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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.