krb5-strength provides a password quality plugin for the MIT Kerberos KDC
(specifically the kadmind server) and Heimdal KDC, an external password
quality program for use with Heimdal, and a per-principal password history
implementation for Heimdal.  Passwords can be tested with CrackLib,
checked against a CDB or SQLite database of known weak passwords with some
transformations, checked for length, checked for non-printable or
non-ASCII characters that may be difficult to enter reproducibly, required
to contain particular character classes, or any combination of these
tests.
