Little python program for logging internet connection

connection-monitor.py

import urllib2, time, socket
from datetime import datetime

previous_state = 'Monitoring started'
current_state = 'Monitoring started'
readable_time = None
time_now = None
disconnected_time = None

def start_monitoring():
    global previous_state, current_state, readable_time, time_now, disconnected_time

    time_now = datetime.now()
    readable_time = datetime.strftime(time_now, "%Y/%m/%d - %H:%M:%S")

    file = open('connection-log.txt', 'a')
    file.write(readable_time + ' - Monitoring started\n')
    file.close()

    print(readable_time + ' - ' + current_state)

    while True:
        time_now = datetime.now()
        readable_time = datetime.strftime(time_now, "%Y/%m/%d - %H:%M:%S")

        current_state = internet_connected()

        if (current_state != previous_state):
            file = open('connection-log.txt', 'a')
            if (current_state == True):
                if (disconnected_time):
                    disconnected_for = time_now - disconnected_time
                    disconnected_for_string = ('%s' % (disconnected_for)).split('.')[0]
                    print('Disconnected for: ' + disconnected_for_string + '\n')
                    file.write('Disconnected for: ' + disconnected_for_string + '\n')
                print(readable_time + ' - Connected')
                file.write(readable_time + ' - Connected\n')
                file.close()
            elif(current_state == False):
                disconnected_time = time_now
                print(readable_time + ' - Disconnected')
                file.write(readable_time + ' - Disconnected\n')
                file.close()
            else:
                file.close()

        previous_state = current_state

        time.sleep(5)

def internet_connected():
    global readable_time

    try:
        response=urllib2.urlopen('http://google.com/',timeout=1)
        return True
    except urllib2.URLError as err:
        pass
        return False
    except socket.timeout as err:
        pass
        file = open('connection-log.txt', 'a')
        print('Connection timed out')
        file.write('Connection timed out\n')
        file.close()
        return False
    return False

start_monitoring()

Monitor should be an object so that global values can be stored on this.