draft-ietf-ipsecme-ikev2-redirect-04.txt   draft-ietf-ipsecme-ikev2-redirect-05.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 13, 2009 February 9, 2009 Expires: September 10, 2009 March 9, 2009
Re-direct Mechanism for IKEv2 Redirect Mechanism for IKEv2
draft-ietf-ipsecme-ikev2-redirect-04.txt draft-ietf-ipsecme-ikev2-redirect-05.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. 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 Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 13, 2009. This Internet-Draft will expire on September 10, 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 in effect on the date of
(http://trustee.ietf.org/license-info) in effect on the date of publication of this document (http://trustee.ietf.org/license-info).
publication of this document. Please review these documents Please review these documents carefully, as they describe your rights
carefully, as they describe your rights and restrictions with respect and restrictions with respect to this document.
to this document.
Abstract Abstract
IKEv2 is a protocol for setting up VPN tunnels from a remote location IKEv2 is a protocol for setting up VPN tunnels from a remote location
to a gateway so that the VPN client can access services in the to a gateway so that the VPN client can access services in the
network behind the gateway. Currently there is no standard mechanism network behind the gateway. Currently there is no standard mechanism
specified that allows an overloaded VPN gateway or a VPN gateway that specified that allows an overloaded VPN gateway or a VPN gateway that
is being shut down for maintenance to re-direct the VPN client to is being shut down for maintenance to redirect the VPN client to
attach to another gateway. This document proposes a re-direct 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 re-direct 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 Exchange with Redirect . . . . . . . . . . . . . . . . . 4
4. Use of Anycast Addresses with the Re-direct 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 Messages . . . . . . . . . . . . . . . . . . . . . . 7
6.1. REDIRECT_SUPPORTED . . . . . . . . . . . . . . . . . . . . 7 6.1. REDIRECT_SUPPORTED . . . . . . . . . . . . . . . . . . . . 7
6.2. REDIRECT . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.2. REDIRECT . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.3. REDIRECTED_FROM . . . . . . . . . . . . . . . . . . . . . 9 6.3. REDIRECTED_FROM . . . . . . . . . . . . . . . . . . . . . 9
7. Use of the Redirect Mechanism between IKEv2 Peers . . . . . . 10 7. Use of the Redirect Mechanism between IKEv2 Peers . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative References . . . . . . . . . . . . . . . . . . . 11 11.1. Normative References . . . . . . . . . . . . . . . . . . . 11
11.2. Informative References . . . . . . . . . . . . . . . . . . 11 11.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 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 redirect mechanism for IKEv2 that enables a
VPN gateway to re-direct 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 re-direct 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 during the IKE_SA_INIT or the IKE_AUTH exchange. Gateway-
initiated re-direct in the middle of a session is also supported. initiated redirect in the middle of a session is also supported. The
The re-direct mechanism can also be used in conjunction with anycast redirect mechanism can also be used in conjunction with anycast
addresses. In this case, anycast address for the cluster of VPN addresses. In this case, anycast address for the cluster of VPN
gateways is stored in the DNS instead of a list of unicast IP gateways is stored in the DNS instead of a list of unicast IP
addresses of the VPN gateways. addresses of the VPN gateways.
The re-direct 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 re-directing 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 be also be used by a
Mobile IPv6 home agent to re-direct a mobile node to another home Mobile IPv6 home agent to redirect a mobile node to another home
agent. agent.
There is a Home Agent Switch mechanism available for re-directing 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 re-directed 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 re-directing 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 Exchange with Redirect
skipping to change at page 4, line 39 skipping to change at page 4, line 39
(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. The VPN client includes
the IP address of the original VPN gateway that re-directed the the IP address of the original VPN gateway that redirected the
client. The IKEv2 exchange then proceeds as normal with the selected client. The IKEv2 exchange then proceeds as normal with the selected
VPN gateway. 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)
skipping to change at page 5, line 31 skipping to change at page 5, line 31
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, a mobile node's
security associations with its home agent may expire while it still security associations with its home agent may expire while it still
has a valid binding cache entry at the home agent. In this case, the has a valid binding cache entry at the home agent. In this case, the
mobile node MUST NOT use the original home agent address as the mobile node MUST NOT use the original home agent address as the
destination address in the IKE_SA_INIT exchange to setup new security destination address in the IKE_SA_INIT exchange to setup new security
associations. It MUST try to setup security associations with its associations. It MUST try to setup security associations with its
existing home agent. existing home agent.
