o Initial IV server to client: HASH(K || H || "B" || session_id) - o Encryption key client to server: HASH(K || H || "C" || session_id) - o Encryption key server to client: HASH(K || H || "D" || session_id) - o Integrity key client to server: HASH(K || H || "E" || session_id) - o Integrity key server to client: HASH(K || H || "F" || session_id) - - Key data MUST be taken from the beginning of the hash output. 128 - bits (16 bytes) MUST be used for algorithms with variable-length - keys. The only variable key length algorithm defined in this document - is arcfour). For other algorithms, as many bytes as are needed are - taken from the beginning of the hash value. If the key length needed - is longer than the output of the HASH, the key is extended by - computing HASH of the concatenation of K and H and the entire key so - far, and appending the resulting bytes (as many as HASH generates) to - the key. This process is repeated until enough key material is - available; the key is taken from the beginning of this value. In - other words: - - K1 = HASH(K || H || X || session_id) (X is e.g. "A") - K2 = HASH(K || H || K1) - K3 = HASH(K || H || K1 || K2) - ... - key = K1 || K2 || K3 || ... - - This process will lose entropy if the amount of entropy in K is - larger than the internal state size of HASH. - -6.3 Taking Keys Into Use - - Key exchange ends by each side sending an SSH_MSG_NEWKEYS message. - This message is sent with the old keys and algorithms. All messages - sent after this message MUST use the new keys and algorithms. - - - When this message is received, the new keys and algorithms MUST be - taken into use for receiving. - - - This message is the only valid message after key exchange, in - addition to SSH_MSG_DEBUG, SSH_MSG_DISCONNECT and SSH_MSG_IGNORE - messages. The purpose of this message is to ensure that a party is - able to respond with a disconnect message that the other party can - understand if something goes wrong with the key exchange. - Implementations MUST NOT accept any other messages after key exchange - before receiving SSH_MSG_NEWKEYS. - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 17] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - byte SSH_MSG_NEWKEYS - - -7. Diffie-Hellman Key Exchange - - The Diffie-Hellman key exchange provides a shared secret that can not - be determined by either party alone. The key exchange is combined - with a signature with the host key to provide host authentication. - - - In the following description (C is the client, S is the server; p is - a large safe prime, g is a generator for a subgroup of GF(p), and q - is the order of the subgroup; V_S is S's version string; V_C is C's - version string; K_S is S's public host key; I_C is C's KEXINIT - message and I_S S's KEXINIT message which have been exchanged before - this part begins): - - - 1. C generates a random number x (1 < x < q) and computes e = g^x - mod p. C sends "e" to S. - - 2. S generates a random number y (0 < y < q) and computes f = g^y - mod p. S receives "e". It computes K = e^y mod p, H = hash(V_C - || V_S || I_C || I_S || K_S || e || f || K) (these elements are - encoded according to their types; see below), and signature s on - H with its private host key. S sends "K_S || f || s" to C. The - signing operation may involve a second hashing operation. - - 3. C verifies that K_S really is the host key for S (e.g. using - certificates or a local database). C is also allowed to accept - the key without verification; however, doing so will render the - protocol insecure against active attacks (but may be desirable - for practical reasons in the short term in many environments). C - then computes K = f^x mod p, H = hash(V_C || V_S || I_C || I_S || - K_S || e || f || K), and verifies the signature s on H. - - Either side MUST NOT send or accept e or f values that are not in the - range [1, p-1]. If this condition is violated, the key exchange - fails. - - - This is implemented with the following messages. The hash algorithm - for computing the exchange hash is defined by the method name, and is - called HASH. The public key algorithm for signing is negotiated with - the KEXINIT messages. - - First, the client sends the following: - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 18] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - byte SSH_MSG_KEXDH_INIT - mpint e - - - The server responds with the following: - - byte SSH_MSG_KEXDH_REPLY - string server public host key and certificates (K_S) - mpint f - string signature of H - - The hash H is computed as the HASH hash of the concatenation of the - following: - - string V_C, the client's version string (CR and NL excluded) - string V_S, the server's version string (CR and NL excluded) - string I_C, the payload of the client's SSH_MSG_KEXINIT - string I_S, the payload of the server's SSH_MSG_KEXINIT - string K_S, the host key - mpint e, exchange value sent by the client - mpint f, exchange value sent by the server - mpint K, the shared secret - - This value is called the exchange hash, and it is used to - authenticate the key exchange. The exchange hash SHOULD be kept - secret. - - - The signature algorithm MUST be applied over H, not the original - data. Most signature algorithms include hashing and additional - padding. For example, "ssh-dss" specifies SHA-1 hashing; in that - case, the data is first hashed with HASH to compute H, and H is then - hashed with SHA-1 as part of the signing operation. - -7.1 diffie-hellman-group1-sha1 - - The "diffie-hellman-group1-sha1" method specifies Diffie-Hellman key - exchange with SHA-1 as HASH, and Oakley group 14 [RFC3526] (2048-bit - MODP Group). It is included below in hexadecimal and decimal. - - The prime p is equal to 2^1024 - 2^960 - 1 + 2^64 * floor( 2^894 Pi + - 129093 ). Its hexadecimal value is: - - FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1 - 29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD - EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245 - E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED - EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381 - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 19] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - FFFFFFFF FFFFFFFF. - - In decimal, this value is: - - 179769313486231590770839156793787453197860296048756011706444 - 423684197180216158519368947833795864925541502180565485980503 - 646440548199239100050792877003355816639229553136239076508735 - 759914822574862575007425302077447712589550957937778424442426 - 617334727629299387668709205606050270810842907692932019128194 - 467627007. - - The generator used with this prime is g = 2. The group order q is (p - - 1) / 2. - -8. Key Re-Exchange - - Key re-exchange is started by sending an SSH_MSG_KEXINIT packet when - not already doing a key exchange (as described in Section Section - 6.1). When this message is received, a party MUST respond with its - own SSH_MSG_KEXINIT message except when the received SSH_MSG_KEXINIT - already was a reply. Either party MAY initiate the re-exchange, but - roles MUST NOT be changed (i.e., the server remains the server, and - the client remains the client). - - - Key re-exchange is performed using whatever encryption was in effect - when the exchange was started. Encryption, compression, and MAC - methods are not changed before a new SSH_MSG_NEWKEYS is sent after - the key exchange (as in the initial key exchange). Re-exchange is - processed identically to the initial key exchange, except for the - session identifier that will remain unchanged. It is permissible to - change some or all of the algorithms during the re-exchange. Host - keys can also change. All keys and initialization vectors are - recomputed after the exchange. Compression and encryption contexts - are reset. - - - It is recommended that the keys are changed after each gigabyte of - transmitted data or after each hour of connection time, whichever - comes sooner. However, since the re-exchange is a public key - operation, it requires a fair amount of processing power and should - not be performed too often. - - - More application data may be sent after the SSH_MSG_NEWKEYS packet - has been sent; key exchange does not affect the protocols that lie - above the SSH transport layer. - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 20] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - -9. Service Request - - After the key exchange, the client requests a service. The service is - identified by a name. The format of names and procedures for defining - new names are defined in [SSH-ARCH]. - - - Currently, the following names have been reserved: - - ssh-userauth - ssh-connection - - Similar local naming policy is applied to the service names, as is - applied to the algorithm names; a local service should use the - "servicename@domain" syntax. - - byte SSH_MSG_SERVICE_REQUEST - string service name - - If the server rejects the service request, it SHOULD send an - appropriate SSH_MSG_DISCONNECT message and MUST disconnect. - - - When the service starts, it may have access to the session identifier - generated during the key exchange. - - - If the server supports the service (and permits the client to use - it), it MUST respond with the following: - - byte SSH_MSG_SERVICE_ACCEPT - string service name - - Message numbers used by services should be in the area reserved for - them (see Section 6 in [SSH-ARCH]). The transport level will - continue to process its own messages. - - - Note that after a key exchange with implicit server authentication, - the client MUST wait for response to its service request message - before sending any further data. - -10. Additional Messages - - Either party may send any of the following messages at any time. - - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 21] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - -10.1 Disconnection Message - - byte SSH_MSG_DISCONNECT - uint32 reason code - string description [RFC2279] - string language tag [RFC3066] - - This message causes immediate termination of the connection. All - implementations MUST be able to process this message; they SHOULD be - able to send this message. - - The sender MUST NOT send or receive any data after this message, and - the recipient MUST NOT accept any data after receiving this message. - The description field gives a more specific explanation in a - human-readable form. The error code gives the reason in a more - machine-readable format (suitable for localization), and can have the - following values: - - #define SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1 - #define SSH_DISCONNECT_PROTOCOL_ERROR 2 - #define SSH_DISCONNECT_KEY_EXCHANGE_FAILED 3 - #define SSH_DISCONNECT_RESERVED 4 - #define SSH_DISCONNECT_MAC_ERROR 5 - #define SSH_DISCONNECT_COMPRESSION_ERROR 6 - #define SSH_DISCONNECT_SERVICE_NOT_AVAILABLE 7 - #define SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8 - #define SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9 - #define SSH_DISCONNECT_CONNECTION_LOST 10 - #define SSH_DISCONNECT_BY_APPLICATION 11 - #define SSH_DISCONNECT_TOO_MANY_CONNECTIONS 12 - #define SSH_DISCONNECT_AUTH_CANCELLED_BY_USER 13 - #define SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14 - #define SSH_DISCONNECT_ILLEGAL_USER_NAME 15 - - If the description string is displayed, control character filtering - discussed in [SSH-ARCH] should be used to avoid attacks by sending - terminal control characters. - -10.2 Ignored Data Message - - byte SSH_MSG_IGNORE - string data - - All implementations MUST understand (and ignore) this message at any - time (after receiving the protocol version). No implementation is - required to send them. This message can be used as an additional - protection measure against advanced traffic analysis techniques. - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 22] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - -10.3 Debug Message - - byte SSH_MSG_DEBUG - boolean always_display - string message [RFC2279] - string language tag [RFC3066] - - All implementations MUST understand this message, but they are - allowed to ignore it. This message is used to pass the other side - information that may help debugging. If always_display is TRUE, the - message SHOULD be displayed. Otherwise, it SHOULD NOT be displayed - unless debugging information has been explicitly requested by the - user. - - - The message doesn't need to contain a newline. It is, however, - allowed to consist of multiple lines separated by CRLF (Carriage - Return - Line Feed) pairs. - - - If the message string is displayed, terminal control character - filtering discussed in [SSH-ARCH] should be used to avoid attacks by - sending terminal control characters. - -10.4 Reserved Messages - - An implementation MUST respond to all unrecognized messages with an - SSH_MSG_UNIMPLEMENTED message in the order in which the messages were - received. Such messages MUST be otherwise ignored. Later protocol - versions may define other meanings for these message types. - - byte SSH_MSG_UNIMPLEMENTED - uint32 packet sequence number of rejected message - - -11. Summary of Message Numbers - - The following message numbers have been defined in this protocol: - - #define SSH_MSG_DISCONNECT 1 - #define SSH_MSG_IGNORE 2 - #define SSH_MSG_UNIMPLEMENTED 3 - #define SSH_MSG_DEBUG 4 - #define SSH_MSG_SERVICE_REQUEST 5 - #define SSH_MSG_SERVICE_ACCEPT 6 - - #define SSH_MSG_KEXINIT 20 - #define SSH_MSG_NEWKEYS 21 - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 23] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - /* Numbers 30-49 used for kex packets. - Different kex methods may reuse message numbers in - this range. */ - - #define SSH_MSG_KEXDH_INIT 30 - #define SSH_MSG_KEXDH_REPLY 31 - - -12. IANA Considerations - - This document is part of a set, the IANA considerations for the SSH - protocol as defined in [SSH-ARCH], [SSH-TRANS], [SSH-USERAUTH], - [SSH-CONNECT] are detailed in [SSH-NUMBERS]. - -13. Security Considerations - - This protocol provides a secure encrypted channel over an insecure - network. It performs server host authentication, key exchange, - encryption, and integrity protection. It also derives a unique - session id that may be used by higher-level protocols. - - Full security considerations for this protocol are provided in - Section 8 of [SSH-ARCH] - -14. Intellectual Property - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementers or users of this specification can - be obtained from the IETF Secretariat. - - The IETF has been notified of intellectual property rights claimed in - regard to some or all of the specification contained in this - document. For more information consult the online list of claimed - rights. - -15. Additional Information - - The current document editor is: [email protected]. Comments on - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 24] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - this internet draft should be sent to the IETF SECSH working group, - details at: http://ietf.org/html.charters/secsh-charter.html - -Normative - - [SSH-ARCH] - Ylonen, T., "SSH Protocol Architecture", I-D - draft-ietf-architecture-15.txt, Oct 2003. - - [SSH-TRANS] - Ylonen, T., "SSH Transport Layer Protocol", I-D - draft-ietf-transport-17.txt, Oct 2003. - - [SSH-USERAUTH] - Ylonen, T., "SSH Authentication Protocol", I-D - draft-ietf-userauth-18.txt, Oct 2003. - - [SSH-CONNECT] - Ylonen, T., "SSH Connection Protocol", I-D - draft-ietf-connect-18.txt, Oct 2003. - - [SSH-NUMBERS] - Lehtinen, S. and D. Moffat, "SSH Protocol Assigned - Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct - 2003. - - [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate - Requirement Levels", BCP 14, RFC 2119, March 1997. - -Informative - - [FIPS-186] - Federal Information Processing Standards Publication, - "FIPS PUB 186, Digital Signature Standard", May 1994. - - [FIPS-197] - NIST, "FIPS PUB 197 Advanced Encryption Standard (AES)", - November 2001. - - [FIPS-46-3] - U.S. Dept. of Commerce, "FIPS PUB 46-3, Data Encryption - Standard (DES)", October 1999. - - [RFC2459] Housley, R., Ford, W., Polk, T. and D. Solo, "Internet - X.509 Public Key Infrastructure Certificate and CRL - Profile", RFC 2459, January 1999. - - [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 25] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - STD 13, RFC 1034, November 1987. - - [RFC3066] Alvestrand, H., "Tags for the Identification of - Languages", BCP 47, RFC 3066, January 2001. - - [RFC1950] Deutsch, L. and J-L. Gailly, "ZLIB Compressed Data Format - Specification version 3.3", RFC 1950, May 1996. - - [RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification - version 1.3", RFC 1951, May 1996. - - [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO - 10646", RFC 2279, January 1998. - - [RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: - Keyed-Hashing for Message Authentication", RFC 2104, - February 1997. - - [RFC2144] Adams, C., "The CAST-128 Encryption Algorithm", RFC 2144, - May 1997. - - [RFC2440] Callas, J., Donnerhacke, L., Finney, H. and R. Thayer, - "OpenPGP Message Format", RFC 2440, November 1998. - - [RFC2693] Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas, - B. and T. Ylonen, "SPKI Certificate Theory", RFC 2693, - September 1999. - - [RFC3526] Kivinen, T. and M. Kojo, "More Modular Exponential (MODP) - Diffie-Hellman groups for Internet Key Exchange (IKE)", - RFC 3526, May 2003. - - [SCHNEIER] - Schneier, B., "Applied Cryptography Second Edition: - protocols algorithms and source in code in C", 1996. - - [TWOFISH] Schneier, B., "The Twofish Encryptions Algorithm: A - 128-Bit Block Cipher, 1st Edition", March 1999. - - - - - - - - - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 26] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - -Authors' Addresses - - Tatu Ylonen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - Darren J. Moffat (editor) - Sun Microsystems, Inc - 17 Network Circle - Menlo Park 95025 - USA - - EMail: [email protected] - -Appendix A. Contibutors - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 27] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - -Intellectual Property Statement - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementors or users of this specification can - be obtained from the IETF Secretariat. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights which may cover technology that may be required to practice - this standard. Please address the information to the IETF Executive - Director. - - The IETF has been notified of intellectual property rights claimed in - regard to some or all of the specification contained in this - document. For more information consult the online list of claimed - rights. - - -Full Copyright Statement - - Copyright (C) The Internet Society (2003). All Rights Reserved. - - This document and translations of it may be copied and furnished to - others, and derivative works that comment on or otherwise explain it - or assist in its implementation may be prepared, copied, published - and distributed, in whole or in part, without restriction of any - kind, provided that the above copyright notice and this paragraph are - included on all such copies and derivative works. However, this - document itself may not be modified in any way, such as by removing - the copyright notice or references to the Internet Society or other - Internet organizations, except as needed for the purpose of - developing Internet standards in which case the procedures for - copyrights defined in the Internet Standards process must be - followed, or as required to translate it into languages other than - English. - - The limited permissions granted above are perpetual and will not be - revoked by the Internet Society or its successors or assignees. - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 28] - -Internet-Draft SSH Transport Layer Protocol Oct 2003 - - - This document and the information contained herein is provided on an - "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING - TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING - BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION - HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF - MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - -Acknowledgment - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Moffat, Editor Expires March 31, 2004 [Page 29]
