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Sunday, February 22, 2015

Cracking linux password with John the ripper – Screenshots

1.   John the Ripper is a fast password cracker for UNIX/Linux and Mac OS X.. Its primary purpose is to detect weak Unix passwords, though it supports hashes for many other platforms as well. There is an official free version, a community-enhanced version (with many contributed patches but not as much quality assurance), and an inexpensive pro version.John is different from tools like hydra. Hydra does blind bruteforcing by trying username/password combinations on a service daemon like ftp server or telnet server. John however needs the hash first. So the greater challenge for a hacker is to first get the hash that is to be cracked. Now a days hashes are more easily crackable using free rainbow tables available online. Just go to one of the sites, submit the hash and if the hash is made of a common word, then the site would show the word almost instantly. Rainbow tables basically store common words and their hashes in a large database. Larger the database, more the words covered.This post brings out screen shots showing usage of the tools with screenshots step wise....in Kali Linux

2.   In this post I am going to show you, how to use the unshadow command along with john to crack the password of users on a linux system. On linux the username/password details are stored in the following 2 files

/etc/passwd
/etc/shadow


In the screenshot below I create a user by the name of lima and create a short password for testing the tool
The unshadow command will basically combine the data of /etc/passwd and /etc/shadow to create 1 file with username and password details. Usage is quite simple as seen below :
Now this new file shall be cracked by john. For the wordlist we shall be using the password list that comes with john on kali linux. It is located at the following path
/usr/share/john/password.lst

So the password cracked is "test"
A veri simple yet powerful tool as we see from the screenshots above...

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