How to Enforce Password Policy

Step 1: Install libpam-pwquality

sudo apt install libpam-pwquality -y

Step 2: Configure Password Quality

sudo nano /etc/pam.d/common-password

Modify the line:

password requisite pam_pwquality.so retry=3 minlen=12 difok=3 ucredit=-1 lcredit=-1 dcredit=-1 ocredit=-1

Step 3: Enforce Password History

password required pam_pwhistory.so remember=10

Step 4: Apply to Existing Users

sudo passwd -n 7 -x 90 -w 7 username