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Diffstat (limited to 'lib/ssh/doc/src/ssh.xml')
| -rw-r--r-- | lib/ssh/doc/src/ssh.xml | 452 |
1 files changed, 308 insertions, 144 deletions
diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml index 72dafc0c09..0516945c0e 100644 --- a/lib/ssh/doc/src/ssh.xml +++ b/lib/ssh/doc/src/ssh.xml @@ -22,54 +22,85 @@ </legalnotice> <title>ssh</title> + <prepared></prepared> + <docno></docno> <date>2007-10-06</date> + <rev></rev> </header> <module>ssh</module> - <modulesummary>Main API of the SSH application</modulesummary> + <modulesummary>Main API of the ssh application</modulesummary> <description> - <p>Interface module for the SSH application. </p> + <p>Interface module for the <c>ssh</c> application.</p> </description> <section> <title>SSH</title> - + <marker id="supported"/> <list type="bulleted"> - <item>SSH requires the crypto and public_key applications.</item> - <item>Supported SSH version is 2.0 </item> - <item>Supported MAC algorithms: hmac-sha2-256 and hmac-sha1</item> - <item>Supported encryption algorithms: aes128-ctr, aes128-cb and 3des-cbc</item> - <item>Supports unicode filenames if the emulator and the underlaying OS supports it. See the DESCRIPTION section in <seealso marker="kernel:file">file</seealso> for information about this subject</item> - <item>Supports unicode in shell and cli</item> + <item>For application dependencies see <seealso marker="SSH_app"> ssh(6)</seealso> </item> + <item>Supported SSH version is 2.0.</item> + <item>Supported public key algorithms: ssh-rsa and ssh-dss.</item> + <item>Supported MAC algorithms: hmac-sha2-256 and hmac-sha1.</item> + <item>Supported encryption algorithms: aes128-ctr, aes128-cb and 3des-cbc.</item> + <item>Supported key exchange algorithms: diffie-hellman-group1-sha1.</item> + <item>Supported compression algorithms: none, zlib, [email protected],</item> + <item>Supports unicode filenames if the emulator and the underlaying OS support it. + See section DESCRIPTION in the + <seealso marker="kernel:file">file</seealso> manual page in <c>kernel</c> + for information about this subject.</item> + <item>Supports unicode in shell and CLI.</item> </list> </section> <section> - <title>DATA TYPES </title> + <title>DATA TYPES</title> <p>Type definitions that are used more than once in - this module and/or abstractions to indicate the intended use of the data - type:</p> - <p><c>boolean() = true | false </c></p> - <p><c>string() = [byte()]</c></p> - <p><c>ssh_daemon_ref() - opaque to the user - returned by ssh:daemon/[1,2,3]</c></p> - <p><c>ssh_connection_ref() - opaque to the user - returned by ssh:connect/3</c></p> - <p><c>ip_address() - inet::ip_address()</c></p> - <p><c>subsystem_spec() = {subsystem_name(), - {channel_callback(), channel_init_args()}} </c></p> - <p><c>subsystem_name() = string() </c></p> - <p><c>channel_callback() = atom() - Name of the erlang module - implementing the subsystem using the ssh_channel behavior see</c> - <seealso marker="ssh_channel">ssh_channel(3)</seealso></p> - <p><c>channel_init_args() = list()</c></p> - </section> + 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>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>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> + <tag><c>channel_init_args() =</c></tag> + <item><p><c>list()</c></p></item> + + <tag><c>algs_list() =</c></tag> + <item><p><c>list( alg_entry() )</c></p></item> + + <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> + + <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> + </taglist> +</section> <funcs> <func> <name>close(ConnectionRef) -> ok </name> - <fsummary>Closes an SSH connection</fsummary> + <fsummary>Closes an SSH connection.</fsummary> <type> <v>ConnectionRef = ssh_connection_ref()</v> </type> @@ -81,104 +112,155 @@ <name>connect(Host, Port, Options) -> </name> <name>connect(Host, Port, Options, Timeout) -> {ok, ssh_connection_ref()} | {error, Reason}</name> - <fsummary>Connect to an ssh server.</fsummary> + <fsummary>Connects to an SSH server.</fsummary> <type> <v>Host = string()</v> <v>Port = integer()</v> - <d>The default is <c><![CDATA[22]]></c>, the assigned well known port + <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(milliseconds)</v> - <d>Negotiation timeout, for connection timeout use the option <c>{connect_timeout, timeout()}</c>.</d> + <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> </type> <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 are:</p> + <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> IP version to use.