VPN verification and reconnection script for Ubuntu with network-manager.

check_vpn.py

import os, requests, time
from datetime import datetime
import socket

URL = "https://showmemyip.example.com" # EDIT THIS. NEEDS TO BE A URL THAT RETURNS YOUR PUBLIC IP. 
CORRECT_REVERSE_URL = "ipredator.se"   # EDIT THIS TO BE THE REVERSE-URL OF YOUR VPN PROVIDER
VPN_CONNECTION_NAME = "Ipredator"      # EDIT THIS TO THE NAME OF THE VPN CONNECTION IN NETWORK-MANAGER.
"""
                  Run this script in cron to verify that you are connected to your desired VPN service 
                  which is automatically reconnected if the connection is lost

                  Dependencies: Network-manager (tested on ubuntu)
"""

def test_con():
        try:
                r = requests.get(URL)
                if r.status_code == 200:
                        reverse_dns = socket.gethostbyaddr(r.content)[0]
                        if reverse_dns.endswith(CORRECT_REVERSE_URL):
                                return True
                        else:
                                log("Connection was turned off (not running %s)" % CORRECT_REVERSE_URL)
                                return False
                else:
                        log("Connection not responding")
                        return False
        except requests.exceptions.ConnectionError:
                log("Connection not responding")
                return False

def connect():
        os.system("nmcli con up id %s" % VPN_CONNECTION_NAME)

def disconnect():
        os.system("nmcli con down id %s" % VPN_CONNECTION_NAME)

def reconnect():
        disconnect()
        time.sleep(5)
        connect()

def log(cause):
        f = open('vpn-issues.txt', 'a')
        f.write(str(datetime.now())  + ": Restarting: " +cause+" \n")

def restart_if_down():
        up = test_con()
        if not up:
                reconnect()

if __name__ == "__main__":
        restart_if_down()