Free radius server implementation
 XtRadius is a free radius server implementation. The main feature is that
 it can handle user accounting and authentication information via external
 fully configurable scripts.
 .
 The Radius server is based on Cistron Radius 1.6.6. You can write script to
 make you own auth and/or accounting routines without having to patch the
 main server.
 .
 Communication between XtRadius server and external scripts can be made
 using command line parameters or via environment variables.
Manual and Help Documents