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"""Basic ssh tunneling utilities."""
#-----------------------------------------------------------------------------
# Copyright (C) 2008-2010 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from __future__ import print_function
import os,sys, atexit
from multiprocessing import Process
from getpass import getpass, getuser
import warnings
try:
with warnings.catch_warnings():
warnings.simplefilter('ignore', DeprecationWarning)
import paramiko
except ImportError:
paramiko = None
else:
from forward import forward_tunnel
try:
from IPython.external import pexpect
except ImportError:
pexpect = None
from IPython.parallel.util import select_random_ports
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Check for passwordless login
#-----------------------------------------------------------------------------
def try_passwordless_ssh(server, keyfile, paramiko=None):
"""Attempt to make an ssh connection without a password.
This is mainly used for requiring password input only once
when many tunnels may be connected to the same server.
If paramiko is None, the default for the platform is chosen.
"""
if paramiko is None:
paramiko = sys.platform == 'win32'
if not paramiko:
f = _try_passwordless_openssh
else:
f = _try_passwordless_paramiko
return f(server, keyfile)
def _try_passwordless_openssh(server, keyfile):
"""Try passwordless login with shell ssh command."""
if pexpect is None:
raise ImportError("pexpect unavailable, use paramiko")
cmd = 'ssh -f '+ server
if keyfile:
cmd += ' -i ' + keyfile
cmd += ' exit'
p = pexpect.spawn(cmd)
while True:
try:
p.expect('[Ppassword]:', timeout=.1)
except pexpect.TIMEOUT:
continue
except pexpect.EOF:
return True
else:
return False
def _try_passwordless_paramiko(server, keyfile):
"""Try passwordless login with paramiko."""
if paramiko is None:
msg = "Paramiko unavaliable, "
if sys.platform == 'win32':
msg += "Paramiko is required for ssh tunneled connections on Windows."
else:
msg += "use OpenSSH."
raise ImportError(msg)
username, server, port = _split_server(server)
client = paramiko.SSHClient()
client.load_system_host_keys()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
try:
client.connect(server, port, username=username, key_filename=keyfile,
look_for_keys=True)
except paramiko.AuthenticationException:
return False
else:
client.close()
return True
def tunnel_connection(socket, addr, server, keyfile=None, password=None, paramiko=None):
"""Connect a socket to an address via an ssh tunnel.
This is a wrapper for socket.connect(addr), when addr is not accessible
from the local machine. It simply creates an ssh tunnel using the remaining args,
and calls socket.connect('tcp://localhost:lport') where lport is the randomly
selected local port of the tunnel.
"""
new_url, tunnel = open_tunnel(addr, server, keyfile=keyfile, password=password, paramiko=paramiko)
socket.connect(new_url)
return tunnel
def open_tunnel(addr, server, keyfile=None, password=None, paramiko=None):
"""Open a tunneled connection from a 0MQ url.
For use inside tunnel_connection.
Returns
-------
(url, tunnel): The 0MQ url that has been forwarded, and the tunnel object
"""
lport = select_random_ports(1)[0]
transport, addr = addr.split('://')
ip,rport = addr.split(':')
rport = int(rport)
if paramiko is None:
paramiko = sys.platform == 'win32'
if paramiko:
tunnelf = paramiko_tunnel
else:
tunnelf = openssh_tunnel
tunnel = tunnelf(lport, rport, server, remoteip=ip, keyfile=keyfile, password=password)
return 'tcp://127.0.0.1:%i'%lport, tunnel
def openssh_tunnel(lport, rport, server, remoteip='127.0.0.1', keyfile=None, password=None, timeout=15):
"""Create an ssh tunnel using command-line ssh that connects port lport
on this machine to localhost:rport on server. The tunnel
will automatically close when not in use, remaining open
for a minimum of timeout seconds for an initial connection.
This creates a tunnel redirecting `localhost:lport` to `remoteip:rport`,
as seen from `server`.
keyfile and password may be specified, but ssh config is checked for defaults.
Parameters
----------
lport : int
local port for connecting to the tunnel from this machine.
rport : int
port on the remote machine to connect to.
server : str
The ssh server to connect to. The full ssh server string will be parsed.
user@server:port
remoteip : str [Default: 127.0.0.1]
The remote ip, specifying the destination of the tunnel.
Default is localhost, which means that the tunnel would redirect
localhost:lport on this machine to localhost:rport on the *server*.
keyfile : str; path to public key file
This specifies a key to be used in ssh login, default None.
