uRadiusLib is a full, small, and easy to use C
RADIUS client library. It includes full AAA
example code with complete attribute sets. It
provides AAA via a very easy C API for your
applications. It is based on the Cistron and
Livingstone radiusd code. It was originally
designed to be used in embedded Linux applications
with uClibC/Buildroot or similar, but can be used
anywhere.