\ No newline at end of file diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-userauth-18.2.ps b/lib/ssh/doc/standard/draft-ietf-secsh-userauth-18.2.ps deleted file mode 100644 index be5799dbce..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-userauth-18.2.ps +++ /dev/null @@ -1,1881 +0,0 @@ -%!PS-Adobe-3.0 -%%BoundingBox: 75 0 595 747 -%%Title: Enscript Output -%%For: Magnus Thoang -%%Creator: GNU enscript 1.6.1 -%%CreationDate: Fri Oct 31 13:35:32 2003 -%%Orientation: Portrait -%%Pages: 8 0 -%%DocumentMedia: A4 595 842 0 () () -%%DocumentNeededResources: (atend) -%%EndComments -%%BeginProlog -%%BeginProcSet: PStoPS 1 15 -userdict begin -[/showpage/erasepage/copypage]{dup where{pop dup load - type/operatortype eq{1 array cvx dup 0 3 index cvx put - bind def}{pop}ifelse}{pop}ifelse}forall -[/letter/legal/executivepage/a4/a4small/b5/com10envelope - /monarchenvelope/c5envelope/dlenvelope/lettersmall/note - /folio/quarto/a5]{dup where{dup wcheck{exch{}put} - {pop{}def}ifelse}{pop}ifelse}forall -/setpagedevice {pop}bind 1 index where{dup wcheck{3 1 roll put} - 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matrix invertmatrix matrix concatmatrix - matrix invertmatrix put -%%EndSetup -%%Page: (0,1) 1 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 1 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 701 M -(Network Working Group T. Ylonen) s -5 690 M -(Internet-Draft SSH Communications Security Corp) s -5 679 M -(Expires: March 2, 2003 D. Moffat, Ed.) s -5 668 M -( Sun Microsystems, Inc) s -5 657 M -( September 2002) s -5 624 M -( SSH Authentication Protocol) s -5 613 M -( draft-ietf-secsh-userauth-18.txt) s -5 591 M -(Status of this Memo) s -5 569 M -( This document is an Internet-Draft and is in full conformance with) s -5 558 M -( all provisions of Section 10 of RFC2026.) s -5 536 M -( Internet-Drafts are working documents of the Internet Engineering) s -5 525 M -( Task Force \(IETF\), its areas, and its working groups. Note that other) s -5 514 M -( groups may also distribute working documents as Internet-Drafts.) s -5 492 M -( Internet-Drafts are draft documents valid for a maximum of six months) s -5 481 M -( and may be updated, replaced, or obsoleted by other documents at any) s -5 470 M -( time. It is inappropriate to use Internet-Drafts as reference) s -5 459 M -( material or to cite them other than as "work in progress.") s -5 437 M -( The list of current Internet-Drafts can be accessed at http://) s -5 426 M -( www.ietf.org/ietf/1id-abstracts.txt.) s -5 404 M -( The list of Internet-Draft Shadow Directories can be accessed at) s -5 393 M -( http://www.ietf.org/shadow.html.) s -5 371 M -( This Internet-Draft will expire on March 2, 2003.) s -5 349 M -(Copyright Notice) s -5 327 M -( Copyright \(C\) The Internet Society \(2002\). All Rights Reserved.) s -5 305 M -(Abstract) s -5 283 M -( SSH is a protocol for secure remote login and other secure network) s -5 272 M -( services over an insecure network. This document describes the SSH) s -5 261 M -( authentication protocol framework and public key, password, and) s -5 250 M -( host-based client authentication methods. Additional authentication) s -5 239 M -( methods are described in separate documents. The SSH authentication) s -5 228 M -( protocol runs on top of the SSH transport layer protocol and provides) s -5 217 M -( a single authenticated tunnel for the SSH connection protocol.) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 1]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 2 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -(Table of Contents) s -5 668 M -( 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 657 M -( 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3) s -5 646 M -( 3. Conventions Used in This Document . . . . . . . . . . . . . 3) s -5 635 M -( 3.1 The Authentication Protocol Framework . . . . . . . . . . . 3) s -5 624 M -( 3.1.1 Authentication Requests . . . . . . . . . . . . . . . . . . 4) s -5 613 M -( 3.1.2 Responses to Authentication Requests . . . . . . . . . . . . 5) s -5 602 M -( 3.1.3 The "none" Authentication Request . . . . . . . . . . . . . 6) s -5 591 M -( 3.1.4 Completion of User Authentication . . . . . . . . . . . . . 6) s -5 580 M -( 3.1.5 Banner Message . . . . . . . . . . . . . . . . . . . . . . . 7) s -5 569 M -( 3.2 Authentication Protocol Message Numbers . . . . . . . . . . 7) s -5 558 M -( 3.3 Public Key Authentication Method: publickey . . . . . . . . 8) s -5 547 M -( 3.4 Password Authentication Method: password . . . . . . . . . . 10) s -5 536 M -( 3.5 Host-Based Authentication: hostbased . . . . . . . . . . . . 11) s -5 525 M -( 4. Security Considerations . . . . . . . . . . . . . . . . . . 12) s -5 514 M -( Normative . . . . . . . . . . . . . . . . . . . . . . . . . 13) s -5 503 M -( Informative . . . . . . . . . . . . . . . . . . . . . . . . 13) s -5 492 M -( Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 14) s -5 481 M -( Intellectual Property and Copyright Statements . . . . . . . 15) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 2]) s -_R -S -PStoPSsaved restore -%%Page: (2,3) 2 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 3 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -(1. Contributors) s -5 668 M -( The major original contributors of this document were: Tatu Ylonen,) s -5 657 M -( Tero Kivinen, Timo J. Rinne, Sami Lehtinen \(all of SSH Communications) s -5 646 M -( Security Corp\), and Markku-Juhani O. Saarinen \(University of) s -5 635 M -( Jyvaskyla\)) s -5 613 M -( The document editor is: [email protected]. Comments on this) s -5 602 M -( internet draft should be sent to the IETF SECSH working group,) s -5 591 M -( details at: http://ietf.org/html.charters/secsh-charter.html) s -5 569 M -(2. Introduction) s -5 547 M -( The SSH authentication protocol is a general-purpose user) s -5 536 M -( authentication protocol. It is intended to be run over the SSH) s -5 525 M -( transport layer protocol [SSH-TRANS]. This protocol assumes that the) s -5 514 M -( underlying protocols provide integrity and confidentiality) s -5 503 M -( protection.) s -5 481 M -( This document should be read only after reading the SSH architecture) s -5 470 M -( document [SSH-ARCH]. This document freely uses terminology and) s -5 459 M -( notation from the architecture document without reference or further) s -5 448 M -( explanation.) s -5 426 M -( The service name for this protocol is "ssh-userauth".) s -5 404 M -( When this protocol starts, it receives the session identifier from) s -5 393 M -( the lower-level protocol \(this is the exchange hash H from the first) s -5 382 M -( key exchange\). The session identifier uniquely identifies this) s -5 371 M -( session and is suitable for signing in order to prove ownership of a) s -5 360 M -( private key. This protocol also needs to know whether the lower-level) s -5 349 M -( protocol provides confidentiality protection.) s -5 327 M -(3. Conventions Used in This Document) s -5 305 M -( The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",) s -5 294 M -( and "MAY" that appear in this document are to be interpreted as) s -5 283 M -( described in [RFC2119]) s -5 261 M -( The used data types and terminology are specified in the architecture) s -5 250 M -( document [SSH-ARCH]) s -5 228 M -( The architecture document also discusses the algorithm naming) s -5 217 M -( conventions that MUST be used with the SSH protocols.) s -5 195 M -(3.1 The Authentication Protocol Framework) s -5 173 M -( The server drives the authentication by telling the client which) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 3]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 4 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( authentication methods can be used to continue the exchange at any) s -5 679 M -( given time. The client has the freedom to try the methods listed by) s -5 668 M -( the server in any order. This gives the server complete control over) s -5 657 M -( the authentication process if desired, but also gives enough) s -5 646 M -( flexibility for the client to use the methods it supports or that are) s -5 635 M -( most convenient for the user, when multiple methods are offered by) s -5 624 M -( the server.) s -5 602 M -( Authentication methods are identified by their name, as defined in) s -5 591 M -( [SSH-ARCH]. The "none" method is reserved, and MUST NOT be listed as) s -5 580 M -( supported. However, it MAY be sent by the client. The server MUST) s -5 569 M -( always reject this request, unless the client is to be allowed in) s -5 558 M -( without any authentication, in which case the server MUST accept this) s -5 547 M -( request. The main purpose of sending this request is to get the list) s -5 536 M -( of supported methods from the server.) s -5 514 M -( The server SHOULD have a timeout for authentication, and disconnect) s -5 503 M -( if the authentication has not been accepted within the timeout) s -5 492 M -( period. The RECOMMENDED timeout period is 10 minutes. Additionally,) s -5 481 M -( the implementation SHOULD limit the number of failed authentication) s -5 470 M -( attempts a client may perform in a single session \(the RECOMMENDED) s -5 459 M -( limit is 20 attempts\). If the threshold is exceeded, the server) s -5 448 M -( SHOULD disconnect.) s -5 426 M -(3.1.1 Authentication Requests) s -5 404 M -( All authentication requests MUST use the following message format.) s -5 393 M -( Only the first few fields are defined; the remaining fields depend on) s -5 382 M -( the authentication method.) s -5 360 M -( byte SSH_MSG_USERAUTH_REQUEST) s -5 349 M -( string user name \(in ISO-10646 UTF-8 encoding [RFC2279]\)) s -5 338 M -( string service name \(in US-ASCII\)) s -5 327 M -( string method name \(US-ASCII\)) s -5 316 M -( The rest of the packet is method-specific.) s -5 294 M -( The user name and service are repeated in every new authentication) s -5 283 M -( attempt, and MAY change. The server implementation MUST carefully) s -5 272 M -( check them in every message, and MUST flush any accumulated) s -5 261 M -( authentication states if they change. If it is unable to flush some) s -5 250 M -( authentication state, it MUST disconnect if the user or service name) s -5 239 M -( changes.) s -5 217 M -( The service name specifies the service to start after authentication.) s -5 206 M -( There may be several different authenticated services provided. If) s -5 195 M -( the requested service is not available, the server MAY disconnect) s -5 184 M -( immediately or at any later time. Sending a proper disconnect) s -5 173 M -( message is RECOMMENDED. In any case, if the service does not exist,) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 4]) s -_R -S -PStoPSsaved restore -%%Page: (4,5) 3 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 5 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( authentication MUST NOT be accepted.) s -5 668 M -( If the requested user does not exist, the server MAY disconnect, or) s -5 657 M -( MAY send a bogus list of acceptable authentication methods, but never) s -5 646 M -( accept any. This makes it possible for the server to avoid) s -5 635 M -( disclosing information on which accounts exist. In any case, if the) s -5 624 M -( user does not exist, the authentication request MUST NOT be accepted.) s -5 602 M -( While there is usually little point for clients to send requests that) s -5 591 M -( the server does not list as acceptable, sending such requests is not) s -5 580 M -( an error, and the server SHOULD simply reject requests that it does) s -5 569 M -( not recognize.) s -5 547 M -( An authentication request MAY result in a further exchange of) s -5 536 M -( messages. All such messages depend on the authentication method) s -5 525 M -( used, and the client MAY at any time continue with a new) s -5 514 M -( SSH_MSG_USERAUTH_REQUEST message, in which case the server MUST) s -5 503 M -( abandon the previous authentication attempt and continue with the new) s -5 492 M -( one.) s -5 470 M -(3.1.2 Responses to Authentication Requests) s -5 448 M -( If the server rejects the authentication request, it MUST respond) s -5 437 M -( with the following:) s -5 415 M -( byte SSH_MSG_USERAUTH_FAILURE) s -5 404 M -( string authentications that can continue) s -5 393 M -( boolean partial success) s -5 371 M -( "Authentications that can continue" is a comma-separated list of) s -5 360 M -( authentication method names that may productively continue the) s -5 349 M -( authentication dialog.) s -5 327 M -( It is RECOMMENDED that servers only include those methods in the list) s -5 316 M -( that are actually useful. However, it is not illegal to include) s -5 305 M -( methods that cannot be used to authenticate the user.) s -5 283 M -( Already successfully completed authentications SHOULD NOT be included) s -5 272 M -( in the list, unless they really should be performed again for some) s -5 261 M -( reason.) s -5 239 M -( "Partial success" MUST be TRUE if the authentication request to which) s -5 228 M -( this is a response was successful. It MUST be FALSE if the request) s -5 217 M -( was not successfully processed.) s -5 195 M -( When the server accepts authentication, it MUST respond with the) s -5 184 M -( following:) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 5]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 6 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( byte SSH_MSG_USERAUTH_SUCCESS) s -5 668 M -( Note that this is not sent after each step in a multi-method) s -5 657 M -( authentication sequence, but only when the authentication is) s -5 646 M -( complete.) s -5 624 M -( The client MAY send several authentication requests without waiting) s -5 613 M -( for responses from previous requests. The server MUST process each) s -5 602 M -( request completely and acknowledge any failed requests with a) s -5 591 M -( SSH_MSG_USERAUTH_FAILURE message before processing the next request.) s -5 569 M -( A request that results in further exchange of messages will be) s -5 558 M -( aborted by a second request. It is not possible to send a second) s -5 547 M -( request without waiting for a response from the server, if the first) s -5 536 M -( request will result in further exchange of messages. No) s -5 525 M -( SSH_MSG_USERAUTH_FAILURE message will be sent for the aborted method.) s -5 503 M -( SSH_MSG_USERAUTH_SUCCESS MUST be sent only once. When) s -5 492 M -( SSH_MSG_USERAUTH_SUCCESS has been sent, any further authentication) s -5 481 M -( requests received after that SHOULD be silently ignored.) s -5 459 M -( Any non-authentication messages sent by the client after the request) s -5 448 M -( that resulted in SSH_MSG_USERAUTH_SUCCESS being sent MUST be passed) s -5 437 M -( to the service being run on top of this protocol. Such messages can) s -5 426 M -( be identified by their message numbers \(see Section Message Numbers) s -5 415 M -( \(Section 3.2\)\).) s -5 393 M -(3.1.3 The "none" Authentication Request) s -5 371 M -( A client may request a list of authentication methods that may) s -5 360 M -( continue by using the "none" authentication method.) s -5 338 M -( If no authentication at all is needed for the user, the server MUST) s -5 327 M -( return SSH_MSG_USERAUTH_SUCCESS. Otherwise, the server MUST return) s -5 316 M -( SSH_MSG_USERAUTH_FAILURE and MAY return with it a list of) s -5 305 M -( authentication methods that can continue.) s -5 283 M -( This method MUST NOT be listed as supported by the server.) s -5 261 M -(3.1.4 Completion of User Authentication) s -5 239 M -( Authentication is complete when the server has responded with) s -5 228 M -( SSH_MSG_USERAUTH_SUCCESS; all authentication related messages) s -5 217 M -( received after sending this message SHOULD be silently ignored.) s -5 195 M -( After sending SSH_MSG_USERAUTH_SUCCESS, the server starts the) s -5 184 M -( requested service.) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 6]) s -_R -S -PStoPSsaved restore -%%Page: (6,7) 4 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 7 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -(3.1.5 Banner Message) s -5 668 M -( In some jurisdictions, sending a warning message before) s -5 657 M -( authentication may be relevant for getting legal protection. Many) s -5 646 M -( UNIX machines, for example, normally display text from `/etc/issue',) s -5 635 M -( or use "tcp wrappers" or similar software to display a banner before) s -5 624 M -( issuing a login prompt.) s -5 602 M -( The SSH server may send a SSH_MSG_USERAUTH_BANNER message at any time) s -5 591 M -( before authentication is successful. This message contains text to) s -5 580 M -( be displayed to the client user before authentication is attempted.) s -5 569 M -( The format is as follows:) s -5 547 M -( byte SSH_MSG_USERAUTH_BANNER) s -5 536 M -( string message \(ISO-10646 UTF-8\)) s -5 525 M -( string language tag \(as defined in [RFC3066]\)) s -5 503 M -( The client SHOULD by default display the message on the screen.) s -5 492 M -( However, since the message is likely to be sent for every login) s -5 481 M -( attempt, and since some client software will need to open a separate) s -5 470 M -( window for this warning, the client software may allow the user to) s -5 459 M -( explicitly disable the display of banners from the server. The) s -5 448 M -( message may consist of multiple lines.) s -5 426 M -( If the message string is displayed, control character filtering) s -5 415 M -( discussed in [SSH-ARCH] SHOULD be used to avoid attacks by sending) s -5 404 M -( terminal control characters.) s -5 382 M -(3.2 Authentication Protocol Message Numbers) s -5 360 M -( All message numbers used by this authentication protocol are in the) s -5 349 M -( range from 50 to 79, which is part of the range reserved for) s -5 338 M -( protocols running on top of the SSH transport layer protocol.) s -5 316 M -( Message numbers of 80 and higher are reserved for protocols running) s -5 305 M -( after this authentication protocol, so receiving one of them before) s -5 294 M -( authentication is complete is an error, to which the server MUST) s -5 283 M -( respond by disconnecting \(preferably with a proper disconnect message) s -5 272 M -( sent first to ease troubleshooting\).) s -5 250 M -( After successful authentication, such messages are passed to the) s -5 239 M -( higher-level service.) s -5 217 M -( These are the general authentication message codes:) s -5 195 M -( #define SSH_MSG_USERAUTH_REQUEST 50) s -5 184 M -( #define SSH_MSG_USERAUTH_FAILURE 51) s -5 173 M -( #define SSH_MSG_USERAUTH_SUCCESS 52) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 7]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 8 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( #define SSH_MSG_USERAUTH_BANNER 53) s -5 668 M -( In addition to the above, there is a range of message numbers) s -5 657 M -( \(60..79\) reserved for method-specific messages. These messages are) s -5 646 M -( only sent by the server \(client sends only SSH_MSG_USERAUTH_REQUEST) s -5 635 M -( messages\). Different authentication methods reuse the same message) s -5 624 M -( numbers.) s -5 602 M -(3.3 Public Key Authentication Method: publickey) s -5 580 M -( The only REQUIRED authentication method is public key authentication.) s -5 569 M -( All implementations MUST support this method; however, not all users) s -5 558 M -( need to have public keys, and most local policies are not likely to) s -5 547 M -( require public key authentication for all users in the near future.) s -5 525 M -( With this method, the possession of a private key serves as) s -5 514 M -( authentication. This method works by sending a signature created) s -5 503 M -( with a private key of the user. The server MUST check that the key) s -5 492 M -( is a valid authenticator for the user, and MUST check that the) s -5 481 M -( signature is valid. If both hold, the authentication request MUST be) s -5 470 M -( accepted; otherwise it MUST be rejected. \(Note that the server MAY) s -5 459 M -( require additional authentications after successful authentication.\)) s -5 437 M -( Private keys are often stored in an encrypted form at the client) s -5 426 M -( host, and the user must supply a passphrase before the signature can) s -5 415 M -( be generated. Even if they are not, the signing operation involves) s -5 404 M -( some expensive computation. To avoid unnecessary processing and user) s -5 393 M -( interaction, the following message is provided for querying whether) s -5 382 M -( authentication using the key would be acceptable.) s -5 360 M -( byte SSH_MSG_USERAUTH_REQUEST) s -5 349 M -( string user name) s -5 338 M -( string service) s -5 327 M -( string "publickey") s -5 316 M -( boolean FALSE) s -5 305 M -( string public key algorithm name) s -5 294 M -( string public key blob) s -5 272 M -( Public key algorithms are defined in the transport layer) s -5 261 M -( specification [SSH-TRANS]. The public key blob may contain) s -5 250 M -( certificates.) s -5 228 M -( Any public key algorithm may be offered for use in authentication.) s -5 217 M -( In particular, the list is not constrained by what was negotiated) s -5 206 M -( during key exchange. If the server does not support some algorithm,) s -5 195 M -( it MUST simply reject the request.) s -5 173 M -( The server MUST respond to this message with either) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 8]) s -_R -S -PStoPSsaved restore -%%Page: (8,9) 5 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 9 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( SSH_MSG_USERAUTH_FAILURE or with the following:) s -5 668 M -( byte SSH_MSG_USERAUTH_PK_OK) s -5 657 M -( string public key algorithm name from the request) s -5 646 M -( string public key blob from the request) s -5 624 M -( To perform actual authentication, the client MAY then send a) s -5 613 M -( signature generated using the private key. The client MAY send the) s -5 602 M -( signature directly without first verifying whether the key is) s -5 591 M -( acceptable. The signature is sent using the following packet:) s -5 569 M -( byte SSH_MSG_USERAUTH_REQUEST) s -5 558 M -( string user name) s -5 547 M -( string service) s -5 536 M -( string "publickey") s -5 525 M -( boolean TRUE) s -5 514 M -( string public key algorithm name) s -5 503 M -( string public key to be used for authentication) s -5 492 M -( string signature) s -5 470 M -( Signature is a signature by the corresponding private key over the) s -5 459 M -( following data, in the following order:) s -5 437 M -( string session identifier) s -5 426 M -( byte SSH_MSG_USERAUTH_REQUEST) s -5 415 M -( string user name) s -5 404 M -( string service) s -5 393 M -( string "publickey") s -5 382 M -( boolean TRUE) s -5 371 M -( string public key algorithm name) s -5 360 M -( string public key to be used for authentication) s -5 338 M -( When the server receives this message, it MUST check whether the) s -5 327 M -( supplied key is acceptable for authentication, and if so, it MUST) s -5 316 M -( check whether the signature is correct.) s -5 294 M -( If both checks succeed, this method is successful. Note that the) s -5 283 M -( server may require additional authentications. The server MUST) s -5 272 M -( respond with SSH_MSG_USERAUTH_SUCCESS \(if no more authentications