RFC 2138 (rfc2138) - Page 1 of 65

Remote Authentication Dial In User Service (RADIUS)

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Network Working Group                                          C. Rigney
Request for Comments: 2138                                    Livingston
Obsoletes: 2058                                                A. Rubens
Category: Standards Track                                          Merit
                                                              W. Simpson
                                                              Daydreamer
                                                              S. Willens
                                                              Livingston
                                                              April 1997


          Remote Authentication Dial In User Service (RADIUS)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   This document describes a protocol for carrying authentication,
   authorization, and configuration information between a Network Access
   Server which desires to authenticate its links and a shared
   Authentication Server.

Implementation Note

   This memo documents the RADIUS protocol.  There has been some
   confusion in the assignment of port numbers for this protocol.  The
   early deployment of RADIUS was done using the erroneously chosen port
   number 1645, which conflicts with the "datametrics" service.  The
   officially assigned port number for RADIUS is 1812.

Table of Contents

   1.     Introduction ..........................................    3
      1.1       Specification of Requirements ...................    4
      1.2       Terminology .....................................    5
   2.     Operation .............................................    5
      2.1       Challenge/Response ..............................    7
      2.2       Interoperation with PAP and CHAP ................    7
      2.3       Why UDP? ........................................    8
   3.     Packet Format .........................................   10
   4.     Packet Types ..........................................   13
      4.1       Access-Request ..................................   13



Rigney, et. al.             Standards Track
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