4. Use of Anycast Addresses with the Re-direct 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.
If an anycast address is returned in response to DNS resolution of an If an anycast address is returned in response to DNS resolution of an
FQDN, the IKEv2 transaction between the VPN client and the VPN FQDN, the VPN client sends the IKE_SA_INIT request to the anycast
gateway is slightly modified. The VPN client sends the IKE_SA_INIT address. The IKE_SA_INIT request is routed to one of the VPN
request to the anycast address. The IKE_SA_INIT request is routed to gateways that is part of the anycast group. The VPN gateway that
one of the VPN gateways that is part of the anycast group. The VPN receives the IKE_SA_INIT request responds with an IKE_SA_INIT reply
gateway that receives the IKE_SA_INIT request responds with an from the anycast address.
IKE_SA_INIT reply from the anycast address.
Initiator Responder (any VPN GW) Initiator Responder (any VPN GW)
--------- ------------------------- --------- -------------------------
(IP_I:500 -> ANYCAST:500) (IP_I:500 -> ANYCAST:500)
HDR(A,0), SAi1, KEi, Ni) --> HDR(A,0), SAi1, KEi, Ni) -->
N(REDIRECT_SUPPORTED) N(REDIRECT_SUPPORTED)
(ANYCAST:500 -> IP_I:500) (ANYCAST:500 -> IP_I:500)
<-- HDR(A,0), N(REDIRECT, IP_R) <-- HDR(A,0), N(REDIRECT, IP_R)
If the destination address on the IKE_SA_INIT request is an anycast If the destination address on the IKE_SA_INIT request is an anycast
address, the VPN gateway that received the IKE_SA_INIT request MUST address, the VPN gateway that received the IKE_SA_INIT request MUST
include the REDIRECT payload to re-direct the VPN client to a unicast include the REDIRECT payload to redirect the VPN client to a unicast
address of one of the VPN gateway. The VPN gateway that received the address of one of the VPN gateway. The VPN gateway that received the
IKE_SA_INIT request MAY re-direct the client to its own unicast IKE_SA_INIT request MAY redirect the client to its own unicast
address, if it is not overloaded. address, if it is not overloaded.
The rest of the IKEv2 exchange is the same as described in Section 3. The rest of the IKEv2 exchange is the same as described in Section 3.
5. Gateway Initiated Redirect 5. Gateway Initiated Redirect
The re-direct mechanism may also be used by a VPN gateway to re- The redirect mechanism may also be used by a VPN gateway to redirect
direct the client to another VPN gateway in middle of a session. To the client to another VPN gateway in middle of a session. To
re-direct a client, the gateway should send an INFORMATIONAL message redirect a client, the gateway should send an INFORMATIONAL message
with the REDIRECT Notify payload. The REDIRECT payload MUST carry with the REDIRECT Notify payload. The REDIRECT payload MUST carry
information about the new VPN gateway. When the client receives this information about the new VPN gateway. When the client receives this
message, it MUST send an empty message as an acknowledgement. Until message, it MUST send an empty message as an acknowledgement. Until
the client responds with an acknowledgement, the gateway SHOULD re- the client responds with an acknowledgement, the gateway SHOULD re-
transmit the re-direct INFORMATIONAL message as described in [2]. transmit the redirect INFORMATIONAL message as described in [2]. The
The following illustrates the INFORMATIONAL message exchange for following illustrates the INFORMATIONAL message exchange for gateway-
gateway-initiated redirect. initiated redirect.
Initiator (VPN client) Responder (VPN GW) Initiator (VPN client) Responder (VPN GW)
---------------------- ------------------ ---------------------- ------------------
<-- HDR, SK {N[REDIRECT, IP_R/FQDN_R]} <-- HDR, SK {N[REDIRECT, IP_R/FQDN_R]}
HDR, SK {} --> HDR, SK {} -->
The INFORMATIONAL message exchange described above is protected by The INFORMATIONAL message exchange described above is protected by
the existing IKEv2 SA between the client and the gateway. the existing IKEv2 SA between the client and the gateway.
