< draft-pauly-ipsecme-tcp-encaps-03.txt   draft-pauly-ipsecme-tcp-encaps-04.txt >
Network T. Pauly Network T. Pauly
Internet-Draft Apple Inc. Internet-Draft Apple Inc.
Intended status: Standards Track S. Touati Intended status: Standards Track S. Touati
Expires: August 18, 2016 Ericsson Expires: October 27, 2016 Ericsson
R. Mantha R. Mantha
Cisco Systems Cisco Systems
February 15, 2016 April 25, 2016
TCP Encapsulation of IKEv2 and IPSec Packets TCP Encapsulation of IKEv2 and IPSec Packets
draft-pauly-ipsecme-tcp-encaps-03 draft-pauly-ipsecme-tcp-encaps-04
Abstract Abstract
This document describes a method to transport IKEv2 and IPSec packets This document describes a method to transport IKEv2 and IPSec packets
over a TCP connection for traversing network middleboxes that may over a TCP connection for traversing network middleboxes that may
block IKEv2 negotiation over UDP. This method, referred to as TCP block IKEv2 negotiation over UDP. This method, referred to as TCP
encapsulation, involves sending all packets for tunnel establishment encapsulation, involves sending all packets for tunnel establishment
as well as tunneled packets over a TCP connection. This method is as well as tunneled packets over a TCP connection. This method is
intended to be used as a fallback option when IKE cannot be intended to be used as a fallback option when IKE cannot be
negotiated over UDP. negotiated over UDP.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on August 18, 2016. This Internet-Draft will expire on October 27, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Prior Work and Motivation . . . . . . . . . . . . . . . . 3 1.1. Prior Work and Motivation . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Configuration . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Configuration . . . . . . . . . . . . . . . . . . . . . . . . 4
3. TCP-Encapsulated Header Formats . . . . . . . . . . . . . . . 5 3. TCP-Encapsulated Header Formats . . . . . . . . . . . . . . . 5
3.1. TCP-Encapsulated IKEv2 Header Format . . . . . . . . . . 5 3.1. TCP-Encapsulated IKEv2 Header Format . . . . . . . . . . 5
3.2. TCP-Encapsulated ESP Header Format . . . . . . . . . . . 6 3.2. TCP-Encapsulated ESP Header Format . . . . . . . . . . . 6
4. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 6 4. TCP-Encapsulated Stream Prefix . . . . . . . . . . . . . . . 6
5. Connection Establishment and Teardown . . . . . . . . . . . . 6 5. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Interaction with NAT Detection Payloads . . . . . . . . . . . 8 6. Connection Establishment and Teardown . . . . . . . . . . . . 7
7. Using MOBIKE with TCP encapsulation . . . . . . . . . . . . . 8 7. Interaction with NAT Detection Payloads . . . . . . . . . . . 8
8. Using IKEv2 Message Fragmentation with TCP encapsulation . . 8 8. Using MOBIKE with TCP encapsulation . . . . . . . . . . . . . 8
9. Considerations for Keep-alives and DPD . . . . . . . . . . . 9 9. Using IKEv2 Message Fragmentation with TCP encapsulation . . 9
10. Middlebox Considerations . . . . . . . . . . . . . . . . . . 9 10. Considerations for Keep-alives and DPD . . . . . . . . . . . 9
11. Performance Considerations . . . . . . . . . . . . . . . . . 10 11. Middlebox Considerations . . . . . . . . . . . . . . . . . . 9
11.1. TCP-in-TCP . . . . . . . . . . . . . . . . . . . . . . . 10 12. Performance Considerations . . . . . . . . . . . . . . . . . 10
11.2. Added Reliability for Unreliable Protocols . . . . . . . 10 12.1. TCP-in-TCP . . . . . . . . . . . . . . . . . . . . . . . 10
11.3. Encryption Overhead . . . . . . . . . . . . . . . . . . 10 12.2. Added Reliability for Unreliable Protocols . . . . . . . 10
11.4. Quality of Service Markings . . . . . . . . . . . . . . 11 12.3. Quality of Service Markings . . . . . . . . . . . . . . 10
11.5. Maximum Segment Size . . . . . . . . . . . . . . . . . . 11 12.4. Maximum Segment Size . . . . . . . . . . . . . . . . . . 10
12. Security Considerations . . . . . . . . . . . . . . . . . . . 11 13. Security Considerations . . . . . . . . . . . . . . . . . . . 11
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
15.1. Normative References . . . . . . . . . . . . . . . . . . 12 16.1. Normative References . . . . . . . . . . . . . . . . . . 11
15.2. Informative References . . . . . . . . . . . . . . . . . 12 16.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Example exchanges of TCP Encapsulation with TLS . . 13 Appendix A. Using TCP encapsulation with TLS . . . . . . . . . . 12
A.1. Establishing an IKEv2 session . . . . . . . . . . . . . . 13 Appendix B. Example exchanges of TCP Encapsulation with TLS . . 13
A.2. Deleting an IKEv2 session . . . . . . . . . . . . . . . . 15 B.1. Establishing an IKEv2 session . . . . . . . . . . . . . . 13
A.3. Re-establishing an IKEv2 session . . . . . . . . . . . . 16 B.2. Deleting an IKEv2 session . . . . . . . . . . . . . . . . 15
A.4. Using MOBIKE between UDP and TCP Encapsulation . . . . . 16 B.3. Re-establishing an IKEv2 session . . . . . . . . . . . . 16
B.4. Using MOBIKE between UDP and TCP Encapsulation . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
IKEv2 [RFC7296] is a protocol for establishing IPSec tunnels, using IKEv2 [RFC7296] is a protocol for establishing IPSec tunnels, using
IKE messages over UDP for control traffic, and using Encapsulating IKE messages over UDP for control traffic, and using Encapsulating
