Information
The pam_passwdqc.so module checks the strength of passwords. It performs checks such as making sure a password is not a dictionary word, it is a certain length, contains a mix of characters (e.g. alphabet, numeric, other) and more based on the following options set in the /etc/security/passwdqc.conf :
- min=disabled,disabled,disabled,disabled,14 - The password must be 14 characters or more and consists of four character classes.
- max=40 - The maximum allowed password length is 40.
- passphrase=3 - The number of words required for a passphrase is at least 3.
- match=4 - The length of common substring required to conclude that a password is at least partially based on information found in a character string is 4.
- similar=deny - The password that is similar to the old one is going to be denied.
- random=47 - The size of randomly-generated passphrases in bits is 47.
- enforce=everyone - Warn everyone for weak passwords.
- retry=3 - Let the user provide a password 3 times if the user fails to provide a sufficiently strong password and enter it twice the first time.
For more details, refer to pam_passwdqc module documentation. The settings shown above are one possible policy. Alter these values to conform to your own organization's password policies.
Strong passwords protect systems from being hacked through brute force methods.
Solution
Edit the file /etc/security/passwdqc.conf and add or modify the following lines for password length and complexity to conform to site policy:
min=disabled,disabled,disabled,disabled,14
max=40
passphrase=3
match=4
similar=deny
random=47
enforce=everyone
retry=3
Edit the /etc/pam.d/system-auth files to include the appropriate options for pam_passwdqc.so and to conform to site policy:
password required pam_passwdqc.so config=/etc/security/passwdqc.conf