MIP6 Working Group G. Giaretta Internet Draft I. Guardini Expires: July 2006 E. Demaria TILab J. Bournelle GET/INT R. Lopez Univ. of Murcia January 2006 Goals for AAA-HA interface draft-ietf-mip6-aaa-ha-goals-01.txt 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 July 27, 2006. Copyright Notice Copyright (C) The Internet Society (2006). All Rights Reserved. Abstract In commercial deployments Mobile IPv6 can be a service offered by a Mobility Services Provider (MSP). In this case all protocol operations may need to be explicitly authorized and traced, requiring the interaction between Mobile IPv6 and the AAA infrastructure. Integrating the AAA infrastructure offers also a solution component for Mobile IPv6 bootstrapping in integrated and split scenarios. Internet-Draft AAA-HA interface goals January 2006 This document describes various scenarios where a AAA interface for Mobile IPv6 is actually required. Additionally, it lists design goals and requirements for such an interface. Conventions used in this document 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]. Table of Contents 1. Introduction................................................3 2. Motivation..................................................4 3. Bootstrapping scenarios.....................................5 3.1 Split Scenario...........................................5 3.2 Integrated Scenario......................................6 4. Goals for the AAA-HA interface..............................7 4.1 General goals............................................7 4.2 Service Authorization....................................7 4.3 Accounting...............................................8 4.4 Mobile Node Authentication...............................8 4.5 Provisioning of configuration parameters.................8 5. IANA Considerations.........................................9 6. Security Considerations....................................10 7. Acknowledgment.............................................11 8. References.................................................12 8.1 Normative References....................................12 8.2 Informative References..................................12 Authors’ Addresses..............................................13 Giaretta, et al. Expires - July 2006 [Page 2] Internet-Draft AAA-HA interface goals January 2006 1. Introduction Mobile IPv6 [2] was originally designed as a protocol without any integration with the AAA infrastructure of the Mobility Service Provider (MSP) that offers mobility service. Nonetheless, in some environments it might be desirable to authenticate the user based on existing credentials stored in the AAA infrastructure, to authorize protocol operations and to enable accounting. Due to this requirement, Mobile IPv6 might require the interaction with the AAA infrastructure. Integrating the AAA infrastructure offers also a solution component for Mobile IPv6 bootstrapping [3] in split [4] and integrated [5] scenarios. This document describes various scenarios where a AAA interface is required. Additionally, it lists design goals and requirements for such an interface. This document only describes requirements, goals and scenarios. It does not provide solutions. Notice that this document builds on the security model of the AAA infrastructure. As such, the end host shares credentials with the home AAA server and the communication between the AAA server and the AAA client can be protected. If the AAA server and the AAA client are not part of the same administrative domain, then some sort of contractual relationship between the involved administrative domains is typically in place in form of roaming agreements. Giaretta, et al. Expires - July 2006 [Page 3] Internet-Draft AAA-HA interface goals January 2006 2. Motivation Mobile IPv6 specification [2] requires that Mobile Nodes (MNs) are provisioned with a set of configuration parameters, namely the Home Address and the Home Agent Address, in order to accomplish a home registration. Moreover MNs and Home Agents (HAs) must share the cryptographic material needed to protect Mobile IPv6 signaling (e.g. shared keys or certificates to setup IPsec security associations). One approach is to statically provision the necessary configuration parameters at MNs and HAs. This solution is sub-optimal from a deployment perspective, especially in large networks with a lot