--- 1/draft-ietf-ipsecme-ikev2-redirect-05.txt 2009-03-24 04:12:04.000000000 +0100 +++ 2/draft-ietf-ipsecme-ikev2-redirect-06.txt 2009-03-24 04:12:04.000000000 +0100 @@ -1,18 +1,18 @@ Network Working Group V. Devarapalli Internet-Draft WiChorus Intended status: Standards Track K. Weniger -Expires: September 10, 2009 March 9, 2009 +Expires: September 24, 2009 March 23, 2009 Redirect Mechanism for IKEv2 - draft-ietf-ipsecme-ikev2-redirect-05.txt + draft-ietf-ipsecme-ikev2-redirect-06.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to format it for publication as an RFC or to translate it into languages other than English. Internet-Drafts are working documents of the Internet Engineering @@ -24,21 +24,21 @@ 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 September 10, 2009. + This Internet-Draft will expire on September 24, 2009. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights @@ -57,30 +57,30 @@ another home agent. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. IKEv2 Exchange with Redirect . . . . . . . . . . . . . . . . . 4 4. Use of Anycast Addresses with the Redirect Mechanism . . . . . 5 5. Gateway Initiated Redirect . . . . . . . . . . . . . . . . . . 6 6. Redirect Messages . . . . . . . . . . . . . . . . . . . . . . 7 - 6.1. REDIRECT_SUPPORTED . . . . . . . . . . . . . . . . . . . . 7 + 6.1. REDIRECT_SUPPORTED . . . . . . . . . . . . . . . . . . . . 8 6.2. REDIRECT . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.3. REDIRECTED_FROM . . . . . . . . . . . . . . . . . . . . . 9 7. Use of the Redirect Mechanism between IKEv2 Peers . . . . . . 10 8. Security Considerations . . . . . . . . . . . . . . . . . . . 10 - 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 + 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 11.1. Normative References . . . . . . . . . . . . . . . . . . . 11 - 11.2. Informative References . . . . . . . . . . . . . . . . . . 11 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 + 11.1. Normative References . . . . . . . . . . . . . . . . . . . 12 + 11.2. Informative References . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 1. Introduction IKEv2 [2] is used for setting up IPsec-based VPNs. The IP address of the VPN gateway can be configured on the VPN client. But this does not scale well, when the number of VPN gateways is large. Dynamic discovery of VPN gateways using DNS is quite widely used too. However, using DNS is not flexible when it comes to assigning a VPN gateway to the VPN client based on the load on the VPN gateways. The @@ -130,20 +130,24 @@ document are to be interpreted as described in [1]. 3. IKEv2 Exchange with Redirect To redirect an IKEv2 session to another VPN gateway, the VPN gateway that initially received the IKE_SA_INIT request selects another VPN gateway and responds to the VPN client with a REDIRECT Notification payload. The mechanism by which the initial VPN gateway selects another VPN gateway is out of scope for this document. The IP address of the selected VPN gateway is sent in the REDIRECT payload. + The gateway MUST include the nonce data from the Ni payload sent by + the initiator in the REDIRECT payload. This prevents certain Denial- + of-Service attacks on the initiator that could be caused by an + attacker injecting IKE_SA_INIT responses with REDIRECT payloads. The VPN client indicates support for the IKEv2 redirect mechanism by including a REDIRECT_SUPPORTED notification message in the initial IKE_SA_INIT request. If the IKE_SA_INIT request did not include the REDIRECT_SUPPORTED payload, the responder MUST NOT send the REDIRECT payload to the VPN client. Initiator Responder (initial VPN GW) --------- ------------------------- @@ -221,26 +225,28 @@ address, if it is not overloaded. The rest of the IKEv2 exchange is the same as described in Section 3. 5. Gateway Initiated Redirect The redirect mechanism may also be used by a VPN gateway to redirect the client to another VPN gateway in middle of a session. To redirect a client, the gateway should send an INFORMATIONAL message with the REDIRECT Notify payload. The REDIRECT payload MUST carry - information about the new VPN gateway. When the client receives this - message, it MUST send an empty message as an acknowledgement. Until - the client responds with an acknowledgement, the gateway SHOULD re- - transmit the redirect INFORMATIONAL message as described in [2]. The - following illustrates the INFORMATIONAL message exchange for gateway- - initiated redirect. + information about the new VPN gateway. The gateway MUST NOT include + any nonce data in the REDIRECT payload, since it is a gateway- + initiated message and is protected by the IKEv2 security association. + When the client receives this message, it MUST send an empty message + as an acknowledgement. Until