are) s -5 261 M -( needed\), or SSH_MSG_USERAUTH_FAILURE \(if the request failed, or more) s -5 250 M -( authentications are needed\).) s -5 228 M -( The following method-specific message numbers are used by the) s -5 217 M -( publickey authentication method.) s -5 195 M -( /* Key-based */) s -5 184 M -( #define SSH_MSG_USERAUTH_PK_OK 60) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 9]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 10 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -(3.4 Password Authentication Method: password) s -5 668 M -( Password authentication uses the following packets. Note that a) s -5 657 M -( server MAY request the user to change the password. All) s -5 646 M -( implementations SHOULD support password authentication.) s -5 624 M -( byte SSH_MSG_USERAUTH_REQUEST) s -5 613 M -( string user name) s -5 602 M -( string service) s -5 591 M -( string "password") s -5 580 M -( boolean FALSE) s -5 569 M -( string plaintext password \(ISO-10646 UTF-8\)) s -5 547 M -( Note that the password is encoded in ISO-10646 UTF-8. It is up to) s -5 536 M -( the server how it interprets the password and validates it against) s -5 525 M -( the password database. However, if the client reads the password in) s -5 514 M -( some other encoding \(e.g., ISO 8859-1 \(ISO Latin1\)\), it MUST convert) s -5 503 M -( the password to ISO-10646 UTF-8 before transmitting, and the server) s -5 492 M -( MUST convert the password to the encoding used on that system for) s -5 481 M -( passwords.) s -5 459 M -( Note that even though the cleartext password is transmitted in the) s -5 448 M -( packet, the entire packet is encrypted by the transport layer. Both) s -5 437 M -( the server and the client should check whether the underlying) s -5 426 M -( transport layer provides confidentiality \(i.e., if encryption is) s -5 415 M -( being used\). If no confidentiality is provided \(none cipher\),) s -5 404 M -( password authentication SHOULD be disabled. If there is no) s -5 393 M -( confidentiality or no MAC, password change SHOULD be disabled.) s -5 371 M -( Normally, the server responds to this message with success or) s -5 360 M -( failure. However, if the password has expired the server SHOULD) s -5 349 M -( indicate this by responding with SSH_MSG_USERAUTH_PASSWD_CHANGEREQ.) s -5 338 M -( In anycase the server MUST NOT allow an expired password to be used) s -5 327 M -( for authentication.) s -5 305 M -( byte SSH_MSG_USERAUTH_PASSWD_CHANGEREQ) s -5 294 M -( string prompt \(ISO-10646 UTF-8\)) s -5 283 M -( string language tag \(as defined in [RFC3066]\)) s -5 261 M -( In this case, the client MAY continue with a different authentication) s -5 250 M -( method, or request a new password from the user and retry password) s -5 239 M -( authentication using the following message. The client MAY also send) s -5 228 M -( this message instead of the normal password authentication request) s -5 217 M -( without the server asking for it.) s -5 195 M -( byte SSH_MSG_USERAUTH_REQUEST) s -5 184 M -( string user name) s -5 173 M -( string service) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 10]) s -_R -S -PStoPSsaved restore -%%Page: (10,11) 6 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 11 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( string "password") s -5 679 M -( boolean TRUE) s -5 668 M -( string plaintext old password \(ISO-10646 UTF-8\)) s -5 657 M -( string plaintext new password \(ISO-10646 UTF-8\)) s -5 635 M -( The server must reply to request message with) s -5 624 M -( SSH_MSG_USERAUTH_SUCCESS, SSH_MSG_USERAUTH_FAILURE, or another) s -5 613 M -( SSH_MSG_USERAUTH_PASSWD_CHANGEREQ. The meaning of these is as) s -5 602 M -( follows:) s -5 580 M -( SSH_MSG_USERAUTH_SUCCESS The password has been changed, and) s -5 569 M -( authentication has been successfully completed.) s -5 547 M -( SSH_MSG_USERAUTH_FAILURE with partial success The password has) s -5 536 M -( been changed, but more authentications are needed.) s -5 514 M -( SSH_MSG_USERAUTH_FAILURE without partial success The password has) s -5 503 M -( not been changed. Either password changing was not supported, or) s -5 492 M -( the old password was bad. Note that if the server has already) s -5 481 M -( sent SSH_MSG_USERAUTH_PASSWD_CHANGEREQ, we know that it supports) s -5 470 M -( changing the password.) s -5 448 M -( SSH_MSG_USERAUTH_CHANGEREQ The password was not changed because) s -5 437 M -( the new password was not acceptable \(e.g. too easy to guess\).) s -5 415 M -( The following method-specific message numbers are used by the) s -5 404 M -( password authentication method.) s -5 382 M -( #define SSH_MSG_USERAUTH_PASSWD_CHANGEREQ 60) s -5 349 M -(3.5 Host-Based Authentication: hostbased) s -5 327 M -( Some sites wish to allow authentication based on the host where the) s -5 316 M -( user is coming from, and the user name on the remote host. While) s -5 305 M -( this form of authentication is not suitable for high-security sites,) s -5 294 M -( it can be very convenient in many environments. This form of) s -5 283 M -( authentication is OPTIONAL. When used, special care SHOULD be taken) s -5 272 M -( to prevent a regular user from obtaining the private host key.) s -5 250 M -( The client requests this form of authentication by sending the) s -5 239 M -( following message. It is similar to the UNIX "rhosts" and) s -5 228 M -( "hosts.equiv" styles of authentication, except that the identity of) s -5 217 M -( the client host is checked more rigorously.) s -5 195 M -( This method works by having the client send a signature created with) s -5 184 M -( the private key of the client host, which the server checks with that) s -5 173 M -( host's public key. Once the client host's identity is established,) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 11]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 12 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( authorization \(but no further authentication\) is performed based on) s -5 679 M -( the user names on the server and the client, and the client host) s -5 668 M -( name.) s -5 646 M -( byte SSH_MSG_USERAUTH_REQUEST) s -5 635 M -( string user name) s -5 624 M -( string service) s -5 613 M -( string "hostbased") s -5 602 M -( string public key algorithm for host key) s -5 591 M -( string public host key and certificates for client host) s -5 580 M -( string client host name \(FQDN; US-ASCII\)) s -5 569 M -( string user name on the client host \(ISO-10646 UTF-8\)) s -5 558 M -( string signature) s -5 536 M -( Public key algorithm names for use in "public key algorithm for host) s -5 525 M -( key" are defined in the transport layer specification. The "public) s -5 514 M -( host key for client host" may include certificates.) s -5 492 M -( Signature is a signature with the private host key of the following) s -5 481 M -( data, in this order:) s -5 459 M -( string session identifier) s -5 448 M -( byte SSH_MSG_USERAUTH_REQUEST) s -5 437 M -( string user name) s -5 426 M -( string service) s -5 415 M -( string "hostbased") s -5 404 M -( string public key algorithm for host key) s -5 393 M -( string public host key and certificates for client host) s -5 382 M -( string client host name \(FQDN; US-ASCII\)) s -5 371 M -( string user name on the client host\(ISO-10646 UTF-8\)) s -5 349 M -( The server MUST verify that the host key actually belongs to the) s -5 338 M -( client host named in the message, that the given user on that host is) s -5 327 M -( allowed to log in, and that the signature is a valid signature on the) s -5 316 M -( appropriate value by the given host key. The server MAY ignore the) s -5 305 M -( client user name, if it wants to authenticate only the client host.) s -5 283 M -( It is RECOMMENDED that whenever possible, the server perform) s -5 272 M -( additional checks to verify that the network address obtained from) s -5 261 M -( the \(untrusted\) network matches the given client host name. This) s -5 250 M -( makes exploiting compromised host keys more difficult. Note that) s -5 239 M -( this may require special handling for connections coming through a) s -5 228 M -( firewall.) s -5 206 M -(4. Security Considerations) s -5 184 M -( The purpose of this protocol is to perform client user) s -5 173 M -( authentication. It assumed that this runs over a secure transport) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 12]) s -_R -S -PStoPSsaved restore -%%Page: (12,13) 7 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 13 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( layer protocol, which has already authenticated the server machine,) s -5 679 M -( established an encrypted communications channel, and computed a) s -5 668 M -( unique session identifier for this session. The transport layer) s -5 657 M -( provides forward secrecy for password authentication and other) s -5 646 M -( methods that rely on secret data.) s -5 624 M -( Full security considerations for this protocol are provided in) s -5 613 M -( Section 8 of [SSH-ARCH]) s -5 591 M -(Normative) s -5 569 M -( [SSH-ARCH]) s -5 558 M -( Ylonen, T., "SSH Protocol Architecture", I-D) s -5 547 M -( draft-ietf-architecture-15.txt, Oct 2003.) s -5 525 M -( [SSH-TRANS]) s -5 514 M -( Ylonen, T., "SSH Transport Layer Protocol", I-D) s -5 503 M -( draft-ietf-transport-17.txt, Oct 2003.) s -5 481 M -( [SSH-USERAUTH]) s -5 470 M -( Ylonen, T., "SSH Authentication Protocol", I-D) s -5 459 M -( draft-ietf-userauth-18.txt, Oct 2003.) s -5 437 M -( [SSH-CONNECT]) s -5 426 M -( Ylonen, T., "SSH Connection Protocol", I-D) s -5 415 M -( draft-ietf-connect-18.txt, Oct 2003.) s -5 393 M -( [SSH-NUMBERS]) s -5 382 M -( Lehtinen, S. and D. Moffat, "SSH Protocol Assigned) s -5 371 M -( Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct) s -5 360 M -( 2003.) s -5 338 M -( [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate) s -5 327 M -( Requirement Levels", BCP 14, RFC 2119, March 1997.) s -5 305 M -(Informative) s -5 283 M -( [RFC3066] Alvestrand, H., "Tags for the Identification of) s -5 272 M -( Languages", BCP 47, RFC 3066, January 2001.) s -5 250 M -( [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO) s -5 239 M -( 10646", RFC 2279, January 1998.) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 13]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 14 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -(Authors' Addresses) s -5 668 M -( Tatu Ylonen) s -5 657 M -( SSH Communications Security Corp) s -5 646 M -( Fredrikinkatu 42) s -5 635 M -( HELSINKI FIN-00100) s -5 624 M -( Finland) s -5 602 M -( EMail: [email protected]) s -5 569 M -( Darren J. Moffat \(editor\)) s -5 558 M -( Sun Microsystems, Inc) s -5 547 M -( 17 Network Circle) s -5 536 M -( Menlo Park 95025) s -5 525 M -( USA) s -5 503 M -( EMail: [email protected]) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 14]) s -_R -S -PStoPSsaved restore -%%Page: (14,15) 8 -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 0.