IPSECME WG A. Noble Internet-Draft S. Gundavelli Intended status: Standards Track Cisco Expires: August 22, 2013 J. Korhonen Nokia Siemens Networks F. Baboescu Broadcom Corporation February 18, 2013 3GPP IMS Option for IKEv2 draft-gundavelli-ipsecme-3gpp-ims-options-00.txt Abstract This document defines two new configuration attributes for Internet Key Exchange Protocol version 2 (IKEv2). These attributes can be used for carrying the IPv4 and IPv6 address of the Proxy-Call Control and Service function (P-CSCF). This is one of the few methods that an IPsec client can obtain the IP address of the P-CSCF function located in the home network. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on August 22, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents Noble, et al. Expires August 22, 2013 [Page 1] Internet-Draft 3GPP IMS Option for IKEv2 February 2013 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Terminology . . . . . . . . . . . . . . . . . . 3 2.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 3. P-CSCF_IP4_ADDRESS Configuration Attribute . . . . . . . . . . 4 4. P-CSCF_IP6_ADDRESS Configuration Attribute . . . . . . . . . . 5 5. Example Scenario . . . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 9.1. Normative References . . . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Noble, et al. Expires August 22, 2013 [Page 2] Internet-Draft 3GPP IMS Option for IKEv2 February 2013 1. Introduction The 3GPP S2b reference point [TS23402], specified by the 3GPP system architecture defines a mechanism for allowing a mobile node attached in an untrusted non-3GPP IP Access Network to securely connect to the 3GPP home network and access IP services. In this scenario, the mobile node establishes an IPsec tunnel to the security gateway called ePDG and which in turn establishes a PMIPv6/GTP tunnel to the PDN gateway where the mobile node's session is anchored. The below figure shows the interworking option for Untrusted Non-3GPP access. +------------+ | ePDG | | +--------+ | +------+ _----_ | | IPsec | | _----_ +-----+ | MN | _( )_ | | Module | | _( )_ | LMA | | |<====( Internet )=====| +--------+ |===( Operator )===|(PGW)| +------+ (_ _) | : | (_Network_) +-----+ '----' | +--------+ | '----' IPsec Tunnel | | PMIPv6 | | PMIPv6/GTP Tunnel | | MAG | | | +--------+ | +------------+ |<------------ IKEv2/IPsec ------> | <-------------PMIPv6/GTP-->| Figure 1: Exchange of IPv4 Traffic Offload Selectors A mobile node in this scenario may potentially need to access the IMS services in the home network. Currently, there are no attributes in IKEv2 that can be used for carrying these information elements. In the absence of these Attributes the mobile node needs to be statically configured with this information and this is proving to be an operational challenge. This specification therefore defines two new IKEv2 attributes [RFC5996] that allows an IPsec gateway to provide the IPv4 and/or IPv6 address of the P-CSCF function. These attributes can be exchanged by IKEv2 peers as part of the configuration payload exchange. 2. Conventions and Terminology Noble, et al. Expires August 22, 2013 [Page 3] Internet-Draft 3GPP IMS Option for IKEv2 February 2013 2.1. Conventions 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 [RFC2119]. 2.2. Terminology All the IKEv2 related terms used in this document are to be interpreted as defined in [RFC5996] and [RFC5739]. All the mobility related terms are to interpreted as defined in [RFC5213] and [RFC5844]. Additionally, this document uses the following terms: Proxy-Call Session Control Function (P-CSCF) The P-CSCF is the entry point to the 3GPP IMS (IP Multimedia Subsystem) domain and serves as the outbound proxy server for the mobile node. The mobile node attaches to the P-CSCF prior to performing IMS registrations and initiating SIP sessions. 3. P-CSCF_IP4_ADDRESS Configuration Attribute The P-CSCF_IP4_ADDRESS configuration attribute is formatted as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R| Attribute Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: IPv4 Address of P-CSCF Reserved (1 bit) Refer to IKEv2 specification Attribute Type (15 bits) Length (2 octets) Length of the value field in octets. In this case, its 4. Noble, et al. Expires August 22, 2013 [Page 4] Internet-Draft 3GPP IMS Option for IKEv2 February 2013 IPv4 Address (4 octets) An IPv4 address of the P-CSCF function. Multiple instances of this Attribute with different values can be present in the configuration payload and there is no implied preferrential order. 