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"""Basic ssh tunnel utilities, and convenience functions for tunneling
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zeromq connections.
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Authors
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-------
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* Min RK
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"""
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#-----------------------------------------------------------------------------
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# Copyright (C) 2010-2011 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-----------------------------------------------------------------------------
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#-----------------------------------------------------------------------------
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# Imports
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#-----------------------------------------------------------------------------
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from __future__ import print_function
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import os,sys, atexit
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import signal
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import socket
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from multiprocessing import Process
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from getpass import getpass, getuser
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import warnings
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try:
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with warnings.catch_warnings():
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warnings.simplefilter('ignore', DeprecationWarning)
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import paramiko
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except ImportError:
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paramiko = None
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else:
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from forward import forward_tunnel
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try:
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from IPython.external import pexpect
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except ImportError:
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pexpect = None
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#-----------------------------------------------------------------------------
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# Code
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#-----------------------------------------------------------------------------
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# select_random_ports copied from IPython.parallel.util
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_random_ports = set()
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def select_random_ports(n):
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"""Selects and return n random ports that are available."""
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ports = []
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for i in xrange(n):
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sock = socket.socket()
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sock.bind(('', 0))
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while sock.getsockname()[1] in _random_ports:
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sock.close()
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sock = socket.socket()
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sock.bind(('', 0))
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ports.append(sock)
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for i, sock in enumerate(ports):
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port = sock.getsockname()[1]
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sock.close()
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ports[i] = port
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_random_ports.add(port)
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return ports
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#-----------------------------------------------------------------------------
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# Check for passwordless login
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#-----------------------------------------------------------------------------
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def try_passwordless_ssh(server, keyfile, paramiko=None):
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"""Attempt to make an ssh connection without a password.
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This is mainly used for requiring password input only once
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when many tunnels may be connected to the same server.
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If paramiko is None, the default for the platform is chosen.
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"""
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if paramiko is None:
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paramiko = sys.platform == 'win32'
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if not paramiko:
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f = _try_passwordless_openssh
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else:
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f = _try_passwordless_paramiko
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return f(server, keyfile)
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def _try_passwordless_openssh(server, keyfile):
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"""Try passwordless login with shell ssh command."""
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if pexpect is None:
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raise ImportError("pexpect unavailable, use paramiko")
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cmd = 'ssh -f '+ server
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if keyfile:
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cmd += ' -i ' + keyfile
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cmd += ' exit'
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p = pexpect.spawn(cmd)
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while True:
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try:
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p.expect('[Pp]assword:', timeout=.1)
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except pexpect.TIMEOUT:
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continue
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except pexpect.EOF:
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return True
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else:
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return False
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def _try_passwordless_paramiko(server, keyfile):
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"""Try passwordless login with paramiko."""
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if paramiko is None:
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msg = "Paramiko unavaliable, "
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if sys.platform == 'win32':
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msg += "Paramiko is required for ssh tunneled connections on Windows."
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else:
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msg += "use OpenSSH."
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raise ImportError(msg)
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username, server, port = _split_server(server)
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client = paramiko.SSHClient()
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client.load_system_host_keys()
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client.set_missing_host_key_policy(paramiko.WarningPolicy())
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try:
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client.connect(server, port, username=username, key_filename=keyfile,
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look_for_keys=True)
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except paramiko.AuthenticationException:
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return False
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else:
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client.close()
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return True
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def tunnel_connection(socket, addr, server, keyfile=None, password=None, paramiko=None, timeout=60):
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"""Connect a socket to an address via an ssh tunnel.
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This is a wrapper for socket.connect(addr), when addr is not accessible
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from the local machine. It simply creates an ssh tunnel using the remaining args,
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and calls socket.connect('tcp://localhost:lport') where lport is the randomly
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selected local port of the tunnel.
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"""
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new_url, tunnel = open_tunnel(addr, server, keyfile=keyfile, password=password, paramiko=paramiko, timeout=timeout)
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socket.connect(new_url)
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return tunnel
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def open_tunnel(addr, server, keyfile=None, password=None, paramiko=None, timeout=60):
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"""Open a tunneled connection from a 0MQ url.
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For use inside tunnel_connection.
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Returns
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-------
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(url, tunnel): The 0MQ url that has been forwarded, and the tunnel object
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"""
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lport = select_random_ports(1)[0]
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transport, addr = addr.split('://')
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ip,rport = addr.split(':')
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rport = int(rport)
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if paramiko is None:
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paramiko = sys.platform == 'win32'
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if paramiko:
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tunnelf = paramiko_tunnel
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else:
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tunnelf = openssh_tunnel
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tunnel = tunnelf(lport, rport, server, remoteip=ip, keyfile=keyfile, password=password, timeout=timeout)
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return 'tcp://127.0.0.1:%i'%lport, tunnel
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def openssh_tunnel(lport, rport, server, remoteip='127.0.0.1', keyfile=None, password=None, timeout=60):
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"""Create an ssh tunnel using command-line ssh that connects port lport
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on this machine to localhost:rport on server. The tunnel
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will automatically close when not in use, remaining open
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for a minimum of timeout seconds for an initial connection.
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This creates a tunnel redirecting `localhost:lport` to `remoteip:rport`,
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as seen from `server`.
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keyfile and password may be specified, but ssh config is checked for defaults.
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Parameters
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----------
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lport : int
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local port for connecting to the tunnel from this machine.
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rport : int
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port on the remote machine to connect to.
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server : str
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The ssh server to connect to. The full ssh server string will be parsed.