of users (e.g., a mobile operator network). For this reason the Mobile IPv6 bootstrapping problem was investigated [3]. Based on the analysed scenarios (i.e. integrated and split), two solutions were developed. The solution for the split scenario is described in [4] and the one for the integrated scenario can be found at [5]. A key point behind these mechanisms is that, whenever static provisioning is not feasible, the AAA infrastructure of the MSP can be used as the central element to enable dynamic Mobile IPv6 bootstrapping. In this case the AAA infrastructure can be exploited to offload the end host's authentication to the AAA server as well as to deliver the necessary configuration parameters to the HA. Moreover, in case Mobile IPv6 is a service offered by a Mobility Service Provider (MSP), all protocol operations (e.g. home registrations) may need to be explicitly authorized and monitored (e.g. for accounting purposes). This can be accomplished relying on the AAA infrastructure of the MSP, that stores users' service profiles and credentials. The deployment of this service model requires the availability of an interface between the AAA infrastructure and the HA, that can be seen as the Network Access Server (NAS) for Mobile IPv6. The core capabilities that should be supported by this interface include Mobile IPv6 service authorization and maintenance (e.g. asynchronous service termination) as well as the exchange of accounting data. This basic set of features is needed in any Mobile IPv6 bootstrapping scenario. There is therefore space for the definition of a general AAA-HA communication interface capable to support the basic features described above (e.g. authorization and accounting) as well as the extended capabilities (e.g. transfer of configuration data) needed to enable various dynamic Mobile IPv6 bootstrapping scenarios. Giaretta, et al. Expires - July 2006 [Page 4] Internet-Draft AAA-HA interface goals January 2006 3. Bootstrapping scenarios This section describes some bootstrapping scenarios in which a communication between the AAA infrastructure of the Mobility Service Provider and the Home Agent is needed. 3.1 Split Scenario In the split scenario [4], there is the assumption that the mobility service and network access service are separate. This implies that the mobility service can be authorized by a different entity deploying its own AAA infrastructure. The entity offering the mobility service is called Mobility Service Provider (MSP) while the entity authorizing the service is the Mobility Service Authorizer (MSA). In this scenario, the Mobile Node discovers the Home Agent Address using the Domain Name Service (DNS). It queries the address based on the Home Agent name or by service name. In the former case, the Mobile Node is configured with the Fully Qualified Domain Name (FDQN) of the Home Agent. In the latter case, the document [4] defines a new service resource record (SRV RR). Then the Mobile Node performs an IKEv2 [6] exchange with the HA to setup IPsec SAs (to protect Mobile IPv6 signaling) and to configure its Home Address (HoA). The IKEv2 Mobile Node to Home Agent authentication can be done using either public key signatures or the Extensible Authentication Protocol (EAP). If EAP is used for authentication, the operator can choose any available EAP authentication methods. Note that even if EAP is used, the MN authenticates the HA using public key signature based authentication. The HA may rely on a remote EAP server. In this case, a AAA protocol such as RADIUS EAP [7] or Diameter EAP Error! Reference source not found. must be used between the HA and the home EAP server. This allows a pool of HAs to rely on the same EAP server to authenticate Mobile Nodes. It also allows the roaming mobility case in which the Mobile Node obtains the mobility service in a different administrative domain (MSP != MSA). The Mobile Node may also want to update its FQDN in the DNS with the newly allocated Home Address. The document [4] recommends that the HA performs the DNS entry update on behalf of the Mobile Node. For that purpose, the Mobile Node indicates its FDQN in the IKEv2 exchange (IDii field in IKE_AUTH) and adds a DNS Update Option in the Binding Update message sent to the HA. When the Mobile Node uses a Home Agent belonging to a different administrative domain (MSP != MSA), the local HA may not share a