# SSH

### MODULE

ssh_connection

### MODULE SUMMARY

This module provides an API to the ssh connection protocol.

### DESCRIPTION

This module provides an API to the ssh connection protocol. Not all features of the connection protocol are officially supported yet. Only the ones supported are documented here.

### COMMON DATA TYPES

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

boolean() = true | false

string() = list of ASCII characters

ssh_connection_ref() - opaque to the user returned by ssh:connect/[1,2,3] or sent to a ssh channel processes

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

### MESSAGES SENT TO CHANNEL PROCESSES

As a result of the connection protocol the following messages may be sent to a channel process.

{ssh_cm, ConnectionRef, {open, ChannelId, RemoteChannelId, {session}}}
{ssh_cm, ConnectionRef, {subsystem, ChannelId, WantReply, Name}}
{ssh_cm, ConnectionRef, {closed, ChannelId}}
{ssh_cm, ConnectionRef, {data, ChannelId, Type, Data}}
{ssh_cm, ConnectionRef, {eof, ChannelId}}
{ssh_cm, ConnectionRef, {exit_signal,ChannelId, Signal, Err, Lang}}
{ssh_cm, ConnectionRef, {exit_status,ChannelId,_Status}}
{ssh_cm, ConnectionRef, {shell, WantReply}}
{ssh_cm, ConnectionRef, {pty, ChannelId, WantReply, Pty}}
{ssh_cm, ConnectionRef, {window_change, ChannelId, Width, Height, PixWidth, PixHeight}}

### EXPORTS

adjust_window(ConnectionRef, Channel, Bytes) -> ok

Types:

ConnectionRef = ssh_connection_ref()
ChannelId = integer()
Bytes = integer()

Adjusts the ssh flowcontrol window. Should be called after handling a {ssh_cm, ConnectionRef, {data, ChannelId, Type, Data}} message in the following way: ssh_connection:adjust_window(ConnectionRef, ChannelId, size(Data)),

close(ConnectionRef, ChannelId) -> ok

Types:

ConnectionRef = ssh_connection_ref()
ChannelId = integer()

Sends a close message on the channel ChannelId

exec(ConnectionRef, ChannelId, Command, TimeOut) -> success | failiure

Types:

ConnectionRef = ssh_connection_ref()
ChannelId = integer()
Command = string()
Timeout = infinity | integer()

Will request that the server start the execution of the given command. Result will be received as N x {ssh_cm, ConnectionRef, {data, ChannelId, Type, Data}} messages followed by {ssh_cm, ConnectionRef, {eof, ChannelId}} {ssh_cm, ConnectionRef, {exit_status, ChannelId, Status}}, {ssh_cm, ConnectionRef, {closed, ChannelId}}

reply_request(ConnectionRef, WantReply, Status, CannelId) -> ok

Types:

ConnectionRef = ssh_connection_ref()
WantReply = boolean()
Status = success | failure
ChannelId = integer()

Send status replies to requests that want such replies. Should be called after handling an ssh_cm-message containing a WantReply.

send(ConnectionRef, ChannelId, Data) ->
send(ConnectionRef, ChannelId, Data, Timeout) ->
send(ConnectionRef, ChannelId, Type, Data) ->
send(ConnectionRef, ChannelId, Type, Data, TimeOut) -> ok | {error, timeout}

Types:

ConnectionRef = ssh_connection_ref()
ChannelId = integer()
Data = binary()
Type = 0 | 1 see RFC 4254
Timeout = infinity | integer()

Sends channel data.

send_eof(ConnectionRef, ChannelId) -> ok

Types:

ConnectionRef = ssh_connection_ref()
ChannelId = integer()

Sends eof on the channel ChannelId.

session_channel(ConnectionRef, Timeout) ->
session_channel(ConnectionRef, InitialWindowSize, MaxPacketSize, Timeout) -> {ok, ChannleId} | {error, Reason}

Types:

ConnectionRef = ssh_connection_ref()
InitialWindowSize = integer()
MaxPacketSize = integer()
Timeout = infinity | integer()

Opens a channel for a ssh session. A session is a remote execution of a program. The program may be a shell, an application, a system command, or some built-in subsystem.

setenv(ConnectionRef, ChannelId, Var, Value, TimeOut) -> success | failure

Types:

ConnectionRef = ssh_connection_ref()
ChannelId = integer()
Var = string()
Value = string()
Timeout = infinity | integer()

Environment variables may be passed to the shell/command to be started later.

shell(ConnectionRef, ChannelId) -> success | failure

Types:

ConnectionRef = ssh_connection_ref()
ChannelId = integer()

Will request that the user's default shell (typically defined in /etc/passwd in UNIX systems) be started at the other end. Messages for the caller to handle:

subsystem(ConnectionRef, ChannelId, Subsystem, Timeout) -> success | failure

Types:

ConnectionRef = ssh_connection_ref()
ChannelId = integer()
Subsystem = string()
Timeout = infinity | integer()

Sends a request to execute a predefined subsystem

ssh 1.0.2
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