Security Payload (ESP) messages for its data traffic. Many network Security Payload (ESP) messages for its data traffic. Many network
middleboxes that filter traffic on public hotspots block all UDP middleboxes that filter traffic on public hotspots block all UDP
traffic, including IKEv2 and IPSec, but allow TCP connections through traffic, including IKEv2 and IPSec, but allow TCP connections through
since they appear to be web traffic. Devices on these networks that since they appear to be web traffic. Devices on these networks that
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initiator and the receiver, then subsequent IKEv2 packets are initiator and the receiver, then subsequent IKEv2 packets are
sent over UDP port 4500 with four bytes of zero at the start of sent over UDP port 4500 with four bytes of zero at the start of
the UDP payload and ESP packets are sent out over UDP port the UDP payload and ESP packets are sent out over UDP port
4500. Some peers default to using UDP encapsulation even when 4500. Some peers default to using UDP encapsulation even when
no NAT are detected on the path as some middleboxes do not no NAT are detected on the path as some middleboxes do not
support IP protocols other than TCP and UDP. support IP protocols other than TCP and UDP.
3. TCP Encapsulation. If both of the other two methods are not 3. TCP Encapsulation. If both of the other two methods are not
available or appropriate, both IKEv2 negotiation packets as available or appropriate, both IKEv2 negotiation packets as
well as ESP packets can be sent over a single TCP connection to well as ESP packets can be sent over a single TCP connection to
the peer. This connection can itself use TLS [RFC5246] or the peer.
other methods if needed. If the connection uses TLS, it will
also be capable of traversing a web proxy [RFC2817].
Direct use of ESP or UDP Encapsulation SHOULD be preferred by IKEv2 Direct use of ESP or UDP Encapsulation should be preferred by IKEv2
implementations due to performance concerns when using TCP implementations due to performance concerns when using TCP
Encapsulation Section 11. Most implementations should use TCP Encapsulation Section 12. Most implementations should use TCP
Encapsulation only on networks where negotiation over UDP has been Encapsulation only on networks where negotiation over UDP has been
attempted without receiving responses from the peer, or if a network attempted without receiving responses from the peer, or if a network
is known to not support UDP. is known to not support UDP.
1.1. Prior Work and Motivation 1.1. Prior Work and Motivation
Encapsulating IKEv2 connections within TCP or TLS streams is a common Encapsulating IKEv2 connections within TCP streams is a common
approach to solve the problem of UDP packets being blocked by network approach to solve the problem of UDP packets being blocked by network
middleboxes. The goal of this document is to promote middleboxes. The goal of this document is to promote
interoperability by providing a standard method of framing IKEv2 and interoperability by providing a standard method of framing IKEv2 and
ESP message within streams, and to provide guidelines for how to ESP message within streams, and to provide guidelines for how to
configure and use TCP encapsulation. configure and use TCP encapsulation.
Some previous solutions include: Some previous solutions include:
Cellular Network Access Interworking Wireless LAN (IWLAN) uses IKEv2 Cellular Network Access Interworking Wireless LAN (IWLAN) uses IKEv2
to create secure connections to cellular carrier networks for to create secure connections to cellular carrier networks for
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exchange. Instead, support for TCP encapsulation must be pre- exchange. Instead, support for TCP encapsulation must be pre-
configured on both the initiator and the responder. configured on both the initiator and the responder.
The configuration defined on each peer should include the following The configuration defined on each peer should include the following
parameters: parameters:
o One or more TCP ports on which the responder will listen for o One or more TCP ports on which the responder will listen for
incoming connections. Note that the initiator may initiate TCP incoming connections. Note that the initiator may initiate TCP
connections to the responder from any local port. connections to the responder from any local port.
o Whether or not to use TLS for connections to a given TCP port. o Optionally, an extra framing protocol to use on top of TCP to
The responder may expect to read encapsulated IKEv2 and ESP further encapsulate the stream of IKEv2 and IPSec packets. See
packets directly from the TCP connection, or it may expect to read Appendix A for a detailed discussion.
them from a stream of TLS data packets. The initiator should be
pre-configured to use TLS or not when communicating with a given
port on the responder.
This document leaves the selection of TCP ports up to This document leaves the selection of TCP ports up to
implementations. If TLS is configured, many implementations will implementations. It's suggested to use TCP port 4500, which is
select to listen on TCP port 443 in order to traverse firewalls. If
TLS is not used, it is suggested to use TCP port 4500, which is
allocated for IPSec NAT Traversal. allocated for IPSec NAT Traversal.
