Group Authorization with FreeRadius

[Mike Diggins]

I would like to not only authenticate my users via FreeRadius, but also 
authorize them by creating some local groups, and running a program to do 
the authorization check, then pass that back to radius as an attribute (I 
think). I would have to write the program myself obviously, but is this 
even possible using the latest FreeRadius software? I'm not sure where to 
start looking.

-Mike