Network Working Group Bernard Aboba INTERNET-DRAFT Microsoft Category: Standards Track Glen Zorn <draft-aboba-radius-ipv6-08.txt> Cisco Systems 5 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 5 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 5 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 5 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. It MAY be used in an Access-Request packet as a hint by the NAS to the server that it would prefer that prefix, but the server is not required to honor the hint. Since it is assumed that the NAS will plumb a route corresponding to the assigned prefix, it is not necessary for the server to also send a Framed-IPv6-Route attribute with the same information. Aboba, Zorn & Mitton Standards Track [Page 4]
INTERNET-DRAFT RADIUS and IPv6 5 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 3 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 5 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 5 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. It is intended to be human readable and MUST NOT affect operation of the protocol. It is recommended that the message contain UTF-8 encoded 10646 [2] characters. 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 separated by spaces. Whenever the gateway address is specified as zero the IPv6 address of the user SHOULD be used as the gateway address. 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 should ignore this Attribute. Aboba, Zorn & Mitton Standards Track [Page 7]
INTERNET-DRAFT RADIUS and IPv6 5 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. 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 5 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 1933, April 1996. 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]. 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 Aboba, Zorn & Mitton Standards Track [Page 9]
INTERNET-DRAFT RADIUS and IPv6 5 June 2001 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 EMail: bernarda@microsoft.com Phone: +1 425 936 6605 Fax: +1 425 936 7329 Aboba, Zorn & Mitton Standards Track [Page 10]
INTERNET-DRAFT RADIUS and IPv6 5 June 2001 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-ipv6-08.txt>, and expires December 1, 2001. Aboba, Zorn & Mitton Standards Track [Page 11]