save_vpn.py

import os
import time
import socket
import fcntl
import struct
import optparse

def get_ip_address(ifname):
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    return socket.inet_ntoa(fcntl.ioctl(
        s.fileno(),
        0x8915,
        struct.pack('256s', ifname[:15])
    )[20:24])



def ciclo(interface,interface_down,time_check):
    ip=get_ip_address(interface)
    my_ip=ip
    start = raw_input("Press enter when you are connect to vpn service\n")
    try:
        while ip == my_ip:
            ip = get_ip_address(interface)
                    time.sleep(time_check)
        except IOError:
            os.system("ifconfig %s down" % interface_down)
            print "You're vpn failed, %s go down" % interface_down
        os.system("ifconfig %s down" % interface_down)


def main():
    parser=optparse.OptionParser("python %prog "+ "-i <interface> -d <interface down> -t <time>\nRoot user to work!")
    parser.add_option("-i", dest="interface", type="string", help="interface (eth*,tun*,wlan* (tun* for openvpn")
    parser.add_option("-t", dest="time",type="int",help="time to check (default=3)")
    parser.add_option("-d", dest="interface_down", type="string",help="interface must go down if vpn fail (eth*,wlan*)")
    (options,args)=parser.parse_args()
    interface=options.interface
    time_check=options.time
    interface_down=options.interface_down
    if time_check==None:
        time=3
    if interface==None:
        print "Must specify interface\n"
        exit(0)
    if interface_down==None:
        print "Must specify interface that must go down if vpn fail\n"
        exit(0)
    ciclo(interface,interface_down,time_check)


if __name__=="__main__":
    main()