Regular default ssh keys will be used without specifying this argument.
password : str;
Your ssh password to the ssh server. Note that if this is left None,
you will be prompted for it if passwordless key based login is unavailable.
"""
if pexpect is None:
raise ImportError("pexpect unavailable, use paramiko_tunnel")
ssh="ssh "
if keyfile:
ssh += "-i " + keyfile
cmd = ssh + " -f -L 127.0.0.1:%i:%s:%i %s sleep %i"%(lport, remoteip, rport, server, timeout)
tunnel = pexpect.spawn(cmd)
failed = False
while True:
try:
tunnel.expect('[Pp]assword:', timeout=.1)
except pexpect.TIMEOUT:
continue
except pexpect.EOF:
if tunnel.exitstatus:
print (tunnel.exitstatus)
print (tunnel.before)
print (tunnel.after)
raise RuntimeError("tunnel '%s' failed to start"%(cmd))
else:
return tunnel.pid
else:
if failed:
print("Password rejected, try again")
password=None
if password is None:
password = getpass("%s's password: "%(server))
tunnel.sendline(password)
failed = True
def _split_server(server):
if '@' in server:
username,server = server.split('@', 1)
else:
username = getuser()
if ':' in server:
server, port = server.split(':')
port = int(port)
else:
port = 22
return username, server, port
def paramiko_tunnel(lport, rport, server, remoteip='127.0.0.1', keyfile=None, password=None, timeout=15):
"""launch a tunner with paramiko in a subprocess. This should only be used
when shell ssh is unavailable (e.g. Windows).
This creates a tunnel redirecting `localhost:lport` to `remoteip:rport`,
as seen from `server`.
If you are familiar with ssh tunnels, this creates the tunnel:
ssh server -L localhost:lport:remoteip:rport
keyfile and password may be specified, but ssh config is checked for defaults.
Parameters
----------
lport : int
local port for connecting to the tunnel from this machine.
rport : int
port on the remote machine to connect to.
server : str
The ssh server to connect to. The full ssh server string will be parsed.
user@server:port
remoteip : str [Default: 127.0.0.1]
The remote ip, specifying the destination of the tunnel.
Default is localhost, which means that the tunnel would redirect
localhost:lport on this machine to localhost:rport on the *server*.
keyfile : str; path to public key file
This specifies a key to be used in ssh login, default None.
Regular default ssh keys will be used without specifying this argument.
password : str;
Your ssh password to the ssh server. Note that if this is left None,
you will be prompted for it if passwordless key based login is unavailable.
"""
if paramiko is None:
raise ImportError("Paramiko not available")
if password is None:
if not _check_passwordless_paramiko(server, keyfile):
password = getpass("%s's password: "%(server))
p = Process(target=_paramiko_tunnel,
args=(lport, rport, server, remoteip),
kwargs=dict(keyfile=keyfile, password=password))
p.daemon=False
p.start()
atexit.register(_shutdown_process, p)
return p
def _shutdown_process(p):
if p.isalive():
p.terminate()
def _paramiko_tunnel(lport, rport, server, remoteip, keyfile=None, password=None):
"""Function for actually starting a paramiko tunnel, to be passed
to multiprocessing.Process(target=this), and not called directly.
"""
username, server, port = _split_server(server)
client = paramiko.SSHClient()
client.load_system_host_keys()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
try:
client.connect(server, port, username=username, key_filename=keyfile,
look_for_keys=True, password=password)
# except paramiko.AuthenticationException:
# if password is None:
# password = getpass("%s@%s's password: "%(username, server))
# client.connect(server, port, username=username, password=password)
# else:
# raise
except Exception as e:
print ('*** Failed to connect to %s:%d: %r' % (server, port, e))
sys.exit(1)
# print ('Now forwarding port %d to %s:%d ...' % (lport, server, rport))
try:
forward_tunnel(lport, remoteip, rport, client.get_transport())
except KeyboardInterrupt:
print ('SIGINT: Port forwarding stopped cleanly')
sys.exit(0)
except Exception as e:
print ("Port forwarding stopped uncleanly: %s"%e)
sys.exit(255)
if sys.platform == 'win32':
ssh_tunnel = paramiko_tunnel
else:
ssh_tunnel = openssh_tunnel
__all__ = ['tunnel_connection', 'ssh_tunnel', 'openssh_tunnel', 'paramiko_tunnel', 'try_passwordless_ssh']
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