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Diffstat (limited to 'lib/ssh/doc/src/ssh.xml')
| -rw-r--r-- | lib/ssh/doc/src/ssh.xml | 1790 |
1 files changed, 964 insertions, 826 deletions
diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml index c641badd9a..03078cfd83 100644 --- a/lib/ssh/doc/src/ssh.xml +++ b/lib/ssh/doc/src/ssh.xml @@ -11,8 +11,8 @@ Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at - - http://www.apache.org/licenses/LICENSE-2.0 + + http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, @@ -31,203 +31,211 @@ <module>ssh</module> <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> + <p>This is the interface module for the <c>SSH</c> application. + The Secure Shell (SSH) Protocol is a protocol for secure remote login + and other secure network services over an insecure network. + See <seealso marker="ssh:SSH_app#supported">ssh(6)</seealso> for details of supported RFCs, versions, + algorithms and unicode handling. + </p> + <p>With the SSH application it is possible to start <i>clients</i> and to start <i>daemons</i> (servers). + </p> + <p>Clients are started with + <seealso marker="#connect/2">connect/2</seealso>, + <seealso marker="#connect/3">connect/3</seealso> or + <seealso marker="#connect/4">connect/4</seealso>. They open an encrypted connection on top of TCP/IP. + In that encrypted connection one or more channels could be opened with + <seealso marker="ssh_connection#session_channel/2">ssh_connection:session_channel/2,4</seealso>. + </p> + <p>Each channel is an isolated "pipe" between a client-side process and a server-side process. Thoose process + pairs could handle for example file transfers (sftp) or remote command execution (shell, exec and/or cli). + If a custom shell is implemented, the user of the client could execute the special commands remotely. Note that + the user is not necessarily a human but probably a system interfacing the SSH app. + </p> + <p>A server-side subssystem (channel) server is requested by the client with + <seealso marker="ssh_connection#subsystem/4">ssh_connection:subsystem/4</seealso>. + </p> + <p>A server (daemon) is started with + <seealso marker="#daemon/2">daemon/1</seealso>, + <seealso marker="#daemon/2">daemon/2</seealso> or + <seealso marker="#daemon/2">daemon/3</seealso>. + Possible channel handlers (subsystems) are declared with the + <seealso marker="#type-subsystem_daemon_option">subsystem</seealso> option when the daemon is started. + </p> + <p>To just run a shell on a remote machine, there are functions that bundles the needed + three steps needed into one: + <seealso marker="#shell/1">shell/1,2,3</seealso>. + Similarily, to just open an sftp (file transfer) connection to a remote machine, the simplest way is to use + <seealso marker="ssh_sftp#start_channel/1">ssh_sftp:start_channel/1,2,3</seealso>. + </p> + <p>To write your own client channel handler, use the behaviour + <seealso marker="ssh_channel">ssh_channel</seealso>. For own server channel handlers use the ssh_daemon_channel + behaviour: see the <seealso marker="ssh_channel#ssh_daemon_channel">note in ssh_channel</seealso>. + </p> + <p>Both clients and daemons accepts options that controls the exact behaviour. Some options are common to both. + The three sets are called + <seealso marker="#type-client_options">Client Options</seealso>, + <seealso marker="#type-daemon_options">Daemon Options</seealso> and + <seealso marker="#type-common_options">Common Options</seealso>. + </p> + <p>The descriptions of the options uses the + <seealso marker="doc/reference_manual:typespec">Erlang Type Language</seealso> with explaining text. + </p> + <note> + <p>The <seealso marker="users_guide">User's Guide</seealso> has examples and a + <seealso marker="using_ssh">Getting Started</seealso> + section. + </p> + </note> </description> <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 - this module, or abstractions to indicate the intended use of the data - type, or both:</p> - <taglist> - <tag><c>boolean() =</c></tag> - <item><p><c>true | false</c></p></item> - - <tag><c>string() =</c></tag> - <item><p><c>[byte()]</c></p></item> - - <tag><c>ssh_daemon_ref() =</c></tag> - <item><p>opaque() - - as returned by <c>ssh:daemon/[1,2,3]</c></p></item> - - <tag><c>ok_error(OKtype) = </c></tag> - <item><p><c>{ok,OKtype} | {error, term()}</c></p></item> - - <tag><c>ok_error() = </c></tag> - <item><p><c>ok_error(term())</c></p></item> - - <tag><c>ssh_connection_ref() =</c></tag> - <item><p>opaque() - as returned by <c>ssh:connect/3</c></p></item> - - <tag><c>ip_address() =</c></tag> - <item><p><c>inet::ip_address()</c></p></item> - - <tag><c>port_number() =</c></tag> - <item><p><c>inet::port_number()</c></p></item> - - <tag><c>subsystem_spec() =</c></tag> - <item><p><c>{subsystem_name(), - {channel_callback(), channel_init_args()}}</c></p></item> - - <tag><c>subsystem_name() =</c></tag> - <item><p><c>string()</c></p></item> - - <tag><c>channel_callback() =</c></tag> - <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> + <title>Keys and files</title> + <p>A number of objects must be present for the SSH application to work. + Thoose objects are per default stored in files. + The default names, paths and file formats are the same as for + <url href="http://www.openssh.com">OpenSSH</url>. Keys could be generated with the <c>ssh-keygen</c> + program from OpenSSH. See the + <seealso marker="using_ssh#running-an-erlang-ssh-daemon">User's Guide</seealso>. + </p> + + <p>The paths could easily be changed by options: + <seealso marker="#type-user_dir_common_option"><c>user_dir</c></seealso> and + <seealso marker="#type-system_dir_daemon_option"><c>system_dir</c></seealso>. + </p> + <p>A completly different storage could be interfaced by writing call-back modules + using the behaviours + <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso> and/or + <seealso marker="ssh_server_key_api">ssh_server_key_api</seealso>. + A callback module is installed with the option + <seealso marker="#type-key_cb_common_option"><c>key_cb</c></seealso> + to the client and/or the daemon. + </p> + + <section> + <title>Daemons</title> + <p>The keys are by default stored in files:</p> + <list> + <item>Mandatory: one or more <i>Host key(s)</i>, both private and public. Default is to + store them in the directory <c>/etc/ssh</c> in the files + <list> + <item><c>ssh_host_dsa_key</c> and <c>ssh_host_dsa_key.pub</c></item> + <item><c>ssh_host_rsa_key</c> and <c>ssh_host_rsa_key.pub</c></item> + <item><c>ssh_host_ecdsa_key</c> and <c>ssh_host_ecdsa_key.pub</c></item> + </list> + <p>The host keys directory could be changed with the option + <seealso marker="#type-system_dir_daemon_option"><c>system_dir</c></seealso>.</p> + </item> + <item>Optional: one or more <i>User's public key</i> in case of <c>publickey</c> authorization. + Default is to store them concatenated in the file <c>.ssh/authorized_keys</c> in the user's home directory. + <p>The user keys directory could be changed with the option + <seealso marker="#type-user_dir_common_option"><c>user_dir</c></seealso>.</p> + </item> + </list> + </section> + + <section> + <title>Clients</title> + <p>The keys and some other data are by default stored in files in the directory <c>.ssh</c> + in the user's home directory.</p> + <p>The directory could be changed with the option + <seealso marker="#type-user_dir_common_option"><c>user_dir</c></seealso>. + </p> + <list> + <item>Optional: a list of <i>Host public key(s)</i> for previously connected hosts. This list + is handled by the SSH application without any need of user assistance. The default + is to store them in the file <c>known_hosts</c>. + <p>The + <seealso marker="#type-host_accepting_client_options">host_accepting_client_options()</seealso> + are associated with this list of keys. + </p> + </item> + <item>Optional: one or more <i>User's private key(s)</i> in case of <c>publickey</c> authorization. + The default files are + <list> + <item><c>id_dsa</c> and <c>id_dsa.pub</c></item> + <item><c>id_rsa</c> and <c>id_rsa.pub</c></item> + <item><c>id_ecdsa</c> and <c>id_ecdsa.pub</c></item> + </list> + </item> + </list> + </section> - <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_server_key_api">ssh_server_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> + </section> - <tag><c>channel_init_args() =</c></tag> - <item><p><c>list()</c></p></item> + <!-- + ================================================================ + = Data types = + ================================================================ + --> - <tag><c>algs_list() =</c></tag> - <item><p><c>list( alg_entry() )</c></p></item> + <datatypes> - <tag><c>alg_entry() =</c></tag> - <item><p><c>{kex, simple_algs()} | {public_key, simple_algs()} | {cipher, double_algs()} | {mac, double_algs()} | {compression, double_algs()}</c></p></item> + <datatype_title>Client Options</datatype_title> - <tag><c>simple_algs() =</c></tag> - <item><p><c>list( atom() )</c></p></item> - - <tag><c>double_algs() =</c></tag> - <item><p><c>[{client2serverlist,simple_algs()},{server2client,simple_algs()}] | simple_algs()</c></p></item> + <datatype> + <name name="client_options"/> + <name name="client_option"/> + <desc> + <p>Options for <seealso marker="#connect/3">clients</seealso>. + The individual options are further explained below or by following the hyperlinks. + </p> + </desc> + </datatype> - <tag><c>modify_algs_list() =</c></tag> - <item><p><c>list( {append,algs_list()} | {prepend,algs_list()} | {rm,algs_list()} )</c></p></item> - </taglist> -</section> + <datatype> + <name name="pref_public_key_algs_client_option"/> + <desc> + <p>List of user (client) public key algorithms to try to use.