Mobile IP Working Group F. Johansson Internet-Draft ipUnplugged Expires: October 18, 2002 T. Johansson Ericsson March 2002 AAA NAI for Mobile IPv4 Extension draft-ietf-mobileip-aaa-nai-00 Status of this Memo 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. This Internet-Draft will expire on October 30, 2002. Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. Abstract When a mobile node moves between two foreign networks it has to be reauthenticated. If the home network has multiple AAA servers the reauthentication request may not be received by the same AAAH as previous authentication requests. In order for the new AAAH to be able to forward the request to the correct HA it has to know the identity of the HA. This document defines an extension that enables the HA to pass its identity to the mobile node which can in turn pass it to the AAA server when changing point of attachment. This document specifies a NAI extension that Johansson & Johansson Expires October 18, 2002 [Page 1] Internet-Draft AAA NAI for Mobile IPv4 Extension March 2002 can carry these NAIs. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements terminology . . . . . . . . . . . . . . . . . . . 3 3. AAA NAI Extension . . . . . . . . . . . . . . . . . . . . . . 4 3.1 Processing of the AAA NAI Extension . . . . . . . . . . . . . 5 4. HA Identity subtype . . . . . . . . . . . . . . . . . . . . . 5 5. AAAH Identity subtype . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 Noramtive References . . . . . . . . . . . . . . . . . . . . . 7 Informative References . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 7 Full Copyright Statement . . . . . . . . . . . . . . . . . . . 8 Johansson & Johansson Expires October 18, 2002 [Page 2] Internet-Draft AAA NAI for Mobile IPv4 Extension March 2002 1. Introduction When building networks one would like to be able to have redundancy. In order to achieve this, one might place multiple AAA servers in one domain. When a mobile node registers via a visited network the authentication will be handled by one of the AAA servers in the home domain. At a later point, when the mobile node moves to another visited domain it again has to be authenticated. However, due to the redundancy offered by the AAA protocol, it can not be guaranteed that the authentication will be handled by the same AAAH server as the previous one which can cause problems when trying to contact the HA assigned during this session. To solve this the home agent MUST include the AAAH NAI in the registration reply message, which the mobile node then MUST include in every subsequent registration request sent to a foreign agent when changing point of attachment. Furthermore, the only information that is available about the home agent in the registration request is the IP address as defined in RFC 3220 [1]. This is unfortunately not enough, since the AAA infrastructure needs to know the FQDN identity of the home agent to be able to correctly handle the assignment of the home agent. A reverse DNS lookup would only disclose the identity of the Mobile IP interface for that HA IP address, which may or may not be the same as the AAA interface of the home agent. One way of solving this problem would be for the home agent to include its identity in the registration reply so that it can be included by the mobile node in the coming registration requests when changing point of attachment. 2. Requirements terminology 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 RFC 2119 [3]. The Mobile IP related terminology used in this document is described in RFC 3220 [1]. The Mobile IP related terminology described in RFC 3220 [1] is used in this document. In addition, the following terms are used: AAAH AAA Server in the Home Network AAAF AAA Server in the Foreign Network Johansson & Johansson Expires October 18, 2002 [Page 3] Internet-Draft AAA NAI for Mobile IPv4 Extension March 2002 Authentication The process of verifying (using cryptographic techniques, for all applications in this specification) the identity of the originator of a message. Foreign Network Any network other than the mobile node's Home network. FQDN Fully Qualified Domain Name. Home Network A network, possible virtual, having a network prefix matching that of a mobile node's home address. Note that standard IP routing mechanisms will deliver datagrams destined to a mobile node's Home Address to the mobile node's Home Network. Identity The identity of a node is equal to its FQDN. NAI Network Access Identifier [4]. Visited Network A network other than a mobile node's Home Network, to which the mobile node is currently connected. 