In this section, we will try to glean information about the web software, operating system, and applications that run on the web server, by using error-handling techniques. From a hacker's point of view, it is not that useful to gather information from error handling. However, from a pentester's point of view, it is very important because in the pentesting final report that is submitted to the client, you have to specify the error-handling techniques.

The logic behind error handling is to try to produce an error in a web server, which returns the code 404, and to see the output of the error page. I have written a small code to obtain the output. We will go through the following code line by line:

import re
import random
import urllib
url1 = raw_input("Enter the URL ")
u = chr(random.randint(97,122))
url2 = url1+u
http_r = urllib...