</p> + <p>The default value is the <c>public_key</c> entry in the list returned by + <seealso marker="#default_algorithms/0">ssh:default_algorithms/0</seealso>. + </p> + <p>If there is no public key of a specified type available, the corresponding entry is ignored. + Note that the available set is dependent on the underlying cryptolib and current user's public keys. + </p> + <p>See also the option <seealso marker="#type-user_dir_common_option"><c>user_dir</c></seealso> + for specifying the path to the user's keys. + </p> + </desc> + </datatype> - <funcs> - - <func> - <name>close(ConnectionRef) -> ok </name> - <fsummary>Closes an SSH connection.</fsummary> - <type> - <v>ConnectionRef = ssh_connection_ref()</v> - </type> - <desc><p>Closes an SSH connection.</p> + <datatype> + <name name="pubkey_passphrase_client_options"/> + <desc> + <p>If the user's DSA, RSA or ECDSA key is protected by a passphrase, it can be + supplied with thoose options. + </p> </desc> - </func> - - <func> - <name>connect(Host, Port, Options) -> </name> - <name>connect(Host, Port, Options, Timeout) -> </name> - <name>connect(TcpSocket, Options) -> </name> - <name>connect(TcpSocket, Options, Timeout) -> - {ok, ssh_connection_ref()} | {error, Reason}</name> - <fsummary>Connects to an SSH server.</fsummary> - <type> - <v>Host = string()</v> - <v>Port = integer()</v> - <d><c><![CDATA[22]]></c> is default, the assigned well-known port - number for SSH.</d> - <v>Options = [{Option, Value}]</v> - <v>Timeout = infinity | integer()</v> - <d>Negotiation time-out in milli-seconds. The default value is <c>infinity</c>. - For connection time-out, use option <c>{connect_timeout, timeout()}</c>.</d> - <v>TcpSocket = port()</v> - <d>The socket is supposed to be from <seealso marker="kernel:gen_tcp#connect-3">gen_tcp:connect</seealso> or <seealso marker="kernel:gen_tcp#accept-1">gen_tcp:accept</seealso> with option <c>{active,false}</c></d> - </type> + </datatype> + + <datatype> + <name name="host_accepting_client_options"/> + <name name="accept_hosts"/> + <name name="fp_digest_alg"/> + <name name="accept_callback"/> + <name name="fingerprint"/> <desc> - <p>Connects to an SSH server. No channel is started. This is done - by calling - <seealso marker="ssh_connection#session_channel/2"> - ssh_connection:session_channel/[2, 4]</seealso>.</p> - <p>Options:</p> <taglist> - <tag><c><![CDATA[{inet, inet | inet6}]]></c></tag> - <item> - <p>IP version to use.</p> - </item> - <tag><marker id="opt_user_dir"></marker><c><![CDATA[{user_dir, string()}]]></c></tag> - <item> - <p>Sets the user directory, that is, the directory containing - <c>ssh</c> configuration files for the user, such as - <c><![CDATA[known_hosts]]></c>, <c><![CDATA[id_rsa, - id_dsa]]></c>, and - <c><![CDATA[authorized_key]]></c>. Defaults to the - directory normally referred to as - <c><![CDATA[~/.ssh]]></c>.</p> - </item> - <tag><c><![CDATA[{dsa_pass_phrase, string()}]]></c></tag> - <item> - <p>If the user DSA key is protected by a passphrase, it can be - supplied with this option. - </p> - </item> - <tag><c><![CDATA[{rsa_pass_phrase, string()}]]></c></tag> - <item> - <p>If the user RSA key is protected by a passphrase, it can be - supplied with this option. - </p> - </item> - <tag><c><![CDATA[{ecdsa_pass_phrase, string()}]]></c></tag> - <item> - <p>If the user ECDSA key is protected by a passphrase, it can be - supplied with this option. - </p> - </item> - <tag> - <c><![CDATA[{silently_accept_hosts, boolean()}]]></c> <br/> - <c><![CDATA[{silently_accept_hosts, CallbackFun}]]></c> <br/> - <c><![CDATA[{silently_accept_hosts, {HashAlgoSpec, CallbackFun} }]]></c> <br/> - <br/> - <c><![CDATA[HashAlgoSpec = crypto:digest_type() | [ crypto:digest_type() ] ]]></c><br/> - <c><![CDATA[CallbackFun = fun(PeerName, FingerPrint) -> boolean()]]></c><br/> - <c><![CDATA[PeerName = string()]]></c><br/> - <c><![CDATA[FingerPrint = string() | [ string() ] ]]></c> - </tag> + <tag><c>silently_accept_hosts</c></tag> <item> - <p>This option guides the <c>connect</c> function how to act when the connected server presents a Host + <p>This option guides the <c>connect</c> function on how to act when the connected server presents a Host Key that the client has not seen before. The default is to ask the user with a question on stdio of whether to accept or reject the new Host Key. - See also the option <seealso marker="#opt_user_dir"><c>user_dir</c></seealso> - for the path to the file <c>known_hosts</c> where previously accepted Host Keys are recorded. - </p> + See the option <seealso marker="#type-user_dir_common_option"><c>user_dir</c></seealso> + for specifying the path to the file <c>known_hosts</c> where previously accepted Host Keys are recorded. + See also the option + <seealso marker="#type-key_cb_common_option">key_cb</seealso> + for the general way to handle keys. + </p> <p>The option can be given in three different forms as seen above:</p> <list> - <item>The value is a <c>boolean()</c>. The value <c>true</c> will make the client accept any unknown - Host Key without any user interaction. The value <c>false</c> keeps the default behaviour of asking the - the user on stdio. + <item>The value is a <c>boolean()</c>. + The value <c>true</c> will make the client accept any unknown Host Key without any user interaction. + The value <c>false</c> preserves the default behaviour of asking the user on stdio. </item> - <item>A <c>CallbackFun</c> will be called and the boolean return value <c>true</c> will make the client - accept the Host Key. A return value of <c>false</c> will make the client to reject the Host Key and therefore - also the connection will be closed. The arguments to the fun are: + <item>An <c>accept_callback()</c> will be called and the boolean return value <c>true</c> + will make the client + accept the Host Key. A return value of <c>false</c> will make the client to reject the Host Key and as a + result the connection will be closed. The arguments to the fun are: <list type="bulleted"> <item><c>PeerName</c> - a string with the name or address of the remote host.</item> <item><c>FingerPrint</c> - the fingerprint of the Host Key as @@ -236,532 +244,334 @@ </item> </list> </item> - <item>A tuple <c>{HashAlgoSpec, CallbackFun}</c>. The <c>HashAlgoSpec</c> specifies which hash algorithm - shall be used to calculate the fingerprint used in the call of the <c>CallbackFun</c>. The <c>HashALgoSpec</c> - is either an atom or a list of atoms as the first argument in - <seealso marker="public_key:public_key#ssh_hostkey_fingerprint-2">public_key:ssh_hostkey_fingerprint/2</seealso>. - If it is a list of hash algorithm names, the <c>FingerPrint</c> argument in the <c>CallbackFun</c> will be - a list of fingerprints in the same order as the corresponding name in the <c>HashAlgoSpec</c> list. + <item>A tuple <c>{HashAlgoSpec, accept_callback}</c>. The <c>HashAlgoSpec</c> + specifies which hash algorithm + shall be used to calculate the fingerprint used in the call of the <c>accept_callback()</c>. + The <c>HashALgoSpec</c> + is either an atom or a list of atoms as the first argument in + <seealso marker="public_key:public_key#ssh_hostkey_fingerprint-2">public_key:ssh_hostkey_fingerprint/2</seealso>. + If it is a list of hash algorithm names, the <c>FingerPrint</c> argument in the + <c>accept_callback()</c> will be + a list of fingerprints in the same order as the corresponding name in the <c>HashAlgoSpec</c> list. </item> </list> </item> - - <tag><c><![CDATA[{save_accepted_host, boolean()}]]></c></tag> - <item> - <p>If <c>true</c>, the client saves an accepted host key to avoid the - accept question the next time the same host is connected. If the option - <c>key_cb</c> is not present, the key is saved in the file "known_hosts". - </p> - <p>If <c>false</c>, the key is not saved and the key will still be unknown - at the next access of the same host. - </p> - </item> - - <tag><c><![CDATA[{user_interaction, boolean()}]]></c></tag> + + <tag><c>user_interaction</c></tag> <item> <p>If <c>false</c>, disables the client to connect to the server if any user interaction is needed, such as accepting the server to be added to the <c>known_hosts</c> file, or - supplying a password. Defaults to <c>true</c>. - Even if user interaction is allowed it can be + supplying a password.</p> + <p>Even if user interaction is allowed it can be suppressed by other options, such as <c>silently_accept_hosts</c> and <c>password</c>. However, those options are not always desirable to use from a security point of view.</p> + <p>Defaults to <c>true</c>.</p> </item> - <tag><c><![CDATA[{disconnectfun, fun(Reason:term()) -> _}]]></c></tag> - <item> - <p>Provides a fun to implement your own logging when a server disconnects the client.</p> - </item> - - <tag><c><![CDATA[{unexpectedfun, fun(Message:term(), Peer) -> report | skip }]]></c></tag> - <item> - <p>Provides a fun to implement your own logging or other action when an unexpected message arrives. - If the fun returns <c>report</c> the usual info report is issued but if <c>skip</c> is returned no - report is generated.</p> - <p><c>Peer</c> is in the format of <c>{Host,Port}</c>.</p> - </item> - - <tag><c><![CDATA[{pref_public_key_algs, list()}]]></c></tag> - <item> - <p>List of user (client) public key algorithms to try to use.