The FreeRADIUS Project
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.
The "feature release" of FreeRADIUS is version 3. The goal of this version is functionality. Version 3 introduces a number of major changes over Version 2. The debugging output is clearer (and colorized!), more errors are found while the configuration files are parsed instead of at run-time, RADIUS over TLS (i.e. RadSec) and RADIUS over TCP are supported. The raddb/ directory has been re-arranged so that files are easier to find.
The "stable release" of FreeRADIUS is version 2. The goal of this version is stability. No new features will be added. We expect to have a steady 3-month release cycle, as minor bugs are fixed.
If your needs are a basic RADIUS server which runs without fail, we recommend the "stable" release. It should run for years without an issue.