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
- Supported MAC algorithms: hmac-sha1
- Supported encryption algorithms: aes128-cb and 3des-cbc
- Supports unicode filenames if the emulator and the underlaying OS supports it. See the DESCRIPTION section in file for information about this subject
- Supports unicode in shell and cli
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(3)
channel_init_args() = list()
Functions
close(ConnectionRef) -> ok
ConnectionRef = ssh_connection_ref()
Closes an SSH connection.
connect(Host, Port, Options) ->
connect(Host, Port, Options, Timeout) -> {ok, ssh_connection_ref()} | {error, Reason}
Host = string()
Port = integer()
Options = [{Option, Value}]
Timeout = infinity | integer(milliseconds)
22
, the assigned well known port
number for SSH.{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}]
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()}
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()]
[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()}
{shell, start, []}
{ssh_cli, {channel_callback(),
channel_init_args()} | no_cli}
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) -> _
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}
Type = permanent | transient | temporary
Reason = term()
Utility function that starts crypto, public_key and the SSH application. Defult type is temporary. See also application(3)
stop_daemon(DaemonRef) ->
stop_daemon(Address, Port) -> ok
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
DaemonRef = ssh_daemon_ref()
Address = ip_address()
Port = integer()
Stops the listener, but leaves existing connections started by the listener up and running.