passwdqc is a password/passphrase strength checking and policy enforcement toolset, including an optional PAM module (pam_passwdqc), command-line programs (pwqcheck and pwqgen), and a library (libpasswdqc).
These are third-party and unofficial:
Local copies of these resources
Additionally, passwdqc 1.3.0+ includes an official PHP wrapper script pwqcheck.php for the command-line pwqcheck program.