Since TCP encapsulation of IKEv2 and IPSec packets adds overhead and Since TCP encapsulation of IKEv2 and IPSec packets adds overhead and
has potential performance trade-offs compared to direct or UDP- has potential performance trade-offs compared to direct or UDP-
encapsulated tunnels (as described in Performance Considerations, encapsulated tunnels (as described in Performance Considerations,
Section 11), when possible, implementations SHOULD prefer IKEv2 Section 12), when possible, implementations SHOULD prefer IKEv2
direct or UDP encapsulated tunnels over TCP encapsulated tunnels. direct or UDP encapsulated tunnels over TCP encapsulated tunnels.
3. TCP-Encapsulated Header Formats 3. TCP-Encapsulated Header Formats
In order to encapsulate IKEv2 and ESP messages within a stream (which In order to encapsulate IKEv2 and ESP messages within a TCP stream, a
may be raw TCP, or TLS over TCP), a 32-bit length field precedes 16-bit length field precedes every message. If the first 32-bits of
every message. If the first 32-bits of the message are zeros (a Non- the message are zeros (a Non-ESP Marker), then the contents comprise
ESP Marker), then the contents comprise an IKEv2 message. Otherwise, an IKEv2 message. Otherwise, the contents comprise an ESP message.
the contents comprise an ESP message. Authentication Header (AH) Authentication Header (AH) messages are not supported for TCP
messages are not supported for TCP encapsulation. encapsulation.
Although a TCP stream may be able to send very long messages, Although a TCP stream may be able to send very long messages,
implementations SHOULD limit message lengths to typical UDP datagram implementations SHOULD limit message lengths to typical UDP datagram
ESP payload lengths. The maximum message length is used as the ESP payload lengths. The maximum message length is used as the
effective MTU for connections that are being encrypted using ESP, so effective MTU for connections that are being encrypted using ESP, so
the maximum message length will influence characteristics of inner the maximum message length will influence characteristics of inner
connections, such as the TCP Maximum Segment Size (MSS). connections, such as the TCP Maximum Segment Size (MSS).
3.1. TCP-Encapsulated IKEv2 Header Format 3.1. TCP-Encapsulated IKEv2 Header Format
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Non-ESP Marker | | Non-ESP Marker |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IKEv2 header [RFC7296] | | |
~ ~ ~ IKEv2 header [RFC7296] ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 Figure 1
The IKE header is preceded by a 32-bit length field in network byte The IKE header is preceded by a 16-bit length field in network byte
order that specifies the length of the IKE packet within the TCP order that specifies the length of the IKE packet within the TCP
stream. As with IKEv2 over UDP port 4500, a zeroed 32-bit Non-ESP stream. As with IKEv2 over UDP port 4500, a zeroed 32-bit Non-ESP
Marker is inserted before the start of the IKEv2 header in order to Marker is inserted before the start of the IKEv2 header in order to
differentiate the traffic from ESP traffic between the same addresses differentiate the traffic from ESP traffic between the same addresses
and ports. and ports.
o Length (4 octets, unsigned integer) - Length of the IKE packet o Length (2 octets, unsigned integer) - Length of the IKE packet
including the Length Field and Non-ESP Marker. including the Length Field and Non-ESP Marker.
3.2. TCP-Encapsulated ESP Header Format 3.2. TCP-Encapsulated ESP Header Format
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ESP header [RFC4303] | | |
~ ~ ~ ESP header [RFC4303] ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2 Figure 2
The ESP header is preceded by a 32-bit length field in network byte The ESP header is preceded by a 16-bit length field in network byte
order that specifies the length of the ESP packet within the TCP order that specifies the length of the ESP packet within the TCP
stream. stream.
o Length (4 octets, unsigned integer) - Length of the ESP packet o Length (2 octets, unsigned integer) - Length of the ESP packet
including the Length Field. including the Length Field.
4. Applicability 4. TCP-Encapsulated Stream Prefix
Each TCP stream used for IKEv2 and IPSec encapsulation MUST begin
with a fixed sequence of five bytes as a magic value, containing the
characters "IKEv2" as ASCII values. This allows peers to
differentiate this protocol from other protocols that may be run over
TCP streams, since the value does not overlap with the valid start of
any other known stream protocol. This value is only sent once, by
the Initiator only, at the beginning of any TCP stream.
0 1 2 3 4
+------+------+------+------+------+
| 0x69 | 0x6b | 0x65 | 0x76 | 0x32 |
+------+------+------+------+------+
Figure 3
5. Applicability
TCP encapsulation is applicable only when it has been configured to TCP encapsulation is applicable only when it has been configured to
be used with specific IKEv2 peers. If a responder is configured to be used with specific IKEv2 peers. If a responder is configured to
use TCP encapsulation, it MUST listen on the configured port(s) in use TCP encapsulation, it MUST listen on the configured port(s) in
case any peers will initiate new IKEv2 sessions. Initiators MAY use case any peers will initiate new IKEv2 sessions. Initiators MAY use
TCP encapsulation for any IKEv2 session to a peer that is configured TCP encapsulation for any IKEv2 session to a peer that is configured
to support TCP encapsulation, although it is recommended that to support TCP encapsulation, although it is recommended that
initiators should only use TCP encapsulation when traffic over UDP is initiators should only use TCP encapsulation when traffic over UDP is
blocked. blocked.
Any specific IKE SA, along with its Child SAs, is either TCP Any specific IKE SA, along with its Child SAs, is either TCP
encapsulated or not. A mix of TCP and UDP encapsulation for a single encapsulated or not. A mix of TCP and UDP encapsulation for a single
SA is not allowed. The exception to this rule is SAs that are SA is not allowed.
migrated between addresses using MOBIKE Section 7.