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -/showpage{}def/copypage{}def/erasepage{}def -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 15 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -(Intellectual Property Statement) s -5 668 M -( The IETF takes no position regarding the validity or scope of any) s -5 657 M -( intellectual property or other rights that might be claimed to) s -5 646 M -( pertain to the implementation or use of the technology described in) s -5 635 M -( this document or the extent to which any license under such rights) s -5 624 M -( might or might not be available; neither does it represent that it) s -5 613 M -( has made any effort to identify any such rights. Information on the) s -5 602 M -( IETF's procedures with respect to rights in standards-track and) s -5 591 M -( standards-related documentation can be found in BCP-11. Copies of) s -5 580 M -( claims of rights made available for publication and any assurances of) s -5 569 M -( licenses to be made available, or the result of an attempt made to) s -5 558 M -( obtain a general license or permission for the use of such) s -5 547 M -( proprietary rights by implementors or users of this specification can) s -5 536 M -( be obtained from the IETF Secretariat.) s -5 514 M -( The IETF invites any interested party to bring to its attention any) s -5 503 M -( copyrights, patents or patent applications, or other proprietary) s -5 492 M -( rights which may cover technology that may be required to practice) s -5 481 M -( this standard. Please address the information to the IETF Executive) s -5 470 M -( Director.) s -5 448 M -( The IETF has been notified of intellectual property rights claimed in) s -5 437 M -( regard to some or all of the specification contained in this) s -5 426 M -( document. For more information consult the online list of claimed) s -5 415 M -( rights.) s -5 382 M -(Full Copyright Statement) s -5 360 M -( Copyright \(C\) The Internet Society \(2002\). All Rights Reserved.) s -5 338 M -( This document and translations of it may be copied and furnished to) s -5 327 M -( others, and derivative works that comment on or otherwise explain it) s -5 316 M -( or assist in its implementation may be prepared, copied, published) s -5 305 M -( and distributed, in whole or in part, without restriction of any) s -5 294 M -( kind, provided that the above copyright notice and this paragraph are) s -5 283 M -( included on all such copies and derivative works. However, this) s -5 272 M -( document itself may not be modified in any way, such as by removing) s -5 261 M -( the copyright notice or references to the Internet Society or other) s -5 250 M -( Internet organizations, except as needed for the purpose of) s -5 239 M -( developing Internet standards in which case the procedures for) s -5 228 M -( copyrights defined in the Internet Standards process must be) s -5 217 M -( followed, or as required to translate it into languages other than) s -5 206 M -( English.) s -5 184 M -( The limited permissions granted above are perpetual and will not be) s -5 173 M -( revoked by the Internet Society or its successors or assignees.) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 15]) s -_R -S -PStoPSsaved restore -userdict/PStoPSsaved save put -PStoPSmatrix setmatrix -595.000000 421.271378 translate -90 rotate -0.706651 dup scale -userdict/PStoPSmatrix matrix currentmatrix put -userdict/PStoPSclip{0 0 moveto - 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto - closepath}put initclip -PStoPSxform concat -%%BeginPageSetup -_S -75 0 translate -/pagenum 16 def -/fname () def -/fdir () def -/ftail () def -/user_header_p false def -%%EndPageSetup -5 723 M -(Internet-Draft SSH Authentication Protocol September 2002) s -5 690 M -( This document and the information contained herein is provided on an) s -5 679 M -( "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING) s -5 668 M -( TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING) s -5 657 M -( BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION) s -5 646 M -( HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF) s -5 635 M -( MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.) s -5 602 M -(Acknowledgment) s -5 580 M -( Funding for the RFC Editor function is currently provided by the) s -5 569 M -( Internet Society.) s -5 129 M -(Ylonen & Moffat Expires March 2, 2003 [Page 16]) s -_R -S -PStoPSsaved restore -%%Trailer -%%Pages: 16 -%%DocumentNeededResources: font Courier-Bold Courier -%%EOF diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-userauth-18.txt b/lib/ssh/doc/standard/draft-ietf-secsh-userauth-18.txt deleted file mode 100644 index 9dae578a35..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-userauth-18.txt +++ /dev/null @@ -1,896 +0,0 @@ - - - -Network Working Group T. Ylonen -Internet-Draft SSH Communications Security Corp -Expires: March 2, 2003 D. Moffat, Ed. - Sun Microsystems, Inc - September 2002 - - - SSH Authentication Protocol - draft-ietf-secsh-userauth-18.txt - -Status of this Memo - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that other - groups may also distribute working documents as Internet-Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at http:// - www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on March 2, 2003. - -Copyright Notice - - Copyright (C) The Internet Society (2002). All Rights Reserved. - -Abstract - - SSH is a protocol for secure remote login and other secure network - services over an insecure network. This document describes the SSH - authentication protocol framework and public key, password, and - host-based client authentication methods. Additional authentication - methods are described in separate documents. The SSH authentication - protocol runs on top of the SSH transport layer protocol and provides - a single authenticated tunnel for the SSH connection protocol. - - - - - - - -Ylonen & Moffat Expires March 2, 2003 [Page 1] - -Internet-Draft SSH Authentication Protocol September 2002 - - -Table of Contents - - 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3. Conventions Used in This Document . . . . . . . . . . . . . 3 - 3.1 The Authentication Protocol Framework . . . . . . . . . . . 3 - 3.1.1 Authentication Requests . . . . . . . . . . . . . . . . . . 4 - 3.1.2 Responses to Authentication Requests . . . . . . . . . . . . 5 - 3.1.3 The "none" Authentication Request . . . . . . . . . . . . . 6 - 3.1.4 Completion of User Authentication . . . . . . . . . . . . . 6 - 3.1.5 Banner Message . . . . . . . . . . . . . . . . . . . . . . . 7 - 3.2 Authentication Protocol Message Numbers . . . . . . . . . . 7 - 3.3 Public Key Authentication Method: publickey . . . . . . . . 8 - 3.4 Password Authentication Method: password . . . . . . . . . . 10 - 3.5 Host-Based Authentication: hostbased . . . . . . . . . . . . 11 - 4. Security Considerations . . . . . . . . . . . . . . . . . . 12 - Normative . . . . . . . . . . . . . . . . . . . . . . . . . 13 - Informative . . . . . . . . . . . . . . . . . . . . . . . . 13 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 14 - Intellectual Property and Copyright Statements . . . . . . . 15 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Moffat Expires March 2, 2003 [Page 2] - -Internet-Draft SSH Authentication Protocol September 2002 - - -1. Contributors - - The major original contributors of this document were: Tatu Ylonen, - Tero Kivinen, Timo J. Rinne, Sami Lehtinen (all of SSH Communications - Security Corp), and Markku-Juhani O. Saarinen (University of - Jyvaskyla) - - The document editor is: [email protected]. Comments on this - internet draft should be sent to the IETF SECSH working group, - details at: http://ietf.org/html.charters/secsh-charter.html - -2. Introduction - - The SSH authentication protocol is a general-purpose user - authentication protocol. It is intended to be run over the SSH - transport layer protocol [SSH-TRANS]. This protocol assumes that the - underlying protocols provide integrity and confidentiality - protection. - - This document should be read only after reading the SSH architecture - document [SSH-ARCH]. This document freely uses terminology and - notation from the architecture document without reference or further - explanation. - - The service name for this protocol is "ssh-userauth". - - When this protocol starts, it receives the session identifier from - the lower-level protocol (this is the exchange hash H from the first - key exchange). The session identifier uniquely identifies this - session and is suitable for signing in order to prove ownership of a - private key. This protocol also needs to know whether the lower-level - protocol provides confidentiality protection. - -3. Conventions Used in This Document - - The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", - and "MAY" that appear in this document are to be interpreted as - described in [RFC2119] - - The used data types and terminology are specified in the architecture - document [SSH-ARCH] - - The architecture document also discusses the algorithm naming - conventions that MUST be used with the SSH protocols. - -3.1 The Authentication Protocol Framework - - The server drives the authentication by telling the client which - - - -Ylonen & Moffat Expires March 2, 2003 [Page 3] - -Internet-Draft SSH Authentication Protocol September 2002 - - - authentication methods can be used to continue the exchange at any - given time. The client has the freedom to try the methods listed by - the server in any order. This gives the server complete control over - the authentication process if desired, but also gives enough - flexibility for the client to use the methods it supports or that are - most convenient for the user, when multiple methods are offered by - the server. - - Authentication methods are identified by their name, as defined in - [SSH-ARCH]. The "none" method is reserved, and MUST NOT be listed as - supported. However, it MAY be sent by the client. The server MUST - always reject this request, unless the client is to be allowed in - without any authentication, in which case the server MUST accept this - request. The main purpose of sending this request is to get the list - of supported methods from the server. - - The server SHOULD have a timeout for authentication, and disconnect - if the authentication has not been accepted within the timeout - period. The RECOMMENDED timeout period is 10 minutes. Additionally, - the implementation SHOULD limit the number of failed authentication - attempts a client may perform in a single session (the RECOMMENDED - limit is 20 attempts). If the threshold is exceeded, the server - SHOULD disconnect. - -3.1.1 Authentication Requests - - All authentication requests MUST use the following message format. - Only the first few fields are defined; the remaining fields depend on - the authentication method. - - byte