the client responds with an + acknowledgement, the gateway SHOULD re-transmit the redirect + INFORMATIONAL message as described in [2]. The following illustrates + the INFORMATIONAL message exchange for gateway-initiated redirect. Initiator (VPN client) Responder (VPN GW) ---------------------- ------------------ <-- HDR, SK {N[REDIRECT, IP_R/FQDN_R]} HDR, SK {} --> The INFORMATIONAL message exchange described above is protected by the existing IKEv2 SA between the client and the gateway. @@ -249,75 +255,75 @@ delete the existing security associations with the old gateway by sending an Informational message with a DELETE payload. The gateway MAY also decide to delete the security associations without any signaling from the client, again by sending an Informational message with a DELETE payload. However, it should allow sufficient time for the client to setup the required security associations with the new security gateway. This time period should be configurable on the gateway. If the gateway decides to redirect the client during the IKE_AUTH - exchange, it prevents the creation of a CHILD SA by sending the - NO_ADDITIONAL_SAS Notify Payload in the IKE_AUTH response. It then - follows up with an INFORMATIONAL message with the REDIRECT payload - immediately. The following shows the message exchange between the - client and the gateway. + exchange, based on the identity presented by the client in the + IKE_AUTH request message, it prevents the creation of a CHILD SA and + sends the REDIRECT payload in the IKE_AUTH response. When the client + receives the IKE_AUTH response with the REDIRECT payload, it SHOULD + delete the existing IKEv2 security association with the gateway. Initiator Responder ( VPN GW) --------- ------------------- (IP_I:500 -> IP_R:500) HDR(A,0), SAi1, KEi, Ni, --> N(REDIRECTED_SUPPORTED) (IP_R:500 -> IP_I:500) <-- HDR(A,B), SAr1, KEr, Nr,[CERTREQ] (IP_I:500 -> IP_R:500) HDR(A,B), SK {IDi, [CERT,] [CERTREQ,] [IDr,]AUTH, SAi2, TSi, TSr} --> (IP_R:500 -> IP_I:500) <-- HDR(A,B), SK {IDr, [CERT,] AUTH, - N(NO_ADDITIONAL_SAS)} - - <-- HDR, SK {N[REDIRECT, IP_R/FQDN_R]} - - HDR, SK {} --> + N[REDIRECT, IP_R/FQDN_R]} - When the client receives the IKE_AUTH response with the - NO_ADDITIONAL_SAS payload from the gateway, it may decide to delete - the IKEv2 SA. In case the gateway receives the INFORMATIONAL message - to delete the IKEv2 SA before sending the REDIRECT message, then the - gateway includes the REDIRECT payload in the response along with the - DELETE payload. + In case the IKE_AUTH exchange involves EAP authentication as + described in Section 2.16 of RFC 4306 [2] or multiple authentication + methods as described in RFC 4739 [6], the IKE_AUTH exchange is more + complicated. The identity presented by the client in the first + IKE_AUTH request might be a temporary one. In addition, the gateway + might decide to redirect the client based on the interaction with the + the AAA server, when EAP authentication is used or the external + authentication server, when multiple authentication methods are used. + In such cases, the exact message in which the gateway sends the + REDIRECT payload is TBD. 6. Redirect Messages 6.1. REDIRECT_SUPPORTED The REDIRECT_SUPPORTED payload is included in the initial IKE_SA_INIT request by the initiator to indicate support for the IKEv2 redirect mechanism described in this document. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Payload |C| RESERVED | Payload Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Protocol ID | SPI Size (=0) | Notify Message Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The 'Next Payload', 'Payload Length', 'Protocol ID', 'SPI Size' and the 'Notify Message Type' fields are the same as described in Section 3.10 of [2]. The 'SPI Size' field MUST be set to 0 to indicate that - the SPI is not present in this message. The 'Protocol ID' should be + the SPI is not present in this message. The 'Protocol ID' MUST be set to 0, since the notification is not specific to a particular security association. The 'Payload Length' field MUST be set to '8'. The 'Notify Message Type' field is set to indicate the REDIRECT_SUPPORTED payload . 