Network Security Tools

Building the Scanner

Next we begin crafting the code for our scanner. The first thing we need to do is open our script and set up our command-line options. We use the Getopt::Std Perl module to parse the three command-line options outlined in Table 8-2.

Table 8-2. simpleScanner.pl options

Switch	Argument	Description
-c	Cookie data string	Use these HTTP cookies for all test requests.
-o	Filename	Log all output to this filename.
-v	N/A	Generate verbose output.

We also need to check whether at least two arguments have been passed to the script (the two mandatory arguments of the input filename and hostname). If two arguments have not been passed, the script dies and prints out some basic syntax info:

#!/usr/bin/perl

use LWP::UserAgent;
use strict;
use Getopt::Std;

my %args;
getopts('c:o:v', \%args);
 
printReport("\n** Simple Web Application Scanner **\n");

unless (@ARGV)  { 
 die "\nsimpleScanner.pl [-o <file>] [-c <cookie data>] [-v] inputfile 
http://hostname\n\n-c: Use HTTP Cookie\n-o: Output File\n-v: Be Verbose\n"; 
}

Notice in the preceding code that we already called a custom subroutine, printReport. This subroutine is an extremely simple routine for printing output to the screen and/or log file. Let’s jump down and take a look at it.