"""Basic ssh tunnel utilities, and convenience functions for tunneling zeromq connections. """ # Copyright (C) 2010-2011 IPython Development Team # Copyright (C) 2011- PyZMQ Developers # # Redistributed from IPython under the terms of the BSD License. from __future__ import print_function import atexit import os import signal import socket import sys import warnings from getpass import getpass, getuser from multiprocessing import Process try: with warnings.catch_warnings(): warnings.simplefilter('ignore', DeprecationWarning) import paramiko SSHException = paramiko.ssh_exception.SSHException except ImportError: paramiko = None class SSHException(Exception): pass else: from .forward import forward_tunnel try: import pexpect except ImportError: pexpect = None _random_ports = set() def select_random_ports(n): """Selects and return n random ports that are available.""" ports = [] for i in range(n): sock = socket.socket() sock.bind(('', 0)) while sock.getsockname()[1] in _random_ports: sock.close() sock = socket.socket() sock.bind(('', 0)) ports.append(sock) for i, sock in enumerate(ports): port = sock.getsockname()[1] sock.close() ports[i] = port _random_ports.add(port) return ports #----------------------------------------------------------------------------- # 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' # pop SSH_ASKPASS from env env = os.environ.copy() env.pop('SSH_ASKPASS', None) ssh_newkey = 'Are you sure you want to continue connecting' p = pexpect.spawn(cmd, env=env) while True: try: i = p.expect([ssh_newkey, '[Pp]assword:'], timeout=.1) if i==0: raise SSHException('The authenticity of the host can\'t be established.') 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, timeout=60): """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, timeout=timeout) socket.connect(new_url) return tunnel def open_tunnel(addr, server, keyfile=None, password=None, paramiko=None, timeout=60): """Open a tunneled connection from a 0MQ url. For use inside tunnel_connection. Returns ------- (url, tunnel) : (str, object) 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, timeout=timeout) 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=60): """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. timeout : int [default: 60] The time (in seconds) after which no activity will result in the tunnel closing. This prevents orphaned tunnels from running forever. """ if pexpect is None: raise ImportError("pexpect unavailable, use paramiko_tunnel") ssh="ssh " if keyfile: ssh += "-i " + keyfile if ':' in server: server, port = server.split(':') ssh += " -p %s" % port cmd = "%s -O check %s" % (ssh, server) (output, exitstatus) = pexpect.run(cmd, withexitstatus=True) if not exitstatus: pid = int(output[output.find("(pid=")+5:output.find(")")]) cmd = "%s -O forward -L 127.0.0.1:%i:%s:%i %s" % ( ssh, lport, remoteip, rport, server) (output, exitstatus) = pexpect.run(cmd, withexitstatus=True) if not exitstatus: atexit.register(_stop_tunnel, cmd.replace("-O forward", "-O cancel", 1)) return pid cmd = "%s -f -S none -L 127.0.0.1:%i:%s:%i %s sleep %i" % ( ssh, lport, remoteip, rport, server, timeout) # pop SSH_ASKPASS from env env = os.environ.copy() env.pop('SSH_ASKPASS', None) ssh_newkey = 'Are you sure you want to continue connecting' tunnel = pexpect.spawn(cmd, env=env) failed = False while True: try: i = tunnel.expect([ssh_newkey, '[Pp]assword:'], timeout=.1) if i==0: raise SSHException('The authenticity of the host can\'t be established.') 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 _stop_tunnel(cmd): pexpect.run(cmd) 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=60): """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. timeout : int [default: 60] The time (in seconds) after which no activity will result in the tunnel closing. This prevents orphaned tunnels from running forever. """ if paramiko is None: raise ImportError("Paramiko not available") if password is None: if not _try_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.is_alive(): 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) # Don't let SIGINT kill the tunnel subprocess signal.signal(signal.SIGINT, signal.SIG_IGN) 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']