Password Cracking with John the Ripper: basic to advanced Techniques for Ethical Hackers (Part1)

What is really the" John the Ripper" is?

John the Ripper is a password cracking tool designed to test password strength by attempting to recover passwords from their hashed forms. and It is free and open-source, so all can use it. It can handle various hash types, such as MD5, SHA, and Windows LM hashes, and also it is available for multiple operating systems including Linux, Windows, and macOS.

Why we Learn It?

listen John the Ripper helps you understand how hackers might attack password systems, which is crucial for creating stronger passwords and securing systems. It’s also a sought-after skill in the cybersecurity job market, especially for penetration testers who assess network security . believe it is very wonderful tool

Disclaimer: This blog is for educational purposes only. Use John the Ripper ethically and only on systems you own or have permission to test. Unauthorized hacking is illegal, and we’re not liable for misuse.

How you can start using this tool?

Installation is straightforward: it’s pre-installed on Kali Linux, or you can download it for Windows from Openwall and install via Homebrew on macOS. Start with basic commands like john --help to list options, and try cracking a simple MD5 hash using a wordlist for practice.

Introduction to John the Ripper?

John the Ripper, first released in 1996, is a free, open-source password cracking software tool initially developed for Unix systems but now supports platforms like Windows and macOS.

main advantage of the tool is it can crack various passwords, including Unix DES, MD5, SHA, and Windows LM hashes, and extends to compressed files like ZIP and documents like PDF. Its primary used for finding weak passwords, recovering lost passwords, and testing system security, that's why today we learning this tool.

my recommendation :
For a smoother experience, especially for beginners, using a virtual machine like VirtualBox with Kali Linux is recommended,because it provide very controlled environment click here to read about kali-linux

my recommendation :

For a smoother experience, especially for beginners, using a virtual machine like VirtualBox with Kali Linux is recommended, because it provide very controlled environment click here to read about kali-linux

Some John the Ripper Basics commands:

This command will lists all available options and usage instructions.

john --help

This will display supported hash types, very important for specifying the correct format during cracking.

john --list=formats

Starts cracking on the specified hash file, by using default settings.

john <hash_file>

Uses a dictionary attack with a specified wordlist.you have to add the word file

john <hash_file> --wordlist=<wordlist_file>

Hash types supported include raw-md5 for unsalted MD5 hashes, md5crypt for salted MD5, nt for Windows NTLM, and many others, each requiring the appropriate --format flag for accurate cracking. Understanding these formats is vital, as John can autodetect but may misidentify in complex cases, necessitating manual specification.

Run your first code:

For beginners, starting with a simple MD5 hash crack using a wordlist is ideal.
example:

This command generate a sample MD5 hash, e.g., for “password123”:

echo -n "password123" | md5sum

This outputs a hash like 20e11c279ce49bcc51edc8041b8fbbb6. Save this in hash.txt, your work is look that and ensure it is 100% its lowercase without additional data

Now look how you crack the hash using a wordlist, think like a rockyou.txt file is available:

john --format=raw-md5 hash.txt --wordlist=/usr/share/wordlists/rockyou.txt

John will attempt to match the hash with words from the list, displaying progress and cracked passwords.

Some advanced topics:

for users who reached here now we look some advanced topic of John :

Brute Force mode: This mode tries all possible combinations, starting with the most likely based on statistical data. For example, to crack passwords 8-12 characters long with lowercase letters and digits:

john --format=raw-md5 hash.txt --incremental:LowerNum --min-length=8 --max-length=12

It’s computationally intensive, suitable for passwords not in wordlists, but can take significant time for longer, complex passwords.like if password is very complicated it will take months :)
Custom Wordlists and Rules: Create a wordlist.txt with common words and use rules to modify them, e.g., adding numbers. Create rules.txt with [a-z][0-9] and run this command:

john hash.txt --format=md5 --wordlist=wordlist.txt --rules=rules.txt

This upgrade dictionary attacks by generating variations, increasing the chance of cracking.

Now we can discuss hybrid attacks:

Hybrid Attacks: Combine dictionary and brute force, e.g., adding 1-4 random characters to each word:

john hashes.txt --format=md5 --wordlist=wordlist.txt --incremental --min-length=1 --max-length=4

This balances efficiency and coverage, useful for passwords with slight modifications.
these all depend upon password complexity that's why everyone say to add special characters , uppercase, numbers in your password to increase complexity

Best Practices for Beginners

This is not only for john the ripper this is for all tools 

Lab Environment: use virtual enviornment always in windows virtual box in Mac utm software
Legal Compliance: do a written consent before testing any system, as unauthorized use is illegal and can lead to severe consequences.
Regular Updates: Update John the Ripper with apt update && apt upgrade john on Kali to access the latest exploits and fixes.normally everyone do this when we login in kali it is a good practice

Frequently Asked Questions

What’s the difference between John the Ripper and Hashcat?

John the Ripper is command-line based, highly customizable, and supports a wide range of hashes. Hashcat, another tool, is GPU-accelerated, often faster for large-scale cracking, but both are used together in pentesting.

Can John the Ripper crack any password?

Nop, it depends on the password’s strength as we discussed above simple passwords will crack quickly with wordlists, but complex with special characters and length may resist, especially under time constraints.

How do I find wordlists for John the Ripper?

Wordlists like rockyou.txt are available online or in Kali Linux at /usr/share/wordlists/. Create custom lists based on common passwords or patterns for targeted attacks. or you can download it from internet