diff options
Diffstat (limited to 'lib/ssh/doc/src/ssh.xml')
| -rw-r--r-- | lib/ssh/doc/src/ssh.xml | 120 |
1 files changed, 90 insertions, 30 deletions
diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml index 2b190c98b6..1e9acf4a99 100644 --- a/lib/ssh/doc/src/ssh.xml +++ b/lib/ssh/doc/src/ssh.xml @@ -32,34 +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: ecdsa-sha2-nistp256, ecdsa-sha2-nistp384, ecdsa-sha2-nistp521, ssh-rsa and ssh-dss.</item> - <item>Supported MAC algorithms: hmac-sha2-256, hmac-sha2-512 and hmac-sha1.</item> - <item>Supported encryption algorithms: aes256-ctr, aes192-ctr, aes128-ctr, aes128-cb and 3des-cbc.</item> - <item>Supported key exchange algorithms: ecdh-sha2-nistp256, ecdh-sha2-nistp384, ecdh-sha2-nistp521, diffie-hellman-group14-sha1, diffie-hellman-group-exchange-sha1, diffie-hellman-group-exchange-sha256 and diffie-hellman-group1-sha1</item> - <item>Supported compression algorithms: none, [email protected] and zlib</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> - <p>The actual set of algorithms can 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="#default_algorithms/0">default_algorithms/0</seealso>. - The user may override the default algorithm configuration both on the server side and the client side. - See the option preferred_algorithms in the <seealso marker="#daemon/1">daemon</seealso> and - <seealso marker="#connect/3">connect</seealso> functions. -</p> - + <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 @@ -462,21 +461,82 @@ kex is implicit but public_key is set explicitly.</p> </warning> </item> - <tag><c><![CDATA[{dh_gex_groups, [{Size=integer(),G=integer(),P=integer()}] | {file,filename()} }]]></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>Sets the groups that the server may choose among when diffie-hellman-group-exchange is negotiated. - See RFC 4419 for details. + <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: + <list type="bulleted"> + <item><c>true</c> if the user and password is valid and</item> + <item><c>false</c> otherwise.</item> + </list> + </p> + <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: + <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> - <p>If the parameter is <c>{file,filename()}</c>, the file must exist and have one or more three-tuples terminated by a dot. The interpretation is as if the tuples had been given directly in the option. The file is read when the daemon starts. + <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: + <list type="bulleted"> + <item><c>disconnect</c> if the connection should be closed immediately after sending a SSH_MSG_DISCONNECT + message.</item> + </list> </p> </item> - <tag><c><![CDATA[{pwdfun, fun(User::string(), password::string()) -> boolean()}]]></c></tag> + <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> |