</item> + <item> + <p>IP version to use.</p> + </item> <tag><c><![CDATA[{user_dir, string()}]]></c></tag> <item> - <p>Sets the user directory i.e. the directory containing - ssh configuration files for the user such as + <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 + id_dsa]]></c>, and <c><![CDATA[authorized_key]]></c>. Defaults to the directory normally referred to as - <c><![CDATA[~/.ssh]]></c> </p> + <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 + <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 + <p>If the user RSA key is protected by a passphrase, it can be supplied with this option. </p> </item> <tag><c><![CDATA[{silently_accept_hosts, boolean()}]]></c></tag> <item> - <p>When true hosts are added to the + <p>When <c>true</c>, hosts are added to the file <c><![CDATA[known_hosts]]></c> without asking the user. - Defaults to false. + Defaults to <c>false</c>. </p> </item> <tag><c><![CDATA[{user_interaction, boolean()}]]></c></tag> <item> - <p>If false disables the client to connect to the server - if any user interaction is needed such as accepting that - the server will be added to the <c>known_hosts</c> file or - supplying a password. Defaults to true. + <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 - suppressed by other options such as silently_accept_hosts and - password. Do note that it may not always be desirable to use - those options from a security point of view.</p> + suppressed by other options, such as <c>silently_accept_hosts</c> + and <c>password</c>. However, those optins are not always desirable + to use from a security point of view.</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[{public_key_alg, 'ssh-rsa' | 'ssh-dss'}]]></c></tag> <item> + <note> + <p>This option is kept for compatibility. It is ignored if the <c>preferred_algorithms</c> + option is used. The equivalence of <c>{public_key_alg,'ssh-dss'}</c> is + <c>{preferred_algorithms, [{public_key,['ssh-dss','ssh-rsa']}]}</c>.</p> + </note> <p>Sets the preferred public key algorithm to use for user - authentication. If the the preferred algorithm fails for - some reason, the other algorithm is tried. The default is + authentication. If the preferred algorithm fails, + the other algorithm is tried. The default is to try <c><![CDATA['ssh-rsa']]></c> first.</p> </item> + <tag><c><![CDATA[{pref_public_key_algs, list()}]]></c></tag> <item> - <p>List of public key algorithms to try to use, 'ssh-rsa' and 'ssh-dss' available. - Will override <c><![CDATA[{public_key_alg, 'ssh-rsa' | 'ssh-dss'}]]></c></p> + <note> + <p>This option is kept for compatibility. It is ignored if the <c>preferred_algorithms</c> + option is used. The equivalence of <c>{pref_public_key_algs,['ssh-dss']}</c> is + <c>{preferred_algorithms, [{public_key,['ssh-dss']}]}</c>.</p> + </note> + <p>List of public key algorithms to try to use. + <c>'ssh-rsa'</c> and <c>'ssh-dss'</c> are available. + Overrides <c><![CDATA[{public_key_alg, 'ssh-rsa' | 'ssh-dss'}]]></c></p> + </item> + + <tag><c><![CDATA[{preferred_algorithms, algs_list()}]]></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> + <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) and public key algorithms are set to their default values, +kex is implicit but public_key is set explicitly.</p> + + <warning> + <p>Changing the values can make a connection less secure. Do not change unless you + 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><c><![CDATA[{connect_timeout, timeout()}]]></c></tag> <item> - <p>Sets a timeout on the transport layer - connection. Defaults to <c>infinity</c>.</p> + <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> </item> <tag><c><![CDATA[{user, string()}]]></c></tag> <item> - <p>Provides a user name. If this option is not given, ssh + <p>Provides a 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[USER]]></c> on UNIX, <c><![CDATA[USERNAME]]></c> on Windows).</p> </item> <tag><c><![CDATA[{password, string()}]]></c></tag> <item> - <p>Provide a password for password authentication. If - this option is not given, the user will be asked for a - password if the password authentication method is + <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[{key_cb, atom()}]]></c></tag> <item> - <p>Module implementing the behaviour <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso>. + <p>Module implementing the behaviour + <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso>. Can be used to customize the handling of public keys. </p> </item> <tag><c><![CDATA[{quiet_mode, atom() = boolean()}]]></c></tag> <item> - <p>If true, the client will not print out anything on authorization.