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#!/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] <remote-addr>:<remote-port>',
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 = raw_input()
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 = raw_input()
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)
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