Diameter Maintenance and J. Bournelle (Ed.) Extensions (DIME) GET/INT Internet-Draft G. Giaretta Expires: December 21, 2006 Telecom Italia H. Tschofenig Siemens June 19, 2006 Mobile IPv6 Bootstrapping using Diameter in the Split Scenario draft-ietf-dime-mip6-split-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 December 21, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract In Mobile IPv6 deployment a need for an interaction between the Home Agent, the AAA infrastructure of the Mobile Service Provider (MSP) and the Mobility Service Authorizer (MSA) has been identified. This document describes how Diameter can be used to perform AAA functionalities for the Mobile IPv6 service in the "split" scenario. Bournelle (Ed.), et al. Expires December 21, 2006 [Page 1] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 For this, it describes two possible approaches. It also explains how Diameter meet the goals outlined in the MIPv6 AAA goals document. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Bootstrapping Mobile IPv6 in the Split Scenario . . . . . . . 3 4. Use of Diameter EAP for the Mobile IPv6 Split Scenario . . . . 5 4.1. NAS-Port-Type AVP . . . . . . . . . . . . . . . . . . . . 6 4.2. A new Application ID . . . . . . . . . . . . . . . . . . . 6 4.3. Accounting for the Mobile IPv6 Service . . . . . . . . . . 6 5. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1. General goals . . . . . . . . . . . . . . . . . . . . . . 7 5.1.1. G1.1 - G1.4 Security . . . . . . . . . . . . . . . . . 7 5.1.2. Dead peer detection - the HA-AAA interface SHOULD support inactive peer detection. . . . . . . . . . . . 7 5.2. Service Authorization . . . . . . . . . . . . . . . . . . 8 5.2.1. G2.1. The HA-AAA interface SHOULD allow the use of Network Access Identifier (NAI) to identify the mobile node. . . . . . . . . . . . . . . . . . . . . . 8 5.2.2. G2.2. The HA SHOULD be able to query the AAAH server to verify Mobile IPv6 service authorization for the mobile node. . . . . . . . . . . . . . . . . . 8 5.2.3. G2.3. The AAAH server SHOULD be able to enforce explicit operational limitations and authorization restrictions on the HA.( e.g. packet filters, QoS parameters). . . . . . . . . . . . . . . . . . . . . . 8 5.2.4. G2.4 - G2.6. Issues addressing the maintenance of a Mobile IPv6 session by the AAAH server, e.g. authorization lifetime, extension of the authorization lifetime and explicit session termination by the AAAH server side. . . . . . . . . . 8 5.3. Accounting - G3.1. The HA-AAA interface MUST support the transfer of accounting records needed for service control and charging . . . . . . . . . . . . . . . . . . . 9 5.4. Mobile Node Authentication (G4.1.) . . . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . . 10 9.2. Informative References . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 13 Bournelle (Ed.), et al. Expires December 21, 2006 [Page 2] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 1. Introduction In Mobile IPv6 deployment, authentication, authorization and accounting issues in the protocol operations are approached by using the AAA infrastructure. [9] presents a number of bootstrapping scenarios using the HA-AAA interface and defines a list of requirements that have to be fulfilled. This document deals with the functional capabilities of the Diameter protocol as a AAA protocol applicable for the split scenario. This document focuses only on the split scenario. A separate document [10] describes a Diameter application for bootstrapping MIPv6 for the integrated scenario. 2. 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 [1]. The MIPv6 bootstrapping terminology is taken from [2]. 3. Bootstrapping Mobile IPv6 in the Split Scenario In the split scenario for bootstrapping Mobile IPv6 [3], the Mobile Node (MN) discovers a Home Agent (belonging to the Mobility Service Provider (MSP)) through DNS. Then, the Mobile Node uses IKEv2 [4] to setup IPsec SAs. Use of IKEv2 also provides a way to authenticate the MN by the Mobility Service Authorizer (MSA). Note that in the same time, the Mobile Node can authenticate the Home Agent. IKEv2 supports the Extensible Authentication Protocol (EAP) to run an EAP method between the MN and the EAP server that is often separated from the IKEv2 responder, i.e., the HA in our scenario. As such, the MN can reuse its credentials (obtained from the MSA) to be authenticated for the IPv6 mobility service. As outlined in [4] a HA-AAA interface is needed. Since, EAP is used to authenticate the MN, the interface between the Home Agent and the AAA server will be based on the Diameter EAP application [5]. Figure 1 represents the architecture of the split scenario. +-------+ IKEv2 +----------------+ Diameter EAP +----+ | Mobile| | Home Agent/ | | | | Node |<----------->| Diameter Client|<-------------------->|AAAH| +-------+ +----------------+ +----+ Figure 1: Diameter EAP for HA-AAA in the Split Scenario Bournelle (Ed.), et al. Expires December 21, 2006 [Page 3] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 The Mobile Node acts as the EAP client and IKEv2 Initiator. The Home agent is the IKEv2 Responder and acts a Diameter client from a AAA perspective. The AAAH is the home AAA server of the MN (i.e. AAA server of the MSA) and relies on a EAP server to authenticate the Mobile Node. If MSP is different from the MSA, the Home Agent may directly contact the AAAH or a local AAA server which will act as a AAA proxy (cf. [5]). Figure 2 shows the message flow. Mobile Node HA/Diameter Client Home AAA/EAP Server ---------- ----------------- ------------------- IKE_SA_INIT (1,2) <------------------------------> HDR, SK{IDi,[CERTREQ,] [IDr,] SAi2, TSi, TSr} (3) -------------------------------> DER (EAP-Response) ------------------------> DEA (EAP-Request) <------------------------ HDR, SK {IDr, [CERT,] AUTH, EAP } <------------------------------- HDR, SK {EAP} --------------------------------> DER (EAP-Response) ------------------------> DEA (EAP-Request) <------------------------ HDR, SK{EAP-Request} <------------------------------- HDR, SK{EAP-Response} --------------------------------> DER (EAP-Response) ------------------------> ... ... DEA (EAP-Success) <------------------------ HDR, SK{EAP-Success} <------------------------------- HDR, SK{AUTH} -------------------------------> HDR, SK {AUTH, SAr2, TSi, TSr } <------------------------------- Bournelle (Ed.), et al. Expires December 21, 2006 [Page 4] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 Figure 2: IKEv2 Diameter EAP Message Flow The interaction between the MN and the HA starts with an IKE_SA_INIT to setup the IKE SA. The MN indicates its desire to use EAP by not including the AUTH payload in the third message. The MN indicates its identity (e.g Network Access Identitifer) using the IDi field. If the Home Agent, acting as an IKEv2 Responder, supports EAP for authentication and relies on a remote AAA server, the Diameter client part of the Home Agent sends a Diameter-EAP-Request (DER) message containing the identity in the EAP-Payload AVP and in the User-Name AVP. The AAAH chooses an authentication method and sends the first EAP-Request in the Diameter-EAP-Answer message. During the EAP authentication phase, the HA relays EAP packets between the MN (EAP client) and the AAAH (Home EAP server). If the authentication succeeds and if the MN is authorized to use Mobile IPv6 service, the AAAH sends a DEA message containing the EAP-success and the AAA-Key derived from the Master Session Key (MSK) exported by the EAP method. Some specific configuration elements may also be sent in AVPs. Note that EAP methods that do not derive keys are not recommended since they cannot bind the EAP method authentication to the IKEv2 authentication. In the latter message, the MN and the HA finalize the IPsec SAs setup to protect Mobile IPv6 signalling. 4. Use of Diameter EAP for the Mobile IPv6 Split Scenario In the split scenario, the Home Agent uses the AAA infrastructure in order to perform authentication, authorization and accounting for the Mobile IPv6 service. This document proposes to reuse the Diameter EAP application [5] since EAP is used by the HA to authenticate the MN inside IKEv2. However, the Diameter EAP application has been designed to perform AAA for the network access service. As the Mobile IPv6 service is different from the network access service, it appears that a Diameter server needs a way to make this distinction. Indeed, even if the authentication is provided by the EAP method, authorization and accounting for network access and IPv6 mobility might be different. The AAA server needs to explicitly authorize the Mobile IPv6 service. It may also need to configure specific parameters for the Mobile IPv6 service such as the type of Home Address to provide to the MN. Accounting may also require other parameters than those defined for network access. [Editor's Note: It is not clear at this point of time which approach is the best to handle this. For this reason, this document explains two possible approaches.] Bournelle (Ed.), et al. Expires December 21, 2006 [Page 5] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 4.1. NAS-Port-Type AVP As explained below, the AAA server needs a way to identify that it is performing AAA operations for the Mobile IPv6 service. One way to do this is to require that the Home Agent puts the NAS-Port-Type AVP indicating that it is a Mobile IPv6 Home Agent in the first DER message. This would be formulated as: "The Home Agent MUST include the NAS-Port-Type AVP". This requires a change in the current ABNF definition of this message. The AAA server would have to check the presence of this AVP in the first received DER message and would have to recognize the new type defined for the Home Agent. [Editor's Note: It is not clear at this point of time if this change in the ABNF definition would require a new Application-Id.] Moreover, the NAS-Port-Type AVP is defined as: "The NAS-Port-Type AVP (AVP Code 61) is of type Enumerated and contains the type of the port on which the NAS is authenticating the user. This AVP SHOULD be present if the NAS uses the same NAS-Port number ranges for different service types concurrently" (see [6]). Hence, if the DIME WG decides to use this approach, it is necessary to define a new type for Home- Agent. If an operator wants to use one AAA server for network access and another one for IPv6 mobility service then the some messages may be routed to the wrong AAA server since routing is also based on the Application-ID. 4.2. A new Application ID The second approach is to require a new application ID for the Mobile IPv6 service. In this case, all messages will be correctly routed to the right Diameter Application. This specific application will specifically handle all AAA Operations for the Mobile IPv6 service as it is done for Mobile IPv4 (cf. [7]). However, the protocol description requires that the new application needs to copy the Diameter messages from the Diameter EAP application. The problem with defining a new Application ID is that every proxies on the path would need a new code to understand this application. 