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diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml index bd0d3d49dd..e6c54d27bf 100644 --- a/lib/ssh/doc/src/ssh.xml +++ b/lib/ssh/doc/src/ssh.xml @@ -1,74 +1,121 @@ -<?xml version="1.0" encoding="iso-8859-1" ?> +<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE erlref SYSTEM "erlref.dtd"> <erlref> <header> <copyright> - <year>2004</year><year>2013</year> + <year>2004</year><year>2015</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> - The contents of this file are subject to the Erlang Public License, - Version 1.1, (the "License"); you may not use this file except in - compliance with the License. You should have received a copy of the - Erlang Public License along with this software. If not, it can be - retrieved online at http://www.erlang.org/. + 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 - Software distributed under the License is distributed on an "AS IS" - basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See - the License for the specific language governing rights and limitations - under the License. + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. </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> + <p>See <seealso marker="ssh:SSH_app#supported">ssh(6)</seealso> for details of supported version, + algorithms and unicode support.</p> </description> - <section> - <title>SSH</title> + <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> - <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-sha1</item> - <item>Supported encryption algorithms: aes128-cb and 3des-cbc</item> - </list> - + <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> + <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() - {N1,N2,N3,N4} % IPv4 | - {K1,K2,K3,K4,K5,K6,K7,K8} % IPv6</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>key_cb() =</c></tag> + <item> + <p><c>atom() | {atom(), list()}</c></p> + <p><c>atom()</c> - Name of the erlang module implementing the behaviours + <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso> or + <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso> as the + case maybe.</p> + <p><c>list()</c> - List of options that can be passed to the callback module.</p> + </item> + <tag><c>channel_init_args() =</c></tag> + <item><p><c>list()</c></p></item> + + <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> @@ -78,143 +125,235 @@ <func> <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> + <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>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> + <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> <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> + <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[{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[{public_key_alg, 'ssh-rsa' | 'ssh-dss'}]]></c></tag> <item> + <note> + <p>This option will be removed in OTP 20, but is kept for compatibility. It is ignored if + the preferred <c>pref_public_key_algs</c> option is used.</p> + </note> <p>Sets the preferred public key algorithm to use for user - authentication. If the the preferred algorithm fails for - some reason, the other algorithm is tried. The default is - to try <c><![CDATA[ssh_rsa]]></c> first.</p> + authentication. If the preferred algorithm fails, + the other algorithm is tried. If <c>{public_key_alg, 'ssh-rsa'}</c> is set, it is translated + to <c>{pref_public_key_algs, ['ssh-rsa','ssh-dss']}</c>. If it is + <c>{public_key_alg, 'ssh-dss'}</c>, it is translated + to <c>{pref_public_key_algs, ['ssh-dss','ssh-rsa']}</c>. + </p> </item> + <tag><c><![CDATA[{pref_public_key_algs, list()}]]></c></tag> <item> - <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> + <p>List of user (client) public key algorithms to try to use.</p> + <p>The default value is + <c><![CDATA[['ssh-rsa','ssh-dss','ecdsa-sha2-nistp256','ecdsa-sha2-nistp384','ecdsa-sha2-nistp521'] ]]></c> + </p> + <p>If there is no public key of a specified type available, the corresponding entry is ignored.</p> + </item> + + <tag><c><![CDATA[{preferred_algorithms, algs_list()}]]></c></tag> + <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>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> + + <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[{dh_gex_limits,{Min=integer(),I=integer(),Max=integer()}}]]></c></tag> + <item> + <p>Sets the three diffie-hellman-group-exchange parameters that guides the connected server in choosing a group. + See RFC 4419 for the function of thoose. The default value is <c>{1024, 6144, 8192}</c>. + </p> </item> + <tag><c><![CDATA[{connect_timeout, timeout()}]]></c></tag> <item> - <p>Sets a 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> + <tag><c><![CDATA[{key_cb, key_cb()}]]></c></tag> <item> - <p>Module implementing the behaviour <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso>. - Can be used to customize the handling of public keys. + <p>Module implementing the behaviour <seealso + marker="ssh_client_key_api">ssh_client_key_api</seealso>. Can be used to + customize the handling of public keys. If callback options are provided + along with the module name, they are made available to the callback + module via the options passed to it under the key 'key_cb_private'. </p> </item> <tag><c><![CDATA[{quiet_mode, atom() = boolean()}]]></c></tag> <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[{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[{ipv6_disabled, boolean()}]]></c></tag> + + <tag><c><![CDATA[{id_string, random | string()}]]></c></tag> <item> - <p>Determines if SSH shall use IPv6 or not.