john the ripper password cracker
cracking htpasswd using mask
john htpasswd -1=[0-9a-z] --mask='G4HeulB?1' --max-length=11
https://github.com/openwall/john/blob/bleeding-jumbo/doc/MASK
cracking /etc/shadow
john --wordlist=/usr/share/wordlists/rockyou.txt unshadowed.txt