</p> + <p>If <c>true</c>, the client does not print anything on authorization.</p> </item> <tag><c><![CDATA[{id_string, random | string()}]]></c></tag> @@ -191,34 +273,41 @@ <tag><c><![CDATA[{fd, file_descriptor()}]]></c></tag> <item> - <p>Allow an existing file descriptor to be used - (simply passed on to the transport protocol).</p></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>Provide, in bytes, when rekeying should be initiated, - defaults to one time each GB and one time per hour.</p> + <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 timeout on connection when no channels are active, default is infinity</p></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> <func> <name>connection_info(ConnectionRef, [Option]) ->[{Option, - Value}] </name> - <fsummary> Retrieves information about a connection. </fsummary> + 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(), {inet::ip_adress(), inet::port_number()}} | - Sockname::{inet::ip_adress(), inet::port_number()} () </v> + <v>option_value() = {{Major::integer(), Minor::integer()}, VersionString::string()} | + User::string() | Peer::{inet:hostname(), {inet::ip_adress(), inet::port_number()}} | + Sockname::{inet::ip_adress(), inet::port_number()}</v> </type> <desc> - <p> Retrieves information about a connection. - </p> + <p>Retrieves information about a connection.</p> </desc> </func> @@ -239,111 +328,154 @@ <desc> <p>Starts a server listening for SSH connections on the given port.</p> - <p>Options are:</p> + <p>Options:</p> <taglist> <tag><c><![CDATA[{inet, inet | inet6}]]></c></tag> - <item> IP version to use when the host address is specified as <c>any</c>. </item> + <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> - Provides specifications for handling of subsystems. The - "sftp" subsystem spec can be retrieved by calling - ssh_sftpd:subsystem_spec/1. If the subsystems option is - not present the value of - <c>[ssh_sftpd:subsystem_spec([])]</c> will be used. It is - of course possible to set the option to the empty list if - you do not want the daemon to run any subsystems at all. + <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> <tag><c><![CDATA[{shell, {Module, Function, Args} | fun(string() = User) - > pid() | fun(string() = User, ip_address() = PeerAddr) -> pid()}]]></c></tag> <item> - Defines the read-eval-print loop used when a shell is - requested by the client. Default is to use the erlang shell: - <c><![CDATA[{shell, start, []}]]></c> + <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> </item> <tag><c><![CDATA[{ssh_cli, {channel_callback(), channel_init_args()} | no_cli}]]></c></tag> <item> - Provides your own CLI implementation, i.e. a channel callback - module that implements a shell and command execution. Note - that you may customize the shell read-eval-print loop using the - option <c>shell</c> which is much less work than implementing - your own CLI channel. If set to <c>no_cli</c> you will disable - CLI channels and only subsystem channels will be allowed. + <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 <c>shell</c>. This means less work than implementing + an own CLI channel. If set to <c>no_cli</c>, the CLI channels + are disabled and only subsystem channels are allowed.</p> </item> <tag><c><![CDATA[{user_dir, String}]]></c></tag> <item> - <p>Sets the user directory i.e. the directory containing - ssh configuration files for the user such as + <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 + id_dsa]]></c>, and <c><![CDATA[authorized_key]]></c>. Defaults to the directory normally referred to as - <c><![CDATA[~/.ssh]]></c> </p> + <c><![CDATA[~/.ssh]]></c>.</p> </item> <tag><c><![CDATA[{system_dir, string()}]]></c></tag> <item> <p>Sets the system directory, containing the host key files - that identifies the host keys for ssh. The default is - <c><![CDATA[/etc/ssh]]></c>, note that for security reasons - this directory is normally only accessible by the root user.