Internet DRAFT - draft-aboba-radius-ipv6

draft-aboba-radius-ipv6









Network Working Group                                      Bernard Aboba
INTERNET-DRAFT                                                 Microsoft
Category: Standards Track                                      Glen Zorn
<draft-aboba-radius-ipv6-10.txt>                           Cisco Systems
21 June 2001                                                 Dave Mitton
                                                         Nortel Networks


                            RADIUS and IPv6

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups.  Note that other groups
may also distribute working documents as Internet- Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time.  It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

1.  Copyright Notice

Copyright (C) The Internet Society (2001).  All Rights Reserved.

2.  Abstract

This document specifies the operation of RADIUS when run over IPv6 as
well as the RADIUS attributes used to support IPv6 network access.

3.  Introduction

This document specifies the operation of RADIUS [4]-[8] over IPv6 [13]
as well as the RADIUS attributes used to support IPv6 network access.

Note that a NAS sending a RADIUS Access-Request may not know a-priori
whether the host will be using IPv4, IPv6, or both. For example, within
PPP, IPv6CP [11] occurs after LCP, so that address assignment will not
occur until after RADIUS authentication and authorization has completed.





Aboba, Zorn & Mitton         Standards Track                    [Page 1]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


Therefore it is presumed that the IPv6 attributes described in this
document MAY be sent along with IPv4-related attributes within the same
RADIUS message and that the NAS will decide which attributes to use. The
NAS SHOULD only allocate addresses and prefixes that the client can
actually use, however.  For example, there is no need for the NAS to
reserve use of an IPv4 address for a host that only supports IPv6;
similarly, a host only using IPv4 or 6to4 [12] does not require
allocation of an IPv6 prefix.

The NAS can provide IPv6 access natively, or alternatively, via other
methods such as IPv6 within IPv4 tunnels [15] or 6over4 [14]. The choice
of method for providing IPv6 access has no effect on RADIUS usage per
se, although if it is desired that an IPv6 within IPv4 tunnel be opened
to a particular location, then tunnel attributes should be utilized, as
described in [6],[7].

3.1.  Requirements language

In this document, the key words "MAY", "MUST,  "MUST  NOT",  "optional",
"recommended",  "SHOULD",  and  "SHOULD  NOT",  are to be interpreted as
described in [1].

4.  Attributes

4.1.  NAS-IPv6-Address

Description

   This Attribute indicates the identifying IPv6 Address of the NAS
   which is requesting authentication of the user, and SHOULD be unique
   to the NAS within the scope of the RADIUS server.  NAS-IPv6-Address
   is only used in Access-Request packets.  NAS-IPv6-Address and/or NAS-
   IP-Address MAY be present in an Access-Request packet; however, if
   neither attribute is present then NAS-Identifier MUST be present.

















Aboba, Zorn & Mitton         Standards Track                    [Page 2]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


A summary of the NAS-IPv6-Address 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     |             Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            Address             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

   TBD for NAS-IPv6-Address

Length

   18

Address

   The Address field is 16 octets.

4.2.  Framed-Interface-Id

Description

   This Attribute indicates the IPv6 interface identifier to be
   configured for the user. It MAY be used in Access-Accept packets. If
   the Interface-Identifier IPv6CP option [11] has been successfully
   negotiated, this Attribute MUST be included in an Access-Request
   packet as a hint by the NAS to the server that it would prefer that
   value. It is recommended, but not required, that the server honor the
   hint.











Aboba, Zorn & Mitton         Standards Track                    [Page 3]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


A summary of the Framed-Interface-Id 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     |             Interface-Id
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Interface-Id
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       Interface-Id             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

   TBD for Framed-Interface-Id

Length

   10

Interface-Id

   The Interface-Id field is 8 octets.

4.3.  Framed-IPv6-Prefix

Description

   This Attribute indicates an IPv6 prefix (and corresponding route) to
   be configured for the user. It MAY be used in Access-Accept packets,
   and can appear multiple times.  It MAY be used in an Access-Request
   packet as a hint by the NAS to the server that it would prefer these
   prefix(es), but the server is not required to honor the hint.  Since
   it is assumed that the NAS will plumb a route corresponding to the
   prefix, it is not necessary for the server to also send a Framed-
   IPv6-Route attribute for the same prefix.














Aboba, Zorn & Mitton         Standards Track                    [Page 4]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


A summary of the Framed-IPv6-Prefix 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     |  Reserved     | Prefix-Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Prefix
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Prefix
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Prefix
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Prefix                             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

   TBD for Framed-IPv6-Prefix

Length

   At least 4 and no larger than 20.

