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NAME
ssh - Main API of the SSH application
DESCRIPTION
Interface module for the SSH application.
SSH
* SSH requires the crypto and public_key applications.
* Supported SSH version is 2.0
* Supported MAC algorithms: hmac-sha1
* Supported encryption algorithms: aes128-cb and 3des-cbc
DATA TYPES
Type definitions that are used more than once in this module and/or abstractions to indicate the intended
use of the data type:
boolean() = true | false
string() = [byte()]
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() - inet::ip_address()
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(3erl)
channel_init_args() = list()
EXPORTS
close(ConnectionRef) -> ok
Types:
ConnectionRef = ssh_connection_ref()
Closes an SSH connection.
connect(Host, Port, Options) ->
connect(Host, Port, Options, Timeout) -> {ok, ssh_connection_ref()} | {error, Reason}
Types:
Host = string()
Port = integer()
The default is 22, the assigned well known port number for SSH.
Options = [{Option, Value}]
Timeout = infinity | integer(milliseconds)
Negotiation timeout, for connection timeout use the option {connect_timeout, timeout()}.
Connects to an SSH server. No channel is started. This is done by calling
ssh_connection:session_channel/[2, 4].
Options are:
{user_dir, string()}:
Sets the user directory i.e. the directory containing ssh configuration files for the user
such as known_hosts, id_rsa, id_dsa and authorized_key. Defaults to the directory normally
referred to as ~/.ssh
{dsa_pass_phrase, string()}:
If the user dsa key is protected by a passphrase it can be supplied with this option.
{rsa_pass_phrase, string()}:
If the user rsa key is protected by a passphrase it can be supplied with this option.
{silently_accept_hosts, boolean()}:
When true hosts are added to the file known_hosts without asking the user. Defaults to false.
{user_interaction, boolean()}:
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.
{public_key_alg, 'ssh-rsa' | 'ssh-dss'}:
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 'ssh-rsa'
first.
{pref_public_key_algs, list()}:
List of public key algorithms to try to use, 'ssh-rsa' and 'ssh-dss' available. Will override
{public_key_alg, 'ssh-rsa' | 'ssh-dss'}
{connect_timeout, timeout()}:
Sets a timeout on the transport layer connection. Defaults to infinity.
{user, string()}:
Provides a user name. If this option is not given, ssh reads from the environment (LOGNAME or
USER on unix, USERNAME on Windows).
{password, string()}:
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.
{key_cb, atom()}:
Module implementing the behaviour ssh_client_key_api. Can be used to customize the handling of
public keys.
{quiet_mode, atom() = boolean()}:
If true, the client will not print out anything on authorization.
{fd, file_descriptor()}:
Allow an existing file descriptor to be used (simply passed on to the transport protocol).
{rekey_limit, integer()}:
Provide, in bytes, when rekeying should be initiated, defaults to one time each GB and one
time per hour.
{idle_time, integer()}:
Sets a timeout on connection when no channels are active, default is infinity
connection_info(ConnectionRef, [Option]) ->[{Option, Value}]
Types:
Option = client_version | server_version | user | peer | sockname
Value = [option_value()]
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()} ()
Retrieves information about a connection.
daemon(Port) ->
daemon(Port, Options) ->
daemon(HostAddress, Port, Options) -> {ok, ssh_daemon_ref()} | {error, atom()}
Types:
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:
{subsystems, [subsystem_spec()]:
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.
{shell, {Module, Function, Args} | fun(string() = User) - > pid() | fun(string() = User,
ip_address() = PeerAddr) -> pid()}:
Defines the read-eval-print loop used when a shell is requested by the client. Default is to
use the erlang shell: {shell, start, []}
{ssh_cli, {channel_callback(), channel_init_args()} | no_cli}:
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 shell which is much less work than implementing your own CLI channel. If set to no_cli
you will disable CLI channels and only subsystem channels will be allowed.
{user_dir, String}:
Sets the user directory i.e. the directory containing ssh configuration files for the user
such as known_hosts, id_rsa, id_dsa and authorized_key. Defaults to the directory normally
referred to as ~/.ssh
{system_dir, string()}:
Sets the system directory, containing the host key files that identifies the host keys for
ssh. The default is /etc/ssh, note that for security reasons this directory is normally only
accessible by the root user.
{auth_methods, string()}:
Comma separated string that determines which authentication methodes that the server should
support and in what order they will be tried. Defaults to "publickey,keyboard-
interactive,password"
{user_passwords, [{string() = User, string() = Password}]}:
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.
{password, string()}:
Provide a global password that will authenticate any user. From a security perspective this
option makes the server very vulnerable.
{pwdfun, fun(User::string(), password::string()) -> boolean()}:
Provide a function for password validation. This is called with user and password as strings,
and should return true if the password is valid and false otherwise.
{key_cb, atom()}:
Module implementing the behaviour ssh_server_key_api. Can be used to customize the handling of
public keys.
{fd, file_descriptor()}:
Allow an existing file-descriptor to be used (simply passed on to the transport protocol).
{failfun, fun(User::string(), PeerAddress::ip_address(), Reason::term()) -> _}:
Provide a fun to implement your own logging when a user fails to authenticate.
{connectfun, fun(User::string(), PeerAddress::ip_address(), Method::string()) ->_}:
Provide a fun to implement your own logging when a user authenticates to the server.
{disconnectfun, fun(Reason:term()) -> _}:
Provide a fun to implement your own logging when a user disconnects from the server.
shell(Host) ->
shell(Host, Option) ->
shell(Host, Port, Option) -> _
Types:
Host = string()
Port = integer()
Options - see ssh:connect/3
Starts an interactive shell via an SSH server on the given Host. The function waits for user
input, and will not return until the remote shell is ended (i.e. exit from the shell).
start() ->
start(Type) -> ok | {error, Reason}
Types:
Type = permanent | transient | temporary
Reason = term()
Utility function that starts crypto, public_key and the SSH application. Defult type is temporary.
See also application(3erl)
stop() -> ok
Stops the SSH application. See also application(3erl)
stop_daemon(DaemonRef) ->
stop_daemon(Address, Port) -> ok
Types:
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
Types:
DaemonRef = ssh_daemon_ref()
Address = ip_address()
Port = integer()
Stops the listener, but leaves existing connections started by the listener up and running.