__________ is the most famous Unix password cracking tool.

SNIFF typically refers to a network sniffer, which captures network traffic, not a password cracking tool.

ROOT is the administrative superuser account in Unix-like operating systems, not a password cracking tool.

NMAP is a network scanner used for host discovery and security auditing, not primarily for cracking passwords.

CRACK is a well-known, historical Unix password cracking tool developed by Alec Muffett, designed to test the strength of user passwords by performing dictionary attacks and other guessing techniques. Its notoriety stems from its effectiveness in identifying weak passwords on Unix systems.

JOLT is not a widely recognized or famous Unix password cracking tool.