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, again by sending an Informational message
for the client to setup the required security associations with the with a DELETE payload. However, it should allow sufficient time for
new security gateway. This time period should be configurable on the the client to setup the required security associations with 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 If the gateway decides to redirect the client during the IKE_AUTH
exchange, it prevents the creation of a CHILD SA by sending the exchange, it prevents the creation of a CHILD SA by sending the
NO_ADDITIONAL_SAS Notify Payload in the IKE_AUTH response. It then NO_ADDITIONAL_SAS Notify Payload in the IKE_AUTH response. It then
follows up with an INFORMATIONAL message with the REDIRECT payload follows up with an INFORMATIONAL message with the REDIRECT payload
immediately. The following shows the message exchange between the immediately. The following shows the message exchange between the
client and the gateway. client and the gateway.
Initiator Responder ( VPN GW) Initiator Responder ( VPN GW)
--------- ------------------- --------- -------------------
(IP_I:500 -> IP_R:500) (IP_I:500 -> IP_R:500)
skipping to change at page 7, line 49 skipping to change at page 7, line 50
the IKEv2 SA. In case the gateway receives the INFORMATIONAL message the IKEv2 SA. In case the gateway receives the INFORMATIONAL message
to delete the IKEv2 SA before sending the REDIRECT message, then the to delete the IKEv2 SA before sending the REDIRECT message, then the
gateway includes the REDIRECT payload in the response along with the gateway includes the REDIRECT payload in the response along with the
DELETE payload. 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 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol ID | SPI Size (=0) | Notify Message Type | | Protocol ID | SPI Size (=0) | Notify Message Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 SPI is not present in this message. The 'Protocol ID' should 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 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 6.2. 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 when the responder wants to re-direct the initiator to responder or an INFORMATIONAL message from the responder, when the
another VPN gateway. The message includes the new responder's IP responder wants to redirect the initiator to another VPN gateway.
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 | |
+---------------+ ~ +---------------+ ~
~ New Responder GW Identity ~ ~ New 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 SPI is not present in this message. The 'Protocol ID' should 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 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 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 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 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 length of the FQDN plus the fixed fields in the message. The '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
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.
skipping to change at page 9, line 20 skipping to change at page 9, line 27
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 identity of the new VPN gateway is carried in the 'New Responder
GW Identity' field. GW Identity' field.
6.3. REDIRECTED_FROM 6.3. 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 re-directed 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 | |
+---------------+ ~ +---------------+ ~
~ 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 SPI is not present in this message. The 'Protocol ID' should 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' The 'Payload Length' field MUST be set to either '13' or '25'
depending on whether an IPv4 or IPv6 address of the original VPN depending on whether an IPv4 or IPv6 address of the original VPN
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 identity of the original VPN gateway is carried in the 'Original
Responder GW Identity' field. Responder GW Identity' field.
7. Use of the Redirect Mechanism between IKEv2 Peers 7. Use of the Redirect Mechanism between IKEv2 Peers
The Re-direct 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. This is especially useful for be used between any two IKEv2 peers. But this protocol is
IKEv2 sessions between two gateway peer routers. asymmetric, meaning that only the original responder can redirect the
original initiator to another server.
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 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 redirecting 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.
9. 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 three 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
skipping to change at page 11, line 26 skipping to change at page 11, line 19
10. 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 and other comments
also like to thank Yaron Sheffer, Sunil Kumar, Fan Zhao, Yoav Nir and which helped improve the document. The authors would also like to
Arnaud Ebalard for their reviews and comments. thank Yaron Sheffer, Sunil Kumar, Fan Zhao, Yoav Nir, Richard
Graveman, and Arnaud Ebalard for their reviews and comments.
11. References 11. References
11.1. 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.
 End of changes. 35 change blocks. 
76 lines changed or deleted 71 lines changed or added

This html diff was produced by rfcdiff 1.35. The latest version is available from http://tools.ietf.org/tools/rfcdiff/