draft-ietf-ipsecme-ikev2-redirect-07.txt   draft-ietf-ipsecme-ikev2-redirect-08.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: October 10, 2009 April 8, 2009 Expires: October 15, 2009 April 13, 2009
Redirect Mechanism for IKEv2 Redirect Mechanism for IKEv2
draft-ietf-ipsecme-ikev2-redirect-07.txt draft-ietf-ipsecme-ikev2-redirect-08.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. This document may not be modified, 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 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 for publication as an RFC or to translate it into languages other
than English. than English.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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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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The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on October 10, 2009. This Internet-Draft will expire on October 15, 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 in effect on the date of Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info). publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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is being shut down for maintenance to redirect the VPN client to is being shut down for maintenance to redirect the VPN client to
attach to another gateway. This document proposes a redirect attach to another gateway. This document proposes a redirect
mechanism for IKEv2. The proposed mechanism can also be used in mechanism for IKEv2. The proposed mechanism can also be used in
Mobile IPv6 to enable the home agent to redirect the mobile node to Mobile IPv6 to enable the home agent to redirect the mobile node to
another home agent. another home agent.
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 Initial Exchange with Redirect . . . . . . . . . . . . . 4
4. Use of Anycast Addresses with the Redirect Mechanism . . . . . 5 4. Use of Anycast Addresses with the Redirect Mechanism . . . . . 5
5. Gateway Initiated Redirect . . . . . . . . . . . . . . . . . . 6 5. Gateway Initiated Redirect . . . . . . . . . . . . . . . . . . 6
6. Redirect Messages . . . . . . . . . . . . . . . . . . . . . . 7 6. Redirect During IKE_AUTH Exchange . . . . . . . . . . . . . . 7
6.1. REDIRECT_SUPPORTED . . . . . . . . . . . . . . . . . . . . 8 7. Redirect Messages . . . . . . . . . . . . . . . . . . . . . . 8
6.2. REDIRECT . . . . . . . . . . . . . . . . . . . . . . . . . 8 7.1. REDIRECT_SUPPORTED . . . . . . . . . . . . . . . . . . . . 8
6.3. REDIRECTED_FROM . . . . . . . . . . . . . . . . . . . . . 9 7.2. REDIRECT . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Use of the Redirect Mechanism between IKEv2 Peers . . . . . . 10 7.3. REDIRECTED_FROM . . . . . . . . . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. Use of the Redirect Mechanism between IKEv2 Peers . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . . 12 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . . 12 12.1. Normative References . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 12.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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 redirect mechanism for IKEv2 that enables a This document proposes a redirect mechanism for IKEv2 that enables a
VPN gateway to redirect the VPN client to another VPN gateway, for VPN gateway to redirect the VPN client to another VPN gateway, for
example, based on the load condition. The redirect can be done example, based on the load condition. The redirect can be done
during during the IKE_SA_INIT or the IKE_AUTH exchange. Gateway- during the IKE_SA_INIT or the IKE_AUTH exchange. Gateway-initiated
initiated redirect in the middle of a session is also supported. The redirect in the middle of a session is also supported. The redirect
redirect mechanism can also be used in conjunction with anycast mechanism can also be used in conjunction with anycast addresses. In
addresses. In this case, anycast address for the cluster of VPN this case, anycast address for the cluster of VPN gateways is stored
gateways is stored in the DNS instead of a list of unicast IP in the DNS instead of a list of unicast IP addresses of the VPN
addresses of the VPN gateways. gateways.
The redirect can also happen because of administrative or optimal The redirect 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 redirecting a VPN client to another exhaustive list of reasons for redirecting 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
precedes the exchange of Mobile IPv6 signaling messages. Therefore precedes the exchange of Mobile IPv6 signaling messages. Therefore
the mechanism described in this document can be also be used by a the mechanism described in this document can also be used by a Mobile
Mobile IPv6 home agent to redirect a mobile node to another home IPv6 home agent to redirect a mobile node to another home agent.
agent.
