forward.py

#!/usr/bin/env python

# Copyright (C) 2003-2007  Robey Pointer <robeypointer@gmail.com>
#
# This file is part of paramiko.
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.

"""
Sample script showing how to do local port forwarding over paramiko.

This script connects to the requested SSH server and sets up local port
forwarding (the openssh -L option) from a local port through a tunneled
connection to a destination reachable from the SSH server machine.
"""

from config import *
import select
try:
    import SocketServer
except ImportError:
    import socketserver as SocketServer

SSH_PORT = 22
DEFAULT_PORT = 4000

g_verbose = True


class ForwardServer (SocketServer.ThreadingTCPServer):
    daemon_threads = True
    allow_reuse_address = True


class Handler (SocketServer.BaseRequestHandler):

    def handle(self):
        try:
            chan = self.ssh_transport.open_channel('direct-tcpip',
                                                   (self.chain_host, self.chain_port),
                                                   self.request.getpeername())
        except Exception as e:
            verbose('Incoming request to %s:%d failed: %s' % (self.chain_host,
                                                              self.chain_port,
                                                              repr(e)))
            return
        if chan is None:
            verbose('Incoming request to %s:%d was rejected by the SSH server.' %
                    (self.chain_host, self.chain_port))
            return

        verbose('Connected!  Tunnel open %r -> %r -> %r' % (self.request.getpeername(),
                                                            chan.getpeername(), (self.chain_host, self.chain_port)))
        while True:
            r, w, x = select.select([self.request, chan], [], [])
            if self.request in r:
                data = self.request.recv(1024)
                if len(data) == 0:
                    break
                try:
                  chan.send(data)
                except EOFError:
                    logger.debug("Chanel closed")
            if chan in r:
                data = chan.recv(1024)
                if len(data) == 0:
                    break
                self.request.send(data)

        peername = self.request.getpeername()
        chan.close()
        self.request.close()
        verbose('Tunnel closed from %r' % (peername,))


def forward_tunnel(local_port, remote_host, remote_port, transport):
    # this is a little convoluted, but lets me configure things for the Handler
    # object.  (SocketServer doesn't give Handlers any way to access the outer
    # server normally.)
    class SubHander (Handler):
        chain_host = remote_host
        chain_port = remote_port
        ssh_transport = transport
    server = ForwardServer(('', local_port), SubHander)
    return server


def verbose(s):
    if g_verbose:
        logger.debug(s)