Network Working Group K. Chowdhury Internet-Draft Nortel Networks Expires: January 10, 2005 A. Lior Bridgewater Systems July 12, 2004 RADIUS Attributes for Mobile IPv6 bootstrapping draft-chowdhury-mip6-bootstrap-radius-00.txt Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. 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 January 10, 2005. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document defines new attributes to facilitate Mobile IPv6 bootstrapping via a RADIUS infrastructure. In an access network where the user attaches to get IPv6 access, there may be a Network Access Server (NAS) or an Access Gateway that will require authentication and authorization. In some cases, this type of access authentication takes place via RADIUS infrastructure. As part of the authentication setup the NAS may receive useful configuration information from the home RADIUS server of the user. In case of Chowdhury & Lior Expires January 10, 2005 [Page 1] Internet-Draft July 2004 Mobile IPv6 access, the Home RADIUS server may assign various information relevant to the user's device for bootstrapping. Table of Contents 1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Home Agent or a List of Home Agents . . . . . . . . . . . 4 2.2 Home Link Prefix or a list of Home Link prefixes . . . . . 5 2.3 Home Address . . . . . . . . . . . . . . . . . . . . . . . 5 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. RADIUS attributes to carry Mobile IPv6 parameters . . . . . . 7 4.1 Home Agent Attribute . . . . . . . . . . . . . . . . . . . 7 4.2 Home Link Prefix Attribute . . . . . . . . . . . . . . . . 7 4.3 Home Address . . . . . . . . . . . . . . . . . . . . . . . 8 5. Table of Attributes . . . . . . . . . . . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 9. Normative References . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . 14 Chowdhury & Lior Expires January 10, 2005 [Page 2] Internet-Draft July 2004 1. Motivation Mobile IPv6 specification [RFC3775] requires a Mobile Node (MN) to perform registration with a Home Agent with information about its current point of attachment (Care-of Address). The Home Agent creates and maintains binding between the MN's Home Address and the MN's Care-of Address. In order to register with a Home Agent, the MN needs to know information such as, the Home Link prefix, the Home Agent Address, the Home Address, the Home Link prefix Length etc. Moreover during normal operation of the Mobile IPv6 session, the MN needs to know the lifetime of the Home Address. The aforementioned set of information may be statically provisioned in the MN. However, static provisioning of this information has its drawbacks. It increases provisioning and network maintenance burden for the operator. Moreover, static provisioning does not allow load balancing, failover, opportunistic home link assignment etc. For example, the user may be accessing the network from a location that may be geographically far away from the preconfigured home link; or the cost of the link between the NAS and the Home Link is too great. In these situations static provisioning may not be desirable. Dynamic assignment of Mobile IPv6 home registration information is a desirable feature for ease of deployment and network maintenance. For this purpose, the Home RADIUS server, which is used for access authentication, can be leveraged to assign some or all of the necessary parameters. The Home RADIUS server may return these parameters to the NAS. The NAS may convey the received information to the MN using various techniques. One such technique may utilize the role of the NAS as a relay agent for Dynamic Host Configuration Protocol. In this case, upon receiving the information from the Home RADIUS server, the NAS forwards the set of parameters to the DHCP server. The DHCP server attaches the information in new DHCP options while responding to an information-request from the MN. The part where the NAS acts as a DHCP relay agent and forwards the received information to the DHCP server is outside the scope of this document. Chowdhury & Lior Expires January 10, 2005 [Page 3] Internet-Draft July 2004 2. Overview | Visited Network | Home Network | +-------+ | +-------+ | | | | | |Visited|----------|--------| Home | |RADIUS | | |RADIUS | | | | | | +-------+ | +-------+ | | | | | +------+ | | +---| DHCP | | | | |Server| | | | +------+ | | | | +-----+ | +-----+ +----+ | | | | Home| | MN |--------------| NAS/| | |Agent| +----+ |Relay| | | | +-----+ | +-----+ In the typical Mobile IPv6 access scenario as shown above, the MN attaches in a visited network. During this attach procedure, the NAS authenticates and authorizes the MN for IPv6 access service. In the scenario shown, the authentication and authorization happens via RADIUS infrastructure. At the time of authorizing the user for IPv6 access, the Home RADIUS server detects that the user is authorized for Mobile IPv6 access. Based on Home network policy, the Home RADIUS server may allocate several parameters to the MN for use during the subsequent Mobile IPv6 Binding Update. A list of such parameters is described in the following sub sections. 