SSH_MSG_USERAUTH_REQUEST - string user name (in ISO-10646 UTF-8 encoding [RFC2279]) - string service name (in US-ASCII) - string method name (US-ASCII) - The rest of the packet is method-specific. - - The user name and service are repeated in every new authentication - attempt, and MAY change. The server implementation MUST carefully - check them in every message, and MUST flush any accumulated - authentication states if they change. If it is unable to flush some - authentication state, it MUST disconnect if the user or service name - changes. - - The service name specifies the service to start after authentication. - There may be several different authenticated services provided. If - the requested service is not available, the server MAY disconnect - immediately or at any later time. Sending a proper disconnect - message is RECOMMENDED. In any case, if the service does not exist, - - - -Ylonen & Moffat Expires March 2, 2003 [Page 4] - -Internet-Draft SSH Authentication Protocol September 2002 - - - authentication MUST NOT be accepted. - - If the requested user does not exist, the server MAY disconnect, or - MAY send a bogus list of acceptable authentication methods, but never - accept any. This makes it possible for the server to avoid - disclosing information on which accounts exist. In any case, if the - user does not exist, the authentication request MUST NOT be accepted. - - While there is usually little point for clients to send requests that - the server does not list as acceptable, sending such requests is not - an error, and the server SHOULD simply reject requests that it does - not recognize. - - An authentication request MAY result in a further exchange of - messages. All such messages depend on the authentication method - used, and the client MAY at any time continue with a new - SSH_MSG_USERAUTH_REQUEST message, in which case the server MUST - abandon the previous authentication attempt and continue with the new - one. - -3.1.2 Responses to Authentication Requests - - If the server rejects the authentication request, it MUST respond - with the following: - - byte SSH_MSG_USERAUTH_FAILURE - string authentications that can continue - boolean partial success - - "Authentications that can continue" is a comma-separated list of - authentication method names that may productively continue the - authentication dialog. - - It is RECOMMENDED that servers only include those methods in the list - that are actually useful. However, it is not illegal to include - methods that cannot be used to authenticate the user. - - Already successfully completed authentications SHOULD NOT be included - in the list, unless they really should be performed again for some - reason. - - "Partial success" MUST be TRUE if the authentication request to which - this is a response was successful. It MUST be FALSE if the request - was not successfully processed. - - When the server accepts authentication, it MUST respond with the - following: - - - - -Ylonen & Moffat Expires March 2, 2003 [Page 5] - -Internet-Draft SSH Authentication Protocol September 2002 - - - byte SSH_MSG_USERAUTH_SUCCESS - - Note that this is not sent after each step in a multi-method - authentication sequence, but only when the authentication is - complete. - - The client MAY send several authentication requests without waiting - for responses from previous requests. The server MUST process each - request completely and acknowledge any failed requests with a - SSH_MSG_USERAUTH_FAILURE message before processing the next request. - - A request that results in further exchange of messages will be - aborted by a second request. It is not possible to send a second - request without waiting for a response from the server, if the first - request will result in further exchange of messages. No - SSH_MSG_USERAUTH_FAILURE message will be sent for the aborted method. - - SSH_MSG_USERAUTH_SUCCESS MUST be sent only once. When - SSH_MSG_USERAUTH_SUCCESS has been sent, any further authentication - requests received after that SHOULD be silently ignored. - - Any non-authentication messages sent by the client after the request - that resulted in SSH_MSG_USERAUTH_SUCCESS being sent MUST be passed - to the service being run on top of this protocol. Such messages can - be identified by their message numbers (see Section Message Numbers - (Section 3.2)). - -3.1.3 The "none" Authentication Request - - A client may request a list of authentication methods that may - continue by using the "none" authentication method. - - If no authentication at all is needed for the user, the server MUST - return SSH_MSG_USERAUTH_SUCCESS. Otherwise, the server MUST return - SSH_MSG_USERAUTH_FAILURE and MAY return with it a list of - authentication methods that can continue. - - This method MUST NOT be listed as supported by the server. - -3.1.4 Completion of User Authentication - - Authentication is complete when the server has responded with - SSH_MSG_USERAUTH_SUCCESS; all authentication related messages - received after sending this message SHOULD be silently ignored. - - After sending SSH_MSG_USERAUTH_SUCCESS, the server starts the - requested service. - - - - -Ylonen & Moffat Expires March 2, 2003 [Page 6] - -Internet-Draft SSH Authentication Protocol September 2002 - - -3.1.5 Banner Message - - In some jurisdictions, sending a warning message before - authentication may be relevant for getting legal protection. Many - UNIX machines, for example, normally display text from `/etc/issue', - or use "tcp wrappers" or similar software to display a banner before - issuing a login prompt. - - The SSH server may send a SSH_MSG_USERAUTH_BANNER message at any time - before authentication is successful. This message contains text to - be displayed to the client user before authentication is attempted. - The format is as follows: - - byte SSH_MSG_USERAUTH_BANNER - string message (ISO-10646 UTF-8) - string language tag (as defined in [RFC3066]) - - The client SHOULD by default display the message on the screen. - However, since the message is likely to be sent for every login - attempt, and since some client software will need to open a separate - window for this warning, the client software may allow the user to - explicitly disable the display of banners from the server. The - message may consist of multiple lines. - - If the message string is displayed, control character filtering - discussed in [SSH-ARCH] SHOULD be used to avoid attacks by sending - terminal control characters. - -3.2 Authentication Protocol Message Numbers - - All message numbers used by this authentication protocol are in the - range from 50 to 79, which is part of the range reserved for - protocols running on top of the SSH transport layer protocol. - - Message numbers of 80 and higher are reserved for protocols running - after this authentication protocol, so receiving one of them before - authentication is complete is an error, to which the server MUST - respond by disconnecting (preferably with a proper disconnect message - sent first to ease troubleshooting). - - After successful authentication, such messages are passed to the - higher-level service. - - These are the general authentication message codes: - - #define SSH_MSG_USERAUTH_REQUEST 50 - #define SSH_MSG_USERAUTH_FAILURE 51 - #define SSH_MSG_USERAUTH_SUCCESS 52 - - - -Ylonen & Moffat Expires March 2, 2003 [Page 7] - -Internet-Draft SSH Authentication Protocol September 2002 - - - #define SSH_MSG_USERAUTH_BANNER 53 - - In addition to the above, there is a range of message numbers - (60..79) reserved for method-specific messages. These messages are - only sent by the server (client sends only SSH_MSG_USERAUTH_REQUEST - messages). Different authentication methods reuse the same message - numbers. - -3.3 Public Key Authentication Method: publickey - - The only REQUIRED authentication method is public key authentication. - All implementations MUST support this method; however, not all users - need to have public keys, and most local policies are not likely to - require public key authentication for all users in the near future. - - With this method, the possession of a private key serves as - authentication. This method works by sending a signature created - with a private key of the user. The server MUST check that the key - is a valid authenticator for the user, and MUST check that the - signature is valid. If both hold, the authentication request MUST be - accepted; otherwise it MUST be rejected. (Note that the server MAY - require additional authentications after successful authentication.) - - Private keys are often stored in an encrypted form at the client - host, and the user must supply a passphrase before the signature can - be generated. Even if they are not, the signing operation involves - some expensive computation. To avoid unnecessary processing and user - interaction, the following message is provided for querying whether - authentication using the key would be acceptable. - - byte SSH_MSG_USERAUTH_REQUEST - string user name - string service - string "publickey" - boolean FALSE - string public key algorithm name - string public key blob - - Public key algorithms are defined in the transport layer - specification [SSH-TRANS]. The public key blob may contain - certificates. - - Any public key algorithm may be offered for use in authentication. - In particular, the list is not constrained by what was negotiated - during key exchange. If the server does not support some algorithm, - it MUST simply reject the request. - - The server MUST respond to this message with either - - - -Ylonen & Moffat Expires March 2, 2003 [Page 8] - -Internet-Draft SSH Authentication Protocol September 2002 - - - SSH_MSG_USERAUTH_FAILURE or with the following: - - byte SSH_MSG_USERAUTH_PK_OK - string public key algorithm name from the request - string public key blob from the request - - To perform actual authentication, the client MAY then send a - signature generated using the private key. The client MAY send the - signature directly without first verifying whether the key is - acceptable. The signature is sent using the following packet: - - byte SSH_MSG_USERAUTH_REQUEST - string user name - string service - string "publickey" - boolean TRUE - string public key algorithm name - string public key to be used for authentication - string signature - - Signature is a signature by the corresponding private key over the - following data, in the following order: - - string session identifier - byte SSH_MSG_USERAUTH_REQUEST - string user name - string service - string "publickey" - boolean TRUE - string public key algorithm name - string public key to be used for authentication - - When the server receives this message, it MUST check whether the - supplied key is acceptable for authentication, and if so, it MUST - check whether the signature is correct. - - If both checks succeed, this method is successful. Note that the - server may require additional authentications. The