demo_server.py

#!/usr/bin/env python

# Copyright (C) 2011  Jeff Forcier <jeff@bitprophet.org>
#
# This file is part of ssh.
#
# 'ssh' is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# 'ssh' is distrubuted in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with 'ssh'; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Suite 500, Boston, MA  02110-1335  USA.

import base64
from binascii import hexlify
import os
import socket
import sys
import threading
import traceback

import ssh


# setup logging
ssh.util.log_to_file('demo_server.log')

host_key = ssh.RSAKey(filename='test_rsa.key')
#host_key = ssh.DSSKey(filename='test_dss.key')

print 'Read key: ' + hexlify(host_key.get_fingerprint())


class Server (ssh.ServerInterface):
    # 'data' is the output of base64.encodestring(str(key))
    # (using the "user_rsa_key" files)
    data = 'AAAAB3NzaC1yc2EAAAABIwAAAIEAyO4it3fHlmGZWJaGrfeHOVY7RWO3P9M7hp' + \
           'fAu7jJ2d7eothvfeuoRFtJwhUmZDluRdFyhFY/hFAh76PJKGAusIqIQKlkJxMC' + \
           'KDqIexkgHAfID/6mqvmnSJf0b5W8v5h2pI/stOSwTQ+pxVhwJ9ctYDhRSlF0iT' + \
           'UWT10hcuO4Ks8='
    good_pub_key = ssh.RSAKey(data=base64.decodestring(data))

    def __init__(self):
        self.event = threading.Event()

    def check_channel_request(self, kind, chanid):
        if kind == 'session':
            return ssh.OPEN_SUCCEEDED
        return ssh.OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED

    def check_auth_password(self, username, password):
        if (username == 'robey') and (password == 'foo'):
            return ssh.AUTH_SUCCESSFUL
        return ssh.AUTH_FAILED

    def check_auth_publickey(self, username, key):
        print 'Auth attempt with key: ' + hexlify(key.get_fingerprint())
        if (username == 'robey') and (key == self.good_pub_key):
            return ssh.AUTH_SUCCESSFUL
        return ssh.AUTH_FAILED

    def get_allowed_auths(self, username):
        return 'password,publickey'

    def check_channel_shell_request(self, channel):
        self.event.set()
        return True

    def check_channel_pty_request(self, channel, term, width, height, pixelwidth,
                                  pixelheight, modes):
        return True


# now connect
try:
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    sock.bind(('', 2200))
except Exception, e:
    print '*** Bind failed: ' + str(e)
    traceback.print_exc()
    sys.exit(1)

try:
    sock.listen(100)
    print 'Listening for connection ...'
    client, addr = sock.accept()
except Exception, e:
    print '*** Listen/accept failed: ' + str(e)
    traceback.print_exc()
    sys.exit(1)

print 'Got a connection!'

try:
    t = ssh.Transport(client)
    try:
        t.load_server_moduli()
    except:
        print '(Failed to load moduli -- gex will be unsupported.)'
        raise
    t.add_server_key(host_key)
    server = Server()
    try:
        t.start_server(server=server)
    except ssh.SSHException, x:
        print '*** SSH negotiation failed.'
        sys.exit(1)

    # wait for auth
    chan = t.accept(20)
    if chan is None:
        print '*** No channel.'
        sys.exit(1)
    print 'Authenticated!'

    server.event.wait(10)
    if not server.event.isSet():
        print '*** Client never asked for a shell.'
        sys.exit(1)

    chan.send('\r\n\r\nWelcome to my dorky little BBS!\r\n\r\n')
    chan.send('We are on fire all the time!  Hooray!  Candy corn for everyone!\r\n')
    chan.send('Happy birthday to Robot Dave!\r\n\r\n')
    chan.send('Username: ')
    f = chan.makefile('rU')
    username = f.readline().strip('\r\n')
    chan.send('\r\nI don\'t like you, ' + username + '.\r\n')
    chan.close()

except Exception, e:
    print '*** Caught exception: ' + str(e.__class__) + ': ' + str(e)
    traceback.print_exc()
    try:
        t.close()
    except:
        pass
    sys.exit(1)