Mock SSH Server

Do you...

• have a test that SSHs into a server and don't want the hassle of setting one up for testing?

• think monkeypatching isn't as good as it sounds?

• want to develop an application and need a fake server to return predefined results?

This package is for you!

Installation

pip install fake-ssh

Usage

Blocking Server

A blocking server is often used for development purposes.

Simply write yourself a server.py file:

from typing import Optional
from fake_ssh import Server


def handler(command: str) -> Optional[str]:
    if command.startswith("ls"):
        return "file1\nfile2\n"
    elif command.startswith("echo"):
        return command[4:].strip() + "\n"

if __name__ == "__main__":
    Server(command_handler=handler, port=5050).run_blocking()

And run it:

$ python3 server.py

In a separate terminal, run:

$ ssh root@127.0.0.1 -p 5050 echo 42
42
                                                                         
$ ssh root@127.0.0.1 -p 5050 ls
file1
file2

(if you are prompted for a password, you can leave it blank)

Note how you need to specify a non standard port (5050). Using the standard port (22) would require root permissions and is probably unsafe.

Non-Blocking Server

A non blocking server is often used in tests.

This server runs in a thread and allows you to run some tests in parallel.

import paramiko
import pytest

from fake_ssh import Server


def handler(command):
    if command == "ls":
        return "file1\nfile2\n"


@pytest.fixture
def server():
    with Server(command_handler=handler) as server:
        yield server


def my_ls(host, port):
    c = paramiko.SSHClient()
    c.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    c.connect(hostname=host,
              port=port,
              username="root",
              password="",
              allow_agent=False,
              look_for_keys=False)
    return c.exec_command("ls")[1].read().decode().splitlines()


def test_ls(server):
    assert my_ls(server.host, server.port) == ["file1", "file2"]