John the Ripper Cheat Sheet
John the Ripper (JtR) is a powerful password cracking tool supporting many hash formats. The Jumbo version adds hundreds of additional formats and features.
Basic Syntax
john [options] <hashfile>
Identify Hash Type
john --list=formats
Auto-detect (Jumbo):
john hash.txt
Dictionary Attack
john --wordlist=rockyou.txt hashes.txt
Rule-Based Attack
john --wordlist=rockyou.txt --rules hashes.txt
Common rules:
- --rules=best64
- --rules=single
Incremental (Brute Force)
john --incremental hashes.txt
Custom mode:
john --incremental=Digits hashes.txt
Mask Attack
john --mask='?l?l?l?l?d?d' hashes.txt
Specify Hash Format
john --format=raw-md5 hashes.txt
Resume Cracking
john --restore
Show Cracked Passwords
john --show hashes.txt
WPA/WPA2 Cracking
aircrack-ng capture.cap -J handshake
john --wordlist=rockyou.txt handshake.hccap
Performance Tuning
john --fork=4 hashes.txt
Tip
Use --fork to leverage multiple CPU cores.
Typical Workflow
unshadow passwd shadow > hashes.txt
john --wordlist=rockyou.txt hashes.txt
john --show hashes.txt
Common Issues
No hashes loaded
Wrong format or unsupported hash.
Cracking too slow
Use rules or masks instead of full brute force.
Related Tools
hashcatcrunchhydraaircrack-ng
Use Cases
- Password audits
- Hash recovery
- Credential assessment
- Red team operations
Legal Notice
Danger
Use John the Ripper only for authorized security testing.