5. Connection Establishment and Teardown 6. Connection Establishment and Teardown
When the IKEv2 initiator uses TCP encapsulation for its negotiation, When the IKEv2 initiator uses TCP encapsulation for its negotiation,
it will initiate a TCP connection to the responder using the it will initiate a TCP connection to the responder using the
configured TCP port. If TLS is being used, it will be negotiated at configured TCP port. The first bytes sent on the stream MUST be the
this point. If a web proxy is applied to the ports for the TCP stream prefix value [Section 4]. After this prefix, encapsulated
connection, and TLS is being used, the initiator can send an HTTP IKEv2 messages will negotiate the IKE SA and initial Child SA
CONNECT message to establish a tunnel through the proxy [RFC2817]. [RFC7296]. After this point, both encapsulated IKE Figure 1 and ESP
Figure 2 messages will be sent over the TCP connection.
Once this connection is established, encapsulated IKEv2 messages will
negotiate the IKE SA and initial Child SA [RFC7296]. After this
point, both encapsulated IKE Figure 1 and ESP Figure 2 messages will
be sent over the TCP connection.
In order to close an IKE session, either the initiator or responder In order to close an IKE session, either the initiator or responder
SHOULD gracefully tear down IKE SAs with DELETE payloads. Once all SHOULD gracefully tear down IKE SAs with DELETE payloads. Once all
SAs have been deleted, the initiator of the original connection MUST SAs have been deleted, the initiator of the original connection MUST
close the TCP connection. close the TCP connection.
An unexpected FIN or a RST on the TCP connection may indicate either An unexpected FIN or a RST on the TCP connection may indicate either
a loss of connectivity, an attack, or some other error. If a DELETE a loss of connectivity, an attack, or some other error. If a DELETE
payload has not been sent, both sides SHOULD maintain the state for payload has not been sent, both sides SHOULD maintain the state for
their SAs for the standard lifetime or time-out period. The original their SAs for the standard lifetime or time-out period. The original
initiator (that is, the endpoint that initiated the TCP connection initiator (that is, the endpoint that initiated the TCP connection
and sent the first IKE_SA_INIT message) is responsible for re- and sent the first IKE_SA_INIT message) is responsible for re-
establishing the TCP connection if it is torn down for any unexpected establishing the TCP connection if it is torn down for any unexpected
reason. Since new TCP connections may use different ports due to NAT reason. Since new TCP connections may use different ports due to NAT
mappings or local port allocations changing, the responder MUST allow mappings or local port allocations changing, the responder MUST allow
packets for existing SAs to be received from new source ports. packets for existing SAs to be received from new source ports.
If TLS is being used, TLS must be re-negotiated on any new TCP A peer MUST discard a partially received message due to a broken
connections created due to a broken connection. TLS Session
Resumption is recommended to improve efficiency.
A peer must discard a partially received message due to a broken
connection. connection.
The streams of data sent over any TCP connection used for this The streams of data sent over any TCP connection used for this
protocol MUST begin with a complete message, which is either an protocol MUST begin with the stream prefix value followed by a
encapsulated IKE or ESP message. If the connection is being used to complete message, which is either an encapsulated IKE or ESP message.
resume a previous IKE session, the responder can recognize the If the connection is being used to resume a previous IKE session, the
session using either the IKE SPI from an encapsulated IKE message or responder can recognize the session using either the IKE SPI from an
the ESP SPI from an encapsulated ESP message. If the session had encapsulated IKE message or the ESP SPI from an encapsulated ESP
been fully established previously, it is suggested that the initiator message. If the session had been fully established previously, it is
send an UPDATE_SA_ADDRESSES message if MOBIKE is supported, or an suggested that the initiator send an UPDATE_SA_ADDRESSES message if
INFORMATIONAL message (a keepalive) otherwise. If either initiator MOBIKE is supported, or an INFORMATIONAL message (a keepalive)
or responder receives a stream that cannot be parsed correctly, it otherwise. If either initiator or responder receives a stream that
MUST close the TCP connection. cannot be parsed correctly, it MUST close the TCP connection.
Multiple TCP connections between the initiator and the responder are Multiple TCP connections between the initiator and the responder are
allowed, but their use must take into account the initiator allowed, but their use must take into account the initiator
capabilities and the deployment model such as to connect to multiple capabilities and the deployment model such as to connect to multiple
gateways handling different ESP SAs when deployed in a high gateways handling different ESP SAs when deployed in a high
availability model. It is also possible to negotiate multiple IKE availability model. It is also possible to negotiate multiple IKE
SAs over the same TCP connection. SAs over the same TCP connection.
The processing of the TCP packets is the same whether its within a The processing of the TCP packets is the same whether its within a
single or multiple TCP connections. single or multiple TCP connections.
6. Interaction with NAT Detection Payloads 7. Interaction with NAT Detection Payloads
When negotiating over UDP port 500, IKE_SA_INIT packets include When negotiating over UDP port 500, IKE_SA_INIT packets include
NAT_DETECTION_SOURCE_IP and NAT_DETECTION_DESTINATION_IP payloads to NAT_DETECTION_SOURCE_IP and NAT_DETECTION_DESTINATION_IP payloads to
determine if UDP encapsulation of IPSec packets should be used. determine if UDP encapsulation of IPSec packets should be used.
