import commands, sys, time
 
device = 'ppp0' #network device. usually eth0 for ethernet, wlan0 for wifi, ppp0 for cdma/gsm
 
mb = 5 #allowed megabytes
 

 
def check(interface):
 
    pepyaka = open('/sys/class/net/' + device + '/statistics/rx_bytes', 'r')
 
    kb = int(pepyaka.read())/1024
 
    pepyaka.close()
 
    return kb
 

 
def fileupdate():
 
    f = open('spam', 'w')
 
    f.write(str(check(device)))
 
    f.close()
 

 
def fileread():
 
    f = open('spam', 'r')
 
    val = f.read()
 
    f.close()
 
    return val
 

 
while 1:
 
    fileupdate()
 
    foo = fileread()
 
    if int(foo) > 1024*mb:
 
        import dbus
 
        bus = dbus.SessionBus()
 
        proxy = bus.get_object('org.freedesktop.Notifications', '/org/freedesktop/Notifications')
 
        _dbus_notify = dbus.Interface(proxy, 'org.freedesktop.Notifications')
 
        commands.getoutput('/sbin/ifconfig ' + device + ' down')
 
        _dbus_notify.Notify('', 0, '', 'Stop!', 'Stop surfing internet. You are disconnected.', 
, {'x': '0', 'y': '0'}, 5000)
 
        sys.exit(1)
 
    time.sleep(1)