There is a Home Agent Switch mechanism available for redirecting a There is a Home Agent Switch mechanism available for redirecting a
mobile node to another home agent, described in [5]. The Home Agent mobile node to another home agent, described in [5]. The Home Agent
Switch mechanism can only be used after the binding cache had been Switch mechanism can only be used after the binding cache had been
created at the home agent for the mobile node. The disadvantage with created at the home agent for the mobile node. The disadvantage with
this is that quite a bit of state is created on the home agent before this is that quite a bit of state is created on the home agent before
the mobile node can be redirected to another home agent. The the mobile node can be redirected to another home agent. The
mechanism described in this document can be used for redirecting a mechanism described in this document can be used for redirecting a
mobile node before any state related to the Mobile IPv6 binding is mobile node before any state related to the Mobile IPv6 binding is
created on the home agent. created on the home agent.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [1]. document are to be interpreted as described in [1].
3. IKEv2 Exchange with Redirect 3. IKEv2 Initial Exchange with Redirect
This section describes the use of Redirect mechanism during the
IKE_SA_INIT exchange. Gateway-initiated redirect and the use of
redirect during IKE_AUTH exchange are explained in subsequent
sections.
To redirect an IKEv2 session to another VPN gateway, the VPN gateway To redirect an IKEv2 session to another VPN gateway, the VPN gateway
that initially received the IKE_SA_INIT request selects another VPN that initially received the IKE_SA_INIT request selects another VPN
gateway and responds to the VPN client with a REDIRECT Notification gateway and responds to the VPN client with a REDIRECT Notification
payload. The mechanism by which the initial VPN gateway selects payload. The mechanism by which the initial VPN gateway selects
another VPN gateway is out of scope for this document. The IP another VPN gateway is out of scope for this document. The IP
address of the selected VPN gateway is sent in the REDIRECT payload. 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 gateway MUST include the nonce data from the Ni payload sent by
the initiator in the REDIRECT payload. This prevents certain Denial- the initiator in the REDIRECT payload. This prevents certain Denial-
of-Service attacks on the initiator that could be caused by an of-Service attacks on the initiator that could be caused by an
attacker injecting IKE_SA_INIT responses with REDIRECT payloads. attacker injecting IKE_SA_INIT responses with REDIRECT payloads.
The VPN client indicates support for the IKEv2 redirect mechanism by The VPN client indicates support for the IKEv2 redirect mechanism and
including a REDIRECT_SUPPORTED notification message in the initial the willingness to be redirected by including a REDIRECT_SUPPORTED
IKE_SA_INIT request. If the IKE_SA_INIT request did not include the notification message in the initial IKE_SA_INIT request. If the
REDIRECT_SUPPORTED payload, the responder MUST NOT send the REDIRECT IKE_SA_INIT request did not include the REDIRECT_SUPPORTED payload,
payload to the VPN client. the responder MUST NOT send the REDIRECT payload to the VPN client.
Initiator Responder (initial VPN GW) Initiator Responder (initial VPN GW)
--------- ------------------------- --------- -------------------------
(IP_I:500 -> Initial_IP_R:500) (IP_I:500 -> Initial_IP_R:500)
HDR(A,0), SAi1, KEi, Ni, --> HDR(A,0), SAi1, KEi, Ni, -->
N(REDIRECT_SUPPORTED) N(REDIRECT_SUPPORTED)
(Initial_IP_R:500 -> IP_I:500) (Initial_IP_R:500 -> IP_I:500)
<-- HDR(A,0), N(REDIRECT, IP_R) <-- HDR(A,0), N(REDIRECT, IP_R)
When the VPN client receives the IKE_SA_INIT response with the When the VPN client receives the IKE_SA_INIT response with the
REDIRECT payload, it initiates a new IKE_SA_INIT exchange with the REDIRECT payload, it initiates a new IKE_SA_INIT exchange with the
VPN gateway listed in the REDIRECT payload. The VPN client includes VPN gateway listed in the REDIRECT payload provided this is allowed
the IP address of the original VPN gateway that redirected the by its IPsec policy. The VPN client includes the IP address of the
client. The IKEv2 exchange then proceeds as normal with the selected original VPN gateway that redirected the client. The IKEv2 exchange
VPN gateway. then proceeds as normal with the selected VPN gateway.
