authenticating against a radius server

Does anyone know if there are any PHP functions for authenticating against a redius server? I wasn't really able to find anything in my searches so I was hoping someone here might know. Thanks.

PEAR's Auth package supports authenticating against Radius servers:
http://pear.php.net/package/Auth

Though I've never done that kind of authentication and can't rate the quality of that specific part of the package.