These payloads contain SHA-1 digests of the SPIs, IP addresses, and These payloads contain SHA-1 digests of the SPIs, IP addresses, and
ports. IKE_SA_INIT packets sent on a TCP connection SHOULD include ports. IKE_SA_INIT packets sent on a TCP connection SHOULD include
these payloads, and SHOULD use the applicable TCP ports when creating these payloads, and SHOULD use the applicable TCP ports when creating
and checking the SHA-1 digests. and checking the SHA-1 digests.
If a NAT is detected due to the SHA-1 digests not matching the If a NAT is detected due to the SHA-1 digests not matching the
expected values, no change should be made for encapsulation of expected values, no change should be made for encapsulation of
subsequent IKEv2 or ESP packets, since TCP encapsulation inherently subsequent IKEv2 or ESP packets, since TCP encapsulation inherently
supports NAT traversal. Implementations MAY use the information that supports NAT traversal. Implementations MAY use the information that
a NAT is present to influence keep-alive timer values. a NAT is present to influence keep-alive timer values.
7. Using MOBIKE with TCP encapsulation 8. Using MOBIKE with TCP encapsulation
When an IKEv2 session is transitioned between networks using MOBIKE When an IKEv2 session is transitioned between networks using MOBIKE
[RFC4555], the initiator of the transition may switch between using [RFC4555], the initiator of the transition may switch between using
TCP encapsulation, UDP encapsulation, or no encapsulation. TCP encapsulation, UDP encapsulation, or no encapsulation.
Implementations that implement both MOBIKE and TCP encapsulation MUST Implementations that implement both MOBIKE and TCP encapsulation MUST
support dynamically enabling and disabling TCP encapsulation as support dynamically enabling and disabling TCP encapsulation as
interfaces change. interfaces change.
The encapsulation method of ESP packets MUST always match the The encapsulation method of ESP packets MUST always match the
encapsulation method of the IKEv2 negotiation, which may be different encapsulation method of the IKEv2 negotiation, which may be different
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SHOULD be sent out first over UDP before attempting over TCP. If SHOULD be sent out first over UDP before attempting over TCP. If
there is a response to the UPDATE_SA_ADDRESSES notification sent over there is a response to the UPDATE_SA_ADDRESSES notification sent over
UDP, then the ESP packets should be sent directly over IP or over UDP UDP, then the ESP packets should be sent directly over IP or over UDP
port 4500 (depending on if a NAT was detected), regardless of if a port 4500 (depending on if a NAT was detected), regardless of if a
connection on a previous network was using TCP encapsulation. connection on a previous network was using TCP encapsulation.
Similarly, if the responder only responds to the UPDATE_SA_ADDRESSES Similarly, if the responder only responds to the UPDATE_SA_ADDRESSES
notification over TCP, then the ESP packets should be sent over the notification over TCP, then the ESP packets should be sent over the
TCP connection, regardless of if a connection on a previous network TCP connection, regardless of if a connection on a previous network
did not use TCP encapsulation. did not use TCP encapsulation.
8. Using IKEv2 Message Fragmentation with TCP encapsulation 9. Using IKEv2 Message Fragmentation with TCP encapsulation
IKEv2 Message Fragmentation [RFC7383] is not required when using TCP IKEv2 Message Fragmentation [RFC7383] is not required when using TCP
encapsulation, since a TCP stream already handles the fragmentation encapsulation, since a TCP stream already handles the fragmentation
of its contents across packets. Since fragmentation is redundant in of its contents across packets. Since fragmentation is redundant in
this case, implementations might choose to not negotiate IKEv2 this case, implementations might choose to not negotiate IKEv2
fragmentation. Even if fragmentation is negotiated, an fragmentation. Even if fragmentation is negotiated, an
implementation MAY choose to not fragment when going over a TCP implementation MAY choose to not fragment when going over a TCP
connection. connection.
If an implementation supports both MOBIKE and IKEv2 fragmentation, it If an implementation supports both MOBIKE and IKEv2 fragmentation, it
SHOULD negotiate IKEv2 fragmentation over a TCP encapsulated session SHOULD negotiate IKEv2 fragmentation over a TCP encapsulated session
in case the session switches to UDP encapsulation on another network. in case the session switches to UDP encapsulation on another network.
9. Considerations for Keep-alives and DPD 10. Considerations for Keep-alives and DPD
Encapsulating IKE and IPSec inside of a TCP connection can impact the Encapsulating IKE and IPSec inside of a TCP connection can impact the
strategy that implementations use to detect peer liveness and to strategy that implementations use to detect peer liveness and to
maintain middlebox port mappings. Peer liveness should be checked maintain middlebox port mappings. Peer liveness should be checked
using IKEv2 Informational packets [RFC7296]. using IKEv2 Informational packets [RFC7296].
