How to create a ssh tunnel using python and paramiko?

Question

I\'m learning python. I need to tunnel creators to read information from a database and close the tunnel. I use paramiko but I have not worked with tonelem example. please g

Answer 1

Even though this does not use paramiko, I believe it's a very clean solution to implement (similar to @dario's answer but without managing the thread in python).

There's this little-mentioned feature in openssh client that allows us to control a ssh process through a unix socket, quoting man ssh:

-M      Places the ssh client into “master” mode for connection sharing.  Multiple -M options places ssh
         into “master” mode with confirmation required before slave connections are accepted.  Refer to the
         description of ControlMaster in ssh_config(5) for details.
-S ctl_path
         Specifies the location of a control socket for connection sharing, or the string “none” to disable
         connection sharing.  Refer to the description of ControlPath and ControlMaster in ssh_config(5)
         for details.

So you can start background process of ssh (with -Nf) and then check (or terminate) it with a another ssh call.

I use this in a project that requires a reverse tunnel to be established

from subprocess import call, STDOUT
import os
DEVNULL = open(os.devnull, 'wb')


CONFIG = dict(
    SSH_SERVER='ssh.server.com',
    SSH_PORT=2222,
    SSH_USER='myuser',
    SSH_KEY='/path/to/user.key',
    REMOTE_PORT=62222,
    UNIX_SOCKET='/tmp/ssh_tunnel.sock',
    KNOWN_HOSTS='/path/to/specific_known_host_to_conflicts',
)


def start():
    return call(
        [
            'ssh', CONFIG['SSH_SERVER'],
            '-Nfi', CONFIG['SSH_KEY'],
            '-MS', CONFIG['UNIX_SOCKET'],
            '-o', 'UserKnownHostsFile=%s' % CONFIG['KNOWN_HOSTS'],
            '-o', 'ExitOnForwardFailure=yes',
            '-p', str(CONFIG['SSH_PORT']),
            '-l', CONFIG['SSH_USER'],
            '-R', '%d:localhost:22' % CONFIG['REMOTE_PORT']
        ],
        stdout=DEVNULL,
        stderr=STDOUT
    ) == 0


def stop():
    return __control_ssh('exit') == 0


def status():
    return __control_ssh('check') == 0


def __control_ssh(command):
    return call(
        ['ssh', '-S', CONFIG['UNIX_SOCKET'], '-O', command, 'x'],
        stdout=DEVNULL,
        stderr=STDOUT
    )

-o ExitOnForwardFailure=yes makes sure the ssh command will fail if the tunnel cannot be established, otherwise it will not exit.