</p> + 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> </item> <tag><c><![CDATA[{auth_methods, string()}]]></c></tag> <item> - <p>Comma separated string that determines which - authentication methodes that the server should support and - in what order they will be tried. Defaults to + <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> </item> <tag><c><![CDATA[{user_passwords, [{string() = User, string() = Password}]}]]></c></tag> <item> - <p>Provide passwords for password authentication.They will - be used when someone tries to connect to the server and - public key user authentication fails. The option provides - a list of valid user names and the corresponding password. + <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> <item> - <p>Provide a global password that will authenticate any + <p>Provides a global password that authenticates any user. From a security perspective this option makes the server very vulnerable.</p> </item> + + <tag><c><![CDATA[{preferred_algorithms, algs_list()}]]></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> + <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) and public key algorithms are set to their default values, +kex is implicit but public_key is set explicitly.</p> + + <warning> + <p>Changing the values can make a connection less secure. Do not change unless you + 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><c><![CDATA[{pwdfun, fun(User::string(), password::string()) -> boolean()}]]></c></tag> <item> - <p>Provide a function for password validation. This is called - with user and password as strings, and should return + <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> </item> <tag><c><![CDATA[{negotiation_timeout, integer()}]]></c></tag> <item> - <p>Max time in milliseconds for the authentication negotiation. The default value is 2 minutes. If the client fails to login within this time, the connection is closed. + <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> <tag><c><![CDATA[{max_sessions, pos_integer()}]]></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. So if set to <c>N</c>, and <c>N</c> clients have connected but not started the login process, the <c>N+1</c> connection attempt will be aborted. If <c>N</c> connections are authenticated and still logged in, no more loggins will be accepted until one of the existing ones log out. + <p>The maximum number of simultaneous sessions that are accepted at any time + for this daemon. This includes sessions that are being authorized. + Thus, if set to <c>N</c>, and <c>N</c> clients have connected but not started + the login process, connection attempt <c>N+1</c> is aborted. + If <c>N</c> connections are authenticated and still logged in, no more logins + are accepted until one of the existing ones log out. </p> - <p>The counter is per listening port, so if two daemons are started, one with <c>{max_sessions,N}</c> and the other with <c>{max_sessions,M}</c> there will be in total <c>N+M</c> connections accepted for the whole ssh application. + <p>The counter is per listening port. Thus, if two daemons are started, one with + <c>{max_sessions,N}</c> and the other with <c>{max_sessions,M}</c>, in total + <c>N+M</c> connections are accepted for the whole <c>ssh</c> application. </p> - <p>Note that if <c>parallel_login</c> is <c>false</c>, only one client at a time may be in the authentication phase. + <p>Notice that if <c>parallel_login</c> is <c>false</c>, only one client + at a time can be in the authentication phase. </p> - <p>As default, the option is not set. This means that the number is not limited. + <p>By default, this option is not set. This means that the number is not limited. </p> </item> <tag><c><![CDATA[{parallel_login, boolean()}]]></c></tag> <item> - <p>If set to false (the default value), only one login is handled a time. If set to true, an unlimited number of login attempts will be allowed simultanously. + <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. </p> - <p>If the <c>max_sessions</c> option is set to <c>N</c> and <c>parallel_login</c> is set to <c>true</c>, the max number of simultaneous login attempts at any time is limited to <c>N-K</c> where <c>K</c> is the number of authenticated connections present at this daemon. + <p>If the <c>max_sessions</c> option is set to <c>N</c> and <c>parallel_login</c> + is set to <c>true</c>, the maximum number of simultaneous login attempts at any time is + limited to <c>N-K</c>, where <c>K</c> is the number of authenticated connections present + at this daemon. </p> <warning> - <p>Do not enable <c>parallel_logins</c> without protecting the server by other means, for example the <c>max_sessions</c> option or a firewall configuration. If set to <c>true</c>, there is no protection against DOS attacks.