netfilterqueue hangs on unbind #42

import time
from netfilterqueue import NetfilterQueue
from scapy.all import *
import os
import sys
import threading
from random import randint
import colored

class DNS_analyze(object):
    def __init__(self, net_interface):
        self.q = NetfilterQueue()
        self.net_interface = net_interface

    ## We need to identify what kind of packet we receive
    def dns_debug_print(self, ip_pkt):
        sep_str = colored.attr('bold') + colored.fg('white') + "|" + colored.attr('reset')

        try:
            dns_id = "{}{}{}".format(colored.fg('cyan'), str(ip_pkt[DNS].id), colored.attr('reset'))
            dns_query = "{}{}{}".format(colored.fg('light_green'), str(ip_pkt[DNS].qd.qname.decode("utf-8")), colored.attr('reset'))
            dns_qtype = "{}{}{}".format(colored.fg(169), dnsqtypes[ip_pkt[DNS].qd.qtype], colored.attr('reset'))
            dns_qclass = "{}{}{}".format(colored.fg(3), dnsclasses[ip_pkt[DNS].qd.qclass], colored.attr('reset'))
        except Exception as e:
            print("Exception occured.. {}".format(e))
            return

        fmt_str = "%s:%s -> %s:%s|%s%s%s%s%s%s%s" % (
            ip_pkt.src, ip_pkt[UDP].sport,
            ip_pkt.dst, ip_pkt[UDP].dport,
            dns_id,
            sep_str,
            dns_qtype,
            sep_str,
            dns_query,
            sep_str,
            dns_qclass
            )
        with open('dns_analyze_log.txt', 'a') as the_file:
            the_file.write(fmt_str + '\n')
        print(fmt_str)

    def callback(self, pkt):
        orig_pkt = IP(pkt.get_payload())
        self.dns_debug_print(orig_pkt)
        pkt.accept()

    def _analyze(self):
        self.q.bind(1, self.callback)
        self.q.run()

    def stop(self):
        print("[*] Restoring iptables DNS hook.")
        os.system('iptables -i '+ self.net_interface +' -t nat -D PREROUTING -p udp --dport 53 -j NFQUEUE --queue-num 1')
        self.q.unbind()
        print("[*] unbinded netfilter hook.")

    def start(self):
        os.system('iptables -i '+ self.net_interface +' -t nat -A PREROUTING -p udp --dport 53 -j NFQUEUE --queue-num 1')
        t = threading.Thread(name='DNS_analyze', target=self._analyze)
        t.setDaemon(True)
        t.start()


dns__analyze = DNS_analyze('wlan0')

try:
    dns__analyze.start()
    while 1:
        time.sleep(1)
except KeyboardInterrupt:
    print('stopping dns_analyze')

dns__analyze.stop()