draft-ietf-ipsecme-ikev2-redirect-03.txt   draft-ietf-ipsecme-ikev2-redirect-04.txt 
Network Working Group V. Devarapalli Network Working Group V. Devarapalli
Internet-Draft WiChorus Internet-Draft WiChorus
Intended status: Standards Track K. Weniger Intended status: Standards Track K. Weniger
Expires: August 6, 2009 Panasonic Expires: August 13, 2009 February 9, 2009
February 2, 2009
Re-direct Mechanism for IKEv2 Re-direct Mechanism for IKEv2
draft-ietf-ipsecme-ikev2-redirect-03.txt draft-ietf-ipsecme-ikev2-redirect-04.txt
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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This Internet-Draft will expire on August 6, 2009. This Internet-Draft will expire on August 13, 2009.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. IKEv2 Exchange with Redirect . . . . . . . . . . . . . . . . . 4 3. IKEv2 Exchange with Redirect . . . . . . . . . . . . . . . . . 4
4. Use of Anycast Addresses with the Re-direct Mechanism . . . . 5 4. Use of Anycast Addresses with the Re-direct Mechanism . . . . 5
5. Gateway Initiated Redirect . . . . . . . . . . . . . . . . . . 6 5. Gateway Initiated Redirect . . . . . . . . . . . . . . . . . . 6
6. Redirect Messages . . . . . . . . . . . . . . . . . . . . . . 7 6. Redirect Messages . . . . . . . . . . . . . . . . . . . . . . 7
6.1. REDIRECT_SUPPORTED . . . . . . . . . . . . . . . . . . . . 7 6.1. REDIRECT_SUPPORTED . . . . . . . . . . . . . . . . . . . . 7
6.2. REDIRECT . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.2. REDIRECT . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.3. REDIRECTED_FROM . . . . . . . . . . . . . . . . . . . . . 8 6.3. REDIRECTED_FROM . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. Use of the Redirect Mechanism between IKEv2 Peers . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
10.1. Normative References . . . . . . . . . . . . . . . . . . . 10 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
10.2. Informative References . . . . . . . . . . . . . . . . . . 10 11.1. Normative References . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 11.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
IKEv2 [2] is used for setting up IPsec-based VPNs. The IP address of 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 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 not scale well, when the number of VPN gateways is large. Dynamic
discovery of VPN gateways using DNS is quite widely used too. discovery of VPN gateways using DNS is quite widely used too.
However, using DNS is not flexible when it comes to assigning a VPN 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 gateway to the VPN client based on the load on the VPN gateways. The
VPN client typically tries to connect to the IP address of the VPN VPN client typically tries to connect to the IP address of the VPN
gateways that appears first in the DNS response. If the VPN tunnel gateways that appears first in the DNS response. If the VPN tunnel
setup fails, then the VPN client tries to attach to the other VPN setup fails, then the VPN client tries to attach to the other VPN
gateways returned in the DNS response. gateways returned in the DNS response.
This document proposes a re-direct mechanism for IKEv2 that enables a This document proposes a re-direct mechanism for IKEv2 that enables a
VPN gateway to re-direct the VPN client to another VPN gateway, for VPN gateway to re-direct the VPN client to another VPN gateway, for
example, based on the load condition. The re-direct is done during example, based on the load condition. The re-direct can be done
the IKE_SA_INIT exchange. The re-direct mechanism can also be used during during the IKE_SA_INIT or the IKE_AUTH exchange. Gateway-
in conjunction with anycast addresses. In this case, anycast address initiated re-direct in the middle of a session is also supported.
for the cluster of VPN gateways is stored in the DNS instead of a The re-direct mechanism can also be used in conjunction with anycast
list of unicast IP addresses of the VPN gateways. addresses. In this case, anycast address for the cluster of VPN
gateways is stored in the DNS instead of a list of unicast IP
addresses of the VPN gateways.
