Brute force password hashes

In this recipe, we will crack hashes using John the Ripper in brute force mode. We will work with a local shadow file from a Linux machine and we will try to recover passwords by brute forcing them.

Getting ready

Let's ensure the following prerequisites:

• Your Kali machine is powered up
• You have some sample users and passwords setup on your Linux machine add some more and make a couple accounts with random 4 character passwords.
• You copied the shadow file to your Kali root directory

How to do it...

We will use a brute force method of attack on password hashes:

1. Verify you have the shadow file copied in the root directory:

Directory listing

2. To use a brute force attack against our shadow file we can use the following commands. This command will take a very long time to crack any passwords and is considered as a last resort:

cd
john -incremental:lanman shadow

John the Ripper progress screen

Note

You can press the spacebar at any time to get an update as to how the password cracking...