Mobile IP Working Group F. Johansson Internet-Draft ipUnplugged Expires: May 31, 2004 T. Johansson Bytemobile December 1, 2003 Mobile IPv4 Extension for carrying Network Access Identifiers 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 May 31, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract When a mobile node moves between two foreign networks it has to be re-authenticated. If for instance the home network has multiple Authentication Authorization and Accounting (AAA) servers the re-authentication request may not be received by the same Home AAA server as previous authentication requests. In order for the new Home AAA server to be able to forward the request to the correct Home Agent it has to know the identity of the Home Agent. This document defines a Mobile IP extension that carries identities in the form of Network Access Identifiers (NAIs), which may be used by an HA to pass its identity to the mobile node which can then pass it on to the new AAA server when changing point of attachment. This extension may also Johansson & Johansson Expires May 31, 2004 [Page 1] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 be used in other situations requiring communication of a NAI between Mobile IP nodes. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements terminology . . . . . . . . . . . . . . . . . . . 3 3. NAI Carrying Extension . . . . . . . . . . . . . . . . . . . . 4 3.1 Processing of the NAI Carrying Extension . . . . . . . . 5 4. HA Identity subtype . . . . . . . . . . . . . . . . . . . . . 5 5. AAAH Identity subtype . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 Normative References . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . 9 Johansson & Johansson Expires May 31, 2004 [Page 2] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 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 result in the new AAAH not knowing which HA the session was assigned to. This document defines a Mobile IP extension which can be used to distribute the information needed to resolve this. Furthermore, the only information that is normally available about the home agent in the registration request is the IP address as defined in RFC 3344 [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 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 have a one-to-one correspondence with the home agent FQDN identity. This is the reason why the HA also includes its own identity in the registration reply. It can then 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 [4]. The Mobile IP related terminology described in RFC 3344 [1] is used in this document. In addition, the following terms are used: AAAH One of possible several AAA Servers in the Home Network FQDN Fully Qualified Domain Name. Identity The identity of a node is equal to its FQDN. NAI Network Access Identifier [2]. Johansson & Johansson Expires May 31, 2004 [Page 3] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 3. NAI Carrying Extension This section defines the NAI Carrying Extension which may be used in Mobile IP Registration Request and Reply messages, and also in Mobile IP Agent Advertisements [1]. The extension may be used by any node that wants to send identity information in the form of a NAI [3]. This document also defines some subtype numbers which identify the specific type of NAI carried, in Section 4 and Section 5. It is expected that other types of NAI will be defined by other documents in the future. Johansson & Johansson Expires May 31, 2004 [Page 4] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 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 particular type NAI which is carried in the NAI field. NAI Contains the NAI [2] in a string format. 3.1 Processing of the NAI Carrying Extension When a mobile node or home agent adds a NAI Carrying Extension to a registration message, the extension MUST appear prior to any authentication extensions. In the event the foreign agent adds a NAI Carrying Extension to a registration message, the extension MUST appear prior to any authentication extensions added by the FA. If an HA has appended a NAI Carrying Extension to a Registration Reply to an MN, and does not receive the NAI extension in subsequent Registration Request messages from the MN, the HA can assume that the MN does not understand this NAI extension. In this case, the HA SHOULD NOT append this NAI extension to further Registration Reply messages to the MN. 4. HA Identity subtype The HA identity uses subtype 1 of the NAI Carrying Extension. It contains the NAI of the HA in the form hostname@realm. Together the hostname and realm forms the complete FQDN (hostname.realm) of the HA. A Home Agent using this extension MUST provide it in the first Registration Reply sent to a Mobile Node which is not currently registered. The extension only need to be included in subsequent Johansson & Johansson Expires May 31, 2004 [Page 5] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 Registration Replies if the same extension is included in Registration Requests received from the same Mobile Node. A mobile node using this extension MUST, if it receives in a registration reply message, provide it in every subsequent registration request when re-authentication is needed. If the mobile node requests a specific home agent and it has the information available it MUST provide this extension in its initial registration request. A foreign agent which receives the Home Agent NAI by this extension in a registration request SHOULD include the Home Agent NAI when requesting Mobile Node authentication through the AAA infrastructure if the AAA protocol used can carry the information. 5. AAAH Identity subtype The AAAH identity uses subtype 2 of the NAI Carrying 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 server. If there exists several AAA servers in the Home Network, a Home Agent providing AAAH selection support according to this document MUST provide the AAAH identity in the first Registration Reply sent to the Mobile Node. The extension only need to be included in subsequent Registration Replies if the same extension is included in Registration Requests received from the same Mobile Node. A mobile node MUST always save the latest AAAH Identity received in a registration reply message and MUST provide the AAAH Identity in every registration request sent when re-authenticating. A foreign agent which receives the AAAH NAI by this extension in a registration request SHOULD include the AAAH NAI provided when requesting Mobile Node authentication through the AAA infrastructure if the AAA protocol used can carry the information. 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. The Mobile IP messages that carry this extension MUST be authenticated as described in [3], unless other authentication methods have been agreed upon. Therefore, this specification does not lessen the security of Mobile IP messages. It should be noted that the identities sent in the extensions Johansson & Johansson Expires May 31, 2004 [Page 6] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 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 This document defines one new mobile IP extension, and one new Mobile IP extension sub-type numbering space to be managed by IANA. Section 3 defines a new Mobile IP extension, the Mobile IP NAI Carrying Extension. The type number for this extension is [TBD, assigned by IANA]. This extension introduces a new sub-type numbering space where the values 1 and 2 has been assigned values in this document. Approval of new Mobile IP NAI Carrying Extension sub-type numbers is subject to Expert Review, and a specification is required [5]. The content and format for this extension is not specific to AAA NAIs, so if in the future new NAIs are defined which does not strictly fall within the category of AAA NAIs, they may nevertheless be accommodated within the subtype numbering space defined for the NAI Carrying Extension defined in this document. The value assigned to the NAI Carrying Extension should be taken 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. Also thanks to Henrik Levkowetz and Kevin Purser for valuable feedback and help when writing this draft. Normative References [1] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, August 2002. [2] Aboba, B. and M. Beadles, "The Network Access Identifier", RFC 2486, January 1999. [3] Calhoun, P. and C. Perkins, "Mobile IP Network Access Identifier Extension for IPv4", RFC 2794, March 2000. [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement Johansson & Johansson Expires May 31, 2004 [Page 7] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 Levels", BCP 14, RFC 2119, March 1997. [5] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Authors' Addresses Fredrik Johansson ipUnplugged AB Arenavagen 23 Stockholm S-121 28 SWEDEN Phone: +46 8 725 5916 EMail: fredrik@ipunplugged.com Tony Johansson Bytemobile Inc 2029 Stierlin Court Mountain View, CA 94043 USA Phone: +1 650 862 0523 EMail: tony.johansson@bytemobile.com Johansson & Johansson Expires May 31, 2004 [Page 8] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Statement Copyright (C) The Internet Society (2003). 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 assignees. 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 Johansson & Johansson Expires May 31, 2004 [Page 9] Internet-Draft MIPv4 Extension for AAA NAIs December 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Johansson & Johansson Expires May 31, 2004 [Page 10]