20042012 Ericsson AB. All Rights Reserved. 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/. 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. ssh Ingela Anderton Andin Håkan Mattsson Håkan Mattsson 2007-10-06 PA1
ssh Main API of the SSH application

Interface module for the SSH application.

SSH ssh requires the crypto and public_key applications. Supported SSH-version is 2.0 Currently supports only a minimum of mac and encryption algorithms i.e. hmac-sha1, and aes128-cb and 3des-cbc.
COMMON DATA TYPES

Type definitions that are used more than once in this module:

boolean() = true | false

string() = list of ASCII characters

ssh_daemon_ref() - opaque to the user returned by ssh:daemon/[1,2,3]

ssh_connection_ref() - opaque to the user returned by ssh:connect/3

ip_address() - {N1,N2,N3,N4} % IPv4 | {K1,K2,K3,K4,K5,K6,K7,K8} % IPv6

subsystem_spec() = {subsystem_name(), {channel_callback(), channel_init_args()}}

subsystem_name() = string()

channel_callback() = atom() - Name of the erlang module implementing the subsystem using the ssh_channel behavior see ssh_channel(3)

channel_init_args() = list()

close(ConnectionRef) -> ok Closes a ssh connection ConnectionRef = ssh_connection_ref()

Closes a ssh connection.

 connect(Host, Port, Options) -> connect(Host, Port, Options, Timeout) -> {ok, ssh_connection_ref()} | {error, Reason} Connect to an ssh server. Host = string() Port = integer() The default is , the registered port for SSH. Options = [{Option, Value}] Timeout = infinity | integer(milliseconds)

Connects to an SSH server. No channel is started this is done by calling ssh_connect:session_channel/2.

Options are:

Sets the user directory e.i. the directory containing ssh configuration files for the user such as , and . Defaults to the directory normally referred to as

If the user dsa key is protected by a pass phrase it can be supplied with this option.

If the user rsa key is protected by a pass phrase it can be supplied with this option.

When true hosts are added to the file without asking the user. Defaults to false.

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 known_hosts file or supplying a password. Defaults to true. 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.

Sets the preferred public key algorithm to use for user authentication. If the the preferred algorithm fails of some reason, the other algorithm is tried. The default is to try first.

List of public key algorithms to try to use, ssh_rsa and ssh_dsa available. Will override

Sets a timeout on the transport layer connection. Defaults to infinity.

Provide a user name. If this option is not given, ssh reads from the environment ( or on unix, on Windows).

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 attempted.

Provide a fun for password authentication. The fun will be called as and should return or .

Provide a special call-back module for key handling. The call-back module should be modeled after the module. The functions that must be exported are: , , and . This is considered somewhat experimental and will be better documented later on.

If true, the client will not print out anything on authorization.

Allow an existing file-descriptor to be used (simply passed on to the transport protocol).

Determines if SSH shall use IPv6 or not.

Sets a timeout on connection when no channels are active, default is infinity

 connection_info(ConnectionRef, [Option]) ->[{Option, Value}] Retrieves information about a connection. Option = client_version | server_version | peer Value = term()

Retrieves information about a connection.

daemon(Port) -> daemon(Port, Options) -> daemon(HostAddress, Port, Options) -> ssh_daemon_ref() Starts a server listening for SSH connections on the given port. Port = integer() HostAddress = ip_address() | any Options = [{Option, Value}] Option = atom() Value = term()

Starts a server listening for SSH connections on the given port.

Options are:

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 [ssh_sftpd:subsystem_spec([])] 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. pid() | fun(string() = User, ip_address() = PeerAddr) -> pid()}]]> Defines the read-eval-print loop used when a shell is requested by the client. Example use the erlang shell: which is the default behavior. Provide your own cli implementation, e.i. 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 shell which is much less work than implementing your own cli channel.

Sets the user directory e.i. the directory containing ssh configuration files for the user such as , and . Defaults to the directory normally referred to as

Sets the system directory, containing the host files that identifies the host for ssh. The default is , note that SSH normally requires the host files there to be readable only by root.

Comma separated string that determines which authentication methodes that the server should support and in what order they will be tried. Defaults to

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.

Provide a global password that will authenticate any user. From a security perspective this option makes the server very vulnerable.

Provide a function for password validation. This is called with user and password as strings, and should return if the password is valid and otherwise.

Allow an existing file-descriptor to be used (simply passed on to the transport protocol).

Determines if SSH shall use IPv6 or not (only used when HostAddress is set to any).

 shell(Host) -> shell(Host, Option) -> shell(Host, Port, Option) -> _ Host = string() Port = integer() Options - see ssh:connect/3

Starts an interactive shell to an SSH server on the given Host. The function waits for user input, and will not return until the remote shell is ended (e.g. on exit from the shell).

start() -> start(Type) -> ok | {error, Reason} Starts the Ssh application. Type = permanent | transient | temporary Reason = term()

Starts the Ssh application. Default type is temporary. See also application(3) Requires that the crypto application has been started.

stop() -> ok Stops the Ssh application.

Stops the Ssh application. See also application(3)

 stop_daemon(DaemonRef) -> stop_daemon(Address, Port) -> ok Stops the listener and all connections started by the listener. DaemonRef = ssh_daemon_ref() Address = ip_address() Port = integer()

Stops the listener and all connections started by the listener.

 stop_listener(DaemonRef) -> stop_listener(Address, Port) -> ok Stops the listener, but leaves existing connections started by the listener up and running. DaemonRef = ssh_daemon_ref() Address = ip_address() Port = integer()

Stops the listener, but leaves existing connections started by the listener up and running.