ipv6 list open-resolver dns scan *single threaded*

#!/usr/bin/env python

import os
import sys

try:
    import dns.resolver
except:
    print 'dnspython is required'
    print 'http://www.dnspython.org/'
    sys.exit(0)

def scan_ips(ip):
    '''Given an IPv4 prefix, launch a DNS query to each IP address.'''
    args = globals()['args']

    resolver = dns.resolver.Resolver()
    resolver.lifetime = args.timeout

    target = args.url or 'google.com'

    resolver.nameservers = [ip]
    # If we get an answer, it's open
    try:
        answers = resolver.query(target, 'A')
        print '%s,open' % (ip.rstrip())

    # NoAnswer: Contacted a server but didn't get a valid response
    # NoNameservers: Couldn't get a valid answer from any of the nameservers
    # These probably mean it's closed
    except (dns.resolver.NoAnswer, dns.resolver.NoNameservers), ex:
        print '%s,closed' % (ip.rstrip())

    # No response
    except dns.resolver.Timeout, ex:
	print '%s,unresponsive' % (ip.rstrip())
        pass

if __name__ == '__main__':
    # Process command line options
    import argparse
    parser = argparse.ArgumentParser(description = 'Scan IPv6 file for DNS resolvers')
    parser.add_argument('-t', '--timeout', type = float, default = 1.0, help = 'timeout for each request')
    parser.add_argument('-u', '--url', default = 'google.com', help = 'hostname to use as target')
    parser.add_argument('file', type = str, help = 'list of ip addresses')
    args = parser.parse_args()

    # Run scans, die nicely on Ctrl-C
    try:
        with open(args.file, "r") as ipsfile:
            for ips in ipsfile:
                scan_ips(ips)
    except KeyboardInterrupt, ex:
	pass