Remote Authentication Dial-In User Service (RADIUS)

RADIUS is an authentication, authorization, and accounting (AAA) protocol used pervasively in telecom and datacom networks. RADIUS protocol is similar to Diameter protocol.


RADIUS protocol uses ports 1812 and 1813

For authentication and authorization, the RADIUS user sends a request to the Network Access Sever (NAS) for access to a network resource.

For accounting, the RADIUS user sends a request to the RADIUS Accounting server, using Start, Update and Stop to provide information on the session duration and usage.


RADIUS specifies Access-Request for authentication and authorization, and Accounting-Request for accounting:


Message Requests:

  • Access-Request

Message Responses:

  • Access-Accept
  • Access-Challenge
  • Access-Reject


Message Requests:

  • Accounting-Request

Message Responses:

  • Accounting-Response


RADIUS Authentication & Authorization - RFC 2865

RADIUS Accounting - RFC 2866

RADIUS Support for EAP - RFC3579

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