In general, TCP port mappings are maintained by NATs longers than UDP In general, TCP port mappings are maintained by NATs longers than UDP
port mappings, so IPSec ESP NAT keep-alives [RFC3948] SHOULD NOT be port mappings, so IPSec ESP NAT keep-alives [RFC3948] SHOULD NOT be
sent when using TCP encapsulation. Any implementation using TCP sent when using TCP encapsulation. Any implementation using TCP
encapsulation MUST silently drop incoming NAT keep-alive packets, and encapsulation MUST silently drop incoming NAT keep-alive packets, and
not treat them as errors. NAT keep-alive packets over a TCP not treat them as errors. NAT keep-alive packets over a TCP
encapsulated IPSec connection will be sent with a length value of 1 encapsulated IPSec connection will be sent with a length value of 1
byte, whose value is 0xFF Figure 2. byte, whose value is 0xFF [Figure 2].
Note that depending on the configuration of TCP and TLS on the Note that depending on the configuration of TCP and TLS on the
connection, TCP keep-alives [RFC1122] and TLS keep-alives [RFC6520] connection, TCP keep-alives [RFC1122] and TLS keep-alives [RFC6520]
may be used. These MUST NOT be used as indications of IKEv2 peer may be used. These MUST NOT be used as indications of IKEv2 peer
liveness. liveness.
10. Middlebox Considerations 11. Middlebox Considerations
Many security networking devices such as Firewalls or Intrusion Many security networking devices such as Firewalls or Intrusion
Prevention Systems, network optimization/acceleration devices and Prevention Systems, network optimization/acceleration devices and
Network Address Translation (NAT) devices keep the state of sessions Network Address Translation (NAT) devices keep the state of sessions
that traverse through them. that traverse through them.
These devices commonly track the transport layer and/or the These devices commonly track the transport layer and/or the
application layer data to drop traffic that is anomalous or malicious application layer data to drop traffic that is anomalous or malicious
in nature. in nature.
A network device that monitors up to the application layer will A network device that monitors up to the application layer will
commonly expect to see HTTP traffic within a TCP socket running over commonly expect to see HTTP traffic within a TCP socket running over
port 80, if non-HTTP traffic is seen (such as TCP encapsulated port 80, if non-HTTP traffic is seen (such as TCP encapsulated
IKEv2), this could be dropped by the security device. In this IKEv2), this could be dropped by the security device.
scenario the IKEv2 and ESP packets are to be TLS encapsulated (using
port 443) to ensure that the security device permits the traffic.
In the case of a TLS proxy, where the network security device
decrypts, inspects and re-encrypts the session the same
considerations must be taken into account as for HTTP, where TLS can
be inspected. In this case the TLS proxy must allow TCP
encapsulation of IKEv2 and IPsec otherwise the session could be
dropped.
A network device that monitors the transport layer will track the A network device that monitors the transport layer will track the
state of TCP sessions, such as TCP sequence numbers. TCP state of TCP sessions, such as TCP sequence numbers. TCP
encapsulation of IKEv2 should therefore use standard TCP behaviors to encapsulation of IKEv2 should therefore use standard TCP behaviors to
avoid being dropped by middleboxes. avoid being dropped by middleboxes.
11. Performance Considerations 12. Performance Considerations
Several aspects of TCP encapsulation for IKEv2 and IPSec packets may Several aspects of TCP encapsulation for IKEv2 and IPSec packets may
negatively impact the performance of connections within the tunnel. negatively impact the performance of connections within the tunnel.
Implementations should be aware of these and take these into Implementations should be aware of these and take these into
consideration when determining when to use TCP encapsulation. consideration when determining when to use TCP encapsulation.
11.1. TCP-in-TCP 12.1. TCP-in-TCP
If the outer connection between IKEv2 peers is over TCP, inner TCP If the outer connection between IKEv2 peers is over TCP, inner TCP
connections may suffer effects from using TCP within TCP. In connections may suffer effects from using TCP within TCP. In
particular, the inner TCP's round-trip-time estimation will be particular, the inner TCP's round-trip-time estimation will be
affected by the burstiness of the outer TCP. This will make loss- affected by the burstiness of the outer TCP. This will make loss-
recovery of the inner TCP traffic less reactive and more prone to recovery of the inner TCP traffic less reactive and more prone to
spurious retransmission timeouts. spurious retransmission timeouts.
11.2. Added Reliability for Unreliable Protocols 12.2. Added Reliability for Unreliable Protocols
Since ESP is an unreliable protocol, transmitting ESP packets over a Since ESP is an unreliable protocol, transmitting ESP packets over a
TCP connection will change the fundamental behavior of the packets. TCP connection will change the fundamental behavior of the packets.
Some application-level protocols that prefer packet loss to delay Some application-level protocols that prefer packet loss to delay
(such as Voice over IP or other real-time protocols) may be (such as Voice over IP or other real-time protocols) may be
negatively impacted if their packets are retransmitted by the TCP negatively impacted if their packets are retransmitted by the TCP
connection due to packet loss. connection due to packet loss.
11.3. Encryption Overhead 12.3. Quality of Service Markings
If TLS or another encryption method is used on the TCP connection,
there may be increased processing overhead for encrypting and
decrypting. This overhead may be experienced as a decrease in
throughput on CPU-limited devices, or an increase in CPU usage or
battery consumption on other devices, therefore the initiator and
responder MUST allow the selection of NULL cipher when using TLS.
Additionally, the TLS record introduces another layer of overhead,
requiring more bytes to transmit a given IKEv2 and IPSec packet.
