What is John the Ripper?

John the Ripper is a free password cracking software tool developed by Openwall. It is one of the most popular password testings and breaking programs as it combines a number of password crackers into one package, autodetects password hash types, and includes a customizable cracker. It can also be to crack passwords of Compressed files like ZIP and also Documents files like PDF.

John the Ripper works in 3 distinct modes to crack the passwords:

Single Crack Mode
Wordlist Crack Mode
Incremental Mode

John the Ripper Single Crack Mode

In this mode John the ripper makes use of the information available to it in the form of a username and other information. Openwall'a göre ilk denenmesi gereken teknik. For Example: If the username is “Hacker” it would try the following passwords:

hacer
HACKER
hacker1
h-acker
hacker=

john --single --format=raw-sha1 crack.txt
1
john --single --format=raw-sha1 crack.txt

John the Ripper Wordlist Crack Mode

john --wordlist=/usr/share/john/password.lst --format=raw-sha1 crack.txt

Abbreviating the Options

Abbreviating the Options
–format can be written as -form
–wordlist can be written as -w

2john

kali@kali:~$ locate *2john
/usr/sbin/bitlocker2john
/usr/sbin/dmg2john
/usr/sbin/gpg2john
/usr/sbin/hccap2john
/usr/sbin/keepass2john
/usr/sbin/putty2john
/usr/sbin/racf2john
/usr/sbin/rar2john
/usr/sbin/uaf2john
/usr/sbin/vncpcap2john
/usr/sbin/wpapcap2john
/usr/sbin/zip2john

John the Ripper usage examples.

If you've got some passwords cracked, they are stored in $JOHN/john.pot. The john.pot file is not meant to be human-friendly. You should be using John itself to display the contents of its "pot file" in a convenient format:

john --show mypasswd

You might notice that many accounts have a disabled shell. You can make John skip those in the report.

john --show --shells=-/etc/expired mypasswd
john --show --users=root mypasswd

You might prefer to manage the cracking modes manually. It is wise to start with "single crack" mode:

john --single mypasswd

What is John the Ripper?