4. P-CSCF_IP6_ADDRESS Configuration Attribute The P-CSCF_IP4_ADDRESS configuration attribute is formatted as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R| Attribute Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | | IPv6 Address | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: IPv6 Address of P-CSCF Reserved (1 bit) Refer to IKEv2 specification Attribute Type (15 bits) Length (2 octets) Length of the value field in octets. In this case, its 16. IPv6 Address (16 octets) An IPv4 address of the P-CSCF function. Multiple instances of this Attribute with different values can be present in the configuration payload and there is no implied preferrential order. 5. Example Scenario The mobile node MAY request the IP address of an P-CSCF function as Noble, et al. Expires August 22, 2013 [Page 5] Internet-Draft 3GPP IMS Option for IKEv2 February 2013 shown below. Client Gateway -------- --------- HDR(IKE_SA_INIT), SAi1, KEi, Ni --> <-- HDR(IKE_SA_INIT), SAr1, KEr, Nr, [CERTREQ] HDR(IKE_AUTH), SK { IDi, CERT, [CERTREQ], AUTH, [IDr], CP(CFG_REQUEST) = { INTERNAL_IP4_ADDRESS(), INTERNAL_IP4_DNS(), P-CSCF_IP4_ADDRESS, P-CSCF_IP6_ADDRESS }, SAi2, TSi = (0, 0-65535, 0.0.0.0-255.255.255.255), TSr = (0, 0-65535, 0.0.0.0-255.255.255.255) } --> <-- HDR(IKE_AUTH), SK { IDr, CERT, AUTH, CP(CFG_REPLY) = { INTERNAL_IP4_ADDRESS(192.0.2.234), P-CSCF_IP4_ADDRESS, P-CSCF_IP6_ADDRESS, INTERNAL_IP4_DNS(198.51.100.33) }, SAr2, TSi = (0, 0-65535, 192.0.2.234-192.0.2.234), TSr = (0, 0-65535, 0.0.0.0-255.255.255.255) } Figure 4: P-CSCF Attribute Exchange 6. IANA Considerations This document requires the following two IANA actions. o Action-1: This specification defines a new IKEv2 attribute for carrying the IPv4 address of P-CSCF function. This attribute is defined in Section 3. The Type value for this Attribute needs to be assigned from the IKEv2 Configuration Payload Attribute Types namespace defined in [RFC5996]. o Action-2: This specification defines a new IKEv2 attribute for carrying the IPv6 address of P-CSCF function. This attribute is Noble, et al. Expires August 22, 2013 [Page 6] Internet-Draft 3GPP IMS Option for IKEv2 February 2013 defined in Section 4. The Type value for this Attribute needs to be assigned from the IKEv2 Configuration Payload Attribute Types namespace defined in [RFC5996]. 7. Security Considerations This document is an extension to IKEv2 [RFC5996] and therefore it inherits all the security properties of IKEv2. The two new IKEv2 attributes defined in this specification are for carrying the IPv4 and IPv6 address of the P-CSCF function. These attributes can be exchanged by IKE peers as part of the configuration payload and the currently defined IKEv2 security framework provides the needed integrity and privacy protection for these attributes. Therefore this specification does not introduce any new security vulnarabilities. 8. Acknowledgements The Authors would like to thank Vojislav Vuecetic, Heather Sze, Sebastian Speicher, Maulik Vaidya for all the discussions related to this topic. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 5996, September 2010. 9.2. Informative References [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [RFC5739] Eronen, P., Laganier, J., and C. Madson, "IPv6 Configuration in Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 5739, February 2010. [RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy Mobile IPv6", RFC 5844, May 2010. Noble, et al. Expires August 22, 2013 [Page 7] Internet-Draft 3GPP IMS Option for IKEv2 February 2013 [TS23402] 3GPP, "Architecture enhancements for non-3GPP accesses", 2012. Authors' Addresses Aeneas Noble Cisco 30 International Pl TEWKSBURY, MASSACHUSETTS 95134 USA Email: noblea@cisco.com Sri Gundavelli Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: sgundave@cisco.com Jouni Korhonen Nokia Siemens Networks Linnoitustie 6 Espoo FIN-02600 Finland Email: jouni.nospam@gmail.com Florin Baboescu Broadcom Corporation 100 Mathilda Place Sunnyvale, CA 94086 USA Email: baboescu@broadcom.com> Noble, et al. Expires August 22, 2013 [Page 8]