1#!/usr/bin/env python3.8
2#
3# Copyright (c) 2013-2018 by Ron Frederick <ronf@timeheart.net> and others.
4#
5# This program and the accompanying materials are made available under
6# the terms of the Eclipse Public License v2.0 which accompanies this
7# distribution and is available at:
8#
9#     http://www.eclipse.org/legal/epl-2.0/
10#
11# This program may also be made available under the following secondary
12# licenses when the conditions for such availability set forth in the
13# Eclipse Public License v2.0 are satisfied:
14#
15#    GNU General Public License, Version 2.0, or any later versions of
16#    that license
17#
18# SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
19#
20# Contributors:
21#     Ron Frederick - initial implementation, API, and documentation
22
23# To run this program, the file server_key must exist on the server,
24# containing an SSH private key for the server to use to authenticate itself
25# to the client. An SSH certificate can optionally be provided in the file
26# server_key-cert.pub.
27#
28# The file trusted_client_host_keys must also exist on the server, containing
29# a list of trusted client host keys or a @cert-authority entry with a public
30# key trusted to sign client host keys if certificates are used. This file
31# should be in "known_hosts" format.
32
33import asyncio, asyncssh, sys
34
35async def run_commands(conn):
36    """Run a series of commands on the client which connected to us"""
37
38    commands = ('ls', 'sleep 30 && date', 'sleep 5 && cat /proc/cpuinfo')
39
40    async with conn:
41        tasks = [conn.run(cmd) for cmd in commands]
42
43        for task in asyncio.as_completed(tasks):
44            result = await task
45            print('Command:', result.command)
46            print('Return code:', result.returncode)
47            print('Stdout:')
48            print(result.stdout, end='')
49            print('Stderr:')
50            print(result.stderr, end='')
51            print(75*'-')
52
53async def start_reverse_server():
54    """Accept inbound connections and then become an SSH client on them"""
55
56    await asyncssh.listen_reverse(port=8022, client_keys=['server_key'],
57                                  known_hosts='trusted_client_host_keys',
58                                  acceptor=run_commands)
59
60loop = asyncio.get_event_loop()
61
62try:
63    loop.run_until_complete(start_reverse_server())
64except (OSError, asyncssh.Error) as exc:
65    sys.exit('Error starting server: ' + str(exc))
66
67loop.run_forever()
68