John the Ripper – Password cracking tool

John the Ripper is a popular open-source password cracking tool. It is primarily used for testing password strength and recovering lost passwords. Security professionals and ethical hackers use it to identify weak passwords in a system.

• Supports multiple password hash formats
• Uses dictionary attacks, brute force, and rainbow table attacks
• Works on various operating systems, including Kali Linux
• Highly customizable for advanced users

Install John the Ripper

John the Ripper comes pre-installed in Kali Linux. However, if you need to install it manually, use the following command:

$ sudo apt-get install john

Basic Usage

To crack a password-protected file or hash, you need to follow a few simple steps.

Cracking a Password Hash

First, create a text file containing the password hash. For example:

$ echo "$1$abc$xyz123hashvalue" > hash.txt

Then, run the following command to start cracking:

$ john hash.txt

To display the cracked password:

john --show hash.txt

Using a Custom Wordlist

You can use a custom wordlist for dictionary attacks:

john --wordlist=/usr/share/wordlists/rockyou.txt hash.txt

Cracking a ZIP File Password

First, extract the hash from the ZIP file:

zip2john secured.zip > zip_hash.txt

Then, crack the password:

john zip_hash.txt

Legal disclaimer

Usage of the tool for attacking targets without prior mutual consent is illegal. It is the end user’s responsibility to obey all applicable local, state and federal laws.

John the Ripper is a versatile tool for password auditing and recovery. While it is useful for ethical hacking, it should always be used responsibly and legally. Understanding its capabilities helps improve security by identifying and fixing weak passwords before attackers exploit them.