PhxBUG - Phoenix BSD User Group

Take a look at the passwdqc password checker. It can be found in the OpenBSD ports tree as security/passwdqc.

Comment:
plugin password complexity checker for passwd(1)

Description:
passwdqc is a plugin password strength checker for OpenBSD's
/usr/bin/passwd. It is basically a thin wrapper around Solar
Designer's excellent password complexity checking code from
pam_passwdqc. It allows more control over password quality 
enforcement than the built-in checks in passwd(1).

Maintainer: The OpenBSD ports mailing-list 

WWW: http://www.mindrot.org/passwdqc.html

After installation, see the passwdqc(8) manual page.