</p> - <p>The default value is the <c>public_key</c> entry in - <seealso marker="#default_algorithms/0">ssh:default_algorithms/0</seealso>. - </p> - <p>If there is no public key of a specified type available, the corresponding entry is ignored. - Note that the available set is dependent on the underlying cryptolib and current user's public keys. - </p> - </item> - - <tag><marker id="option_preferred_algorithms"></marker> - <c><![CDATA[{preferred_algorithms, algs_list()}]]></c></tag> + <tag><c>save_accepted_host</c></tag> <item> - <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>If <c>true</c>, the client saves an accepted host key to avoid the + accept question the next time the same host is connected. If the option + <seealso marker="#type-key_cb_common_option"><c>key_cb</c></seealso> + is not present, the key is saved in the file "known_hosts". See option + <seealso marker="#type-user_dir_common_option"><c>user_dir</c></seealso> for + the location of that file. </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, - [{public_key,['ssh-rsa','ssh-dss']}, - {cipher,[{client2server,['aes128-ctr']}, - {server2client,['aes128-cbc','3des-cbc']}]}, - {mac,['hmac-sha2-256','hmac-sha1']}, - {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) is implicit but public_key is set explicitly.</p> - - <p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p> - - <warning> - <p>Changing the values can make a connection less secure. Do not change unless you - know exactly what you are doing. If you do not understand the values then you - are not supposed to change them.</p> - </warning> - </item> - - <tag><marker id="option_modify_algorithms"></marker> - <c><![CDATA[{modify_algorithms, modify_algs_list()}]]></c></tag> - <item> - <p>Modifies the list of algorithms to use in the algorithm negotiation. The modifications are - applied after the option <c>preferred_algorithms</c> (if existing) is applied.</p> - <p>The algoritm for modifications works like this:</p> - <list> - <item> - <p>Input is the <c>modify_algs_list()</c> and a set of algorithms <c>A</c> - obtained from the <c>preferred_algorithms</c> option if existing, or else from the - <seealso marker="ssh#default_algorithms-0">ssh:default_algorithms/0</seealso>. - </p> - </item> - <item> - <p>The head of the <c>modify_algs_list()</c> modifies <c>A</c> giving the result <c>A'</c>.</p> - <p>The possible modifications are:</p> - <list> - <item> - <p>Append or prepend supported but not enabled algorithm(s) to the list of - algorithms. If the wanted algorithms already are in <c>A</c> they will first - be removed and then appended or prepended, - </p> - </item> - <item> - <p>Remove (rm) one or more algorithms from <c>A</c>. - </p> - </item> - </list> - </item> - <item> - <p>Repeat the modification step with the tail of <c>modify_algs_list()</c> and the resulting - <c>A'</c>. - </p> - </item> - </list> - <p>If an unsupported algorithm is in the <c>modify_algs_list()</c>, it will be silently ignored</p> - <p>If there are more than one modify_algorithms options, the result is undefined.</p> - <p>Here is an example of this option:</p> - <code> -{modify_algorithms, - [{prepend, [{kex, ['diffie-hellman-group1-sha1']}], - {rm, [{compression, [none]}]} - ] -} -</code> - <p>The example specifies that:</p> - <list> - <item><p>the old key exchange algorithm 'diffie-hellman-group1-sha1' should be - the main alternative. It will be the main alternative since it is prepened to the list</p> - </item> - <item><p>The compression algorithm none (= no compression) is removed so compression is enforced</p> - </item> - </list> - <p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p> - </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>If <c>false</c>, the key is not saved and the key will still be unknown + at the next access of the same host. </p> + <p>Defaults to <c>true</c></p> </item> - <tag><c><![CDATA[{connect_timeout, timeout()}]]></c></tag> + <tag><c>quiet_mode</c></tag> <item> - <p>Sets a time-out on the transport layer - connection. For <c>gen_tcp</c> the time is in milli-seconds and the default value is - <c>infinity</c>.</p> + <p>If <c>true</c>, the client does not print anything on authorization.</p> + <p>Defaults to <c>false</c></p> </item> + </taglist> + </desc> + </datatype> - <tag><c><![CDATA[{auth_methods, string()}]]></c></tag> - <item> - <p>Comma-separated string that determines which - authentication methods that the client shall support and - in which order they are tried. Defaults to - <c><![CDATA["publickey,keyboard-interactive,password"]]></c></p> - </item> - - <tag><c><![CDATA[{user, string()}]]></c></tag> + <datatype> + <name name="authentication_client_options"/> + <desc> + <taglist> + <tag><c>user</c></tag> <item> - <p>Provides a username. If this option is not given, <c>ssh</c> + <p>Provides the username. If this option is not given, <c>ssh</c> reads from the environment (<c><![CDATA[LOGNAME]]></c> or <c><![CDATA[USER]]></c> on UNIX, <c><![CDATA[USERNAME]]></c> on Windows).</p> </item> - <tag><c><![CDATA[{password, string()}]]></c></tag> + <tag><c>password</c></tag> <item> <p>Provides a password for password authentication. If this option is not given, the user is asked for a password, if the password authentication method is attempted.</p> </item> - - <!--tag><c><![CDATA[{send_ext_info, boolean()}]]></c></tag> - <item> - <p>Send a list of extensions to the server if the server has asked for it. See - <url href="https://tools.ietf.org/html/draft-ietf-curdle-ssh-ext-info">Draft-ietf-curdle-ssh-ext-info (work in progress)</url> for details. - </p> - <p>Currently the client do not react on any extensions. - </p> - <p>Default value is <c>true</c>. - </p> - </item--> - - <tag><c><![CDATA[{recv_ext_info, boolean()}]]></c></tag> - <item> - <p>Tell the server that the client accepts extension negotiation. See - <url href="https://tools.ietf.org/html/draft-ietf-curdle-ssh-ext-info">Draft-ietf-curdle-ssh-ext-info (work in progress)</url> for details. - </p> - <p>Currently implemented extension is <c>server-sig-algs</c> which is the list of the server's preferred - user's public key algorithms. - </p> - <p>Default value is <c>true</c>. - </p> - </item> - - <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. 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> - <item> - <p>If <c>true</c>, the client does not print anything on authorization.</p> - </item> - - <tag><c><![CDATA[{id_string, random | string()}]]></c></tag> - <item> - <p>The string that the client presents to a connected server initially. The default value is "Erlang/VSN" where VSN is the ssh application version number. - </p> - <p>The value <c>random</c> will cause a random string to be created at each connection attempt. This is to make it a bit more difficult for a malicious peer to find the ssh software brand and version. - </p> - </item> - - <tag><c><![CDATA[{fd, file_descriptor()}]]></c></tag> - <item> - <p>Allows an existing file descriptor to be used - (by passing it on to the transport protocol).</p></item> - <tag><c><![CDATA[{rekey_limit, integer()}]]></c></tag> - <item> - <p>Provides, in bytes, when rekeying is to be initiated. - Defaults to once per each GB and once per hour.</p> - </item> - <tag><c><![CDATA[{idle_time, integer()}]]></c></tag> - <item> - <p>Sets a time-out on a connection when no channels are active. - Defaults to <c>infinity</c>.</p></item> - <tag><c><![CDATA[{ssh_msg_debug_fun, fun(ConnectionRef::ssh_connection_ref(), AlwaysDisplay::boolean(), Msg::binary(), LanguageTag::binary()) -> _}]]></c></tag> - <item> - <p>Provide a fun to implement your own logging of the SSH message SSH_MSG_DEBUG. The last three parameters are from the message, see RFC4253, section 11.3. The <c>ConnectionRef</c> is the reference to the connection on which the message arrived. The return value from the fun is not checked.</p> - <p>The default behaviour is ignore the message. - To get a printout for each message with <c>AlwaysDisplay = true</c>, use for example <c>{ssh_msg_debug_fun, fun(_,true,M,_)-> io:format("DEBUG: ~p~n", [M]) end}</c></p> - </item> - </taglist> - </desc> - </func> + </desc> + </datatype> - <func> - <name>connection_info(ConnectionRef, [Option]) ->[{Option, - Value}]</name> - <fsummary>Retrieves information about a connection.</fsummary> - <type> - <v>Option = client_version | server_version | user | peer | sockname </v> - <v>Value = [option_value()] </v> - <v>option_value() = {{Major::integer(), Minor::integer()}, VersionString::string()} | - User::string() | Peer::{inet:hostname(), {ip_address(), port_number()}} | - Sockname::{ip_address(), port_number()}</v> - </type> + <datatype> + <name name="diffie_hellman_group_exchange_client_option"/> <desc> - <p>Retrieves information about a connection.</p> + <p>Sets the three diffie-hellman-group-exchange parameters that guides the connected server in choosing a group. + See + <url href="https://tools.ietf.org/html/rfc4419">RFC 4419</url> + for the details. The default value is <c>{1024, 6144, 8192}</c>. + </p> </desc> - </func> - - <func> - <name>daemon(Port) -> </name> - <name>daemon(Port, Options) -> </name> - <name>daemon(HostAddress, Port, Options) -> </name> - <name>daemon(TcpSocket) -> </name> - <name>daemon(TcpSocket, Options) -> {ok, ssh_daemon_ref()} | {error, atom()}</name> - <fsummary>Starts a server listening for SSH connections - on the given port.