security association with the home DNS server. In this case, the Giaretta, et al. Expires - July 2006 [Page 5] Internet-Draft AAA-HA interface goals January 2006 document [4] suggests the home AAA server to be responsible of the update. Thus the HA should send to the home AAA server the FDQN-HoA pair through the AAA protocol. Note that the AAA exchange between the HA and the AAA infrastructure is normally terminated before the HA receives the Binding Update message. The reason is that the authentication has succeeded if the Mobile Node is able to send the BU. 3.2 Integrated Scenario In the integrated scenario [5], the assumption is which the mobile user's mobility service is authorized by the same authorizer than network access service. Basically Mobility Service Authorizer (MSA) and the Access Service Authorizer (ASA) are the same entity. The scenario considers two cases: 1. Mobile Node requests a home agent to its home domain (ASA/MSA) 2. Mobile Node requests a home agent to the Access Service Provider (ASP) In the first case, Home Agent is allocated by user's home domain. In the second case it is allocated by user's visited domain. In both cases, it is assumed that the AAA server in the home domain (AAAH) authorizes both network access service and mobility service. In this scenario, Mobile Node discovers the Home Agent Address using DHCPv6. During network access service authentication and authorization, AAAH also verifies if authenticating user is authorized to use mobility service. In affirmative case, AAAH sends to the Network Access Server (NAS) where the Mobile Node is attached, the information about the assigned home agent. Then NAS stores that information. To request home agent data, Mobile Node sends a DHCPv6 Information Request to the All_DHCP_Relay_Agents_and_Servers multicast address. With this request, Mobile Node can specify if it wants a home agent provided by the visited domain (ASP) or by the home domain (ASA). In both cases, the NAS acts a DHCPv6 relay. When the NAS receives DHCPv6 Information Request then it attaches home agent information received from AAAH in a new DHC Relay Agent Option defined in [5]. In case Mobile Node cannot acquire home agent information via DHCPv6, it can try the default mechanism based on DNS described in [4]. After the Mobile Node has acquired home agent information, the mechanism used to bootstrap the HoA, IPsec Security Association, and Authentication and Authorization with the MSA is the same described in the bootstrapping solution for split scenario [4]. Giaretta, et al. Expires - July 2006 [Page 6] Internet-Draft AAA-HA interface goals January 2006 4. Goals for the AAA-HA interface The motivations and scenarios illustrated in previous sections raise the need to define an interface between the AAAH server and the HA. The following sections list a set of goals for this interface. 4.1 General goals G1.1 The AAAH server and the HA MUST be able to authenticate each other (mutual authentication) in order to prevent the installation of unauthorized state on the HA. G1.2 The AAA-HA interface MUST provide integrity protection in order to prevent any alteration of exchanged data (e.g. Mobile IPv6 configuration parameters). G1.3 The AAA-HA interface MUST provide replay protection. G1.4 The AAA-HA interface SHOULD provide confidentiality since it may be used to transfer keying material (e.g. shared key generated during EAP authentication). G1.5 The AAA-HA interface should support inactive peer detection. This functionality can be used by the AAAH server to maintain a list of active HAs (e.g. useful for HA selection). 4.2 Service Authorization G2.1 The AAA-HA interface SHOULD allow the use of Network Access Identifier (NAI) to identify the mobile node. G2.2 The HA SHOULD be able to query the AAAH server to verify Mobile IPv6 service authorization for the mobile node. G2.3 The AAAH server MAY enforce explicit operational limitations and authorization restrictions on the HA (e.g. packet filters, QoS parameters). G2.4 The AAAH server MUST be able to send an authorization lifetime to the HA to limit Mobile IPv6 session duration for the MN. G2.5 The HA MUST be able to request to the AAAH server an extension of the authorization lifetime granted to the MN. G2.6 The AAAH server MUST be able to force the HA to terminate an active Mobile IPv6 session for authorization policy reasons (e.g. credit exhaustion). Giaretta, et al. Expires - July 2006 [Page 7] Internet-Draft AAA-HA interface goals January 2006 4.3 Accounting G3.1 The AAA-HA interface must support the transfer of accounting records needed for service control and charging. These include (but may not be limited to): time of binding cache entry creation and deletion, octets sent and received by the mobile node in Bi-directional Tunneling, etc. 4.4 Mobile Node Authentication G4.1 The AAA-HA interface MUST support pass-through EAP authentication with the HA working as EAP authenticator operating in pass-through mode and the AAAH server working as back-end authentication server. 