The re-direct can also happen because of administrative or optimal The re-direct can also happen because of administrative or optimal
routing reasons. This document does not attempt to provide an routing reasons. This document does not attempt to provide an
exhaustive list of reasons for re-directing a VPN client to another exhaustive list of reasons for re-directing a VPN client to another
VPN gateway. VPN gateway.
Mobile IPv6 [3] may use IKEv2 for mutual authentication between the Mobile IPv6 [3] may use IKEv2 for mutual authentication between the
mobile node and the home agent. IKEv2 may also be used for home mobile node and the home agent. IKEv2 may also be used for home
address configuration and setting up IPsec security associations for address configuration and setting up IPsec security associations for
protecting Mobile IPv6 signaling messages [4]. The IKEv2 exchange protecting Mobile IPv6 signaling messages [4]. The IKEv2 exchange
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Once the client sends an acknowledgement to the gateway, it SHOULD Once the client sends an acknowledgement to the gateway, it SHOULD
delete the existing security associations with the old gateway by delete the existing security associations with the old gateway by
sending an Informational message with a DELETE payload. The gateway sending an Informational message with a DELETE payload. The gateway
MAY also decide to delete the security associations without any MAY also decide to delete the security associations without any
signaling from the client. However, it should allow sufficient time signaling from the client. However, it should allow sufficient time
for the client to setup the required security associations with the for the client to setup the required security associations with the
new security gateway. This time period should be configurable on the new security gateway. This time period should be configurable on the
gateway. gateway.
If the gateway decides to re-direct 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.
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 {} -->
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.
6. Redirect Messages 6. Redirect Messages
6.1. REDIRECT_SUPPORTED 6.1. REDIRECT_SUPPORTED
The REDIRECT_SUPPORTED payload is included in the initial IKE_SA_INIT The REDIRECT_SUPPORTED payload is included in the initial IKE_SA_INIT
request by the initiator to indicate support for the IKEv2 re-direct request by the initiator to indicate support for the IKEv2 re-direct
mechanism described in this document. mechanism described in this document.
1 2 3 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 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
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information that is sent to identify the new VPN gateway. The information that is sent to identify the new VPN gateway. The
following values are reserved by this document. following values are reserved by this document.
1 - IPv4 address of the original VPN gateway 1 - IPv4 address of the original VPN gateway
2 - IPv6 address of the original VPN gateway 2 - IPv6 address of the original VPN gateway
All other values for this field are reserved and MUST NOT be used. All other values for this field are reserved and MUST NOT be used.
The identity of the original VPN gateway is carried in the 'Original The identity of the original VPN gateway is carried in the 'Original
Responder GW Identity' field. Responder GW Identity' field.
7. Security Considerations 7. Use of the Redirect Mechanism between IKEv2 Peers
The Re-direct mechanism described in this document is mainly intended
for use in client-gateway scenarios. However, the mechanism can also
be used between any two IKEv2 peers. This is especially useful for
IKEv2 sessions between two gateway peer routers.
When used between a client and gateway, the re-direct procedure is
always initiated by the gateway. But when used between two IKEv2
peers, either of the IKEv2 end points can initiate the re-direct
message. In order to prevent any race condition that might occur if
both decide to re-direct at the same time, the responder MUST NOT
respond to re-direct message from the initiator, if it has already
decided to re-direct the initiator.
Both IKEv2 peers SHOULD indicate support for the re-direct mechanism
if they support it and are willing to process REDIRECT notification
messages. This is done by including the REDIRECT_SUPPORTED payload
in the IKE_SA_INIT exchange by both peers. REDIRECT Notification
messages MUST NOT be sent unless the peer has indicated support for
it.