</fsummary> - <type> - <v>Port = integer()</v> - <v>HostAddress = ip_address() | any | loopback</v> - <v>Options = [{Option, Value}]</v> - <v>Option = atom()</v> - <v>Value = term()</v> - <v>TcpSocket = port()</v> - <d>The socket is supposed to be from <seealso marker="kernel:gen_tcp#connect-3">gen_tcp:connect</seealso> or <seealso marker="kernel:gen_tcp#accept-1">gen_tcp:accept</seealso> with option <c>{active,false}</c></d> - </type> - <desc> - <p>Starts a server listening for SSH connections on the given - port. If the <c>Port</c> is 0, a random free port is selected. See - <seealso marker="#daemon_info/1">daemon_info/1</seealso> about how to find the selected port number.</p> - - <p>Please note that by historical reasons both the <c>HostAddress</c> argument and the inet socket option - <c>ip</c> set the listening address. This is a source of possible inconsistent settings.</p> + </datatype> - <p>The rules for handling the two address passing options are:</p> - <list> - <item>if <c>HostAddress</c> is an IP-address, that IP-address is the listening address. - An 'ip'-option will be discarded if present.</item> + <datatype> + <name name="connect_timeout_client_option"/> + <desc> + <p>Sets a timeout on the transport layer connect time. + For <seealso marker="kernel:gen_tcp"><c>gen_tcp</c></seealso> the time is in milli-seconds and the default + value is <c>infinity</c>. + </p> + <p>See the parameter <c>Timeout</c> in <seealso marker="#connect/4">connect/4</seealso> for + a timeout of the negotiation phase. + </p> + </desc> + </datatype> - <item>if <c>HostAddress</c> is <c>loopback</c>, the listening address - is <c>loopback</c> and an loopback address will be choosen by the underlying layers. - An 'ip'-option will be discarded if present.</item> + <datatype> + <name name="recv_ext_info_client_option"/> + <desc> + <p>Make the client tell the server that the client accepts extension negotiation, that is, + include <c>ext-info-c</c> in the kexinit message sent. See + <url href="https://tools.ietf.org/html/rfc8308">RFC 8308</url> + for details and <seealso marker="SSH_app#supported-ext-info">ssh(6)</seealso> + for a list of currently implemented extensions. + </p> + <p> + Default value is <c>true</c> which is compatible with other implementations not supporting ext-info. + </p> + </desc> + </datatype> - <item>if <c>HostAddress</c> is <c>any</c> and no 'ip'-option is present, the listening address is - <c>any</c> and the socket will listen to all addresses</item> + <!--................................................................--> + <datatype_title>Daemon Options (Server Options)</datatype_title> - <item>if <c>HostAddress</c> is <c>any</c> and an 'ip'-option is present, the listening address is - set to the value of the 'ip'-option</item> - </list> + <datatype> + <name name="daemon_options"/> + <name name="daemon_option"/> + <desc> + <p>Options for <seealso marker="#daemon/1">daemons</seealso>. + The individual options are further explained below or by following the hyperlinks. + </p> + </desc> + </datatype> - <p>Options:</p> - <taglist> - <tag><c><![CDATA[{inet, inet | inet6}]]></c></tag> - <item><p>IP version to use when the host address is specified as <c>any</c>.</p></item> - <tag><c><![CDATA[{subsystems, [subsystem_spec()]}]]></c></tag> - <item> - <p>Provides specifications for handling of subsystems. The - "sftp" subsystem specification is retrieved by calling - <c>ssh_sftpd:subsystem_spec/1</c>. If the subsystems option is - not present, the value of - <c>[ssh_sftpd:subsystem_spec([])]</c> is used. - The option can be set to the empty list if - you do not want the daemon to run any subsystems.</p> - </item> + + <datatype> + <name name="subsystem_daemon_option"/> + <name name="subsystem_spec"/> + <desc> + <p>Defines a subsystem in the daemon.</p> + <p>The <c>subsystem_name</c> is the name that a client requests to start with for example + <seealso marker="ssh_connection#subsystem/4">ssh_connection:subsystem/4</seealso>. + </p> + <p>The <c>channel_callback</c> is the module that implements the <c>ssh_daemon_channel</c> + behaviour in the daemon. See the section + <seealso marker="using_ssh#usersguide_creating_a_subsystem">Creating a Subsystem</seealso> + in the User's Guide for more information and an example. + </p> + <p>If the subsystems option is not present, the value of <c>ssh_sftpd:subsystem_spec([])</c> is used. + This enables the sftp subsystem by default. + The option can be set to the empty list if you do not want the daemon to run any subsystems.</p> + </desc> + </datatype> - <tag><marker id="daemon_opt_shell"/> - <c><![CDATA[{shell, {Module, Function, Args} | - fun(string() = User) - > pid() | fun(string() = User, - ip_address() = PeerAddr) -> pid()}]]></c></tag> + <datatype> + <name name="shell_daemon_option"/> + <name name="'shell_fun/1'"/> + <name name="'shell_fun/2'"/> + <desc> + <p>Defines the read-eval-print loop used in a daemon when a shell is requested by the client. + The default is to use the Erlang shell: <c><![CDATA[{shell, start, []}]]></c> + </p> + <p>See the option <seealso marker="#type-exec_daemon_option"><c>exec</c></seealso> + for a description of how the daemon execute exec-requests depending on + the shell- and exec-options.</p> + </desc> + </datatype> + + <datatype> + <name name="exec_daemon_option"/> + <name name="'exec_fun/1'"/> + <name name="'exec_fun/2'"/> + <name name="'exec_fun/3'"/> + <name name="exec_result"/> + <desc> + <p>This option changes how the daemon execute exec-requests from clients. The term in the return value + is formatted to a string if it is a non-string type. No trailing newline is added in the ok-case but in the + error case.</p> + <p>Error texts are returned on channel-type 1 which usually is piped to <c>stderr</c> on e.g Linux systems. + Texts from a successful execution will in similar manner be piped to <c>stdout</c>. The exit-status code + is set to 0 for success and -1 for errors. The exact results presented on the client side depends on the + client and the client's operating system. + </p> + <p>The option cooperates with the daemon-option <seealso marker="#type-shell_daemon_option"><c>shell</c></seealso> + in the following way:</p> + <taglist> + <tag>1. If the exec-option is present (the shell-option may or may not be present):</tag> <item> - <p>Defines the read-eval-print loop used when a shell is - requested by the client. The default is to use the Erlang shell: - <c><![CDATA[{shell, start, []}]]></c></p> - <p>See the option <seealso marker="#daemon_opt_exec"><c>exec</c></seealso> - for a description of how the daemon execute exec-requests depending on - the shell- and exec-options.</p> + <p>The exec-option fun is called with the same number of parameters as the arity of the fun, + and the result is returned to the client. + </p> </item> - - <tag><marker id="daemon_opt_exec"/> - <c><![CDATA[{exec, {direct, exec_spec()}}]]></c> - <br/><c>where:</c> - <br/><c>exec_spec() = </c> - <br/><c> fun(Cmd::string()) -> ok_error()</c> - <br/><c> | fun(Cmd::string(), User::string()) -> ok_error()</c> - <br/><c> | fun(Cmd::string(), User::string(), ClientAddr::{ip_address(), port_number()}) -> ok_error()</c> - </tag> + + <tag>2. If the exec-option is absent, but a shell-option is present with the default Erlang shell:</tag> <item> - <p>This option changes how the daemon execute exec-requests from clients. The term in <c>ok_error()</c> - is formatted to a string if it is a non-string type. No trailing newline is added in the ok-case but in the - error case.</p> - <p>Error texts are returned on channel-type 1 which usually are piped to <c>stderr</c> on e.g Linux systems. - Texts from a successful execution will in similar manner be piped to <c>stdout</c>. The exit-status code - is set to 0 for success and -1 for errors. The exact results presented on the client side depends on the - client. - </p> - <p>The option cooperates with the daemon-option <seealso marker="#daemon_opt_shell"><c>shell</c></seealso> - in the following way:</p> - <taglist> - <tag>1. If the exec-option is present (the shell-option may or may not be present):</tag> - <item> - <p>The exec-option fun is called with the same number of parameters as the arity of the fun, - and the result is returned to the client. - </p> - </item> - - <tag>2. If the exec-option is absent, but a shell-option is present with the default Erlang shell:</tag> - <item> - <p>The default Erlang evaluator is used and the result is returned to the client.</p> - </item> - - <tag>3. If the exec-option is absent, but a shell-option is present that is not the default Erlang shell:</tag> - <item> - <p>The exec-request is not evaluated and an error message is returned to the client.</p> - </item> - - <tag>4. If neither the exec-option nor the shell-option is present:</tag> - <item> - <p>The default Erlang evaluator is used and the result is returned to the client.</p> - </item> - </taglist> - <p>If a custom CLI is installed (see the option <seealso marker="#daemon_opt_ssh_cli"><c>ssh_cli</c></seealso>) - the rules above are replaced by thoose implied by the custom CLI. - </p> - <note> - <p>The exec-option has existed for a long time but has not previously been documented. The old - definition and behaviour are retained but obey the rules 1-4 above if conflicting. - The old and undocumented style should not be used in new programs.</p> - </note> + <p>The default Erlang evaluator is used and the result is returned to the client.