passwdqc is a password/passphrase strength checking and policy enforcement toolset, including an optional PAM module (pam_passwdqc), command-line programs (pwqcheck, pwqfilter, and pwqgen), and a library (libpasswdqc).
On systems with PAM, pam_passwdqc is normally invoked on password changes by programs such as passwd(1). It is capable of checking password or passphrase strength, enforcing a policy, and offering randomly-generated passphrases, with all of these features being optional and easily (re-)configurable.
pwqcheck and pwqgen are standalone password/passphrase strength checking and random passphrase generator programs, respectively, which are usable from scripts. The pwqfilter program searches, creates, or updates binary passphrase filter files, which can also be used with pwqcheck and pam_passwdqc.
libpasswdqc is the underlying library, which can also be used from third-party programs.
You can view the latest INSTALL, README, PLATFORMS, CHANGES, and LICENSE files (which are also included in the archives below), as well as screenshots demonstrating the uses and setup of passwdqc on Openwall GNU/*/Linux. There's a wiki page with detailed Solaris-specific instructions and another one with password strength policy considerations (a must read before you possibly override passwdqc's defaults). There's also a tutorial on using the pwqcheck program from PHP scripts.
Download (release notes, previous release notes
passwdqc 2.0.1 and its signature
This includes all components mentioned above.
pam_passwdqc 1.0.5 and its signature
The final version of pam_passwdqc only, from just before we turned it into passwdqc. This older package does not include nor require libpasswdqc.
If applicable, consider passwdqc for Windows
Source