4.3. Accounting for the Mobile IPv6 Service Concerning Accounting, the Diameter Mobile IPv4 Application [7] defines the following AVPs: Accounting-Input-Octets (Number of octets in IP packets received from the user), Accounting-Output-Octets (Number of octets in IP packets sent by the user, Accounting-Input- Packets (Number of IP packets received from the user), Accounting- Bournelle (Ed.), et al. Expires December 21, 2006 [Page 6] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 Output-Packets (Number of IP packets sent by the user). These AVPs may be re-used for the Mobile IPv6 service. However, due to some optimizations for Mobile IPv6, the HA may not see all the IP traffic resulting from the activation of this service. [Editor's Note: As the document describing goals for this interface is not finalized, other parameters may be needed in the future.] 5. Goals In this section, we present how the goals for a HA-AAA interface presented in [9] are met by this proposal. Note that the two approaches presented above does not affect what is described here. [Editor's Note: the goals presented here are those described in [9]. Future revision of the mentionned document will affect this section.] 5.1. General goals 5.1.1. G1.1 - G1.4 Security As design goals for an AAA interface, G1.1 - G1.4 goals specify standard requirements for a AAA protocol - mutual authentication of the peers, integrity, replay protection and confidentiality. The Diameter Base Protocol requires IPsec or TLS to provide hop-by-hop security. 5.1.2. Dead peer detection - the HA-AAA interface SHOULD support inactive peer detection. Two possible approaches might be considered here: o The AAAH server and the Home Agent establish a transport connection between each other. It is the case if the Diameter Client of the HA has a direct route to its AAA server. In this case Diameter heartbeat messages called Device-Watchdog-Request/ Answer [8], which are exchanged over this connection to test for its aliveness, can be used to detect inactivity between the two Diameter peers. o The AAAH server and the Home Agent do not have transport connection. In this case inactive peer detection functionality should be provided into the Diameter session - service stateless Diameter sessions might be established between the AAAH server and the range of MSP's Home Agents for detecting HAs availability. Bournelle (Ed.), et al. Expires December 21, 2006 [Page 7] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 5.2. Service Authorization 5.2.1. G2.1. The HA-AAA interface SHOULD allow the use of Network Access Identifier (NAI) to identify the mobile node. Identification by the User-Name AVP [8], which has a format consistent with the NAI specifications, is common for Diameter applications. Diameter provides functionality for routing of Diameter requests based on the information included in the User-Name AVP. The Mobile Node provides its NAI using the IDi field during the IKEv2 exchange with the HA. 5.2.2. G2.2. The HA SHOULD be able to query the AAAH server to verify Mobile IPv6 service authorization for the mobile node. The goal of this document is to explain how to use Diameter to perform AAA operations for the Mobile IPv6 service. The Authentication is done through the use of EAP. The Mobile IPv6 service Authorization is an explicit goal of this document. [Editor's note: As explained above, how the AAA server know that it is for Mobile IPv6 service has not yet been decided by the DIME WG.] 5.2.3. G2.3. The AAAH server SHOULD be able to enforce explicit operational limitations and authorization restrictions on the HA.( e.g. packet filters, QoS parameters). Several present Diameter applications, standardized or under work-in- progress address an operation and authorization control for specific services and have defined appropriate AVPs. The NAS-Filter-Rule AVP, defined by Diameter NASREQ application [6], provides IP packet filter description. QoS-Filter-Rule AVP defined by Diameter NASREQ application and by the Diameter QoS application [11] provide QoS parameter description. The Credit Control application [12] provides support for prepaid services, tariff switching, cost control over requested services. The available funcationalities might be re-used in this document. 