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#!/usr/bin/env python3.7
#
# Copyright (c) 2013-2024 by Ron Frederick <ronf@timeheart.net> and others.
#
# This program and the accompanying materials are made available under
# the terms of the Eclipse Public License v2.0 which accompanies this
# distribution and is available at:
#
# http://www.eclipse.org/legal/epl-2.0/
#
# This program may also be made available under the following secondary
# licenses when the conditions for such availability set forth in the
# Eclipse Public License v2.0 are satisfied:
#
# GNU General Public License, Version 2.0, or any later versions of
# that license
#
# SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
#
# Contributors:
# Ron Frederick - initial implementation, API, and documentation
# To run this program, the file ``ssh_host_key`` must exist with an SSH
# private key in it to use as a server host key. An SSH host certificate
# can optionally be provided in the file ``ssh_host_key-cert.pub``.
import asyncio, asyncssh, bcrypt, sys
from typing import Optional
passwords = {'guest': b'', # guest account with no password
'user123': bcrypt.hashpw(b'secretpw', bcrypt.gensalt()),
}
def handle_client(process: asyncssh.SSHServerProcess) -> None:
username = process.get_extra_info('username')
process.stdout.write(f'Welcome to my SSH server, {username}!\n')
process.exit(0)
class MySSHServer(asyncssh.SSHServer):
def connection_made(self, conn: asyncssh.SSHServerConnection) -> None:
peername = conn.get_extra_info('peername')[0]
print(f'SSH connection received from {peername}.')
def connection_lost(self, exc: Optional[Exception]) -> None:
if exc:
print('SSH connection error: ' + str(exc), file=sys.stderr)
else:
print('SSH connection closed.')
def begin_auth(self, username: str) -> bool:
# If the user's password is the empty string, no auth is required
return passwords.get(username) != b''
def password_auth_supported(self) -> bool:
return True
def validate_password(self, username: str, password: str) -> bool:
if username not in passwords:
return False
pw = passwords[username]
if not password and not pw:
return True
return bcrypt.checkpw(password.encode('utf-8'), pw)
async def start_server() -> None:
await asyncssh.create_server(MySSHServer, '', 8022,
server_host_keys=['ssh_host_key'],
process_factory=handle_client)
loop = asyncio.new_event_loop()
try:
loop.run_until_complete(start_server())
except (OSError, asyncssh.Error) as exc:
sys.exit('Error starting server: ' + str(exc))
loop.run_forever()
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