x2go.rforward module

X2Go reverse SSH/Paramiko tunneling provides X2Go sound, X2Go printing and X2Go sshfs for folder sharing and mounting remote devices in X2Go terminal server sessions.

class x2go.rforward.X2GoRevFwChannelThread(channel, remote=None, **kwargs)[source]

Bases: gevent.threading.Thread

Starts a thread for each incoming Paramiko/SSH data channel trough the reverse forwarding tunnel.

class x2go.rforward.X2GoRevFwTunnel(server_port, remote_host, remote_port, ssh_transport, session_instance=None, logger=None, loglevel=56)[source]

Bases: gevent.threading.Thread

x2go.rforward.X2GoRevFwTunnel class objects are used to reversely tunnel X2Go audio, X2Go printing and X2Go folder sharing / device mounting through Paramiko/SSH.

cancel_port_forward(address, port)[source]

Cancel a port forwarding request. This cancellation request is sent to the server and on the server the port forwarding should be unregistered.

Parameters:
  • address (str) – remote server address
  • port (int) – remote port
notify()[source]

Notify an x2go.rforward.X2GoRevFwTunnel instance of an incoming Paramiko/SSH channel.

If an incoming reverse tunnel channel appropriate for this instance has been detected, this method gets called from the x2go.session.X2GoSession‘s transport TCP handler.

The sent notification will trigger a thread.Condition() waiting for notification in L{X2GoRevFwTunnel.run()}.

pause()[source]

Prevent acceptance of new incoming connections through the Paramiko/SSH reverse forwarding tunnel. Also, any active connection on this x2go.rforward.X2GoRevFwTunnel instance will be closed immediately, if this method is called.

resume()[source]

Resume operation of the Paramiko/SSH reverse forwarding tunnel and continue accepting new incoming connections.

run()[source]

This method gets run once an x2go.rforward.X2GoRevFwTunnel has been started with its L{start()} method. Use x2go.rforward.X2GoRevFwTunnel.stop_thread() to stop the reverse forwarding tunnel again. You can also temporarily lock the tunnel down with L{X2GoRevFwTunnel.pause()} and L{X2GoRevFwTunnel.resume()}).

L{X2GoRevFwTunnel.run()} waits for notifications of an appropriate incoming Paramiko/SSH channel (issued by L{X2GoRevFwTunnel.notify()}). Appropriate in this context means, that its start point on the X2Go server matches the class’s property server_port.

Once a new incoming channel gets announced by the L{notify()} method, a new x2go.rforward.X2GoRevFwChannelThread instance will be initialized. As a data stream handler, the function L{x2go_rev_forward_channel_handler()} will be used.

The channel will last till the connection gets dropped on the X2Go server side or until the tunnel gets paused by an L{X2GoRevFwTunnel.pause()} call or stopped via the L{X2GoRevFwTunnel.stop_thread()} method.

stop_thread()[source]

Stops this x2go.rforward.X2GoRevFwTunnel thread completely.

x2go.rforward.x2go_rev_forward_channel_handler(chan=None, addr='', port=0, parent_thread=None, logger=None)[source]

Handle the data stream of a requested channel that got set up by a x2go.rforward.X2GoRevFwTunnel (Paramiko/SSH reverse forwarding tunnel).

The channel (and the corresponding connections) close either ...

  • ... if the connecting application closes the connection and thus, drops the channel, or
  • ... if the x2go.rforward.X2GoRevFwTunnel parent thread gets paused. The call of L{X2GoRevFwTunnel.pause()} on the instance can be used to shut down all incoming tunneled SSH connections associated to this x2go.rforward.X2GoRevFwTunnel instance from within a Python X2Go application.
Parameters:
  • chan (class) – channel (Default value = None)
  • addr (str) – bind address (Default value = ‘’)
  • port (int) – bind port (Default value = 0)
  • parent_thread (x2go.rforward.X2GoRevFwTunnel instance) – the calling x2go.rforward.X2GoRevFwTunnel instance (Default value = None)
  • logger (x2go.logger.X2GoLogger instance) – you can pass an x2go.logger.X2GoLogger object to the x2go.rforward.X2GoRevFwTunnel constructor (Default value = None)
x2go.rforward.x2go_transport_tcp_handler(chan, origin, server)[source]

An X2Go customized TCP handler for the Paramiko/SSH Transport() class.

Incoming channels will be put into Paramiko’s default accept queue. This corresponds to the default behaviour of Paramiko’s Transport class.

However, additionally this handler function checks the server port of the incoming channel and detects if there are Paramiko/SSH reverse forwarding tunnels waiting for the incoming channels. The Paramiko/SSH reverse forwarding tunnels are initiated by an x2go.session.X2GoSession instance (currently supported: reverse tunneling auf audio data, reverse tunneling of SSH requests).

If the server port of an incoming Paramiko/SSH channel matches the configured port of an x2go.rforward.X2GoRevFwTunnel instance, this instance gets notified of the incoming channel and a new x2go.rforward.X2GoRevFwChannelThread is started. This x2go.rforward.X2GoRevFwChannelThread then takes care of the new channel’s incoming data stream.

Parameters:
  • chan (paramiko.Channel object) – a Paramiko channel object
  • origin (tuple) – host/port tuple where a connection originates from
  • server (tuple) – host/port tuple where to connect to