server MUST - respond with SSH_MSG_USERAUTH_SUCCESS (if no more authentications are - needed), or SSH_MSG_USERAUTH_FAILURE (if the request failed, or more - authentications are needed). - - The following method-specific message numbers are used by the - publickey authentication method. - - /* Key-based */ - #define SSH_MSG_USERAUTH_PK_OK 60 - - - - -Ylonen & Moffat Expires March 2, 2003 [Page 9] - -Internet-Draft SSH Authentication Protocol September 2002 - - -3.4 Password Authentication Method: password - - Password authentication uses the following packets. Note that a - server MAY request the user to change the password. All - implementations SHOULD support password authentication. - - byte SSH_MSG_USERAUTH_REQUEST - string user name - string service - string "password" - boolean FALSE - string plaintext password (ISO-10646 UTF-8) - - Note that the password is encoded in ISO-10646 UTF-8. It is up to - the server how it interprets the password and validates it against - the password database. However, if the client reads the password in - some other encoding (e.g., ISO 8859-1 (ISO Latin1)), it MUST convert - the password to ISO-10646 UTF-8 before transmitting, and the server - MUST convert the password to the encoding used on that system for - passwords. - - Note that even though the cleartext password is transmitted in the - packet, the entire packet is encrypted by the transport layer. Both - the server and the client should check whether the underlying - transport layer provides confidentiality (i.e., if encryption is - being used). If no confidentiality is provided (none cipher), - password authentication SHOULD be disabled. If there is no - confidentiality or no MAC, password change SHOULD be disabled. - - Normally, the server responds to this message with success or - failure. However, if the password has expired the server SHOULD - indicate this by responding with SSH_MSG_USERAUTH_PASSWD_CHANGEREQ. - In anycase the server MUST NOT allow an expired password to be used - for authentication. - - byte SSH_MSG_USERAUTH_PASSWD_CHANGEREQ - string prompt (ISO-10646 UTF-8) - string language tag (as defined in [RFC3066]) - - In this case, the client MAY continue with a different authentication - method, or request a new password from the user and retry password - authentication using the following message. The client MAY also send - this message instead of the normal password authentication request - without the server asking for it. - - byte SSH_MSG_USERAUTH_REQUEST - string user name - string service - - - -Ylonen & Moffat Expires March 2, 2003 [Page 10] - -Internet-Draft SSH Authentication Protocol September 2002 - - - string "password" - boolean TRUE - string plaintext old password (ISO-10646 UTF-8) - string plaintext new password (ISO-10646 UTF-8) - - The server must reply to request message with - SSH_MSG_USERAUTH_SUCCESS, SSH_MSG_USERAUTH_FAILURE, or another - SSH_MSG_USERAUTH_PASSWD_CHANGEREQ. The meaning of these is as - follows: - - SSH_MSG_USERAUTH_SUCCESS The password has been changed, and - authentication has been successfully completed. - - SSH_MSG_USERAUTH_FAILURE with partial success The password has - been changed, but more authentications are needed. - - SSH_MSG_USERAUTH_FAILURE without partial success The password has - not been changed. Either password changing was not supported, or - the old password was bad. Note that if the server has already - sent SSH_MSG_USERAUTH_PASSWD_CHANGEREQ, we know that it supports - changing the password. - - SSH_MSG_USERAUTH_CHANGEREQ The password was not changed because - the new password was not acceptable (e.g. too easy to guess). - - The following method-specific message numbers are used by the - password authentication method. - - #define SSH_MSG_USERAUTH_PASSWD_CHANGEREQ 60 - - -3.5 Host-Based Authentication: hostbased - - Some sites wish to allow authentication based on the host where the - user is coming from, and the user name on the remote host. While - this form of authentication is not suitable for high-security sites, - it can be very convenient in many environments. This form of - authentication is OPTIONAL. When used, special care SHOULD be taken - to prevent a regular user from obtaining the private host key. - - The client requests this form of authentication by sending the - following message. It is similar to the UNIX "rhosts" and - "hosts.equiv" styles of authentication, except that the identity of - the client host is checked more rigorously. - - This method works by having the client send a signature created with - the private key of the client host, which the server checks with that - host's public key. Once the client host's identity is established, - - - -Ylonen & Moffat Expires March 2, 2003 [Page 11] - -Internet-Draft SSH Authentication Protocol September 2002 - - - authorization (but no further authentication) is performed based on - the user names on the server and the client, and the client host - name. - - byte SSH_MSG_USERAUTH_REQUEST - string user name - string service - string "hostbased" - string public key algorithm for host key - string public host key and certificates for client host - string client host name (FQDN; US-ASCII) - string user name on the client host (ISO-10646 UTF-8) - string signature - - Public key algorithm names for use in "public key algorithm for host - key" are defined in the transport layer specification. The "public - host key for client host" may include certificates. - - Signature is a signature with the private host key of the following - data, in this order: - - string session identifier - byte SSH_MSG_USERAUTH_REQUEST - string user name - string service - string "hostbased" - string public key algorithm for host key - string public host key and certificates for client host - string client host name (FQDN; US-ASCII) - string user name on the client host(ISO-10646 UTF-8) - - The server MUST verify that the host key actually belongs to the - client host named in the message, that the given user on that host is - allowed to log in, and that the signature is a valid signature on the - appropriate value by the given host key. The server MAY ignore the - client user name, if it wants to authenticate only the client host. - - It is RECOMMENDED that whenever possible, the server perform - additional checks to verify that the network address obtained from - the (untrusted) network matches the given client host name. This - makes exploiting compromised host keys more difficult. Note that - this may require special handling for connections coming through a - firewall. - -4. Security Considerations - - The purpose of this protocol is to perform client user - authentication. It assumed that this runs over a secure transport - - - -Ylonen & Moffat Expires March 2, 2003 [Page 12] - -Internet-Draft SSH Authentication Protocol September 2002 - - - layer protocol, which has already authenticated the server machine, - established an encrypted communications channel, and computed a - unique session identifier for this session. The transport layer - provides forward secrecy for password authentication and other - methods that rely on secret data. - - Full security considerations for this protocol are provided in - Section 8 of [SSH-ARCH] - -Normative - - [SSH-ARCH] - Ylonen, T., "SSH Protocol Architecture", I-D - draft-ietf-architecture-15.txt, Oct 2003. - - [SSH-TRANS] - Ylonen, T., "SSH Transport Layer Protocol", I-D - draft-ietf-transport-17.txt, Oct 2003. - - [SSH-USERAUTH] - Ylonen, T., "SSH Authentication Protocol", I-D - draft-ietf-userauth-18.txt, Oct 2003. - - [SSH-CONNECT] - Ylonen, T., "SSH Connection Protocol", I-D - draft-ietf-connect-18.txt, Oct 2003. - - [SSH-NUMBERS] - Lehtinen, S. and D. Moffat, "SSH Protocol Assigned - Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct - 2003. - - [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate - Requirement Levels", BCP 14, RFC 2119, March 1997. - -Informative - - [RFC3066] Alvestrand, H., "Tags for the Identification of - Languages", BCP 47, RFC 3066, January 2001. - - [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO - 10646", RFC 2279, January 1998. - - - - - - - - - -Ylonen & Moffat Expires March 2, 2003 [Page 13] - -Internet-Draft SSH Authentication Protocol September 2002 - - -Authors' Addresses - - Tatu Ylonen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - Darren J. Moffat (editor) - Sun Microsystems, Inc - 17 Network Circle - Menlo Park 95025 - USA - - EMail: [email protected] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Moffat Expires March 2, 2003 [Page 14] - -Internet-Draft SSH Authentication Protocol September 2002 - - -Intellectual Property Statement - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementors or users of this specification can - be obtained from the IETF Secretariat. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights which may cover technology that may be required to practice - this standard. Please address the information to the IETF Executive - Director. - - The IETF has been notified of intellectual property rights claimed in - regard to some or all of the specification contained in this - document. For more information consult the online list of claimed - rights. - - -Full Copyright Statement - - Copyright (C) The Internet Society (2002). All Rights Reserved. - - This document and translations of it may be copied and furnished to - others, and derivative works that comment on or otherwise explain it - or assist in its implementation may be prepared, copied, published - and distributed, in whole or in part, without restriction of any - kind, provided that the above copyright notice and this paragraph are - included on all such copies and derivative works. However, this - document itself may not be modified in any way, such as by removing - the copyright notice or references to the Internet Society or other - Internet organizations, except as needed for the purpose of - developing Internet standards in which case the procedures for - copyrights defined in the Internet Standards process must be - followed, or as required to translate it into languages other than - English. - - The limited permissions granted above are perpetual and will not be - revoked by the Internet Society or its successors or assignees. - - - -Ylonen & Moffat Expires March 2, 2003 [Page 15] - -Internet-Draft SSH Authentication Protocol September 2002 - - - This document and the information contained herein is provided on an - "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING - TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING - BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION - HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF - MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - -Acknowledgment - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Ylonen & Moffat Expires March 2, 2003 [Page 16]
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