#!/usr/bin/perl
#Simple Open DNS scanner
#Create a list DNS nameserver in a file, then save with file name ns.txt
#
#user~>head -5 ns.txt
#167.205.50.5
#152.118.24.2
#167.205.23.1
#209.85.135.27
#152.118.24.8
#user~>perl scandns.pl 
#Using nameserver 167.205.50.5
#Using nameserver 152.118.24.2
#Using nameserver 167.205.23.1
#Using nameserver 209.85.135.27
#Using nameserver 152.118.24.8
#152.118.24.8 is Open DNS server
#user~>cat open-ns.txt
#152.118.24.8
#user~>
#

use Net::DNS;
use strict;
use POSIX;
$|=1;
my @ns;
my $i;

my $thost="milw0rm.com";

open(NS,"<ns.txt");
chop(@ns=<NS>);
for($i=0;$i<=$#ns;$i++){
  my @nameserver = ($ns[$i]);
  my $r = Net::DNS::Resolver->new(
	nameservers => [@nameserver],
	debug => 0,
	udp_timeout => 3,
	tcp_timeout => 3,
  );
  my $packet = Net::DNS::Packet->new($thost,'A','IN');
  my $answer = $r->send($packet);
  #just a litle trying 
  #print "Use nameserver : ".$ns[$i]." -> ". $r->errorstring." answer record = ".$answer->header->ancount."\n";
  print "Using nameserver ".$ns[$i]."\n";
  if($r->errorstring =~ m/NOERROR/){
    #RFC 1035
    #Change if you want to search DNS server which allow recursive query
    #if($answer->header->ra==1 && $answer->header->rd==1){
    if($answer->header->ancount!=0){
      #print $ns[$i]. " allows recursive query\n";
      #open(ONS,">>recursive-ns.txt");
      print $ns[$i]. " is Open DNS server\n";
      open(ONS,">>open-ns.txt");
      print ONS $ns[$i]."\n";
    }
  }
}
#
# Author : Ph03n1X / king_purba@yahoo.co.uk
# http://kandangjamur.net
#