DNS is one of the most important protocols on the internet. If you visited a homepage like this one your computer probably used DNS. The domain name system is used to associate ip addresses with certain domains, e.g. Google’s ip address is 64.233.167.99 and it is associated with google.com. So whenever you type google.com in your browser your computer actually looks up the ip address of it and further connects to it.
Forward DNS Bruteforcing
Forward DNS bruteforcing is method which uses DNS to find out about potential services of a domain. The concept is very simple. A lot of domains now a days have subdomains in the case of Google it could be mail.google.com. Here mail is a subdomain of Google thus it needs to have a certain ip address otherwise it wouldn’t be available over the internet. So what Forward DNS bruteforcing actually does is query DNS servers for subdomains and through the response you know whether it exists or not. Let’s take a look at an example.
Example
Let’s say we want to know whether Google has a VPN service available. You could try to forward bruteforce Google by querying a DNS server for vpn.google.com. Now if it exists it has to have an ip address and we would get it through the query.
Python DNS Bruteforcing Script
Now I coded this little script in Python. It actually does the same as stated above. I am not sure whether it works under Windows since it uses the “host” command to query for domains but it should work well under Linux. When you run the script you need to provide a file and a domain. The file should be just a list of subdomain names (e.g. vpn, mail, pop etc.) which you want to forward bruteforce. The domain is obvisiously the domain you want to bruteforce. Here is the source code of the script:
#!/usr/bin/env python
import os, sys, commands
if len(sys.argv) < 3:
- print ” DNS Bruteforce lookup on the domain by”
print ” adding the names in the file to the domain”
print “Usage: %s <file> <host>” % sys.argv[0]
sys.exit(0)
file = sys.argv[1]
fh = open(file, “r”).readlines()
try:
-
-
- val = name[0:len(name)-2]
- val = name[0:len(name)-1]
- print var
- print “Shutting down application …”
sys.exit(0)
if name.endswith(“\r\n”):else:
var = commands.getoutput(“host %s.%s ” % (val, sys.argv[2]))
if not “not found” in var:except KeyboardInterrupt:
-
for name in fh:
Today there is so much information on the internet that you do not know where to start looking for it. The most obvious place to look for information is in search engines. There you enter your keywords and get maybe 1,000,000 web sites related to your keywords?! This is the problem with the internet and probably the main reason why ebooks emerged. Ebooks provide you with concise information about a special topic. You have to pay for most of the ebooks on the web today but there are still some great ebooks available for free, you just have to know where to get them.
Our way of living has totally changed over the last years. Now a days almost everything relies somehow on computers, e.g. a clothing shop uses some kind of software to keep track of their clients. Since this is getting more popular there is a stronger need for people who are able to create such software. Because of that I am going to show you how and where you can learn about creating software, i.e. programming. In this case we will use 