</p> </item> - - <tag><marker id="daemon_opt_ssh_cli"/> - <c><![CDATA[{ssh_cli, {channel_callback(), - channel_init_args()} | no_cli}]]></c></tag> + + <tag>3. If the exec-option is absent, but a shell-option is present that is not the default Erlang shell:</tag> <item> - <p>Provides your own CLI implementation, that is, a channel callback - module that implements a shell and command execution. The shell - read-eval-print loop can be customized, using the - option <seealso marker="#daemon_opt_shell"><c>shell</c></seealso>. This means less work than implementing - an own CLI channel. If <c>ssh_cli</c> is set to <c>no_cli</c>, the CLI channels - like <seealso marker="#daemon_opt_shell"><c>shell</c></seealso> - and <seealso marker="#daemon_opt_exec"><c>exec</c></seealso> - are disabled and only subsystem channels are allowed.</p> + <p>The exec-request is not evaluated and an error message is returned to the client.</p> </item> - <tag><c><![CDATA[{user_dir, string()}]]></c></tag> + + <tag>4. If neither the exec-option nor the shell-option is present:</tag> <item> - <p>Sets the user directory. That is, the directory containing - <c>ssh</c> configuration files for the user, such as - <c><![CDATA[known_hosts]]></c>, <c><![CDATA[id_rsa, - id_dsa]]></c>, and - <c><![CDATA[authorized_key]]></c>. Defaults to the - directory normally referred to as - <c><![CDATA[~/.ssh]]></c>.</p> + <p>The default Erlang evaluator is used and the result is returned to the client.</p> </item> - <tag><c><![CDATA[{system_dir, string()}]]></c></tag> + </taglist> + <p>If a custom CLI is installed (see the option <seealso marker="#type-ssh_cli_daemon_option"><c>ssh_cli</c></seealso>) + the rules above are replaced by thoose implied by the custom CLI. + </p> + <note> + <p>The exec-option has existed for a long time but has not previously been documented. The old + definition and behaviour are retained but obey the rules 1-4 above if conflicting. + The old and undocumented style should not be used in new programs.</p> + </note> + </desc> + </datatype> + + <datatype> + <name name="ssh_cli_daemon_option"/> + <desc> + <p>Provides your own CLI implementation in a daemon.</p> + <p>It is a channel callback module that implements a shell + and command execution. The shell's read-eval-print loop can be customized, using the + option <seealso marker="#type-shell_daemon_option"><c>shell</c></seealso>. This means less work than implementing + an own CLI channel. If <c>ssh_cli</c> is set to <c>no_cli</c>, the CLI channels + like <seealso marker="#type-shell_daemon_option"><c>shell</c></seealso> + and <seealso marker="#type-exec_daemon_option"><c>exec</c></seealso> + are disabled and only subsystem channels are allowed.</p> + </desc> + </datatype> + + <datatype> + <name name="authentication_daemon_options"/> + <name name="prompt_texts"/> + <name name="kb_int_tuple"/> + <name name="kb_int_fun_3"/> + <name name="pwdfun_2"/> + <name name="pwdfun_4"/> + <desc> + <taglist> + <tag><marker id="type-system_dir_daemon_option"/><c>system_dir</c></tag> <item> <p>Sets the system directory, containing the host key files that identify the host keys for <c>ssh</c>. Defaults to - <c><![CDATA[/etc/ssh]]></c>. For security reasons, - this directory is normally accessible only to the root user.</p> + <c>/etc/ssh</c>.</p> + <p>For security reasons, this directory is normally accessible only to the root user.</p> + <p>See also the option + <seealso marker="#type-key_cb_common_option">key_cb</seealso> + for the general way to handle keys. + </p> </item> - <tag><c><![CDATA[{auth_methods, string()}]]></c></tag> + <tag><c>auth_method_kb_interactive_data</c></tag> <item> - <p>Comma-separated string that determines which - authentication methods that the server is to support and - in what order they are tried. Defaults to - <c><![CDATA["publickey,keyboard-interactive,password"]]></c></p> - <p>Note that the client is free to use any order and to exclude methods.</p> - </item> - - <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> + <p>Sets the text strings that the daemon sends to the client for presentation to the user when + using <c>keyboard-interactive</c> authentication.</p> + <p>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> <p>The parameter <c>Echo</c> guides the client about need to hide the password.</p> <p>The default value is: - <c>{auth_method_kb_interactive_data, {"SSH server", "Enter password for \""++User++"\"", "password: ", false}></c></p> + <c>{auth_method_kb_interactive_data, {"SSH server", "Enter password for \""++User++"\"", "password: ", false}></c> + </p> </item> - <tag><c><![CDATA[{user_passwords, [{string() = User, - string() = Password}]}]]></c></tag> + <tag><c>user_passwords</c></tag> <item> - <p>Provides passwords for password authentication. The passwords - are used when someone tries to connect to the server and - public key user-authentication fails. The option provides + <p>Provides passwords for password authentication. The passwords are used when someone tries + to connect to the server and public key user-authentication fails. The option provides a list of valid usernames and the corresponding passwords. </p> </item> - <tag><c><![CDATA[{password, string()}]]></c></tag> + + <tag><c>password</c></tag> <item> - <p>Provides a global password that authenticates any - user. From a security perspective this option makes - the server very vulnerable.</p> + <p>Provides a global password that authenticates any user.</p> + <warning> + <p>Intended to facilitate testing.</p> + <p>From a security perspective this option makes the server very vulnerable.</p> + </warning> </item> - <tag><c><![CDATA[{preferred_algorithms, algs_list()}]]></c></tag> + <tag><c>pwdfun</c> with <c>pwdfun_4()</c></tag> <item> - <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>Provides a function for password validation. This could used for calling an external system or handeling + passwords stored as hash values. </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, - [{public_key,['ssh-rsa','ssh-dss']}, - {cipher,[{client2server,['aes128-ctr']}, - {server2client,['aes128-cbc','3des-cbc']}]}, - {mac,['hmac-sha2-256','hmac-sha1']}, - {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) is implicit but public_key is set explicitly.</p> - - <p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</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>.</p> + <p>To facilitate for instance 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>. + </p> + + <p>The fun should return: + </p> + <list type="bulleted"> + <item><c>true</c> if the user and password is valid</item> + <item><c>false</c> if the user or password is invalid</item> + <item><c>disconnect</c> if a SSH_MSG_DISCONNECT message should be sent immediately. It will + be followed by a close of the underlying tcp connection.</item> + <item><c>{true, NewState:any()}</c> if the user and password is valid</item> + <item><c>{false, NewState:any()}</c> if the user or password is invalid</item> + </list> - <warning> - <p>Changing the values can make a connection less secure. Do not change unless you - know exactly what you are doing. If you do not understand the values then you - are not supposed to change them.</p> - </warning> + <p>A third usage is to block login attempts from a missbehaving peer. The <c>State</c> described above + can be used for this. The return value <c>disconnect</c> is useful for this.</p> </item> - <tag><marker id="option_modify_algorithms"></marker> - <c><![CDATA[{modify_algorithms, modify_algs_list()}]]></c></tag> + <tag><c>pwdfun</c> with <c>pwdfun_2()</c></tag> <item> - <p>Modifies the list of algorithms to use in the algorithm negotiation. The modifications are - applied after the option <c>preferred_algorithms</c> is applied (if existing)</p> - <p>The possible modifications are to:</p> - <list> - <item><p>Append or prepend supported but not enabled algorithm(s) to the list of - algorithms.</p><p>If the wanted algorithms already are in the list of algorithms, they will first - be removed and then appended or prepended. - </p> - </item> - <item><p>Remove (rm) one or more algorithms from the list of algorithms.</p></item> + <p>Provides a function for password validation. This function is called with user and password + as strings, and returns:</p> + <list type="bulleted"> + <item><c>true</c> if the user and password is valid</item> + <item><c>false</c> if the user or password is invalid</item> </list> - <p>If an unsupported algorithm is in the list, it will be silently ignored</p> - - <p>Here is an example of this option:</p> - <code> -{modify_algorithms, - [{prepend, [{kex, ['diffie-hellman-group1-sha1']}], - {rm, [{compression, [none]}]} - ] -} -</code> - <p>The example specifies that:</p> - <list> - <item><p>the old key exchange algorithm 'diffie-hellman-group1-sha1' should be - the main alternative. It will be the main alternative since it is prepened to the list</p> - </item> - <item><p>The compression algorithm none (= no compression) is removed so compression is enforced</p> - </item> - </list> - <p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p> + <p>This variant is kept for compatibility.