Initiator Responder (Selected VPN GW) Initiator Responder (Selected VPN GW)
--------- --------------------------- --------- ---------------------------
(IP_I:500 -> IP_R:500) (IP_I:500 -> IP_R:500)
HDR(A,0), SAi1, KEi, Ni, --> HDR(A,0), SAi1, KEi, Ni, -->
N(REDIRECTED_FROM, Initial_IP_R) N(REDIRECTED_FROM, Initial_IP_R)
(IP_R:500 -> IP_I:500) (IP_R:500 -> IP_I:500)
<-- HDR(A,B), SAr1, KEr, Nr,[CERTREQ] <-- HDR(A,B), SAr1, KEr, Nr,[CERTREQ]
(IP_I:500 -> IP_R:500) (IP_I:500 -> IP_R:500)
HDR(A,B), SK {IDi, [CERT,] [CERTREQ,] HDR(A,B), SK {IDi, [CERT,] [CERTREQ,]
[IDr,]AUTH, SAi2, TSi, TSr} --> [IDr,]AUTH, SAi2, TSi, TSr} -->
(IP_R:500 -> IP_I:500) (IP_R:500 -> IP_I:500)
<-- HDR(A,B), SK {IDr, [CERT,] AUTH, <-- HDR(A,B), SK {IDr, [CERT,] AUTH,
SAr2, TSi, TSr} SAr2, TSi, TSr}
When this mechanism is used with Mobile IPv6, a mobile node's When this mechanism is used with Mobile IPv6, care must be taken to
security associations with its home agent may expire while it still ensure that the home agent information is consistent with the IKEv2
has a valid binding cache entry at the home agent. In this case, the gateway information. The Mobile IPv6 home agent discovery mechanisms
mobile node MUST NOT use the original home agent address as the (for instance, RFC 5026 [4]) would have configured the mobile node
destination address in the IKE_SA_INIT exchange to setup new security with a particular home agent. When the mobile node initiates an
associations. It MUST try to setup security associations with its IKEv2 exchange with the home agent and is redirected to another
existing home agent. gateway, the home agent information should also be updated, subject
to the policy on the mobile node.
4. Use of Anycast Addresses with the Redirect Mechanism 4. Use of Anycast Addresses with the Redirect Mechanism
The use of anycast addresses will avoid having to configure a The use of anycast addresses will avoid having to configure a
particular VPN gateway's IP address in the DNS. Instead, the anycast particular VPN gateway's IP address in the DNS. Instead, the anycast
address that represents the group of VPN gateways is stored in the address that represents the group of VPN gateways is stored in the
DNS. When the VPN client performs a DNS lookup for the VPN gateway, DNS. When the VPN client performs a DNS lookup for the VPN gateway,
it receives the anycast address of the VPN gateway in the DNS it receives the anycast address of the VPN gateway in the DNS
response. response.
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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, again by sending an Informational message signaling from the client, again by sending an Informational message
with a DELETE payload. However, it should allow sufficient time for with a DELETE payload. However, it should allow sufficient time for
the client to setup the required security associations with the new the client to setup the required security associations with the new
security gateway. This time period should be configurable on the security gateway. This time period should be configurable on the
gateway. gateway.
6. Redirect During IKE_AUTH Exchange
If the gateway decides to redirect the client during the IKE_AUTH If the gateway decides to redirect the client during the IKE_AUTH
exchange, based on the identity presented by the client in the exchange, based on the identity presented by the client in the
IKE_AUTH request message, it prevents the creation of a CHILD SA and 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 sends the REDIRECT payload in the IKE_AUTH response. When the client
receives the IKE_AUTH response with the REDIRECT payload, it SHOULD receives the IKE_AUTH response with the REDIRECT payload, it SHOULD
delete the existing IKEv2 security association with the gateway. delete the existing IKEv2 security association with the gateway. The
gateway MUST verify the client's AUTH payload before sending the
Redirect payload, and the client MUST verify the gateway's AUTH
payload before acting on the Redirect payload.
Initiator Responder ( VPN GW) Initiator Responder ( VPN GW)
--------- ------------------- --------- -------------------
(IP_I:500 -> IP_R:500) (IP_I:500 -> IP_R:500)
HDR(A,0), SAi1, KEi, Ni, --> HDR(A,0), SAi1, KEi, Ni, -->
N(REDIRECTED_SUPPORTED) N(REDIRECTED_SUPPORTED)
(IP_R:500 -> IP_I:500) (IP_R:500 -> IP_I:500)
<-- HDR(A,B), SAr1, KEr, Nr,[CERTREQ] <-- HDR(A,B), SAr1, KEr, Nr,[CERTREQ]
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In case the IKE_AUTH exchange involves EAP authentication as In case the IKE_AUTH exchange involves EAP authentication as
described in Section 2.16 of RFC 4306 [2] or multiple authentication 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 methods as described in RFC 4739 [6], the IKE_AUTH exchange is more
complicated. The identity presented by the client in the first complicated. The identity presented by the client in the first
IKE_AUTH request might be a temporary one. In addition, the gateway IKE_AUTH request might be a temporary one. In addition, the gateway
might decide to redirect the client based on the interaction with the might decide to redirect the client based on the interaction with the
the AAA server, when EAP authentication is used or the external the AAA server, when EAP authentication is used or the external
authentication server, when multiple authentication methods are used. authentication server, when multiple authentication methods are used.