11.4. Quality of Service Markings
Quality of Service (QoS) markings, such as DSCP and Traffic Class, Quality of Service (QoS) markings, such as DSCP and Traffic Class,
should be used with care on TCP connections used for encapsulation. should be used with care on TCP connections used for encapsulation.
Individual packets SHOULD NOT use different markings than the rest of Individual packets SHOULD NOT use different markings than the rest of
the connection, since packets with different priorities may be routed the connection, since packets with different priorities may be routed
differently and cause unnecessary delays in the connection. differently and cause unnecessary delays in the connection.
11.5. Maximum Segment Size 12.4. Maximum Segment Size
A TCP connection used for IKEv2 encapsulation SHOULD negotiate its A TCP connection used for IKEv2 encapsulation SHOULD negotiate its
maximum segment size (MSS) in order to avoid unnecessary maximum segment size (MSS) in order to avoid unnecessary
fragmentation of packets. fragmentation of packets.
12. Security Considerations 13. Security Considerations
IKEv2 responders that support TCP encapsulation may become vulnerable IKEv2 responders that support TCP encapsulation may become vulnerable
to new Denial-of-Service (DoS) attacks that are specific to TCP, such to new Denial-of-Service (DoS) attacks that are specific to TCP, such
as SYN-flooding attacks. Responders should be aware of this as SYN-flooding attacks. Responders should be aware of this
additional attack-surface. additional attack-surface.
Attackers may be able to disrupt the TCP connection by sending Attackers may be able to disrupt the TCP connection by sending
spurious RST packets. Due to this, implementations SHOULD make sure spurious RST packets. Due to this, implementations SHOULD make sure
that IKE session state persists even if the underlying TCP connection that IKE session state persists even if the underlying TCP connection
is torn down. is torn down.
If TLS is used on the encapsulating TCP connection it should not be 14. IANA Considerations
considered as a security measure, and no TLS profile is recommended
by this specification. The security of the IKEv2 session is entirely
derived from the IKEv2 negotiation and key establishment.
13. IANA Considerations
This memo includes no request to IANA. This memo includes no request to IANA.
TCP port 4500 is already allocated to IPSec. This port MAY be used TCP port 4500 is already allocated to IPSec. This port MAY be used
for the protocol described in this document, but implementations MAY for the protocol described in this document, but implementations MAY
prefer to use other ports based on local policy. We foresee some prefer to use other ports based on local policy.
implementations using TCP port 443 to more easily pass through some
middleboxes [I-D.tschofenig-hourglass].
14. Acknowledgments 15. Acknowledgments
The authors would like to acknowledge the input and advice of Stuart The authors would like to acknowledge the input and advice of Stuart
Cheshire, Delziel Fernandes, Yoav Nir, Christoph Paasch, Yaron Cheshire, Delziel Fernandes, Yoav Nir, Christoph Paasch, Yaron
Sheffer, David Schinazi, Graham Bartlett, Byju Pularikkal, March Wu Sheffer, David Schinazi, Graham Bartlett, Byju Pularikkal, March Wu
and Kingwel Xie. Special thanks to Eric Kinnear for his and Kingwel Xie. Special thanks to Eric Kinnear for his
implementation work. implementation work.
15. References 16. References
15.1. Normative References 16.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2 Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <http://www.rfc-editor.org/info/rfc7296>. 2014, <http://www.rfc-editor.org/info/rfc7296>.
15.2. Informative References 16.2. Informative References
[I-D.nir-ipsecme-ike-tcp] [I-D.nir-ipsecme-ike-tcp]
Nir, Y., "A TCP transport for the Internet Key Exchange", Nir, Y., "A TCP transport for the Internet Key Exchange",
draft-nir-ipsecme-ike-tcp-01 (work in progress), July draft-nir-ipsecme-ike-tcp-01 (work in progress), July
2012. 2012.
[I-D.tschofenig-hourglass]
Tschofenig, H., "The New Waist of the Hourglass", draft-
tschofenig-hourglass-00 (work in progress), July 2012.
[RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, Communication Layers", STD 3, RFC 1122,
DOI 10.17487/RFC1122, October 1989, DOI 10.17487/RFC1122, October 1989,
<http://www.rfc-editor.org/info/rfc1122>. <http://www.rfc-editor.org/info/rfc1122>.
[RFC2817] Khare, R. and S. Lawrence, "Upgrading to TLS Within [RFC2817] Khare, R. and S. Lawrence, "Upgrading to TLS Within
HTTP/1.1", RFC 2817, DOI 10.17487/RFC2817, May 2000, HTTP/1.1", RFC 2817, DOI 10.17487/RFC2817, May 2000,
<http://www.rfc-editor.org/info/rfc2817>. <http://www.rfc-editor.org/info/rfc2817>.
[RFC3948] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M. [RFC3948] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.
skipping to change at page 13, line 21 skipping to change at page 12, line 43
Layer Security (TLS) and Datagram Transport Layer Security Layer Security (TLS) and Datagram Transport Layer Security
(DTLS) Heartbeat Extension", RFC 6520, (DTLS) Heartbeat Extension", RFC 6520,
DOI 10.17487/RFC6520, February 2012, DOI 10.17487/RFC6520, February 2012,
<http://www.rfc-editor.org/info/rfc6520>. <http://www.rfc-editor.org/info/rfc6520>.