</p> </item> + </taglist> + </desc> + </datatype> - <tag><c><![CDATA[{dh_gex_groups, [{Size=integer(),G=integer(),P=integer()}] | {file,filename()} {ssh_moduli_file,filename()} }]]></c></tag> + <datatype> + <name name="diffie_hellman_group_exchange_daemon_option"/> + <name name="explicit_group"/> + <name name="explicit_group_file"/> + <name name="ssh_moduli_file"/> + <desc> + <taglist> + <tag><c>dh_gex_groups</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: + See + <url href="https://tools.ietf.org/html/rfc4419">RFC 4419</url> + for details. The three variants of this option are: </p> <taglist> <tag><c>{Size=integer(),G=integer(),P=integer()}</c></tag> @@ -783,7 +593,7 @@ </p> </item> - <tag><c><![CDATA[{dh_gex_limits,{Min=integer(),Max=integer()}}]]></c></tag> + <tag><c>dh_gex_limits</c></tag> <item> <p>Limits what a client can ask for in diffie-hellman-group-exchange. The limits will be @@ -794,57 +604,29 @@ </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> + <p>See + <url href="https://tools.ietf.org/html/rfc4419">RFC 4419</url> + for the function of the Max and Min values.</p> </item> + </taglist> + </desc> + </datatype> - <tag><c><![CDATA[{negotiation_timeout, integer()}]]></c></tag> - <item> - <p>Maximum time in milliseconds for the authentication negotiation. - Defaults to 120000 (2 minutes). If the client fails to log in within this time, - the connection is closed. - </p> - </item> + <datatype> + <name name="negotiation_timeout_daemon_option"/> + <desc> + <p>Maximum time in milliseconds for the authentication negotiation. + Defaults to 120000 ms (2 minutes). If the client fails to log in within this time, + the connection is closed. + </p> + </desc> + </datatype> - <tag><c><![CDATA[{max_sessions, pos_integer()}]]></c></tag> + <datatype> + <name name="hardening_daemon_options"/> + <desc> + <taglist> + <tag><c>max_sessions</c></tag> <item> <p>The maximum number of simultaneous sessions that are accepted at any time for this daemon. This includes sessions that are being authorized. @@ -864,7 +646,7 @@ </p> </item> - <tag><c><![CDATA[{max_channels, pos_integer()}]]></c></tag> + <tag><c>max_channels</c></tag> <item> <p>The maximum number of channels with active remote subsystem that are accepted for each connection to this daemon</p> @@ -872,8 +654,7 @@ </p> </item> - - <tag><c><![CDATA[{parallel_login, boolean()}]]></c></tag> + <tag><c>parallel_login</c></tag> <item> <p>If set to false (the default value), only one login is handled at a time. If set to true, an unlimited number of login attempts are allowed simultaneously. @@ -890,171 +671,543 @@ </warning> </item> - <tag><c><![CDATA[{minimal_remote_max_packet_size, non_negative_integer()}]]></c></tag> + <tag><c>minimal_remote_max_packet_size</c></tag> <item> - <p>The least maximum packet size that the daemon will accept in channel open requests from the client. The default value is 0. + <p>The least maximum packet size that the daemon will accept in channel open requests from the client. + The default value is 0. </p> </item> + + </taglist> + </desc> + </datatype> + + <datatype> + <name name="callbacks_daemon_options"/> + <desc> + <taglist> + <tag><c>connectfun</c></tag> + <item> + <p>Provides a fun to implement your own logging when a user authenticates to the server.</p> + </item> - <tag><c><![CDATA[{id_string, random | string()}]]></c></tag> + <tag><c>failfun</c></tag> <item> - <p>The string the daemon will present to a connecting peer initially. The default value is "Erlang/VSN" where VSN is the ssh application version number. - </p> - <p>The value <c>random</c> will cause a random string to be created at each connection attempt. This is to make it a bit more difficult for a malicious peer to find the ssh software brand and version. - </p> + <p>Provides a fun to implement your own logging when a user fails to authenticate.</p> </item> + </taglist> + </desc> + </datatype> - <tag><c><![CDATA[{send_ext_info, boolean()}]]></c></tag> - <item> - <p>Send a list of extensions to the client if the client has asked for it. See - <url href="https://tools.ietf.org/html/draft-ietf-curdle-ssh-ext-info">Draft-ietf-curdle-ssh-ext-info (work in progress)</url> for details. - </p> - <p>Currently implemented extension is sending <c>server-sig-algs</c> which is the list of the server's preferred - user's public key algorithms. - </p> - <p>Default value is <c>true</c>. - </p> - </item> + <datatype> + <name name="send_ext_info_daemon_option"/> + <desc> + <p>Make the server (daemon) tell the client that the server accepts extension negotiation, that is, + include <c>ext-info-s</c> in the kexinit message sent. See + <url href="https://tools.ietf.org/html/rfc8308">RFC 8308</url> + for details and <seealso marker="SSH_app#supported-ext-info">ssh(6)</seealso> + for a list of currently implemented extensions. + </p> + <p>Default value is <c>true</c> which is compatible with other implementations not supporting ext-info. + </p> + </desc> + </datatype> - <!--tag><c><![CDATA[{recv_ext_info, boolean()}]]></c></tag> - <item> - <p>Tell the client that the server accepts extension negotiation. See - <url href="https://tools.ietf.org/html/draft-ietf-curdle-ssh-ext-info">Draft-ietf-curdle-ssh-ext-info (work in progress)</url> for details. - </p> - <p>Default value is <c>true</c>. - </p> - </item--> - <tag><c><![CDATA[{key_cb, key_cb()}]]></c></tag> + <!--................................................................--> + <datatype_title>Options common to clients and daemons</datatype_title> + <datatype> + <name name="common_options"/> + <name name="common_option"/> + <desc><p>The options above can be used both in clients and in daemons (servers). They are further explained below.</p> + </desc> + </datatype> + + <datatype> + <name name="user_dir_common_option"/> + <desc> + <p>Sets the user directory. That is, the directory containing <c>ssh</c> configuration + files for the user, such as + <c>known_hosts</c>, <c>id_rsa</c>, <c>id_dsa</c>>, <c>id_ecdsa</c> and <c>authorized_key</c>. + Defaults to the directory normally referred to as <c>~/.ssh</c>. + </p> + <p>See also the option + <seealso marker="#type-key_cb_common_option">key_cb</seealso> + for the general way to handle keys. + </p> + </desc> + </datatype> + + <datatype> + <name name="profile_common_option"/> + <desc> + <p>Used together with <c>ip-address</c> and <c>port</c> to + uniquely identify a ssh daemon. This can be useful in a + virtualized environment, where there can be more that one + server that has the same <c>ip-address</c> and + <c>port</c>. If this property is not explicitly set, it is + assumed that the the <c>ip-address</c> and <c>port</c> + uniquely identifies the SSH daemon. + </p> + </desc> + </datatype> + + <datatype> + <name name="max_idle_time_common_option"/> + <desc> + <p>Sets a time-out on a connection when no channels are active. Defaults to <c>infinity</c>.</p> + </desc> + </datatype> + + <datatype> + <name name="rekey_limit_common_option"/> + <desc> + <p>Sets a limit, in bytes, when rekeying is to be initiated. + Defaults to once per each GB and once per hour.</p> + </desc> + </datatype> + + <datatype> + <name name="key_cb_common_option"/> + <desc> + <p>Module implementing the behaviour + <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso> and/or + <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> + <p>The <c>Opts</c> defaults to <c>[]</c> when only the <c>Module</c> is specified. + </p> + <p>The default value of this option is <c>{ssh_file, []}</c>. + </p> + <p>A call to the call-back function <c>F</c> will be</p> + <code> + Module:F(..., [{key_cb_private,Opts}|UserOptions]) + </code> + <p>where <c>...</c> are arguments to <c>F</c> as in + <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso> and/or + <seealso marker="ssh_server_key_api">ssh_server_key_api</seealso>. + The <c>UserOptions</c> are the options given to <c>ssh:connect</c>, <c>ssh:shell</c> or <c>ssh:daemon</c>. + </p> + + </desc> + </datatype> + + <datatype> + <name name="disconnectfun_common_option"/> + <desc> + <p>Provides a fun to implement your own logging when the peer disconnects.</p> + </desc> + </datatype> + + <datatype> + <name name="unexpectedfun_common_option"/> + <desc> + <p>Provides a fun to implement your own logging or other action when an unexpected message arrives. + If the fun returns <c>report</c> the usual info report is issued but if <c>skip</c> is returned no + report is generated.</p> + </desc> + </datatype> + + <datatype> + <name name="ssh_msg_debug_fun_common_option"/> + <desc> + <p>Provide a fun to implement your own logging of the SSH message SSH_MSG_DEBUG. + The last three parameters are from the message, see + <url href="https://tools.ietf.org/html/rfc4253#section-11.3">RFC 4253, section 11.3</url>. + The <seealso marker="#type-connection_ref"><c>connection_ref()</c></seealso> is the reference + to the connection on which the message arrived. + The return value from the fun is not checked. + </p> + <p>The default behaviour is ignore the message. + To get a printout for each message with <c>AlwaysDisplay = true</c>, + use for example <c>{ssh_msg_debug_fun, fun(_,true,M,_)-> io:format("DEBUG: ~p~n", [M]) end}</c></p> + </desc> + </datatype> + + <datatype> + <name name="id_string_common_option"/> + <desc> + <p>The string the daemon will present to a connecting peer initially. + The default value is "Erlang/VSN" where VSN is the ssh application version number. + </p> + <p>The value <c>random</c> will cause a random string to be created at each connection attempt. + This is to make it a bit more difficult for a malicious peer to find the ssh software brand and version. + </p> + <p>The value <c>{random, Nmin, Nmax}</c> will make a random string with at least <c>Nmin</c> characters and + at most <c>Nmax</c> characters. + </p> + </desc> + </datatype> + + <datatype> + <name name="preferred_algorithms_common_option"/> + <name name="algs_list"/> + <name name="alg_entry"/> + <name name="kex_alg"/> + <name name="pubkey_alg"/> + <name name="cipher_alg"/> + <name name="mac_alg"/> + <name name="compression_alg"/> + <name name="double_algs"/> + + <desc> + <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, + [{public_key,['ssh-rsa','ssh-dss']}, + {cipher,[{client2server,['aes128-ctr']}, + {server2client,['aes128-cbc','3des-cbc']}]}, + {mac,['hmac-sha2-256','hmac-sha1']}, + {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) is implicit but public_key is set explicitly.