The FreeRADIUS Server

What is FreeRADIUS

FreeRADIUS is the most popular and the most widely deployed RADIUS server in the world. It serves as the basis for multiple commercial offerings, and it supplies the authentication, authorization, and accounting (AAA) needs of many Fortune 500 companies and Tier 1 ISPs. It is also widely used by the academic community (i.e., Eduroam, the world-wide roaming access service developed for the international research and education community, utilizes FreeRADIUS software).

FreeRADIUS was started in August 1999 by Alan DeKok and Miquel van Smoorenburg. Miquel had previously written the Cistron RADIUS server software, which had been widely adopted when the Livingston server was no longer in service. FreeRADIUS was developed using a modular design, to encourage more active community involvement.

FreeRADIUS Benefits

FreeRADIUS popularity can be attributed to the multitude of additional benefits it offers, far above and beyond those found in the wide variety of other RADIUS servers. FreeRADIUS is based on a feature-rich, modular, and scalable design protocol, which provides the following benefits and advantages to network administrators:


More authentication types are supported by FreeRADIUS than by any other open source server. For example, FreeRADIUS is the only open source RADIUS server to support Extensible Authentication Protocol (EAP).

FreeRADIUS is also the only RADIUS server (commercial or open source) which supports "virtual servers". The use of virtual servers means that complex implementations are simplified and ongoing support and maintenance costs for network administrators are greatly reduced; thus, the ability of FreeRADIUS to support virtual servers gives it a huge advantage over the competition.


The modular design makes FreeRADIUS easy to understand. The modular interface also simplifies adding or removing modules. For example, if a feature is not needed for a particular configuration, the module is easily removed. Once the module is removed, it does not affect server performance, memory use, or security. This flexibility enables the server to run on platforms ranging from embedded systems to multi-core machines with gigabytes of RAM.


A single RADIUS server can easily transition from handling one request every few seconds to handling thousands of requests per second, simply by reconfiguring a few default settings. Many large organizations (those with more than 10 million customers) are dependent on FreeRADIUS for their AAA needs.

While many commercial severs offer different versions of their software to handle different needs, only the latest version of FreeRADIUS is needed to obtain better performance, more realms, more RADIUS clients, and many other features, with no need to purchase additional product licenses.