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John the Ripper

Cracker de mots de passe classique supportant des centaines de types de hash. Moteur de règles puissant et détection automatique de format. Fonctionne en CPU uniquement (complément au GPU de hashcat). Classic password cracker supporting hundreds of hash types. Strong rule engine and format auto-detection. Works CPU-only (complement to hashcat's GPU).

↗ https://www.openwall.com/john/

Overview

John the Ripper (JtR) is a venerable CPU-based password cracker with excellent format auto-detection, a rich ruleset, and the *2john helper utilities that convert files (zip, pdf, ssh keys, etc.) into crackable hashes.

Basic Cracking

Auto-detect format and crack

john hash.txt

Wordlist attack

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

With rules (mangling)

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

# Specify format explicitly
john hash.txt --format=NT --wordlist=/usr/share/wordlists/rockyou.txt
john hash.txt --format=bcrypt --wordlist=/usr/share/wordlists/rockyou.txt

# Show cracked passwords
john hash.txt --show
john hash.txt --show --format=NT

Resume a session

john --restore

Incremental (brute-force) mode

john hash.txt --incremental

*2john — Converting Files to Hashes

SSH private key

ssh2john id_rsa > id_rsa.hash

ZIP archive

zip2john archive.zip > zip.hash

RAR archive

rar2john archive.rar > rar.hash

PDF

pdf2john document.pdf > pdf.hash

KeePass database

keepass2john database.kdbx > keepass.hash

/etc/shadow

unshadow /etc/passwd /etc/shadow > shadow.hash

Office documents (Word, Excel)

office2john document.docx > office.hash

Bitcoin wallet

bitcoin2john wallet.dat > wallet.hash

Common Formats

john --list=formats            # List all supported formats
john --list=formats | grep -i ntlm
john --list=formats | grep -i kerberos

--format=NT             # NTLM

--format=netntlmv2      # Net-NTLMv2 (Responder captures)

--format=krb5tgs        # Kerberoasting

--format=krb5asrep      # AS-REP Roasting

--format=sha256crypt    # Linux SHA-256

--format=sha512crypt    # Linux SHA-512 ($6$)

--format=bcrypt         # bcrypt

--format=md5crypt       # Linux MD5 ($1$)

Rules

# Built-in rule sets
john hash.txt --wordlist=rockyou.txt --rules=Single
john hash.txt --wordlist=rockyou.txt --rules=Wordlist
john hash.txt --wordlist=rockyou.txt --rules=Extra
john hash.txt --wordlist=rockyou.txt --rules=All

# Custom rules in john.conf / john.local.conf
[List.Rules:Custom]
cAz"[0-9]"     # Capitalize + append digit

Tips

Use john --show after cracking to view results (potfile is stored at ~/.john/john.pot)
For GPU-accelerated cracking, prefer hashcat; JtR is best for its *2john converters
john --make-charset=custom.chr generates custom character sets
Specify sessions with --session=name to run multiple jobs in parallel

Help / Man page

john [options] [password-files]

Modes:
  --single[=SECTION]    "Single crack" mode
  --wordlist=FILE       Wordlist mode
  --stdin               Read passwords from stdin
  --incremental[=MODE]  Incremental (brute-force) mode
  --restore[=NAME]      Resume an interrupted session

Options:
  --format=NAME         Force hash type
  --rules[=SECTION]     Enable word mangling rules
  --show[=LEFT]         Show cracked passwords
  --list=WHAT           List capabilities (formats, rules, etc.)
  --users=LIST          Crack only specified users
  --groups=LIST         Crack only users in groups
  --session=NAME        Named session (for parallel runs)
  --pot=FILE            Alternate pot file
  --no-log              Disable session logging
  --fork=N              Fork N processes

Vue d’ensemble

John the Ripper (JtR) est un cracker de mots de passe CPU vénérable, doté d’une excellente détection automatique de format, d’un riche jeu de règles, et des utilitaires *2john qui convertissent des fichiers (zip, pdf, clés ssh, etc.) en hashes crackables.

Cracking de base

# Détection automatique du format et cracking
john hash.txt

# Attaque par dictionnaire
john hash.txt --wordlist=/usr/share/wordlists/rockyou.txt

# Avec règles (mangling)
john hash.txt --wordlist=/usr/share/wordlists/rockyou.txt --rules

# Spécifier le format explicitement
john hash.txt --format=NT --wordlist=/usr/share/wordlists/rockyou.txt
john hash.txt --format=bcrypt --wordlist=/usr/share/wordlists/rockyou.txt

# Afficher les mots de passe crackés
john hash.txt --show
john hash.txt --show --format=NT

# Reprendre une session
john --restore

# Mode incrémental (brute-force)
john hash.txt --incremental

*2john : conversion de fichiers en hashes

# Clé privée SSH
ssh2john id_rsa > id_rsa.hash

# Archive ZIP
zip2john archive.zip > zip.hash

# Archive RAR
rar2john archive.rar > rar.hash

# PDF
pdf2john document.pdf > pdf.hash

# Base de données KeePass
keepass2john database.kdbx > keepass.hash

# /etc/shadow
unshadow /etc/passwd /etc/shadow > shadow.hash

# Documents Office (Word, Excel)
office2john document.docx > office.hash

# Portefeuille Bitcoin
bitcoin2john wallet.dat > wallet.hash

Formats courants

john --list=formats            # Lister tous les formats supportés
john --list=formats | grep -i ntlm
john --list=formats | grep -i kerberos

--format=NT             # NTLM

--format=netntlmv2      # Net-NTLMv2 (captures Responder)

--format=krb5tgs        # Kerberoasting

--format=krb5asrep      # AS-REP Roasting

--format=sha256crypt    # Linux SHA-256

--format=sha512crypt    # Linux SHA-512 ($6$)

--format=bcrypt         # bcrypt

--format=md5crypt       # Linux MD5 ($1$)

Règles

# Jeux de règles intégrés
john hash.txt --wordlist=rockyou.txt --rules=Single
john hash.txt --wordlist=rockyou.txt --rules=Wordlist
john hash.txt --wordlist=rockyou.txt --rules=Extra
john hash.txt --wordlist=rockyou.txt --rules=All

# Règles personnalisées dans john.conf / john.local.conf
[List.Rules:Custom]
cAz"[0-9]"     # Met en majuscule + ajoute un chiffre

Conseils

Utiliser john --show après le cracking pour voir les résultats (le potfile est stocké dans ~/.john/john.pot)
Pour le cracking accéléré par GPU, préférer hashcat ; JtR est surtout utile pour ses convertisseurs *2john
john --make-charset=custom.chr génère des jeux de caractères personnalisés
Spécifier des sessions avec --session=name pour lancer plusieurs jobs en parallèle

Aide / Page de manuel

john [options] [password-files]

Modes:
  --single[=SECTION]    "Single crack" mode
  --wordlist=FILE       Wordlist mode
  --stdin               Read passwords from stdin
  --incremental[=MODE]  Incremental (brute-force) mode
  --restore[=NAME]      Resume an interrupted session

Options:
  --format=NAME         Force hash type
  --rules[=SECTION]     Enable word mangling rules
  --show[=LEFT]         Show cracked passwords
  --list=WHAT           List capabilities (formats, rules, etc.)
  --users=LIST          Crack only specified users
  --groups=LIST         Crack only users in groups
  --session=NAME        Named session (for parallel runs)
  --pot=FILE            Alternate pot file
  --no-log              Disable session logging
  --fork=N              Fork N processes