</p> + + <p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p> + + <p>If an algorithm name occurs more than once in a list, the behaviour is undefined. The tags in the property lists + are also assumed to occur at most one time. + </p> + + <warning> + <p>Changing the values can make a connection less secure. Do not change unless you + know exactly what you are doing. If you do not understand the values then you + are not supposed to change them.</p> + </warning> + </desc> + </datatype> + + <datatype> + <name name="modify_algorithms_common_option"/> + <name name="modify_algs_list"/> + <desc> + <p>Modifies the list of algorithms to use in the algorithm negotiation. The modifications are + applied after the option <c>preferred_algorithms</c> (if existing) is applied.</p> + <p>The algoritm for modifications works like this:</p> + <list> <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. 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>Input is the <c>modify_algs_list()</c> and a set of algorithms <c>A</c> + obtained from the <c>preferred_algorithms</c> option if existing, or else from the + <seealso marker="ssh#default_algorithms-0">ssh:default_algorithms/0</seealso>. </p> </item> - - <tag><c>{profile, atom()}</c></tag> <item> - <p>Used together with <c>ip-address</c> and <c>port</c> to - uniquely identify a ssh daemon. This can be useful in a - virtualized environment, where there can be more that one - server that has the same <c>ip-address</c> and - <c>port</c>. If this property is not explicitly set, it is - assumed that the the <c>ip-address</c> and <c>port</c> - uniquely identifies the SSH daemon. - </p> + <p>The head of the <c>modify_algs_list()</c> modifies <c>A</c> giving the result <c>A'</c>.</p> + <p>The possible modifications are:</p> + <list> + <item> + <p>Append or prepend supported but not enabled algorithm(s) to the list of + algorithms. If the wanted algorithms already are in <c>A</c> they will first + be removed and then appended or prepended, + </p> + </item> + <item> + <p>Remove (rm) one or more algorithms from <c>A</c>. + </p> + </item> + </list> </item> - - <tag><c><![CDATA[{fd, file_descriptor()}]]></c></tag> - <item> - <p>Allows an existing file-descriptor to be used - (passed on to the transport protocol).</p></item> - <tag><c><![CDATA[{failfun, fun(User::string(), - PeerAddress::ip_address(), Reason::term()) -> _}]]></c></tag> <item> - <p>Provides a fun to implement your own logging when a user fails to authenticate.</p> + <p>Repeat the modification step with the tail of <c>modify_algs_list()</c> and the resulting + <c>A'</c>. + </p> </item> - <tag><c><![CDATA[{connectfun, fun(User::string(), PeerAddress::ip_address(), - Method::string()) ->_}]]></c></tag> - <item> - <p>Provides a fun to implement your own logging when a user authenticates to the server.</p> + </list> + <p>If an unsupported algorithm is in the <c>modify_algs_list()</c>, it will be silently ignored</p> + <p>If there are more than one modify_algorithms options, the result is undefined.</p> + <p>Here is an example of this option:</p> + <code> + {modify_algorithms, + [{prepend, [{kex, ['diffie-hellman-group1-sha1']}], + {rm, [{compression, [none]}]} + ] + } + </code> + <p>The example specifies that:</p> + <list> + <item><p>the old key exchange algorithm 'diffie-hellman-group1-sha1' should be + the main alternative. It will be the main alternative since it is prepened to the list</p> </item> - <tag><c><![CDATA[{disconnectfun, fun(Reason:term()) -> _}]]></c></tag> - <item> - <p>Provides a fun to implement your own logging when a user disconnects from the server.</p> + <item><p>The compression algorithm none (= no compression) is removed so compression is enforced</p> </item> + </list> + <p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p> + </desc> + </datatype> - <tag><c><![CDATA[{unexpectedfun, fun(Message:term(), Peer) -> report | skip }]]></c></tag> - <item> - <p>Provides a fun to implement your own logging or other action when an unexpected message arrives. - If the fun returns <c>report</c> the usual info report is issued but if <c>skip</c> is returned no - report is generated.</p> - <p><c>Peer</c> is in the format of <c>{Host,Port}</c>.</p> - </item> - <tag><c><![CDATA[{idle_time, integer()}]]></c></tag> - <item> - <p>Sets a time-out on a connection when no channels are active. - Defaults to <c>infinity</c>.</p> - </item> + <datatype> + <name name="inet_common_option"/> + <desc> + <p>IP version to use when the host address is specified as <c>any</c>.</p> + </desc> + </datatype> - <tag><c><![CDATA[{ssh_msg_debug_fun, fun(ConnectionRef::ssh_connection_ref(), AlwaysDisplay::boolean(), Msg::binary(), LanguageTag::binary()) -> _}]]></c></tag> - <item> - <p>Provide a fun to implement your own logging of the SSH message SSH_MSG_DEBUG. The last three parameters are from the message, see RFC4253, section 11.3. The <c>ConnectionRef</c> is the reference to the connection on which the message arrived. The return value from the fun is not checked.</p> - <p>The default behaviour is ignore the message. - To get a printout for each message with <c>AlwaysDisplay = true</c>, use for example <c>{ssh_msg_debug_fun, fun(_,true,M,_)-> io:format("DEBUG: ~p~n", [M]) end}</c></p> - </item> + <datatype> + <name name="auth_methods_common_option"/> + <desc> + <p>Comma-separated string that determines which authentication methods that the client shall + support and in which order they are tried. Defaults to <c>"publickey,keyboard-interactive,password"</c> + </p> + <p>Note that the client is free to use any order and to exclude methods. + </p> + </desc> + </datatype> - </taglist> - </desc> - </func> + <datatype> + <name name="fd_common_option"/> + <desc> + <p>Allows an existing file-descriptor to be used (passed on to the transport protocol).</p> + </desc> + </datatype> - <func> - <name>daemon_info(Daemon) -> {ok, [DaemonInfo]} | {error,Error}</name> - <fsummary>Get info about a daemon</fsummary> - <type> - <v>DaemonInfo = {port,Port::pos_integer()} | {listen_address, any|ip_address()} | {profile,atom()}</v> - <v>Port = integer()</v> - <v>Error = bad_daemon_ref</v> - </type> + <!--................................................................--> + <datatype_title>Other data types</datatype_title> + + <datatype> + <name name="host"/> + <desc> + </desc> + </datatype> + + <datatype> + <name name="ip_port"/> <desc> - <p>Returns a key-value list with information about the daemon. For now, only the listening port is returned. This is intended for the case the daemon is started with the port set to 0.</p> </desc> + </datatype> + + <datatype> + <name name="mod_args"/> + <desc> + </desc> + </datatype> + + <datatype> + <name name="mod_fun_args"/> + <desc> + </desc> + </datatype> + + <datatype> + <name name="open_socket"/> + <desc> + <p>The socket is supposed to be result of a <seealso marker="kernel:gen_tcp#connect-3">gen_tcp:connect</seealso> + or a <seealso marker="kernel:gen_tcp#accept-1">gen_tcp:accept</seealso>. The socket must be in passive + mode (that is, opened with the option <c>{active,false})</c>. + </p> + </desc> + </datatype> + + <datatype> + <name name="daemon_ref"/> + <desc> + <p>Opaque data type representing a daemon.</p> + <p>Returned by the functions <seealso marker="ssh#daemon-1"><c>daemon/1,2,3</c></seealso>.</p> + </desc> + </datatype> + + <datatype> + <name>connection_ref()</name> + <desc> + <p>Opaque data type representing a connection between a client and a server (daemon).</p> + <p>Returned by the functions + <seealso marker="ssh#connect-3"><c>connect/2,3,4</c></seealso> and + <seealso marker="ssh_sftp#start_channel-2"><c>ssh_sftp:start_channel/2,3</c></seealso>. + </p> + </desc> + </datatype> + + <datatype> + <name name="channel_id"/> + <desc> + <p>Opaque data type representing a channel inside a connection.</p> + <p>Returned by the functions + <seealso marker="ssh_connection#session_channel/2">ssh_connection:session_channel/2,4</seealso>. + </p> + </desc> + </datatype> + + + <datatype> + <name>opaque_client_options</name> + <name>opaque_daemon_options</name> + <name>opaque_common_options</name> + <desc> + <marker id="type-opaque_client_options"/> + <marker id="type-opaque_daemon_options"/> + <marker id="type-opaque_common_options"/> + <p>Opaque types that define experimental options that are not to be used in products.</p> + </desc> + </datatype> + </datatypes> + +<!-- + ================================================================ + = Function definitions = + ================================================================ +--> + + <funcs> + +<!-- CLOSE/1 --> + <func> + <name name="close" arity="1"/> + <fsummary>Closes an SSH connection.</fsummary> + <desc><p>Closes an SSH connection.</p></desc> </func> + +<!-- CONNECT/2 etc --> + <func> + <name>connect(Host, Port, Options) -> Result </name> + <name>connect(Host, Port, Options, NegotiationTimeout) -> Result </name> + <name>connect(TcpSocket, Options) -> Result</name> + <name>connect(TcpSocket, Options, NegotiationTimeout) -> Result</name> + <fsummary>Connects to an SSH server.