2.1 Home Agent or a List of Home Agents The Home network provider may decide to assign a Home Agent to the MN that is in close proximity to the point of attachment (e.g. determined by the NAS-ID). There may be other reasons for assigning Home Agents to the MN, e.g. load sharing in the network. The Home network may also assign a list of Home Agents for the MN to choose from. Chowdhury & Lior Expires January 10, 2005 [Page 4] Internet-Draft July 2004 2.2 Home Link Prefix or a list of Home Link prefixes For the same reason as HA assignment, the Home network may assign a Home Link that is in close proximity to the point of attachment (NAS-ID). The Home RADIUS server may also assign a list of Home Link prefixes to the MN and allow the MN to choose one. The MN can perform [RFC3775] specific procedures to discover other information for Mobile IPv6 registration. The length of the assigned prefix(es) can be included as well. 2.3 Home Address The Home RADIUS server may assign a Home Address to the MN. This allows the network operator to support mobile devices that are not configured with static addresses. The lifetime of the Home Address can be indicated along with the address. Chowdhury & Lior Expires January 10, 2005 [Page 5] Internet-Draft July 2004 3. Terminology The keywords "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. Chowdhury & Lior Expires January 10, 2005 [Page 6] Internet-Draft July 2004 4. RADIUS attributes to carry Mobile IPv6 parameters This section defines format and syntax for the attribute that carries the Mobile IPv6 parameters described in section 2. The attributes MAY be present in Access-Accept, Accounting-Request. 4.1 Home Agent Attribute This attribute is sent by the RADIUS server to the NAS in an Access-Accept message. The attribute carries one or more assigned Home Agent addresses to the NAS. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address of assigned HA-1 | | ... | | IPv6 address of assigned HA-n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: ASSIGNED-HA-TYPE to be defined by IANA. Length: >= 20 octets Reserved: Reserved for future use. All bits set to 0. IPv6 address of assigned HA-1 to HA-n: 128-bit IPv6 address of one or more assigned Home Agents. The addresses appear in the order of preference. 4.2 Home Link Prefix Attribute This attribute is sent by the RADIUS server to the NAS in an Access-Accept message. The attribute carries the assigned Home Link prefix or a list of assigned Home Link Prefixes. to the NAS. Chowdhury & Lior Expires January 10, 2005 [Page 7] Internet-Draft July 2004 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 | HL Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address of assigned HL-1 | | ... | | IPv6 address of assigned HL-n ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: ASSIGNED-HL-TYPE to be defined by IANA. Length: >= 4 octets + the minimum length of a prefix. HL Length: 8-bit unsigned integer, representing the length in octets of the Home Link Prefix(es). Reserved: Reserved for future use. All bits set to 0. IPv6 address of assigned HL-1 to HL-n: Home Link prefixes (upper order bits) of the assigned Home Links where the MN should send binding update. The Home Link prefixes appear in the order of preference. 4.3 Home Address This attribute is sent by the RADIUS server to the NAS in an Access-Accept message. The attribute carries the assigned Home IPv6 Address for the MN. 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 | Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | Chowdhury & Lior Expires January 10, 2005 [Page 8] Internet-Draft July 2004 | | | Assigned IPv6 Home Address | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: ASSIGNED-HOA-TYPE to be defined by IANA. Length: >= 20 octets. Lifetime: 16-bit unsigned integer. The number of time units remaining before the IPv6 Home Address MUST be considered expired. A value of zero indicates that the IPv6 Home Address has expired. One time unit is 4 seconds. Assigned IPv6 Home Address: IPv6 Home Address that is assigned to the MN. Chowdhury & Lior Expires January 10, 2005 [Page 9] Internet-Draft July 2004 5. Table of Attributes The following table provides a guide to which attributes may be found in RADIUS message and in what number. Request Accept Reject Challenge # Attribute 0 0-1 0 0 TBD Home Agent 0 0-1 0 0 TBD Home Link Prefix 0 0-1 0 0 TBD Home Address The following table defines the meaning of the above table entries. 0 This attribute MUST NOT be present. 0-1 Zero or one instance of this attribute MAY be present. Chowdhury & Lior Expires January 10, 2005 [Page 10] Internet-Draft July 2004 6. Security Considerations Assignment of these values to a user should be based on successful authentication of the user's access at the NAS. The Home RADIUS server should only assign these values to an user who is authorized for Mobile IPv6 service (this check could be performed with user's subscription profile in the Home Network). The NAS to the Home RADIUS server transactions must be adequately secured. Otherwise there is a possibility that the user may receive fraudulent values from a rogue RADIUS server potentially hijacking the user's Mobile IPv6 session. These new attributes do not introduce additional security threats besides the one identified in [RFC2865]. Chowdhury & Lior Expires January 10, 2005 [Page 11] Internet-Draft July 2004 7. IANA Considerations The RADIUS attribute types: ASSIGNED-HA-TYPE, ASSIGNED-HL-TYPE, ASSIGNED-HOA-TYPE Must be assigned by IANA. Chowdhury & Lior Expires January 10, 2005 [Page 12] Internet-Draft July 2004 8. Acknowledgements Thanks to the following individuals for their review and constructive comments during the development of this document: Mark Watson, Jayshree Bharatia. 9 Normative References [RFC2865] Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000. [RFC3775] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. Authors' Addresses Kuntal Chowdhury Nortel Networks 2221 Lakeside Blvd. Richardson, TX 75082 US Phone: +1 972-685-7788 EMail: chowdury@nortelnetworks.com Avi Lior Bridgewater Systems 303 Terry Fox Drive, Suite 100 Ottawa, Ontario Canada K2K 3J1 Phone: +1 613-591-6655 EMail: avi@bridgewatersystems.com Chowdhury & Lior Expires January 10, 2005 [Page 13] Internet-Draft July 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat 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 implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Chowdhury & Lior Expires January 10, 2005 [Page 14]