8. Security Considerations
An eavesdropper on the path between VPN client and server may send a An eavesdropper on the path between VPN client and server may send a
redirect to the client upon receiving an IKE_SA_INIT message from redirect to the client upon receiving an IKE_SA_INIT message from
this client. This is no problem regarding DoS attacks for the VPN this client. This is no problem regarding DoS attacks for the VPN
connection, since an on-path-attacker can as well drop the connection, since an on-path-attacker can as well drop the
IKE_SA_INIT requests to prevent VPN access for the client. But an IKE_SA_INIT requests to prevent VPN access for the client. But an
eavesdropper on the path between VPN client and server can redirect a eavesdropper on the path between VPN client and server can redirect a
large number of clients to a victim, which is then flooded with large number of clients to a victim, which is then flooded with
IKE_SA_INIT requests. Flooding only happens if many clients initiate IKE_SA_INIT requests. Flooding only happens if many clients initiate
IKEv2 exchange at almost the same time, which is considered a rare IKEv2 exchange at almost the same time, which is considered a rare
event. However, this may happen if a Home Agent/VPN server is event. However, this may happen if a Home Agent/VPN server is
shutdown for maintenance and all clients need to re-establish VPN shutdown for maintenance and all clients need to re-establish VPN
connections with another Home Agent/VPN server or if the on-path connections with another Home Agent/VPN server or if the on-path
attacker forces all IPsec security associations to expire by dropping attacker forces all IPsec security associations to expire by dropping
all received IKEv2 messages. all received IKEv2 messages.
The use of REDIRECTED_FROM payload is intended to discourage a rogue The use of REDIRECTED_FROM payload is intended to discourage a rogue
VPN gateway from re-directing a large number of VPN clients to a VPN gateway from re-directing a large number of VPN clients to a
particular VPN gateway. It does not prevent such a DoS attack. particular VPN gateway. It does not prevent such a DoS attack.
8. IANA Considerations 9. IANA Considerations
This document defines four new IKEv2 Notification Message types as This document defines four new IKEv2 Notification Message types as
described in Section 6. The four Notify Message Types must be described in Section 6. The three Notify Message Types must be
assigned values between 16396 and 40959. assigned values between 16396 and 40959.
o REDIRECT_SUPPORTED o REDIRECT_SUPPORTED
o REDIRECT o REDIRECT
o REDIRECTED_FROM o REDIRECTED_FROM
9. Acknowledgements 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 [6]. It
was then added to an early draft version of RFC 5026 and later 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 [6]
and RFC 5026 are acknowledged. and RFC 5026 are acknowledged.
Thanks to Pasi Eronen, with whom the solution described in this Thanks to Pasi Eronen, with whom the solution described in this
document was extensively discussed. Thanks to Tero Kivinen for document was extensively discussed. Thanks to Tero Kivinen for
suggesting the use of REDIRECTED_FROM payload. The authors would suggesting the use of REDIRECTED_FROM payload. The authors would
also like to thank Yaron Sheffer, Sunil Kumar, Fan Zhao, Yoav Nir and also like to thank Yaron Sheffer, Sunil Kumar, Fan Zhao, Yoav Nir and
Arnaud Ebalard for their reviews and comments. Arnaud Ebalard for their reviews and comments.
10. References 11. References
10.1. Normative References 11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306, [2] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306,
December 2005. December 2005.
10.2. Informative References 11.2. Informative References
[3] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in [3] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004. IPv6", RFC 3775, June 2004.
[4] Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6 [4] Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6
Bootstrapping in Split Scenario", RFC 5026, October 2007. Bootstrapping in Split Scenario", RFC 5026, October 2007.
[5] Haley, B., Devarapalli, V., Deng, H., and J. Kempf, "Mobility [5] Haley, B., Devarapalli, V., Deng, H., and J. Kempf, "Mobility
Header Home Agent Switch Message", RFC 5142, January 2008. Header Home Agent Switch Message", RFC 5142, January 2008.
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Authors' Addresses Authors' Addresses
Vijay Devarapalli Vijay Devarapalli
WiChorus WiChorus
3590 North First St 3590 North First St
San Jose, CA 95134 San Jose, CA 95134
USA USA
Email: vijay@wichorus.com Email: vijay@wichorus.com
Killian Weniger Kilian Weniger
Panasonic R&D Center Germany
Monzastr. 4c
Langen 63225
Germany
Email: kilian.weniger@eu.panasonic.com Email: kilian.weniger@googlemail.com
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