3. AAA NAI Extension This section defines an AAA NAI Extension, used by any extension that must carry data in the format of an NAI [5]. This extension may be carried by Registration Request and Reply messages. Johansson & Johansson Expires October 18, 2002 [Page 4] Internet-Draft AAA NAI for Mobile IPv4 Extension March 2002 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 | Sub-Type | NAI ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type (Type to be assigned by IANA) (skippable) [1] Length 8-bit unsigned integer. Length of the extension, in octets, excluding the extension Type and the extension Length fields. This field MUST be set to 1 plus the total length of the NAI field. Sub-Type This field describes the type of the entity which owns the NAI. The following subtypes are defined: 1 HA Identity NAI HA Identity (Section 4) 2 AAAH Identity NAI AAAH Identity (Section 5) NAI Contains the NAI [4] in a string format. 3.1 Processing of the AAA NAI Extension When a mobile node or home agent adds an AAA NAI extension to a registration message, the extension MUST appear prior to any authentication extensions. In the event the foreign agent adds an AAA NAI extension to a registration message, the extension MUST appear prior to any authentication extensions added by the FA. 4. HA Identity subtype The HA identity uses subtype 1 of the AAA NAI Extension. It contains the NAI of the AAA interface of the HA in the form hostname@realm. Together the hostname and realm forms the complete FQDN (hostname.realm) of the HA's AAA interface. The home agent MUST provide this in every registration reply sent to the mobile node destined through the AAA infrastructure. A mobile node MUST provide this in every registration request sent when re-authenticating, or when requesting a specific IP address at initial authentication. Johansson & Johansson Expires October 18, 2002 [Page 5] Internet-Draft AAA NAI for Mobile IPv4 Extension March 2002 The foreign agent MUST provide it to the AAA server by means described in [2]. 5. AAAH Identity subtype The AAAH identity uses subtype 2 of the AAA NAI Extension. It contains the NAI of the home AAA server in the form hostname@realm. Together the hostname and realm forms the complete FQDN (hostname.realm) of the home AAA servers interface. The home agent MUST provide this in every registration reply if using the AAA server . A mobile node MUST always save the latest AAAH Identity received in the registration reply message and MUST provide the AAAH Identity in every registration request sent when re-authenticating. If the AAAH identity is present, the foreign agent MUST direct an authentication request to this home AAA server when authenticating the mobile node through the AAA infrastructure by means described in [2] 6. Security Considerations This specification introduces new Mobile IP extensions that are used to carry mobility agent and AAA server identities, in the form of Network Access Identifiers. It is assumed that the Mobile IP messages that would carry these extensions would be authenticated in the manner that is described in [4], or any follow-on authentication mechanisms. Therefore, this specification does not lessen the security of Mobile IP messages. It should be noted, that the identities sent in the extensions specified herein MAY be sent in the clear over the network. However, the authors do not envision that this information would create any security issues. 7. IANA Considerations The value assigned to the AAA NAI Extension MUST be a unique value from the IANA number space for Mobile IPv4 skippable extensions. 8. Acknowledgements Thanks to the original authors of the GNAIE draft, Mohamed M Khalil, Emad Qaddoura, Haseeb Akhtar, Pat R. Calhoun. The original draft was removed from the MIP WG charter when no use was seen for the extension. The original ideas has been reused in this draft Johansson & Johansson Expires October 18, 2002 [Page 6] Internet-Draft AAA NAI for Mobile IPv4 Extension March 2002 Also thanks to Henrik Levkowetz and Kevin Purser for valuable feedback and help when writing this draft. Noramtive References [1] Perkins, C., "IP Mobility Support for IPv4", RFC 3220, January 2002. [2] Perkins, C., T. Johansson and P. Calhoun, "Diameter Mobile IPv4 Application", draft-ietf-aaa-diameter-mobileip-09 (work in progress), March 2002. Informative References [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [4] Aboba, B. and M. Beadles, "The Network Access Identifier", RFC 2486, January 1999. [5] Calhoun, P. and C. Perkins, "Mobile IP Network Access Identifier Extension for IPv4", RFC 2794, March 2000. Authors' Addresses Fredrik Johansson ipUnplugged AB Arenavagen 33 Stockholm S-121 28 SWEDEN Phone: +46 8 725 5916 EMail: fredrik@ipunplugged.com Tony Johansson Ericsson Inc 2100 Shattuck Ave. CA 94704 USA Phone: +1 510 541 8783 EMail: tony.johansson@ericsson.com Johansson & Johansson Expires October 18, 2002 [Page 7] Internet-Draft AAA NAI for Mobile IPv4 Extension March 2002 Full Copyright Statement Copyright (C) The Internet Society (2002). All Rights Reserved. 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