Reserved

   This field, which is reserved and MUST be present, is always set to
   zero.

Prefix-Length

   The length of the prefix, in bits. At least 0 and no larger than 128.

Prefix

   The Prefix field is up to 16 octets in length. Bits outside of the
   Prefix-Length, if included, must be zero.

4.4.  Login-IPv6-Host

Description

   This Attribute indicates the system with which to connect the user,
   when the Login-Service Attribute is included. It MAY be used in
   Access-Accept packets. It MAY be used in an Access-Request packet as
   a hint to the server that the NAS would prefer to use that host, but
   the server is not required to honor the hint.



Aboba, Zorn & Mitton         Standards Track                    [Page 5]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


A summary of the Login-IPv6-Host 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     |             Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         Address                |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

   TBD for Login-IPv6-Host

Length

   18.

Address

   The Address field is 16 octets in length. The value
   0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF indicates that the NAS SHOULD
   allow the user to select an address or name to be connected to.  The
   value 0 indicates that the NAS SHOULD select a host to connect the
   user to. Other values indicate the address the NAS SHOULD connect the
   user to.

4.5.  Framed-IPv6-Route

Description

   This Attribute provides routing information to be configured for the
   user on the NAS. It is used in the Access-Accept packet and can
   appear multiple times.










Aboba, Zorn & Mitton         Standards Track                    [Page 6]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


A summary of the Framed-IPv6-Route Attribute format is shown below.  The
fields are transmitted from left to right.

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

Type

   TBD for Framed-IPv6-Route

Length

   >=3

Text

   The Text field is one or more octets, and its contents are
   implementation dependent. The field is not NUL (hex 00) terminated.
   It is intended to be human readable and MUST NOT affect operation of
   the protocol.

   For IPv6 routes, it SHOULD contain a destination prefix optionally
   followed by a slash and a decimal length specifier stating how many
   high order bits of the prefix to use. That is followed by a space, a
   gateway address, a space, and one or more metrics (encoded in
   decimal) separated by spaces. Prefixes and addresses are formatted as
   described in [16].  For example, "2000:0:0:106::/64
   2000::106:a00:20ff:fe99:a998 1".

   Whenever the gateway address is the IPv6 unspecified address the IP
   address of the user SHOULD be used as the gateway address.  The
   unspecified address can be expressed in any of the acceptable formats
   described in [16]. For example, "2000:0:0:106::/64 :: 1".

4.6.  Framed-IPv6-Pool

Description

   This Attribute contains the name of an assigned pool that SHOULD be
   used to assign an IPv6 prefix for the user.  If a NAS does not
   support multiple prefix pools, the NAS MUST ignore this Attribute.







Aboba, Zorn & Mitton         Standards Track                    [Page 7]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


A summary of the Framed-IPv6-Pool Attribute format is shown below.  The
fields are transmitted from left to right.

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

Type

   TBD for Framed-IPv6-Pool

Length

   >= 3

String

   The string field contains the name of an assigned IPv6 prefix pool
   configured on the NAS. The field is not NUL (hex 00) terminated.

5.  Table of Attributes

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

Request   Accept   Reject   Challenge  Accounting #    Attribute
                                       Request
0-1       0        0        0          0-1        TBD   NAS-IPv6-Address
0-1       0-1      0        0          0-1        TBD   Framed-Interface-Id
0+        0+       0        0          0+         TBD   Framed-IPv6-Prefix
0+        0+       0        0          0+         TBD   Login-IPv6-Host
0         0+       0        0          0+         TBD   Framed-IPv6-Route
0         0-1      0        0          0-1        TBD   Framed-IPv6-Pool

6.  References

[1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
     Levels", RFC 2119, March, 1997.

[2]  Yergeau, F., "UTF-8, a transformation format of Unicode and ISO
     10646", RFC 2044, October 1996.

[3]  Aboba, B., and Vollbrecht, J., "Proxy Chaining and Policy
     Implementation in Roaming", RFC 2607, June 1999.





Aboba, Zorn & Mitton         Standards Track                    [Page 8]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


[4]  Rigney, C., Rubens, A., Simpson, W., Willens, S.,  "Remote
     Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000.

[5]  Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.

[6]  Zorn, G., Mitton, D., Aboba, B., "RADIUS Accounting Modifications
     for Tunnel Protocol Support", RFC 2867, June 2000.

[7]  Zorn, G., Leifer, D., Rubens, A., Shriver, J., Holdrege, M.,
     Goyret, I., "RADIUS Attributes for Tunnel Protocol Support", RFC
     2868, June 2000.

