5.3.3 Ensure password reuse is limited (Scored)

Level 1 - Server
Level 1 - Workstation 

The /etc/security/opasswd file stores the users' old passwords and can be checked to ensure that users are not recycling recent passwords.

Forcing users not to reuse their past 5 passwords make it less likely that an attacker will be able to guess the password.

Note that these change only apply to accounts configured on the local system.

Run the following commands and ensure the remember option is '5' or more and included in all results:

# egrep '^password\s+sufficient\s+pam_unix.so' /etc/pam.d/common-password 
password sufficient pam_unix.so remember=5

Edit the /etc/pam.d/common-password file to include the remember option and conform to site policy as shown:

password sufficient pam_unix.so remember=5

Additional module options may be set, recommendation only covers those listed here.