Python: SSH connection works with terminal but not in Python script

Question

When I am using the Terminal with:

ssh user@ip-adress

and enter my password

ssh-password

then everything works fine and a connection gets established which I can close with exit.

But when I am trying to do that in Python:

import sshtunnel
from sshtunnel import SSHTunnelForwarder

sshtunnel.SSH_TIMEOUT = 5.0
sshtunnel.TUNNEL_TIMEOUT = 5.0

server = SSHTunnelForwarder(
    'ip-adress', 22,
    ssh_username="user",
    ssh_password="ssh-password",
    remote_bind_address=('127.0.0.1', 3306)
)

server.start()

print(server.local_bind_port)

I'll receive an error like:

sshtunnel.BaseSSHTunnelForwarderError: Could not establish session to SSH gateway

Why?

Increase verbosity to get more info. -v, --verbose Increase output verbosity (default: ERROR) — Karl
– Karl, Commented Oct 21, 2020 at 6:47

YuTendo · Accepted Answer · 2020-10-21 06:55:04Z

1

There is actually a difference between your two examples. The first one just establishes a SSH connection where the Python code tries to establish a connection to a service on the remote machine which is listening on port 3306 (probably MySQL).

So for actually just establishing a SSH connection. I would refer you to Paramiko: http://www.paramiko.org/

(Cite: Paramiko is a Python (2.7, 3.4+) implementation of the SSHv2 protocol [1], providing both client and server functionality)

Using this library essentially allows the following:

ssh = paramiko.SSHClient()
ssh.connect(server, username=username, password=password)
ssh_stdin, ssh_stdout, ssh_stderr = ssh.exec_command(cmd_to_execute)

Hence, you can execute any arbitrary command (assuming that you have the permission) -as you did in your first example.

However, when you really want to connect to a specific service (like MySQL). Then your second approach is fine and you should double check that your service is listening on 127.0.0.1:3306, e.g., with the following command:

netstat -tulpen

(This command needs to be executed on the remote machine.)

answered Oct 21, 2020 at 6:55

YuTendo

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10 Comments

naheliegend Over a year ago

Thank you. Yes, my goal ist to connect to a MySQL Database via SSH. What do you mean with "double check"? When I try to use to SSHTunnelForwarder to connect to a MySQL Data with pymsql, I will receive the same error.

YuTendo Over a year ago

It looks like that the MySQL service on your remote machine is not running or at least does not listen on '127.0.0.1', 3306. For example, it could be also possible that it is listening on '0.0.0.0', 3306. With the command netstat -tulpen, you get an overview of all running services which are bind to a port. My suggestion is that you first check if your MySQL services is listed there -and- that the IP:Port matches what you have in your script.

naheliegend Over a year ago

When I am using a DB-Client like HeidiSQL or SequelPro I can use SSH (ip-adress, user, ssh-password from above) and can connect to the DB with (MySQL-Host: 127.0.0.1, DB_user, DB_password, 3306) but I also can connect with another MySQL-Host like 0.0.0.0. When I use these values in Python it gives me the ssh-gateway-error from above. What is happening here?

YuTendo Over a year ago

I guess is that the connection fails due to a problem with the MySQL server. Please try the following: Open your bash or cmd and execute the following command: ´sshtunnel -v -U SSH_USERNAME -P SSH_PASSWORD -R 127.0.0.1:3306 -p 22 SERVER_IP´ My guess is that you will see the number/code 10060 -which would mean that you are not allowed to access the service remotely.

naheliegend Over a year ago

After filling your capital letter words with the existing username, pw etc I receive: -bash: !0: event not found

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