6.2. REDIRECT The REDIRECT payload is included in an IKE_SA_INIT response from the @@ -330,25 +336,28 @@ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Payload |C| RESERVED | Payload Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Protocol ID | SPI Size (=0) | Notify Message Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | GW Ident Type | | +---------------+ ~ ~ New Responder GW Identity ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - + | | + ~ Nonce Data ~ + | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The 'Next Payload', 'Payload Length', 'Protocol ID', 'SPI Size' and the 'Notify Message Type' fields are the same as described in Section 3.10 of [2]. The 'SPI Size' field MUST be set to 0 to indicate that - the SPI is not present in this message. The 'Protocol ID' should be + the SPI is not present in this message. The 'Protocol ID' MUST be set to 0, since the notification is not specific to a particular security association. If the IP address of the new VPN gateway is sent, the 'Payload Length' field MUST be set to either '13' or '25' depending on whether an IPv4 or IPv6 address is sent in the message. If the FQDN of the new VPN gateway is sent, the 'Payload Length' field is set to the length of the FQDN plus the fixed fields in the message. The 'Notify Message Type' field is set to indicate the REDIRECT payload . The 'GW Identity Type' field indicates the @@ -356,20 +365,28 @@ The following values are reserved by this document. 1 - IPv4 address of the new VPN gateway 2 - IPv6 address of the new VPN gateway 3 - FQDN of the new VPN gateway All other values for this field are reserved and MUST NOT be used. The identity of the new VPN gateway is carried in the 'New Responder GW Identity' field. + The 'Nonce Data' field carries the nonce data from the Ni payload + sent by the initiator. The size of the nonce MUST be between 16 and + 256 bytes as described in Section 3.9 of [2]. The 'Nonce Data' field + is present in the REDIRECT payload only when the REDIRECT payload is + sent in the IKE_SA_INIT response message. It MUST NOT be included in + the REDIRECT payload if sent in an IKE_AUTH response or in a gateway- + initiated redirect message. + 6.3. REDIRECTED_FROM The REDIRECTED_FROM message type is included in the IKE_SA_INIT request from the initiator to the new VPN gateway to indicate the IP address of the original VPN gateway that redirected the initiator. The original VPN gateway's IP address is included in the message. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ @@ -379,21 +396,21 @@ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | GW Ident Type | | +---------------+ ~ ~ Original Responder GW Identity ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The 'Next Payload', 'Payload Length', 'Protocol ID', 'SPI Size' and the 'Notify Message Type' fields are the same as described in Section 3.10 of [2] The 'SPI Size' field MUST be set to 0 to indicate that - the SPI is not present in this message. The 'Protocol ID' should be + the SPI is not present in this message. The 'Protocol ID' MUST be set to 0, since the notification is not specific to a particular security association. The 'Payload Length' field MUST be set to either '13' or '25' depending on whether an IPv4 or IPv6 address of the original VPN gateway is sent in the message. The 'Notify Message Type' field is set to indicate the REDIRECTED_FROM payload . The 'GW Identity Type' field indicates the type of information that is sent to identify the new VPN gateway. The following values are reserved by this document. @@ -439,23 +456,23 @@ This document defines four new IKEv2 Notification Message types as described in Section 6. The three Notify Message Types must be assigned values between 16396 and 40959. o REDIRECT_SUPPORTED o REDIRECT o REDIRECTED_FROM 10. Acknowledgements - The use of anycast address with IKEv2 was first described in [6]. It + The use of anycast address with IKEv2 was first described in [7]. It was then added to an early draft version of RFC 5026 and later - removed before the RFC was published. Therefore the authors of [6] + removed before the RFC was published. Therefore the authors of [7] and RFC 5026 are acknowledged. Thanks to Pasi Eronen, with whom the solution described in this document was extensively discussed. Thanks to Tero Kivinen for suggesting the use of REDIRECTED_FROM payload and other comments which helped improve the document. The authors would also like to thank Yaron Sheffer, Sunil Kumar, Fan Zhao, Yoav Nir, Richard Graveman, and Arnaud Ebalard for their reviews and comments. 11. References @@ -472,21 +489,25 @@ [3] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [4] Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6 Bootstrapping in Split Scenario", RFC 5026, October 2007. [5] Haley, B., Devarapalli, V., Deng, H., and J. Kempf, "Mobility Header Home Agent Switch Message", RFC 5142, January 2008. - [6] Weniger, K. and F. Dupont, "IKEv2-based Home Agent Assignment in + [6] Eronen, P. and J. Korhonen, "Multiple Authentication Exchanges + in the Internet Key Exchange (IKEv2) Protocol", RFC 4739, + November 2006. + + [7] Weniger, K. and F. Dupont, "IKEv2-based Home Agent Assignment in Mobile IPv6/NEMO Bootstrapping", draft-dupont-ikev2-haassign-02 (work in progress), January 2007. Authors' Addresses Vijay Devarapalli WiChorus 3590 North First St San Jose, CA 95134 USA