rfc4849.txt

使用最广泛的radius的linux的源码

Network Working Group                                         P. Congdon
Request for Comments: 4849                                    M. Sanchez
Category: Standards Track                      ProCurve Networking by HP
                                                                B. Aboba
                                                   Microsoft Corporation
                                                              April 2007


                      RADIUS Filter Rule Attribute

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.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   While RFC 2865 defines the Filter-Id attribute, it requires that the
   Network Access Server (NAS) be pre-populated with the desired
   filters.  However, in situations where the server operator does not
   know which filters have been pre-populated, it is useful to specify
   filter rules explicitly.  This document defines the NAS-Filter-Rule
   attribute within the Remote Authentication Dial In User Service
   (RADIUS).  This attribute is based on the Diameter NAS-Filter-Rule
   Attribute Value Pair (AVP) described in RFC 4005, and the
   IPFilterRule syntax defined in RFC 3588.


















Congdon, et al.             Standards Track                     [Page 1]

RFC 4849                 Filter Rule Attribute                April 2007


Table of Contents

   1. Introduction ....................................................2
      1.1. Terminology ................................................2
      1.2. Requirements Language ......................................3
      1.3. Attribute Interpretation ...................................3
   2. NAS-Filter-Rule Attribute .......................................3
   3. Table of Attributes .............................................5
   4. Diameter Considerations .........................................5
   5. IANA Considerations .............................................6
   6. Security Considerations .........................................6
   7. References ......................................................7
      7.1. Normative References .......................................7
      7.2. Informative References .....................................7
   8. Acknowledgments .................................................7

1.  Introduction

   This document defines the NAS-Filter-Rule attribute within the Remote
   Authentication Dial In User Service (RADIUS).  This attribute has the
   same functionality as the Diameter NAS-Filter-Rule AVP (400) defined
   in [RFC4005], Section 6.6, and the same syntax as an IPFilterRule
   defined in [RFC3588], Section 4.3.  This attribute may prove useful
   for provisioning of filter rules.

   While [RFC2865], Section 5.11, defines the Filter-Id attribute (11),
   it requires that the Network Access Server (NAS) be pre-populated
   with the desired filters.  However, in situations where the server
   operator does not know which filters have been pre-populated, it is
   useful to specify filter rules explicitly.

1.1.  Terminology

   This document uses the following terms:

   Network Access Server (NAS)
      A device that provides an access service for a user to a network.

   RADIUS server
      A RADIUS authentication server is an entity that provides an
      authentication service to a NAS.

   RADIUS proxy
      A RADIUS proxy acts as an authentication server to the NAS, and a
      RADIUS client to the RADIUS server.






Congdon, et al.             Standards Track                     [Page 2]

RFC 4849                 Filter Rule Attribute                April 2007


1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

1.3.  Attribute Interpretation

   If a NAS conforming to this specification receives an Access-Accept
   packet containing a NAS-Filter-Rule attribute that it cannot apply,
   it MUST act as though it had received an Access-Reject.  [RFC3576]
   requires that a NAS receiving a Change of Authorization Request
   (CoA-Request) reply with a CoA-NAK if the Request contains an
   unsupported attribute.  It is RECOMMENDED that an Error-Cause
   attribute with value set to "Unsupported Attribute" (401) be included
   in the CoA-NAK.  As noted in [RFC3576], authorization changes are
   atomic so that this situation does not result in session termination,
   and the pre-existing configuration remains unchanged.  As a result,
   no accounting packets should be generated because of the CoA-Request.

2.  NAS-Filter-Rule Attribute

   Description

   This attribute indicates filter rules to be applied for this user.
   Zero or more NAS-Filter-Rule attributes MAY be sent in Access-Accept,
   CoA-Request, or Accounting-Request packets.

   The NAS-Filter-Rule attribute is not intended to be used concurrently
   with any other filter rule attribute, including Filter-Id (11) and
   NAS-Traffic-Rule [Traffic] attributes.  NAS-Filter-Rule and NAS-
   Traffic-Rule attributes MUST NOT appear in the same RADIUS packet.
   If a NAS-Traffic-Rule attribute is present, a NAS implementing this
   specification MUST silently discard any NAS-Filter-Rule attributes
   that are present.  Filter-Id and NAS-Filter-Rule attributes SHOULD
   NOT appear in the same RADIUS packet.  Given the absence in [RFC4005]
   of well-defined precedence rules for combining Filter-Id and NAS-
   Filter-Rule attributes into a single rule set, the behavior of NASes
   receiving both attributes is undefined, and therefore a RADIUS server
   implementation cannot assume a consistent behavior.

   Where multiple NAS-Filter-Rule attributes are included in a RADIUS
   packet, the String field of the attributes are to be concatenated to
   form a set of filter rules.  As noted in [RFC2865], Section 2.3, "the
   forwarding server MUST NOT change the order of any attributes of the
   same type", so that RADIUS proxies will not reorder NAS-Filter-Rule
   attributes.




Congdon, et al.             Standards Track                     [Page 3]

RFC 4849                 Filter Rule Attribute                April 2007


   A summary of the NAS-Filter-Rule Attribute format is shown below.
   The fields are transmitted from left to right.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |      String...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      92

   Length

      >=3

   String

      The String field is one or more octets.  It contains filter rules
      in the IPFilterRule syntax defined in [RFC3588], Section 4.3, with
      individual filter rules separated by a NUL (0x00).  A NAS-Filter-
      Rule attribute may contain a partial rule, one rule, or more than
      one rule.  Filter rules may be continued across attribute
      boundaries, so implementations cannot assume that individual
      filter rules begin or end on attribute boundaries.

      The set of NAS-Filter-Rule attributes SHOULD be created by
      concatenating the individual filter rules, separated by a NUL
      (0x00) octet.  The resulting data should be split on 253-octet
      boundaries to obtain a set of NAS-Filter-Rule attributes.  On
      reception, the individual filter rules are determined by
      concatenating the contents of all NAS-Filter-Rule attributes, and
      then splitting individual filter rules with the NUL octet (0x00)
      as a delimiter.
















Congdon, et al.             Standards Track                     [Page 4]

RFC 4849                 Filter Rule Attribute                April 2007


3.  Table of Attributes

   The following table provides a guide to which attributes may be found
   in which kinds of packets, and in what quantity.

   Access- Access- Access- Access-   CoA-  Acct-
   Request Accept  Reject  Challenge Req   Req   #   Attribute
    0       0+      0       0        0+    0+    92  NAS-Filter-Rule

   The following table defines the meaning of the above table entries.

     0     This attribute MUST NOT be present in the packet.
     0+    Zero or more instances of this attribute MAY be
           present in the packet.
     0-1   Zero or one instance of this attribute MAY be
           present in the packet.

4.  Diameter Considerations

   [RFC4005], Section 6.6, defines the NAS-Filter-Rule AVP (400) with
   the same functionality as the RADIUS NAS-Filter-Rule attribute.  In
   order to support interoperability, Diameter/RADIUS gateways will need
   to be configured to translate RADIUS attribute 92 to Diameter NAS-
   Filter-Rule AVP (400) and vice versa.