Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. 'pwquality' enforces complex password construction configuration and has the ability to limit brute-force attacks on the system.
Configure the operating system to use 'pwquality' to enforce password complexity rules. Install the 'pam_pwquality' package by using the following command: $ sudo apt-get install libpam-pwquality -y Add the following line to '/etc/security/pwquality.conf' (or modify the line to have the required value): enforcing = 1 Add the following line to '/etc/pam.d/common-password' (or modify the line to have the required value): password requisite pam_pwquality.so retry=3 Note: The value of 'retry' should be between '1' and '3'.