In such cases, the gateway should send the REDIRECT notification In such cases, the gateway should send the REDIRECT notification
payload in the final IKE_AUTH response message that carries the AUTH payload in the final IKE_AUTH response message that carries the AUTH
payload and the traffic selectors. payload and the traffic selectors. The gateway MUST NOT send and the
client MUST NOT accept a redirect in an earlier IKE_AUTH message.
6. Redirect Messages 7. Redirect Messages
6.1. REDIRECT_SUPPORTED 7.1. 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 redirect request by the initiator to indicate support for the IKEv2 redirect
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Payload |C| RESERVED | Payload Length | | Next Payload |C| RESERVED | Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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the 'Notify Message Type' fields are the same as described in Section 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 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' MUST 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 set to 0, since the notification is not specific to a particular
security association. security association.
The 'Payload Length' field MUST be set to '8'. The 'Notify Message The 'Payload Length' field MUST be set to '8'. The 'Notify Message
Type' field is set to indicate the REDIRECT_SUPPORTED payload <value Type' field is set to indicate the REDIRECT_SUPPORTED payload <value
to be assigned by IANA>. to be assigned by IANA>.
6.2. REDIRECT 7.2. REDIRECT
The REDIRECT payload is included in an IKE_SA_INIT response from the The REDIRECT payload is included in an IKE_SA_INIT response from the
responder or an INFORMATIONAL message from the responder, when the responder or an INFORMATIONAL message from the responder, when the
responder wants to redirect the initiator to another VPN gateway. responder wants to redirect the initiator to another VPN gateway.
The message includes the new responder's IP address. The message includes the new responder's IP address.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Payload |C| RESERVED | Payload Length | | Next Payload |C| RESERVED | Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol ID | SPI Size (=0) | Notify Message Type | | Protocol ID | SPI Size (=0) | Notify Message Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GW Ident Type | | | GW Ident Type | GW Ident Len | |
+---------------+ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~
~ New Responder GW Identity ~ ~ New Responder GW Identity ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Nonce Data ~ ~ Nonce Data ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The 'Next Payload', 'Payload Length', 'Protocol ID', 'SPI Size' and The 'Next Payload', 'Payload Length', 'Protocol ID', 'SPI Size' and
the 'Notify Message Type' fields are the same as described in Section 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 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' MUST 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 set to 0, since the notification is not specific to a particular
security association. security association.
The 'Payload Length' field is set to the length in octets of the The 'Payload Length' field is set to the length in octets of the
entire payload, including the generic payload header. 'Notify entire payload, including the generic payload header. 'Notify
Message Type' field is set to indicate the REDIRECT payload <value to Message Type' field is set to indicate the REDIRECT payload <value to
skipping to change at page 9, line 23 skipping to change at page 9, line 41
Message Type' field is set to indicate the REDIRECT payload <value to Message Type' field is set to indicate the REDIRECT payload <value to
be assigned by IANA>. The 'GW Identity Type' field indicates the be assigned by IANA>. The 'GW Identity Type' field indicates the
type of information that is sent to identify the new VPN gateway. type of information that is sent to identify the new VPN gateway.
The following values are reserved by this document. The following values are reserved by this document.
1 - IPv4 address of the new VPN gateway 1 - IPv4 address of the new VPN gateway
2 - IPv6 address of the new VPN gateway 2 - IPv6 address of the new VPN gateway
3 - FQDN 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. 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 The 'GW Ident Len' field is set to the length of the gateway identity
GW Identity' field. information. 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 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 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 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 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 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- the REDIRECT payload if sent in an IKE_AUTH response or in a gateway-
initiated redirect message. initiated redirect message.
