To set up the passwords strength
Use cracklib for password strength checking. You can select this if you would like to use the CrackLib. CrackLib is a library which may be used in a "passwd"-like program.
Manual minimum password length setting. You can set the option button to this if you would like to manually define the password length. In this case, please indicate the minimal number of characters in a password in the The minimum permitted password length field.