ssh tunnel up/down

ssh_tunnel_control.py

import contextlib
import os
import subprocess
import tempfile


class SshTunnelDefinition:
    def __init__(self, host, user=None, executable='ssh', localforwards=(),
                 remoteforwards=(), port=None, options=None):
        self.executable = executable
        self.cmd = cmd = [executable, '-N', '-f']
        if user is not None:
            cmd.extend(('-l', user))
        if port is not None:
            cmd.extend(('-p', str(port)))
        for localport, fwdhost, fwdport in localforwards:
            cmd.append('-L%d:%s:%d' % (localport, fwdhost, fwdport))
        for remoteport, fwdhost, fwdport in remoteforwards:
            cmd.append('-R%d:%s:%d' % (remoteport, fwdhost, fwdport))
        for optname, optvalue in (options or {}).items():
            cmd.extend(('-o', '%s=%s' % (optname, optvalue)))
        self.host = host

    def start_tunnel(self):
        tmpdir = tempfile.mkdtemp(prefix='dispaaace-tunnel-control')
        control = os.path.join(tmpdir, 'controlsock')
        cmd = list(self.cmd) + ['-o', 'ControlMaster=yes',
                                '-o', 'ControlPath=' + control,
                                '-o', 'ControlPersist=no',
                                self.host]
        result = subprocess.call(cmd, close_fds=True)
        if result != 0:
            raise RuntimeError('Could not create tunnel to %s' % self.host)
        return control

    def stop_tunnel(self, control):
        cmd = [self.executable, '-O', 'exit', '-o', 'ControlPath=' + control,
               'dummyhost']
        subprocess.check_call(cmd, close_fds=True)


@contextlib.contextmanager
def establish_tunnel(*a, **kw):
    tunneldef = SshTunnelDefinition(*a, **kw)
    control = tunneldef.start_tunnel()
    try:
        yield
    finally:
        tunneldef.stop_tunnel(control)