6.3. REDIRECTED_FROM 7.3. REDIRECTED_FROM
The REDIRECTED_FROM message type is included in the IKE_SA_INIT 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 request from the initiator to the new VPN gateway to indicate the IP
address of the original VPN gateway that redirected the initiator. address of the original VPN gateway that redirected the initiator.
The original VPN gateway's IP address is included in the message. The original VPN gateway's IP address is included in the message.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Payload |C| RESERVED | Payload Length | | Next Payload |C| RESERVED | Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol ID | SPI Size (=0) | Notify Message Type | | Protocol ID | SPI Size (=0) | Notify Message Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GW Ident Type | | | GW Ident Type | GW Ident Len | |
+---------------+ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~
~ Original Responder GW Identity ~ ~ Original Responder GW Identity ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The 'Next Payload', 'Payload Length', 'Protocol ID', 'SPI Size' and The 'Next Payload', 'Payload Length', 'Protocol ID', 'SPI Size' and
the 'Notify Message Type' fields are the same as described in Section 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 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' MUST 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 set to 0, since the notification is not specific to a particular
security association. security association.
skipping to change at page 10, line 25 skipping to change at page 10, line 44
gateway is sent in the message. The 'Notify Message Type' field is gateway is sent in the message. The 'Notify Message Type' field is
set to indicate the REDIRECTED_FROM payload <value to be assigned by set to indicate the REDIRECTED_FROM payload <value to be assigned by
IANA>. The 'GW Identity Type' field indicates the type of IANA>. The 'GW Identity Type' field indicates the type of
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 'GW Ident Len' field is set to the length of the gateway identity
Responder GW Identity' field. information. The identity of the original VPN gateway is carried in
the 'Original Responder GW Identity' field.
7. Use of the Redirect Mechanism between IKEv2 Peers 8. Use of the Redirect Mechanism between IKEv2 Peers
The Redirect mechanism described in this document is mainly intended The Redirect mechanism described in this document is mainly intended
for use in client-gateway scenarios. However, the mechanism can also for use in client-gateway scenarios. However, the mechanism can also
be used between any two IKEv2 peers. But this protocol is be used between any two IKEv2 peers. But this protocol is
asymmetric, meaning that only the original responder can redirect the asymmetric, meaning that only the original responder can redirect the
original initiator to another server. original initiator to another server.
8. Security Considerations 9. 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
skipping to change at page 11, line 22 skipping to change at page 11, line 40
MUST NOT result in the modification of the PAD entries on the client. MUST NOT result in the modification of the PAD entries on the client.
The new gateway, to which the client is redirected to should be The new gateway, to which the client is redirected to should be
subject to the same authentication and authorization requirements as subject to the same authentication and authorization requirements as
the original gateway. To support a scenario where the FQDN of the the original gateway. To support a scenario where the FQDN of the
gateway is in the client's PAD entry and the client is redirected to gateway is in the client's PAD entry and the client is redirected to
another gateway in the same administrative domain, one can either another gateway in the same administrative domain, one can either
configure all the possible gateways from the domain or use a wildcard configure all the possible gateways from the domain or use a wildcard
entry like, for example, GW*.example.com, in the client's entry like, for example, GW*.example.com, in the client's
corresponding PAD entry. corresponding PAD entry.
9. IANA Considerations 10. 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 three Notify Message Types must be described in Section 7. 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
10. Acknowledgements 11. Acknowledgements
The use of anycast address with IKEv2 was first described in [7]. 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 was then added to an early draft version of RFC 5026 and later
removed before the RFC was published. Therefore the authors of [7] removed before the RFC was published. Therefore the authors of [7]
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 and other comments suggesting the use of REDIRECTED_FROM payload and other comments
which helped improve the document. The authors would also like to which helped improve the document. The authors would also like to
thank Yaron Sheffer, Sunil Kumar, Fan Zhao, Yoav Nir, Richard thank Yaron Sheffer, Sunil Kumar, Fan Zhao, Yoav Nir, Richard
Graveman, Kanagavel Rajan, Srini Addepalli, and Arnaud Ebalard for Graveman, Kanagavel Rajan, Srini Addepalli, and Arnaud Ebalard for
their reviews and comments. their reviews and comments.
11. References 12. References
11.1. Normative References 12.1. 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.
11.2. Informative References 12.2. 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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