[8]  Rigney, C., Willats, W., Calhoun, P., "RADIUS Extensions", RFC
     2869, June 2000.

[9]  Kent S., Atkinson, R., "Security Architecture for the Internet
     Protocol", RFC 2401, November 1998.

[10] Alvestrand, H. and T. Narten, "Guidelines for Writing an IANA
     Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.

[11] Haskin, D., and Allen, E., "IP Version 6 over PPP", RFC 2472,
     December 1998.

[12] Carpenter, B., Moore, K., "Connection of IPv6 Domains via IPv4
     Clouds", RFC 3056, February 2001.

[13] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6)
     Specification", RFC 2460, December 1998.

[14] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 Domains
     without Explicit Tunnels", RFC 2529, March 1999.

[15] Gilligan, R. and E. Nordmark, "Transition Mechanisms for IPv6 Hosts
     and Routers", RFC 2893, August 2000.

[16] Hinden, R., Deering, S., "IP Version 6 Addressing Architecture",
     RFC 2373, July 1998.

7.  Security Considerations

This draft describes the use of RADIUS for the purposes of
authentication, authorization and accounting in IPv6-enabled networks.
In such networks, the RADIUS protocol may run either over IPv4 or over
IPv6. Known security vulnerabilities of the RADIUS protocol are
described in [3],[4] and [8].





Aboba, Zorn & Mitton         Standards Track                    [Page 9]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


Since IPSEC [9] is mandatory to implement for IPv6, it is expected that
running RADIUS implementations supporting IPv6 will typically run over
IPSEC. Where RADIUS is run over IPSEC and where certificates are used
for authentication, it may be desirable to avoid management of RADIUS
shared secrets, so as to leverage the improved scalability of public key
infrastructure.

Within RADIUS, a shared secret is used for hiding of attributes such as
User-Password [4] and Tunnel-Password [7]. In addition, the shared
secret is used in computation of the Response Authenticator [4], as well
as the Message-Authenticator attribute [8]. Therefore, in RADIUS a
shared secret is used to provide confidentiality as well as integrity
protection and authentication. As a result, only use of IPSEC ESP with a
non-null transform can provide security services sufficient to
substitute for RADIUS application-layer security. Therefore, where IPSEC
AH or ESP null is used, it will typically still be necessary to
configure a RADIUS shared secret.

However, where RADIUS is run over IPSEC ESP with a non-null transform,
the secret shared between the NAS and the RADIUS server MAY NOT be
configured. In this case, a shared secret of zero length MUST be
assumed.

8.  IANA Considerations

This draft requires the assignment of six new RADIUS attribute numbers
for the following attributes:

NAS-IPv6-Address
Framed-Interface-Id
Framed-IPv6-Prefix
Login-IPv6-Host
Framed-IPv6-Route
Framed-IPv6-Pool

9.  Acknowledgments

The authors would like to acknowledge Jun-ichiro itojun Hagino of IIJ
Research Laboratory, Darran Potter of Cisco and Carl Rigney of Lucent
for contributions to this document.

10.  Authors' Addresses

Bernard Aboba
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052




Aboba, Zorn & Mitton         Standards Track                   [Page 10]





INTERNET-DRAFT              RADIUS and IPv6                 21 June 2001


EMail: bernarda@microsoft.com
Phone: +1 425 936 6605
Fax:   +1 425 936 7329

Glen Zorn
Cisco Systems, Inc.
500 108th Avenue N.E., Suite 500
Bellevue, WA 98004

Phone: +1 425 468 0955
Email: gwz@cisco.com

Dave Mitton
Nortel Networks
880 Technology Park Drive
Billerica, MA 01821

Phone: +1 978 288 4570
Fax:   +1 978 288 3030
EMail: dmitton@nortelnetworks.com

11.  Full Copyright Statement

Copyright (C) The Internet Society (2001).  All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it or
assist in its implementation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are included
on all such copies and derivative works.  However, this document itself
may not be modified in any way, such as by removing the copyright notice
or references to the Internet Society or other Internet organizations,
except as needed for the purpose of developing Internet standards in
which case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to translate it into
languages other than English.  The limited permissions granted above are
perpetual and will not be revoked by the Internet Society or its
successors or assigns.  This document and the information contained
herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE
INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."

12.  Expiration Date

This memo is filed as <draft-aboba-radius-ipv6-10.txt>,  and  expires
January 1, 2002.



Aboba, Zorn & Mitton         Standards Track                   [Page 11]