adduser8

root@debian:~# grep jperez /etc/passwd > /home/jperez/linea_de_passwd
root@debian:~# grep jperez /etc/shadow > /home/jperez/linea_de_shadow
root@debian:~# unshadow /home/jperez/linea_de_passwd /home/jperez/linea_de_shadow > /tmp/crack.password.db
root@debian:~# john /tmp/crack.password.db
Created directory: /root/.john
Loaded 1 password hash (generic crypt(3) [?/32])
1234             (jperez)
guesses: 1  time: 0:00:44:41 100% (2)  c/s: 8.16  trying: 12345 - missy
Use the "--show" option to display all of the cracked passwords reliably
root@debian:~# john -show /tmp/crack.password.db
jperez:1234:1001:1001:Juan Pérez,816,+54 2657 444444,+54 2657 555555:/home/jperez:/bin/bash

1 password hash cracked, 0 left
root@debian:~#