#!/usr/bin/python """ 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. It uses SocketServer and select, so may not work on Windows. """ import sys import os import socket import select import SocketServer import getpass import base64 from optparse import OptionParser import paramiko DEFAULT_PORT = 4000 SSH_PORT = 22 VERBOSE = True READPASS = False 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, e: verbose('Incoming request to %s:%d failed: %s' % (self.chain_host, self.chain_port, repr(e))) return verbose('Connected! Tunnel open.') 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 chan.send(data) if chan in r: data = chan.recv(1024) if len(data) == 0: break self.request.send(data) chan.close() self.request.close() verbose('Tunnel closed.') 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 ForwardServer(('', local_port), SubHander).serve_forever() def load_host_keys(): filename = os.path.expanduser('~/.ssh/known_hosts') keys = {} try: f = open(filename, 'r') except Exception, e: print '*** Unable to open host keys file (%s)' % filename return for line in f: keylist = line.split(' ') if len(keylist) != 3: continue hostlist, keytype, key = keylist hosts = hostlist.split(',') for host in hosts: if not keys.has_key(host): keys[host] = {} keys[host][keytype] = base64.decodestring(key) f.close() return keys def find_default_key_file(): filename = os.path.expanduser('~/.ssh/id_rsa') if os.access(filename, os.R_OK): return filename filename = os.path.expanduser('~/.ssh/id_dsa') if os.access(filename, os.R_OK): return filename return '' def verbose(s): if VERBOSE: print s ##### parser = OptionParser(usage='usage: %prog [options] :', version='%prog 1.0') parser.add_option('-q', '--quiet', action='store_false', dest='verbose', default=VERBOSE, help='squelch all informational output') parser.add_option('-l', '--local-port', action='store', type='int', dest='port', default=DEFAULT_PORT, help='local port to forward (default: %d)' % DEFAULT_PORT) parser.add_option('-r', '--host', action='store', type='string', dest='ssh_host', help='SSH host to tunnel through (required)') parser.add_option('-p', '--port', action='store', type='int', dest='ssh_port', default=SSH_PORT, help='SSH port to tunnel through (default: %d)' % SSH_PORT) parser.add_option('-u', '--user', action='store', type='string', dest='user', default=getpass.getuser(), help='username for SSH authentication (default: %s)' % getpass.getuser()) parser.add_option('-K', '--key', action='store', type='string', dest='keyfile', default=find_default_key_file(), help='private key file to use for SSH authentication') parser.add_option('', '--no-key', action='store_false', dest='use_key', default=True, help='don\'t look for or use a private key file') parser.add_option('-P', '--password', action='store_true', dest='readpass', default=READPASS, help='read password (for key or password auth) from stdin') options, args = parser.parse_args() VERBOSE = options.verbose READPASS = options.readpass if len(args) != 1: parser.error('Incorrect number of arguments.') remote_host = args[0] if ':' not in remote_host: parser.error('Remote port missing.') remote_host, remote_port = remote_host.split(':', 1) try: remote_port = int(remote_port) except: parser.error('Remote port must be a number.') if not options.ssh_host: parser.error('SSH host is required.') if ':' in options.ssh_host: options.ssh_host, options.ssh_port = options.ssh_host.split(':', 1) try: options.ssh_port = int(options.ssh_port) except: parser.error('SSH port must be a number.') host_keys = load_host_keys() if not host_keys.has_key(options.ssh_host): print '*** Warning: no host key for %s' % options.ssh_host expected_host_key_type = None expected_host_key = None else: expected_host_key_type = host_keys[options.ssh_host].keys()[0] expected_host_key = host_keys[options.ssh_host][expected_host_key_type] key = None password = None if options.use_key: try: key = paramiko.RSAKey.from_private_key_file(options.keyfile) except paramiko.PasswordRequiredException: if not READPASS: print '*** Password needed for keyfile (use -P): %s' % options.keyfile sys.exit(1) key_password = getpass.getpass('Enter password for key: ') try: key = paramiko.RSAKey.from_private_key_file(options.keyfile, key_password) except: print '*** Unable to read keyfile: %s' % options.keyfile sys.exit(1) except: pass if key is None: # try reading a password then if not READPASS: print '*** Either a valid private key or password is required (use -K or -P).' sys.exit(1) password = getpass.getpass('Enter password: ') verbose('Connecting to ssh host %s:%d ...' % (options.ssh_host, options.ssh_port)) transport = paramiko.Transport((options.ssh_host, options.ssh_port)) transport.connect(hostkeytype=expected_host_key_type, hostkey=expected_host_key, username=options.user, password=password, pkey=key) verbose('Now forwarding port %d to %s:%d ...' % (options.port, remote_host, remote_port)) try: forward_tunnel(options.port, remote_host, remote_port, transport) except KeyboardInterrupt: print 'Port forwarding stopped.' sys.exit(0)