</p> + <p>Do not enable <c>parallel_logins</c> without protecting the server by other means, + for example, by the <c>max_sessions</c> option or a firewall configuration. If set to + <c>true</c>, there is no protection against DOS attacks.</p> </warning> </item> @@ -363,45 +495,76 @@ <tag><c><![CDATA[{key_cb, atom()}]]></c></tag> <item> - <p>Module implementing the behaviour <seealso marker="ssh_server_key_api">ssh_server_key_api</seealso>. + <p>Module implementing the behaviour + <seealso marker="ssh_server_key_api">ssh_server_key_api</seealso>. Can be used to customize the handling of public keys. </p> </item> <tag><c><![CDATA[{fd, file_descriptor()}]]></c></tag> <item> - <p>Allow an existing file-descriptor to be used - (simply passed on to the transport protocol).</p></item> - <tag><c><![CDATA[{failfun, fun(User::string(), PeerAddress::ip_address(), Reason::term()) -> _}]]></c></tag> + <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>Provide a fun to implement your own logging when a user fails to authenticate.</p> + <p>Provides a fun to implement your own logging when a user fails to authenticate.</p> </item> - <tag><c><![CDATA[{connectfun, fun(User::string(), PeerAddress::ip_address(), Method::string()) ->_}]]></c></tag> + <tag><c><![CDATA[{connectfun, fun(User::string(), PeerAddress::ip_address(), + Method::string()) ->_}]]></c></tag> <item> - <p>Provide a fun to implement your own logging when a user authenticates to the server.</p> + <p>Provides a fun to implement your own logging when a user authenticates to the server.</p> </item> <tag><c><![CDATA[{disconnectfun, fun(Reason:term()) -> _}]]></c></tag> <item> - <p>Provide a fun to implement your own logging when a user disconnects from the server.</p> + <p>Provides a fun to implement your own logging when a user disconnects from the server.</p> </item> - </taglist> - </desc> + + <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> + <func> + <name>default_algorithms() -> algs_list()</name> + <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> + </desc> + </func> <func> <name>shell(Host) -> </name> <name>shell(Host, Option) -> </name> <name>shell(Host, Port, Option) -> _</name> - <fsummary> </fsummary> + <fsummary>Starts an interactive shell over an SSH server.</fsummary> <type> - <v> Host = string()</v> - <v> Port = integer()</v> - <v> Options - see ssh:connect/3</v> + <v>Host = string()</v> + <v>Port = integer()</v> + <v>Options - see ssh:connect/3</v> </type> <desc> - <p>Starts an interactive shell via an SSH server on the + <p>Starts an interactive shell over an SSH server on the given <c>Host</c>. The function waits for user input, - and will not return until the remote shell is ended (i.e. + and does not return until the remote shell is ended (that is, exit from the shell). </p> </desc> @@ -410,28 +573,29 @@ <func> <name>start() -> </name> <name>start(Type) -> ok | {error, Reason}</name> - <fsummary>Starts the SSH application. </fsummary> + <fsummary>Starts the SSH application.</fsummary> <type> <v>Type = permanent | transient | temporary</v> <v>Reason = term() </v> </type> <desc> - <p>Utility function that starts crypto, public_key and the SSH - application. Defult type is temporary. - See also <seealso marker="kernel:application">application(3)</seealso> - </p> + <p>Utility function that starts the applications <c>crypto</c>, <c>public_key</c>, + and <c>ssh</c>. Default type is <c>temporary</c>. + For more information, see the <seealso marker="kernel:application">application(3)</seealso> + manual page in <c>kernel</c>.</p> </desc> </func> <func> <name>stop() -> ok | {error, Reason}</name> - <fsummary>Stops the SSH application.</fsummary> + <fsummary>Stops the <c>ssh</c> application.</fsummary> <type> <v>Reason = term()</v> </type> <desc> - <p>Stops the SSH application. See also - <seealso marker="kernel:application">application(3)</seealso></p> + <p>Stops the <c>ssh</c> application. + For more information, see the <seealso marker="kernel:application">application(3)</seealso> + manual page in <c>kernel</c>.</p> </desc> </func> @@ -455,7 +619,7 @@ <name>stop_listener(DaemonRef) -> </name> <name>stop_listener(Address, Port) -> ok </name> <fsummary>Stops the listener, but leaves existing connections started - by the listener up and running.</fsummary> + by the listener operational.</fsummary> <type> <v>DaemonRef = ssh_daemon_ref()</v> <v>Address = ip_address()</v> @@ -463,7 +627,7 @@ </type> <desc> <p>Stops the listener, but leaves existing connections started - by the listener up and running.</p> + by the listener operational.</p> </desc> </func> |