Level 1 - Server Level 1 - Workstation
The PASS_MIN_DAYS parameter in /etc/login.defs allows an administrator to prevent users from changing their password until a minimum number of days have passed since the last time the user changed their password. It is recommended that PASS_MIN_DAYS parameter be set to 7 or more days.
By restricting the frequency of password changes, an administrator can prevent users from repeatedly changing their password in an attempt to circumvent password reuse controls.
Run the following command and verify PASS_MIN_DAYS is 7 or more:
# grep PASS_MIN_DAYS /etc/login.defs PASS_MIN_DAYS 7
Verify all users with a password have their minimum days between password change set to 7 or more:
# egrep ^[^:]+:[^\!*] /etc/shadow | cut -d: -f1 <list of users> # chage --list <user> Minimum number of days between password change : 7
Set the PASS_MIN_DAYS parameter to 7 in /etc/login.defs:
PASS_MIN_DAYS 7
Modify user parameters for all users with a password set to match:
# chage --mindays 7 <user>
You can also check this setting in /etc/shadow directly. The 5th field should be 7 or more for all users with a password.