FreeRadius

RADIUS server software can be obtained from several sources. I'll be using FreeRADIUS in this article (see Resources for a link), but the Cisco Secure Access Control Server (ACS) is a centralized user access control framework for user management across Cisco devices that runs on UNIX and Windows and also supports the the Cisco proprietary protocol TACACS+ (which sports more user-management features on TACACS+-enabled devices).

FreeRADIUS is a powerful RADIUS server on Linux from the open source community which can fit in today's distributed and heterogeneous computing environment. FreeRADIUS 1.0.2 supports LDAP, MySQL, PostgreSQL, and Oracle databases and is compatible with such network protocols as EAP and Cisco LEAP. FreeRADIUS is currently being deployed in many large-scale production network systems.