</p> + <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>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 | peer</v> - <v>Value = term() </v> + <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> </type> <desc> - <p> Retrieves information about a connection. - </p> + <p>Retrieves information about a connection.</p> </desc> </func> <func> <name>daemon(Port) -> </name> <name>daemon(Port, Options) -> </name> - <name>daemon(HostAddress, Port, Options) -> {ok, - ssh_daemon_ref()} | {error, atom()}</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> @@ -223,129 +362,383 @@ <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.</p> - <p>Options are:</p> + 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>Options:</p> <taglist> - <tag><c><![CDATA[{subsystems, [subsystem_spec()]]]></c></tag> + <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> - Provides specifications for handling of subsystems. The - "sftp" subsystem spec can be retrieved by calling - ssh_sftpd:subsystem_spec/1. If the subsystems option in - 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()}}]]></c></tag> + <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. + <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> + <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[{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>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> + </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[{pwdfun, fun(User::string(), password::string() -> boolean()}]]></c></tag> + + <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>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> + + <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[{dh_gex_groups, [{Size=integer(),G=integer(),P=integer()}] | {file,filename()} {ssh_moduli_file,filename()} }]]></c></tag> + <item> + <p>Defines the groups the server may choose among when diffie-hellman-group-exchange is negotiated. + See RFC 4419 for details. The three variants of this option are: + </p> + <taglist> + <tag><c>{Size=integer(),G=integer(),P=integer()}</c></tag> + <item>The groups are given explicitly in this list. There may be several elements with the same <c>Size</c>. + In such a case, the server will choose one randomly in the negotiated Size. + </item> + <tag><c>{file,filename()}</c></tag> + <item>The file must have one or more three-tuples <c>{Size=integer(),G=integer(),P=integer()}</c> + terminated by a dot. The file is read when the daemon starts. + </item> + <tag><c>{ssh_moduli_file,filename()}</c></tag> + <item>The file must be in + <seealso marker="public_key:public_key#dh_gex_group/4">ssh-keygen moduli file format</seealso>. + The file is read when the daemon starts. + </item> + </taglist> + <p>The default list is fetched from the + <seealso marker="public_key:public_key#dh_gex_group/4">public_key</seealso> application. + </p> + </item> + + <tag><c><![CDATA[{dh_gex_limits,{Min=integer(),Max=integer()}}]]></c></tag> + <item> + <p>Limits what a client can ask for in diffie-hellman-group-exchange. + The limits will be + <c>{MaxUsed = min(MaxClient,Max), MinUsed = max(MinClient,Min)}</c> where <c>MaxClient</c> and + <c>MinClient</c> are the values proposed by a connecting client. + </p> + <p>The default value is <c>{0,infinity}</c>. + </p> + <p>If <c>MaxUsed < MinUsed</c> in a key exchange, it will fail with a disconnect. + </p> + <p>See RFC 4419 for the function of the Max and Min values.</p> + </item> + + <tag><c><![CDATA[{pwdfun, fun(User::string(), Password::string(), PeerAddress::{ip_adress(),port_number()}, State::any()) -> boolean() | disconnect | {boolean(),any()} }]]></c></tag> <item> - <p>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 could used for calling an external system or if + passwords should be stored as a hash. The fun returns: + </p> + <list type="bulleted"> + <item><c>true</c> if the user and password is valid and</item> + <item><c>false</c> otherwise.