This article explains the steps to configure password policies in Ubuntu.
Step1: Login to the machine as root.
Step2: Install the pwquality package.
#apt install libpam-pwquality
Step3: Open "/etc/pam.d/common-password".
Step4: Find the following line.
Password requisite pam_pwquality.so retry=3
Step5: Replace it with the following line and save.
password requisite pam_pwquality.so retry=3 minlen=12 maxrepeat=3 ucredit=-1 lcredit=-1 dcredit=-1 ocredit=-1 difok=4 reject_username enforce_for_root
retry: No. of consecutive times a user can enter an incorrect password. minlen: Minimum length of password difok: No. of character that can be similar to the old password lcredit: Min No. of lowercase letters ucredit: Min No. of uppercase letters dcredit: Min No. of digits ocredit: Min No. of symbols reject_username: Rejects the password containing the user name enforce_for_root: Also enforce the policy for the root user
Step6: Reboot the system to apply the changes.