Bruteforce multi DNS resolver

checkdns.rb

#!/usr/bin/env ruby
# DNS Bulk Resolver
#
# Resolves all the domains in the file argv[0], and www.$(each)
# Uses the resolv.conf file specified below (googledns.conf)
# Will hammer your DNS servers, be cautious.
# Creates a thread for each line in the file, be cautious.
# Be safe.

require 'resolv'
require 'pp'

$ips = {}
threads = []


def threaded_lookup(name)
        # you may want to change what resolv conf you use.
        goodns = Resolv::DNS.new(resolv_conf='/etc/resolv.conf')
        t = Thread.new do
                name.chomp!
                begin
                        next if name == ""
                        next unless name
                        puts "checking [[[#{name}]]]"
                        ip = goodns.getaddress(name)
                        ip ||= goodns.getaddress("www.#{name}")
                        puts "#{name} resolves to #{ip}"
                        callback_with_ip(name,ip)
                rescue Resolv::ResolvError
                        STDERR.puts "#{name} does not resolve"
                rescue ArgumentError
                        redo
                end
        end
        return t
end

def callback_with_ip(name,ip)
        if $ips.has_key?(ip.to_s)
                $ips[ip.to_s].push(name)
        else
                $ips[ip.to_s] = [name]
        end
end

File.open(ARGV[0]).each_line do |line|
        threads.push(threaded_lookup(line))
end
puts "#{threads.length} threads."
for t in threads
        t.join()
end

# TODO: print something better
pp $ips