</fsummary> + <type> + <v>Host = <seealso marker="#type-host">host()</seealso></v> + <v>Port = <seealso marker="kernel:inet#type-port_number">inet:port_number()</seealso></v> + <v>Options = <seealso marker="#type-client_options">client_options()</seealso></v> + <v>TcpSocket = <seealso marker="#type-open_socket">open_socket()</seealso></v> + <v>NegotiationTimeout = timeout()</v> + <v>Result = {ok, <seealso marker="#type-connection_ref">connection_ref()</seealso>} | {error, term()}</v> + </type> + <desc> + <p>Connects to an SSH server at the <c>Host</c> on <c>Port</c>. + </p> + <p>As an alternative, an already open TCP socket could be passed to the function in <c>TcpSocket</c>. + The SSH initiation and negotiation will be initiated on that one with the SSH that should be at the + other end. + </p> + <p>No channel is started. This is done by calling <seealso marker="ssh_connection#session_channel/2"> + ssh_connection:session_channel/[2, 4]</seealso>. + </p> + <p>The <c>NegotiationTimeout</c> is in milli-seconds. The default value is <c>infinity</c>. + For connection timeout, use the option + <seealso marker="#type-connect_timeout_client_option"><c>connect_timeout</c></seealso>. + </p> + </desc> + </func> + +<!-- CONNECTION_INFO/1, CONNECTION_INFO/2 --> + <func> + <name name="connection_info" arity="2"/> + <fsummary>Retrieves information about a connection.</fsummary> + <desc> + <p>Retrieves information about a connection. The list <c>Keys</c> defines which information that + is returned.</p> + </desc> + </func> + +<!-- DEAMON/1,2,3 --> + <func> + <name>daemon(Port | TcpSocket) -> Result</name> + <name>daemon(Port | TcpSocket, Options) -> Result</name> + <name>daemon(HostAddress, Port, Options) -> Result</name> + <fsummary>Starts a server listening for SSH connections.</fsummary> + <type> + <v>Port = integer()</v> + <v>TcpSocket = <seealso marker="#type-open_socket">open_socket()</seealso></v> + <v>Options = <seealso marker="#type-daemon_options">daemon_options()</seealso></v> + <v>HostAddress = <seealso marker="#type-host">host()</seealso> | any</v> + <v>Result = {ok, <seealso marker="#type-daemon_ref">daemon_ref()</seealso>} | {error, atom()}</v> + </type> + <desc> + <p>Starts a server listening for SSH connections on the given port. If the <c>Port</c> is 0, + a random free port is selected. See <seealso marker="#daemon_info/1">daemon_info/1</seealso> + about how to find the selected port number. + </p> + <p>As an alternative, an already open TCP socket could be passed to the function in <c>TcpSocket</c>. + The SSH initiation and negotiation will be initiated on that one when an SSH starts at the other end + of the TCP socket. + </p> + <p>For a description of the options, see <seealso marker="#type-daemon_options">Daemon Options</seealso>. + </p> + <p>Please note that by historical reasons both the <c>HostAddress</c> argument and the + <seealso marker="kernel:gen_tcp#type-connect_option">gen_tcp connect_option() <c>{ip,Address}</c></seealso> + set the listening address. This is a source of possible inconsistent settings. + </p> + <p>The rules for handling the two address passing options are:</p> + <list> + <item>if <c>HostAddress</c> is an IP-address, that IP-address is the listening address. + An 'ip'-option will be discarded if present.</item> + + <item>if <c>HostAddress</c> is the atom <c>loopback</c>, the listening address + is <c>loopback</c> and an loopback address will be choosen by the underlying layers. + An 'ip'-option will be discarded if present.</item> + + <item>if <c>HostAddress</c> is the atom <c>any</c> and no 'ip'-option is present, the listening address is + <c>any</c> and the socket will listen to all addresses</item> + + <item>if <c>HostAddress</c> is <c>any</c> and an 'ip'-option is present, the listening address is + set to the value of the 'ip'-option</item> + </list> + </desc> + </func> + +<!-- DAEMON_INFO/1 --> + <func> + <name name="daemon_info" arity="1"/> + <fsummary>Get info about a daemon</fsummary> + <desc> + <p>Returns a key-value list with information about the daemon.</p> + </desc> + </func> + +<!-- DEFAULT_ALGORITHMS/0 --> <func> - <name>default_algorithms() -> algs_list()</name> + <name name="default_algorithms" arity="0"/> <fsummary>Get a list declaring the supported algorithms</fsummary> <desc> <p>Returns a key-value list, where the keys are the different types of algorithms and the values are the - algorithms themselves. An example:</p> - <code> -20> ssh:default_algorithms(). -[{kex,['diffie-hellman-group1-sha1']}, - {public_key,['ssh-rsa','ssh-dss']}, - {cipher,[{client2server,['aes128-ctr','aes128-cbc','3des-cbc']}, - {server2client,['aes128-ctr','aes128-cbc','3des-cbc']}]}, - {mac,[{client2server,['hmac-sha2-256','hmac-sha1']}, - {server2client,['hmac-sha2-256','hmac-sha1']}]}, - {compression,[{client2server,[none,zlib]}, - {server2client,[none,zlib]}]}] -21> -</code> + algorithms themselves.</p> + <p>See the <seealso marker="configure_algos#example_default_algorithms">User's Guide</seealso> for + an example.</p> </desc> </func> +<!-- SHELL/1,2,3 --> <func> - <name>shell(Host) -> </name> - <name>shell(Host, Option) -> </name> - <name>shell(Host, Port, Option) -> </name> - <name>shell(TcpSocket) -> _</name> - <fsummary>Starts an interactive shell over an SSH server.</fsummary> + <name>shell(Host | TcpSocket) -> Result </name> + <name>shell(Host | TcpSocket, Options) -> Result </name> + <name>shell(Host, Port, Options) -> Result </name> + <fsummary>Starts an interactive shell on a remote SSH server.</fsummary> <type> - <v>Host = string()</v> - <v>Port = integer()</v> - <v>Options - see ssh:connect/3</v> - <v>TcpSocket = port()</v> - <d>The socket is supposed to be from <seealso marker="kernel:gen_tcp#connect-3">gen_tcp:connect</seealso> or <seealso marker="kernel:gen_tcp#accept-1">gen_tcp:accept</seealso> with option <c>{active,false}</c></d> + <v>Host = <seealso marker="#type-host">host()</seealso></v> + <v>TcpSocket = <seealso marker="#type-open_socket">open_socket()</seealso></v> + <v>Port = <seealso marker="kernel:inet#type-port_number">inet:port_number()</seealso></v> + <v>Options = <seealso marker="#type-client_options">client_options()</seealso></v> + <v>Result = ok | {error, Reason::term()}</v> </type> <desc> - <p>Starts an interactive shell over an SSH server on the - given <c>Host</c>. The function waits for user input, - and does not return until the remote shell is ended (that is, + <p>Connects to an SSH server at <c>Host</c> and <c>Port</c> (defaults to 22) and starts an + interactive shell on that remote host. + </p> + <p>As an alternative, an already open TCP socket could be passed to the function in <c>TcpSocket</c>. + The SSH initiation and negotiation will be initiated on that one and finaly a shell will be started + on the host at the other end of the TCP socket. + </p> + <p>For a description of the options, see <seealso marker="#type-client_options">Client Options</seealso>.</p> + <p>The function waits for user input, and does not return until the remote shell is ended (that is, exit from the shell). </p> </desc> </func> <func> - <name>start() -> </name> - <name>start(Type) -> ok | {error, Reason}</name> + <name name="start" arity="0"/> + <name name="start" arity="1"/> <fsummary>Starts the SSH application.</fsummary> - <type> - <v>Type = permanent | transient | temporary</v> - <v>Reason = term() </v> - </type> <desc> <p>Utility function that starts the applications <c>crypto</c>, <c>public_key</c>, and <c>ssh</c>. Default type is <c>temporary</c>. @@ -1064,11 +1217,8 @@ </func> <func> - <name>stop() -> ok | {error, Reason}</name> + <name name="stop" arity="0"/> <fsummary>Stops the <c>ssh</c> application.</fsummary> - <type> - <v>Reason = term()</v> - </type> <desc> <p>Stops the <c>ssh</c> application. For more information, see the <seealso marker="kernel:application">application(3)</seealso> @@ -1077,34 +1227,22 @@ </func> <func> - <name>stop_daemon(DaemonRef) -> </name> - <name>stop_daemon(Address, Port) -> ok </name> - <fsummary>Stops the listener and all connections started by - the listener.</fsummary> - <type> - <v>DaemonRef = ssh_daemon_ref()</v> - <v>Address = ip_address()</v> - <v>Port = integer()</v> - </type> + <name name="stop_daemon" arity="1"/> + <name name="stop_daemon" arity="2"/> + <name name="stop_daemon" arity="3"/> + <fsummary>Stops the listener and all connections started by the listener.</fsummary> <desc> - <p>Stops the listener and all connections started by - the listener.</p> + <p>Stops the listener and all connections started by the listener.</p> </desc> </func> <func> - <name>stop_listener(DaemonRef) -> </name> - <name>stop_listener(Address, Port) -> ok </name> - <fsummary>Stops the listener, but leaves existing connections started - by the listener operational.</fsummary> - <type> - <v>DaemonRef = ssh_daemon_ref()</v> - <v>Address = ip_address()</v> - <v>Port = integer()</v> - </type> + <name name="stop_listener" arity="1"/> + <name name="stop_listener" arity="2"/> + <name name="stop_listener" arity="3"/> + <fsummary>Stops the listener, but leaves existing connections started by the listener operational.</fsummary> <desc> - <p>Stops the listener, but leaves existing connections started - by the listener operational.</p> + <p>Stops the listener, but leaves existing connections started by the listener operational.</p> </desc> </func> |