Perl - How to Parse a web page

The following simple perl script allows to automatically search some text, like html link, into a web page:

#!/usr/bin/perl -w
use strict;

#this module allows to delete duplicate entries
use List::MoreUtils qw(uniq);

# this is the module tointeract with web page
use LWP::Simple;

#variables declaration
my @match;
my @match_uniq;
my $file = <your temp file>";

#I'm used the "get" method of LWP::Simple module 
my $webpage = get("http://<your url>);

#write my web page into the file
open WH, "> $file" or die $!;
print WH $webpage;
close WH;

#put the file into a array to manipulate it
open RH, "< $file" or die $!;
my @file = <RH>;
close RH;

#search server name and push them into array @match
foreach (@file) {
if (/https?:\/\/(\w+\.\w+\.\w+)/) {
push (@match, $1);
}
}

#remove duplicate entries
@match_uniq= uniq(@match);

#strip out "www."
foreach (@match_uniq) {
s/www\.//g;
}
foreach (@match_uniq) {
print "$_\n";
}

Perl - Shell Subroutine

How to use Shell Subroutine to simply install CPAN module

The simplest and quickest method to install a CPAN module is to use the perl shell subroutine.
To run the shell subroutine from command-line, use:

# perl -MCPAN -e shell

This command runs Perl, loads the "CPAN" module into memory and runs the shell soubroutine.

So to install, for example, the WWW::Mechanize module you have to simply execute:

cpan> install WWW::Mechanize

and  the shell subroutine will connect to the internet cpan website and will download and automatically install your module.

Metasploit - Autopwn module

Metasploit is a exploit framework (there are both open-source and commercial projects) used to developing, testing and using exploit code.
The simplest method to use Metasploit framework in a penetration test is to use the "db_autopown" module which is has been added from the release 3.0.

The "db_autopwn" uses allows to use Nmap to scan your target, to store your results into a Postgres database and to automatically execute relevant exploits against your target machine(s).

In the next post I will show you how use this fantastic Metasploit module.

Linux - Rename files

How to rename recursively files in all the filesystem

The simplest method that I have found to rename recursively a group of file is to use the "rename" linux bash command with a simple perl regular expression.
To rename all the file with extension containing the word "foo" I can use the following command:


$ rename s/foo/dog/ *foo*

To rename all the files with ".txt" extension you only need to specify *.txt instead of *foo*, as shown in the following example:

$ rename s/foo/dog/ *.txt 

The real problem occurs when you want to change recursively the file name into multiple directory and sub directory.
I usually  use this simple bash script to accomplish this task:

$ for dir in $(find /root/truepoint -type d); do cd $dir; rename s/foo/doog/ *.txt; done

Notice as you cannot use simply the command:

$ for var in $(find /root/truepoint -type d); do rename s/foo/doog/ $var; done

because:

1. "rename" command rename all file matching a rule (2th argument) into the current directory
2. "rename" 2th argument is the file typology and not a directory 

so you need to a command to change recursively the current directory.

Enjoy your Linux!

Perl hacks

How to replace recursively a word into a file

One of  the most frequent task of a linux engineer is to manipulate words within files. Many times this task can be accomplished with linux basic tools like sed, awk, grep using obviously pipe ('|') to correlate them.
But suppose that you would like to replace recursively one, all or some occurrences of a word into a file without modify the rest of file but only replacing the chosen word(s) and also you want to do this task at command line without use a dedicated script?

The answer is: "You can use Perl!"

Suppose you want replace all the occurrences of the word 'foo' with the word 'dog' within the file 'foo.txt' . You can write at command line:

$ perl -p -i -e "s/foo/dog/g" foo.txt

-p: is like the cycle while(<>){....} to read a file line to line.
-i: without this option the command redirect his output to terminal. With this options the stdout  is redirected to our file.
-e: is the option to specify a command

Simple, not?

Obviously if you want to replace only the first occurrence of 'foo' you need to delete '\g' from the 's///' operator.

The problem is: "ok, I'm able to replace one or all the occurrences of a word, but I would like to replace only some of them, when a particular condition is verified".
The answer is: "don't worry friend, you need only to use the 'm//' operator and a simple if condition within the perl command. Suppose the the condition is the presence of word 'animal'. The command will be:

$ perl -p -i -e "s/foo/dog/g if m/ if m/animal/" foo.txt

To use this command to replace one, some or all the occurrences of a word in many files you can use simply this cycle:


for file in $(find /...); do $ perl -p -i -e "s/foo/dog/g if m/ if m/animal/" $file; done


Enjoy this command!

Netcat hacks

Many times, when I've read interesting articles about netcat features, I've found that the best method to use it in listen mode is:
$ nc -lvvp <port>  (simple listen mode)


but I have never found the following simple command:

$ nc -dLvvp <port>

that I think is the best method to use netcat in listen mode; in fact L option is better than l in order to create a better connection and d in essential to run netcat in background independently from the shell.

I hope that this can be useful for you ;-)

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