5.2.4. G2.4 - G2.6. Issues addressing the maintenance of a Mobile IPv6 session by the AAAH server, e.g. authorization lifetime, extension of the authorization lifetime and explicit session termination by the AAAH server side. Diameter base protocol provides a powerful set of commands and AVPs for management of the authorization and accounting sessions. A number of AVPs (Auth-Lifetime-AVP, Grace-Period-AVP, Session-Timeout- Bournelle (Ed.), et al. Expires December 21, 2006 [Page 8] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 AVP) handle the duration (in time) of an authorization session [8]. Additional AVPs for measuring the authorization duration in units different that time are specified too [12]. Exchanging of application specific authorization request/answer messages provides extension of the authorization session. Initiation of the re- authorization by both sides could be supported. Both sides could initiate session termination, by using Diameter Session Termination and Abort Session messages. All these are applied to the Diameter session used for authorization of a Mobile IPv6 session and need to be applied appropriately to this Mobile IPv6 session too. 5.3. Accounting - G3.1. The HA-AAA interface MUST support the transfer of accounting records needed for service control and charging Diameter accounting protocol provides a variety of options - real- time accounting, event/session-type accounting records, fault resilience, correlation of accounting records. Requirements for the accounting services over AAAH-HA interface are standard. Definition or re-used of AVPs for the specific accounting records combined with the functionality of the Diameter accounting protocol should provide desired accounting services. 5.4. Mobile Node Authentication (G4.1.) These issues require the functionality of AAAH server working as a back-end authentication server and HA working as NAS and EAP authenticator in pass-through mode for providing a mobile node authentication. This functionality is provided by the Diameter NASREQ [6] and the Diameter EAP applications [5] application, and will be re-used in this document. 6. Security Considerations [Editor's Note: Since the document is not complete it is necessary to state that the security consideration section is incomplete as well. Hence, it is only possible to refer to the security issues raised in the Mobile IPv6 and Diameter protocol related documents mentioned here, such as [9] and [8].] 7. IANA Considerations [Editor's note: Since the document is not complete, the IANA considerations is incomplete as well.] Bournelle (Ed.), et al. Expires December 21, 2006 [Page 9] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 8. Acknowledgements The authors would like to thanks Jari Arkko, Tolga Asversen, Pasi Eronen, Santiago Zapata Hernandez, Jouni Korhonen, Anders Kristensen, Avi Lior, John Loughney, Lionel Morand and Yoshihiro Ohba for their inputs to the "Application-ID for the Mobile IPv6 split scenario ?" discussion. 9. References 9.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Giaretta, G. and A. Patel, "Problem Statement for bootstrapping Mobile IPv6", draft-ietf-mip6-bootstrap-ps-05 (work in progress), May 2006. [3] Giaretta, G., "Mobile IPv6 bootstrapping in split scenario", draft-ietf-mip6-bootstrapping-split-02 (work in progress), March 2006. [4] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306, December 2005. [5] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible Authentication Protocol (EAP) Application", RFC 4072, August 2005. [6] Calhoun, P., Zorn, G., Spence, D., and D. Mitton, "Diameter Network Access Server Application", RFC 4005, August 2005. [7] Calhoun, P., Johansson, T., Perkins, C., Hiller, T., and P. McCann, "Diameter Mobile IPv4 Application", RFC 4004, August 2005. [8] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, "Diameter Base Protocol", RFC 3588, September 2003. 9.2. Informative References [9] Giaretta, G., "Goals for AAA-HA interface", draft-ietf-mip6-aaa-ha-goals-01 (work in progress), January 2006. [10] Tschofenig, H., "Diameter MIPv6 Application for the Integrated Bournelle (Ed.), et al. Expires December 21, 2006 [Page 10] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 Scenario", draft-tschofenig-dime-mip6-integrated-00 (work in progress), March 2006. [11] Alfano, F., "Diameter Quality of Service Application", draft-tschofenig-dime-diameter-qos-00 (work in progress), March 2006. [12] Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J. Loughney, "Diameter Credit-Control Application", RFC 4006, August 2005. [13] Chowdhury, K. and A. Yegin, "MIP6-bootstrapping via DHCPv6 for the Integrated Scenario", draft-ietf-mip6-bootstrapping-integrated-dhc-01 (work in progress), June 2006. Bournelle (Ed.), et al. Expires December 21, 2006 [Page 11] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 Authors' Addresses Julien Bournelle GET/INT 9 rue Charles Fourier Evry 91011 France Email: julien.bournelle@int-evry.fr Gerardo Giaretta Telecom Italia Lab via G. Reiss Romoli, 274 TORINO, 10148 Italy Email: gerardo.giaretta@telecomitalia.it Hannes Tschofenig Siemens Otto-Hahn-Ring 6 Munich, Bavaria 81739 Germany Email: Hannes.Tschofenig@siemens.com URI: http://www.tschofenig.com Bournelle (Ed.), et al. Expires December 21, 2006 [Page 12] Internet-Draft MIP6 Bootstrapping with Diameter June 2006 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. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Bournelle (Ed.), et al. Expires December 21, 2006 [Page 13]