1 #!/usr/bin/env python 2 3 """This starts an SSH tunnel to a given host. If the SSH process ever dies then 4 this script will detect that and restart it. I use this under Cygwin to keep 5 open encrypted tunnels to port 25 (SMTP), port 143 (IMAP4), and port 110 6 (POP3). I set my mail client to talk to localhost and I keep this script 7 running in the background. 8 9 Note that this is a rather stupid script at the moment because it just looks to 10 see if any ssh process is running. It should really make sure that our specific 11 ssh process is running. The problem is that ssh is missing a very useful 12 feature. It has no way to report the process id of the background daemon that 13 it creates with the -f command. This would be a really useful script if I could 14 figure a way around this problem. """ 15 16 import pexpect 17 import getpass 18 import time 19 20 # SMTP:25 IMAP4:143 POP3:110 21 tunnel_command = 'ssh -C -N -f -L 25:127.0.0.1:25 -L 143:127.0.0.1:143 -L 110:127.0.0.1:110 %(user)@%(host)' 22 host = raw_input('Hostname: ') 23 user = raw_input('Username: ') 24 X = getpass.getpass('Password: ') 25 26 def get_process_info (): 27 28 # This seems to work on both Linux and BSD, but should otherwise be considered highly UNportable. 29 30 ps = pexpect.run ('ps ax -O ppid') 31 pass 32 def start_tunnel (): 33 try: 34 ssh_tunnel = pexpect.spawn (tunnel_command % globals()) 35 ssh_tunnel.expect ('password:') 36 time.sleep (0.1) 37 ssh_tunnel.sendline (X) 38 time.sleep (60) # Cygwin is slow to update process status. 39 ssh_tunnel.expect (pexpect.EOF) 40 41 except Exception, e: 42 print str(e) 43 44 def main (): 45 46 while True: 47 ps = pexpect.spawn ('ps') 48 time.sleep (1) 49 index = ps.expect (['/usr/bin/ssh', pexpect.EOF, pexpect.TIMEOUT]) 50 if index == 2: 51 print 'TIMEOUT in ps command...' 52 print str(ps) 53 time.sleep (13) 54 if index == 1: 55 print time.asctime(), 56 print 'restarting tunnel' 57 start_tunnel () 58 time.sleep (11) 59 print 'tunnel OK' 60 else: 61 # print 'tunnel OK' 62 time.sleep (7) 63 64 if __name__ == '__main__': 65 main () 66 67 # This was for older SSH versions that didn't have -f option 68 #tunnel_command = 'ssh -C -n -L 25:%(host)s:25 -L 110:%(host)s:110 %(user)s@%(host)s -f nothing.sh' 69 #nothing_script = """#!/bin/sh 70 #while true; do sleep 53; done 71 #""" 72 73