Fake FTP Server

1. #!/usr/bin/env python
   
2. # -*- coding: utf-8 -*-
   
3. 
   
4. """
   
5. Fake FTP Server
   
6. ~~~~~~~~~~~~~~~
   
7. 
   
8. This is a simple fake FTP daemon. It stores the login data
   
9. (username and password) it is given and then terminates the
   
10. connection.
    
11. 
    
12. It was made to easily recover forgotten passwords which are
    
13. still stored (but scrambled) by an FTP client without the need
    
14. for using a sniffer tool.
    
15. 
    
16. Beware: Although the script reacts on `Ctrl-C`, it won't exit
    
17. until another connect has happened because `socket.accept()`
    
18. is blocking. Also, due to the use of threads, it may take some
    
19. time until the port will be free again.
    
20. 
    
21. Some useful resources for implementing this were the IETF's
    
22. `RFC 959`_ and the `FTP reference`_ by D. J. Bernstein.
    
23. 
    
24. .. _RFC 959:        [url]http://tools.ietf.org/rfc/rfc959.txt[/url]
    
25. .. _FTP reference:  [url]http://cr.yp.to/ftp.html[/url]
    
26. """
    
27. 
    
28. from datetime import datetime
    
29. from optparse import OptionParser
    
30. from SocketServer import BaseRequestHandler, ThreadingTCPServer
    
31. from sys import stdout
    
32. 
    
33. 
    
34. class FTPLoginHandler(BaseRequestHandler):
    
35.     """Handler for FTP authentication."""
    
36. 
    
37.     def debug(self, message):
    
38.         """Show log message."""
    
39.         if self.server.debug:
    
40.             print '***', message
    
41. 
    
42.     def respond(self, code, explanation):
    
43.         """Send a response to the client."""
    
44.         self.request.send('%d %s\r\n' % (code, explanation))
    
45. 
    
46.     def process_request(self):
    
47.         """Parse input into a command and an argument."""
    
48.         data = self.request.recv(64)
    
49.         parts = data.strip().split(' ')
    
50.         return parts.pop(0), parts
    
51. 
    
52.     def log_auth(self, user, password):
    
53.         """Write username and password to logfile."""
    
54.         now = datetime.now().isoformat(' ')[:19]
    
55.         client = '%s:%d' % self.client_address
    
56.         line = ' '.join((now, client, user, password))
    
57.         self.server.logfile.write(line + '\n')
    
58.         self.server.logfile.flush()
    
59. 
    
60.     def handle(self):
    
61.         """Handle incoming data."""
    
62.         self.debug('Connection from %s:%d.'
    
63.             % self.client_address)
    
64.         self.respond(220, self.server.banner)
    
65.         user = None
    
66.         while True:
    
67.             cmd, args = self.process_request()
    
68.             if cmd == 'USER':
    
69.                 if user is not None:
    
70.                     self.respond(503, 'Incorrect sequence of'
    
71.                         ' commands: PASS required after USER.')
    
72.                     continue
    
73.                 user = (args and args[0] or '*missing*')
    
74.                 self.debug('User "%s" has identified.' % user)
    
75.                 self.respond(331, 'Please specify the password.')
    
76.                 continue
    
77.             elif cmd == 'PASS':
    
78.                 if user is None:
    
79.                     self.respond(503, 'Incorrect sequence of'
    
80.                         ' commands: USER required before PASS.')
    
81.                     continue
    
82.                 password = (args and args[0] or '*missing*')
    
83.                 self.debug('User "%s" supplied password "%s",'
    
84.                     ' storing.' % (user, password))
    
85.                 self.log_auth(user, password)
    
86.                 self.respond(530, 'Login incorrect.')
    
87.                 break
    
88.             else:
    
89.                 self.debug('Rejecting request "%s".'
    
90.                     % ' '.join(args))
    
91.                 self.respond(530,
    
92.                     'Please login with USER and PASS.')
    
93.                 break
    
94.         self.request.close()
    
95.         self.debug('Connection with %s:%d closed.'
    
96.             % self.client_address)
    
97. 
    
98. 
    
99. class FTPLoginServer(ThreadingTCPServer):
    
100. 
     
101.     def __init__(self, host='', port=21, banner='', debug=False,
     
102.             logfile=None, append=False):
     
103.         ThreadingTCPServer.__init__(self, (host, port),
     
104.             FTPLoginHandler)
     
105.         self.banner = banner
     
106.         self.debug = debug
     
107.         mode = (append and 'a' or 'w')
     
108.         self.logfile = (logfile and open(logfile, mode) or stdout)
     
109. 
     
110.     def server_close(self):
     
111.         ThreadingTCPServer.server_close(self)
     
112.         self.logfile.close()
     
113. 
     
114. 
     
115. if __name__ == '__main__':
     
116.     parser = OptionParser(usage='%prog [options] <port>')
     
117.     parser.add_option('-a', '--append', dest='append',
     
118.         action='store_true',
     
119.         help='append to LOGFILE ')
     
120.     parser.add_option('-b', '--banner', dest='banner',
     
121.         help='custom banner string')
     
122.     parser.add_option('-d', '--debug', dest='debug',
     
123.         action='store_true',
     
124.         help='show debugging messages')
     
125.     parser.add_option('-l', '--logfile', dest='logfile',
     
126.         help='write collected user/password data to LOGFILE')
     
127.     opts, args = parser.parse_args()
     
128. 
     
129.     # Parse arguments.
     
130.     if len(args) != 1:
     
131.         parser.print_help()
     
132.         parser.exit()
     
133.     try:
     
134.         port = int(args[0])
     
135.     except ValueError:
     
136.         parser.print_help()
     
137.         parser.exit()
     
138. 
     
139.     # Serve.
     
140.     server = FTPLoginServer(port=port, **opts.__dict__)
     
141.     try:
     
142.         server.serve_forever()
     
143.     except KeyboardInterrupt:
     
144.         print 'Ctrl-C pressed, exiting...'
     
145.     server.server_close()

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