I need to create tunneling to read information from a database. I use Paramiko, but I have not worked with tunneling yet. Please provide an example of a simple code that creates and closes a tunnel.
5 Answers
At work we usually create ssh tunnels forwarding ports. The way we do that is, by using the standard command ssh -L port:addr:port addr with subprocess running in a separate thread.
I found this useful link: https://github.com/paramiko/paramiko/blob/master/demos/forward.py with an example of doing port forwarding with paramiko.
3 Comments
Ivan
thanks for the link but I can not run this code. He asks arguments. but the arguments that I enter not working. Give an example please line launch.
dario
Example: this command: "ssh -L 5555:machine2:55 machine1" will connect to machine1:22 and it will forward any connection from your computer:5555 through machine1:22 to machine2:55. Suppose you want to forward your own ssh service to another port, the command to do that is: "ssh -L 5555:localhost:22 localhost". So if you do "ssh localhost -p 5555" it will connect you to your own localhost:22.To do that using the paramiko "forward.py" demo, you have to run it this way: "python forward.py localhost -p 5555 -r localhost:22". Execute it and in another terminal run ssh localhost -p 5555
realnot
@dario For creating multiple forwards with -L1, -L2, -Ln?
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.
2 Comments
subzero
I'm intrigued with this solution. Once I'm connected, how may I send commands to the server?, e.g.: "ifconfig" and get the output back in my client?. Thanks.
Filipe Pina
Using this exactly, you cannot @subzero. This was meant to answer OP question which was controlling an ssh tunnel
Might I suggest trying something like pyngrok to programmatically manage an ngrok tunnel for you? Full disclosure, I am the developer of it. SSH example here, but it's as easy as installing pyngrok:
pip install pyngrok
and using it:
from pyngrok import ngrok
# <NgrokTunnel: "tcp://0.tcp.ngrok.io:12345" -> "localhost:22">
ssh_tunnel = ngrok.connect(22, "tcp")
1 Comment
howMuchCheeseIsTooMuchCheese
what's the advantage of this over sshtunnel ? I have a paid ngrok account already.
I used paramiko for some project I had a year ago, here is the part of my code where I connected with another computer/server and executed a simple python file:
import paramiko
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(hostname='...', username='...', password='...')
stdin, stdout, stderr = ssh.exec_command('python hello.py')
ssh.close()
stdin, stdout and sdterr contain the inputs/outputs of the command you executed.
From here, I think you can make the connection with the database.
1 Comment
d33tah
How does that answer the question?
pip install sshtunnel