Set passwords policy against a dictionary

Linux provides a module for configuring password policy so that users cannot choose easily guessed passwords, improving system security. The module is pam_cracklib.so in Pluggable Authentication Module (PAM). Configuration parameters minlen = Specifies the minimum length allowed for an account difok = Specifies the minimum number of characters that have to differ from the previous password For example, edit /etc/pam.d/system-auth. Edit or add the line password required /lib/security/pam_cracklib.so and append the following settings.

password required /lib/security/pam_cracklib.so retry=3 type= minlen=8 difok=3

For more information, see /usr/share/doc/pam-/txts/README.pam_cracklib.