</item> + </list> + <p>This fun can also be used to make delays in authentication tries for example by calling + <seealso marker="stdlib:timer#sleep/1">timer:sleep/1</seealso>. To facilitate counting of failed tries + the <c>State</c> variable could be used. This state is per connection only. The first time the pwdfun + is called for a connection, the <c>State</c> variable has the value <c>undefined</c>. + The pwdfun can return - in addition to the values above - a new state + as: + </p> + <list type="bulleted"> + <item><c>{true, NewState:any()}</c> if the user and password is valid or</item> + <item><c>{false, NewState:any()}</c> if the user or password is invalid</item> + </list> + <p>A third usage is to block login attempts from a missbehaving peer. The <c>State</c> described above + can be used for this. In addition to the responses above, the following return value is introduced: + </p> + <list type="bulleted"> + <item><c>disconnect</c> if the connection should be closed immediately after sending a SSH_MSG_DISCONNECT + message.</item> + </list> + </item> + + <tag><c><![CDATA[{pwdfun, fun(User::string(), Password::string()) -> boolean()}]]></c></tag> + <item> + <p>Provides a function for password validation. This function is called + with user and password as strings, and returns <c><![CDATA[true]]></c> if the password is valid and <c><![CDATA[false]]></c> otherwise.</p> + <p>This option (<c>{pwdfun,fun/2}</c>) is the same as a subset of the previous + (<c>{pwdfun,fun/4}</c>). It is kept for compatibility.</p> </item> - <tag><c><![CDATA[{key_cb, atom()}]]></c></tag> + + <tag><c><![CDATA[{negotiation_timeout, integer()}]]></c></tag> <item> - <p>Module implementing the behaviour <seealso marker="ssh_server_key_api">ssh_server_key_api</seealso>. - Can be used to customize the handling of public keys. + <p>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. + 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. 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>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>By default, this option is not set. This means that the number is not limited. + </p> + </item> + + <tag><c><![CDATA[{max_channels, pos_integer()}]]></c></tag> + <item> + <p>The maximum number of channels with active remote subsystem that are accepted for + each connection to this daemon</p> + <p>By default, this option is not set. This means that the number is not limited. + </p> + </item> + + + <tag><c><![CDATA[{parallel_login, boolean()}]]></c></tag> + <item> + <p>If set to false (the default value), only one login is handled at a time. + 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 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, 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> + + <tag><c><![CDATA[{minimal_remote_max_packet_size, non_negative_integer()}]]></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> + </item> + + <tag><c><![CDATA[{id_string, random | string()}]]></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> </item> + + <tag><c><![CDATA[{key_cb, key_cb()}]]></c></tag> + <item> + <p>Module implementing the behaviour <seealso + marker="ssh_server_key_api">ssh_server_key_api</seealso>. Can be used to + customize the handling of public keys. 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>{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> + </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[{ip_v6_disabled, boolean()}]]></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>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> <item> - <p>Determines if SSH shall use IPv6 or not (only used when - HostAddress is set to any).</p></item> - <tag><c><![CDATA[{failfun, fun()}]]></c></tag> + <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 fails to authenticate.</p> + <p>Provides a fun to implement your own logging when a user disconnects from the server.</p> </item> - <tag><c><![CDATA[{connectfun, fun()}]]></c></tag> + + <tag><c><![CDATA[{unexpectedfun, fun(Message:term(), Peer) -> report | skip }]]></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 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[{disconnectfun, fun()}]]></c></tag> + + <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 when a user disconnects from the server.</p> + <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> + + </taglist> + </desc> + </func> + + <func> + <name>daemon_info(Daemon) -> {ok, [{port,Port}]} | {error,Error}</name> + <fsummary>Get info about a daemon</fsummary> + <type> + <v>Port = integer()</v> + <v>Error = bad_daemon_ref</v> + </type> + <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> + </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> + <name>shell(Host, Port, Option) -> </name> + <name>shell(TcpSocket) -> _</name> + <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> + <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 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> @@ -354,25 +747,29 @@ <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 </name> - <fsummary>Stops the SSH application.</fsummary> + <name>stop() -> ok | {error, Reason}</name> + <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> @@ -396,7 +793,7 @@ <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> @@ -404,7 +801,7 @@ </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> |