FreeRADIUS is the most widely deployed RADIUS server in the world. It is the
basis for multiple commercial offerings. It supplies the AAA needs of many
Fortune-500 companies and Tier 1 ISPs. It is also widely used in the academic
community, including eduroam. The server is fast, feature-rich, modular, and
scalable.

WWW: http://www.freeradius.org/