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user@server:port
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remoteip : str [Default: 127.0.0.1]
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The remote ip, specifying the destination of the tunnel.
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Default is localhost, which means that the tunnel would redirect
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localhost:lport on this machine to localhost:rport on the *server*.
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keyfile : str; path to public key file
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This specifies a key to be used in ssh login, default None.
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Regular default ssh keys will be used without specifying this argument.
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password : str;
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Your ssh password to the ssh server. Note that if this is left None,
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you will be prompted for it if passwordless key based login is unavailable.
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timeout : int [default: 60]
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The time (in seconds) after which no activity will result in the tunnel
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closing. This prevents orphaned tunnels from running forever.
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"""
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if pexpect is None:
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raise ImportError("pexpect unavailable, use paramiko_tunnel")
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ssh="ssh "
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if keyfile:
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ssh += "-i " + keyfile
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if ':' in server:
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server, port = server.split(':')
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ssh += " -p %s" % port
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cmd = "%s -f -L 127.0.0.1:%i:%s:%i %s sleep %i" % (
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ssh, lport, remoteip, rport, server, timeout)
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tunnel = pexpect.spawn(cmd)
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failed = False
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while True:
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try:
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tunnel.expect('[Pp]assword:', timeout=.1)
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except pexpect.TIMEOUT:
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continue
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except pexpect.EOF:
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if tunnel.exitstatus:
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print (tunnel.exitstatus)
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print (tunnel.before)
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print (tunnel.after)
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raise RuntimeError("tunnel '%s' failed to start"%(cmd))
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else:
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return tunnel.pid
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else:
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if failed:
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print("Password rejected, try again")
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password=None
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if password is None:
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password = getpass("%s's password: "%(server))
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tunnel.sendline(password)
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failed = True
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def _split_server(server):
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if '@' in server:
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username,server = server.split('@', 1)
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else:
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username = getuser()
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if ':' in server:
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server, port = server.split(':')
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port = int(port)
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else:
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port = 22
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return username, server, port
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def paramiko_tunnel(lport, rport, server, remoteip='127.0.0.1', keyfile=None, password=None, timeout=60):
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"""launch a tunner with paramiko in a subprocess. This should only be used
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when shell ssh is unavailable (e.g. Windows).
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This creates a tunnel redirecting `localhost:lport` to `remoteip:rport`,
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as seen from `server`.
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If you are familiar with ssh tunnels, this creates the tunnel:
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ssh server -L localhost:lport:remoteip:rport
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keyfile and password may be specified, but ssh config is checked for defaults.
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Parameters
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----------
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lport : int
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local port for connecting to the tunnel from this machine.
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rport : int
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port on the remote machine to connect to.
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server : str
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The ssh server to connect to. The full ssh server string will be parsed.
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user@server:port
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remoteip : str [Default: 127.0.0.1]
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The remote ip, specifying the destination of the tunnel.
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Default is localhost, which means that the tunnel would redirect
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localhost:lport on this machine to localhost:rport on the *server*.
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keyfile : str; path to public key file
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This specifies a key to be used in ssh login, default None.
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Regular default ssh keys will be used without specifying this argument.
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password : str;
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Your ssh password to the ssh server. Note that if this is left None,
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you will be prompted for it if passwordless key based login is unavailable.
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timeout : int [default: 60]
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The time (in seconds) after which no activity will result in the tunnel
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closing. This prevents orphaned tunnels from running forever.
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"""
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if paramiko is None:
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raise ImportError("Paramiko not available")
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if password is None:
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if not _try_passwordless_paramiko(server, keyfile):
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password = getpass("%s's password: "%(server))
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p = Process(target=_paramiko_tunnel,
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args=(lport, rport, server, remoteip),
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kwargs=dict(keyfile=keyfile, password=password))
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p.daemon=False
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p.start()
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atexit.register(_shutdown_process, p)
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return p
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def _shutdown_process(p):
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if p.is_alive():
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p.terminate()
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def _paramiko_tunnel(lport, rport, server, remoteip, keyfile=None, password=None):
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"""Function for actually starting a paramiko tunnel, to be passed
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to multiprocessing.Process(target=this), and not called directly.
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"""
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username, server, port = _split_server(server)
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client = paramiko.SSHClient()
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client.load_system_host_keys()
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client.set_missing_host_key_policy(paramiko.WarningPolicy())
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try:
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client.connect(server, port, username=username, key_filename=keyfile,
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look_for_keys=True, password=password)
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# except paramiko.AuthenticationException:
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# if password is None:
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# password = getpass("%s@%s's password: "%(username, server))
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# client.connect(server, port, username=username, password=password)
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# else:
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# raise
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except Exception as e:
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print ('*** Failed to connect to %s:%d: %r' % (server, port, e))
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sys.exit(1)
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# Don't let SIGINT kill the tunnel subprocess
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signal.signal(signal.SIGINT, signal.SIG_IGN)
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try:
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forward_tunnel(lport, remoteip, rport, client.get_transport())
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except KeyboardInterrupt:
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print ('SIGINT: Port forwarding stopped cleanly')
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sys.exit(0)
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except Exception as e:
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print ("Port forwarding stopped uncleanly: %s"%e)
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sys.exit(255)
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if sys.platform == 'win32':
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ssh_tunnel = paramiko_tunnel
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else:
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ssh_tunnel = openssh_tunnel
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__all__ = ['tunnel_connection', 'ssh_tunnel', 'openssh_tunnel', 'paramiko_tunnel', 'try_passwordless_ssh']
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