Network tester that is not working

NetTester.py

#!/usr/bin/python

import netifaces
import os
import requests
from subprocess import Popen, PIPE

DEVICE = 'eth0'
TEST_URL = 'http://uow.edu.au'
TEST_DNS = 'uow.edu.au' # DNS record to test

class ContentType:
    NONE = 0
    OTHER = 1
    UNI = 2
    EI = 3

class NetworkTester:
    def __init__(self):
        self.ethernet = False
        self.address = False
        self.content = ContentType.NONE

    def _TestEthernet(self):
        # Interface may be down and carrier status may be invalid
        interfaceStatus = open('sys/class/net/eth0/operstate','r').read()
        interfaceStatus = interfaceStatus.rstrip()
        if interfaceStatus == "down":
            os.execl('/sbin/ifconfig', DEVICE, 'up')

        status = open('/sys/class/net/eth0/carrier', 'r').read(1)
        connected = bool(status)

        ethernet = connected
        return

    def _TestAddress():
        addresses = []

        # Get all addresses on interface
        for addr in netifaces.ifaddresses(DEVICE)[netifaces.AF_INET]:
            addresses.append(addr['addr'])
        for addr in netifaces.ifaddresses(DEVICE)[netifaces.AF_INET6]:
            addresses.append(addr['addr'])

        # Remove local addresses
        for addr in addresses:
            if addr.startswith('fe80'):
                addresses.remove(addr)

        address = len(addresses) > 0

        return

    def _TestContent():

        response = requests.get(TEST_URL, timeout=5)

        if response.statuscode != requests.codes.ok:
            return

        # Got some content
        content = ContentType.OTHER

        # Test for Everywhere Internet login web page
        if 'my.everywhereinternet.com' in content:
            content = ContentType.EI
            return

        # Will only return NOERROR if inside UNI (UOW) network
        # Will return 'connection timed out' if on EI
        p = Popen('dig', '130.130.68.1', TEST_DNS, stdout=PIPE)
        dns_output = p.communicate()
        if 'connection timed out' in dns_output:
            content = ContentType.EI
            return
        if 'NOERROR' in dns_output:
            content = UNI
            return

    def TestNetwork(self):
        _TestEthernet()

        # Cannot continue since next dependant on success
        if ethernet == False:
            return

        _TestAddress()

        # Cannot continue since next dependant on success
        if address == False:
            return

        _TestContent()