4.5 Provisioning of configuration parameters G5.1 The HA should be able to communicate to the AAAH server the Home Address allocated to the MN (e.g. for allowing the AAAH server to perform DNS update on behalf of the MN). Giaretta, et al. Expires - July 2006 [Page 8] Internet-Draft AAA-HA interface goals January 2006 5. IANA Considerations No new message formats or services are defined in this document. Giaretta, et al. Expires - July 2006 [Page 9] Internet-Draft AAA-HA interface goals January 2006 6. Security Considerations As stated in section 4.1 the AAA-HA interface must provide mutual authentication, integrity and replay protection. Furthermore, if security parameters (e.g. IKE pre-shared key) are transferred through this interface, confidentiality is a feature that is strongly recommended to be supported. However note that some suitable interfaces may not provide end-to-end confidentiality between AAA and HA (e.g. AAA protocols). Giaretta, et al. Expires - July 2006 [Page 10] Internet-Draft AAA-HA interface goals January 2006 7. Acknowledgments The authors would like to thank James Kempf, Alper Yegin, Vijay Devarapalli, Basavaraj Patil, Gopal Dommety for their comments and feedback. Moreover the authors would like to thank Hannes Tschofenig for his deep technical and editorial review of the draft. Giaretta, et al. Expires - July 2006 [Page 11] Internet-Draft AAA-HA interface goals January 2006 8. References 8.1 Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. 8.2 Informative References [3] Patel, A. et al. "Problem Statement for bootstrapping Mobile IPv6", draft-ietf-mip6-bootstrap-ps-02 (work in progress), March 2005. [4] Giaretta, G., Kempf, J. and Devarapalli, V., "Mobile IPv6 bootstrapping in split scenario", draft-ietf-mip6-bootstrapping- split-01 (work in progress), October 2005. [5] Chowdhury, K. and Yegin, A., "MIP6-bootstrapping via DHCPv6 for the Integrated Scenario", draft-ietf-mip6-bootstrapping-integrated-dhc- 00 (work in progress), October 2005. [6] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", draft-ietf- ipsec-ikev2-17 (work in progress), September 2004. [7] Aboba, B. and Calhoun, P., "RADIUS (Remote Authentication Dial In User Service) Support For Extensible Authentication Protocol (EAP)", RFC 3579, September 2003. [8] Eronen, P., Hiller, T. and Zorn, G., "Diameter Extensible Authentication Protocol (EAP) Application", RFC 4072, August 2005. [9] Chowdhury, K. and Lior, A., "RADIUS Attributes for Mobile IPv6 bootstrapping", draft-chowdhury-mip6-bootstrap-radius-01 (work in progress), October 2004. [10] Jang, H. J. and Yegin, A., "DHCP Option for Home Agent Discovery in MIPv6", draft-jang-dhc-haopt-01 (work in progress), April 2005. [11] Giaretta, G., Guardini, I., Demaria, E., Bournelle, J., Laurent- Maknavicius, M., "MIPv6 Authorization and Configuration based on EAP", draft-giaretta-mip6-authorization-eap-02 (work in progress), September 2004. Giaretta, et al. Expires - July 2006 [Page 12] Internet-Draft AAA-HA interface goals January 2006 Authors’ Addresses Gerardo Giaretta Telecom Italia Lab via G. Reiss Romoli, 274 10148 TORINO Italy Phone: +39 011 2286904 Email: gerardo.giaretta@tilab.com Ivano Guardini Telecom Italia Lab via G. Reiss Romoli, 274 10148 TORINO Italy Phone: +39 011 2285424 Email: ivano.guardini@tilab.com Elena Demaria Telecom Italia Lab via G. Reiss Romoli, 274 10148 TORINO Italy Phone: +39 011 2285403 Email: elena.demaria@tilab.com Julien Bournelle GET/INT 9 rue Charles Fourier Evry 91011 France Email: julien.bournelle@int-evry.fr Rafa Marin Lopez University of Murcia 30071 Murcia Spain EMail: rafa@dif.um.es Giaretta, et al. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Giaretta, et al. Expires - July 2006 [Page 14]