[RFC7383] Smyslov, V., "Internet Key Exchange Protocol Version 2 [RFC7383] Smyslov, V., "Internet Key Exchange Protocol Version 2
(IKEv2) Message Fragmentation", RFC 7383, (IKEv2) Message Fragmentation", RFC 7383,
DOI 10.17487/RFC7383, November 2014, DOI 10.17487/RFC7383, November 2014,
<http://www.rfc-editor.org/info/rfc7383>. <http://www.rfc-editor.org/info/rfc7383>.
Appendix A. Example exchanges of TCP Encapsulation with TLS Appendix A. Using TCP encapsulation with TLS
A.1. Establishing an IKEv2 session This section provides recommendations on the support of TLS with the
TCP encapsulation.
When using TCP encapsulation, implementations may choose to use TLS
[RFC5246], to be able to traverse middle-boxes, which may block non
HTTP traffic.
If a web proxy is applied to the ports for the TCP connection, and
TLS is being used, the initiator can send an HTTP CONNECT message to
establish a tunnel through the proxy [RFC2817].
The use of TLS should be configurable on the peers. The responder
may expect to read encapsulated IKEv2 and ESP packets directly from
the TCP connection, or it may expect to read them from a stream of
TLS data packets. The initiator should be pre-configured to use TLS
or not when communicating with a given port on the responder.
When new TCP connections are re-established due to a broken
connection, TLS must be re-negotiated. TLS Session Resumption is
recommended to improve efficiency in this case.
The security of the IKEv2 session is entirely derived from the IKVEv2
negotiation and key establishment, therefore When TLS is used on the
TCP connection, both the initiator and responder MUST allow for the
NULL cipher to be selected.
Implementations must be aware that the use of TLS introduces another
layer of overhead requiring more bytes to transmit a given IKEv2 and
IPSec packet.
Appendix B. Example exchanges of TCP Encapsulation with TLS
B.1. Establishing an IKEv2 session
Client Server Client Server
---------- ---------- ---------- ----------
-------------------- TCP Connection ------------------- -------------------- TCP Connection -------------------
1) (IP_I:Port_I -> IP_R:TCP443 or TCP4500) 1) (IP_I:Port_I -> IP_R:TCP443 or TCP4500)
TcpSyn ----------> TcpSyn ---------->
<---------- TcpSyn,Ack <---------- TcpSyn,Ack
TcpAck ----------> TcpAck ---------->
--------------------- TLS Session --------------------- --------------------- TLS Session ---------------------
2) ClientHello ----------> 2) ClientHello ---------->
skipping to change at page 14, line 49 skipping to change at page 14, line 49
EAP ----------> EAP ---------->
repeat 1..N times repeat 1..N times
<---------- EAP <---------- EAP
final IKE_AUTH ----------> final IKE_AUTH ---------->
HDR, SK {AUTH} HDR, SK {AUTH}
<---------- final IKE_AUTH <---------- final IKE_AUTH
HDR, SK {AUTH, CP(CFG_REPLY), HDR, SK {AUTH, CP(CFG_REPLY),
SA, TSi, TSr, ...} SA, TSi, TSr, ...}
-------------- IKEv2 Tunnel Established ------------- -------------- IKEv2 Tunnel Established -------------
Figure 3 Figure 4
1. Client establishes a TCP connection with the server on port 443 1. Client establishes a TCP connection with the server on port 443
or 4500. or 4500.
2. Client initiates TLS handshake. During TLS handshake, the 2. Client initiates TLS handshake. During TLS handshake, the
server SHOULD NOT request the client's' certificate, since server SHOULD NOT request the client's' certificate, since
authentication is handled as part of IKEv2 negotiation. authentication is handled as part of IKEv2 negotiation.
3. Client and server establish an IKEv2 connection. This example 3. Client and server establish an IKEv2 connection. This example
shows EAP-based authentication, although any authentication shows EAP-based authentication, although any authentication
type may be used. type may be used.
A.2. Deleting an IKEv2 session B.2. Deleting an IKEv2 session
Client Server Client Server
---------- ---------- ---------- ----------
---------------------- IKEv2 Session -------------------- ---------------------- IKEv2 Session --------------------
1) INFORMATIONAL ----------> 1) INFORMATIONAL ---------->
HDR, SK {[N,] [D,] HDR, SK {[N,] [D,]
[CP,] ...} [CP,] ...}
<---------- INFORMATIONAL <---------- INFORMATIONAL
HDR, SK {[N,] [D,] HDR, SK {[N,] [D,]
[CP], ...} [CP], ...}
skipping to change at page 15, line 38 skipping to change at page 15, line 38
--------------------- TLS Session --------------------- --------------------- TLS Session ---------------------
2) close_notify ----------> 2) close_notify ---------->
<---------- close_notify <---------- close_notify
-------------------- TCP Connection ------------------- -------------------- TCP Connection -------------------
3) TcpFin ----------> 3) TcpFin ---------->
<---------- Ack <---------- Ack
<---------- TcpFin <---------- TcpFin
Ack ----------> Ack ---------->
--------------------- Tunnel Deleted ------------------- --------------------- Tunnel Deleted -------------------
Figure 4 Figure 5
1. Client and server exchange INFORMATIONAL messages to notify IKE 1. Client and server exchange INFORMATIONAL messages to notify IKE
SA deletion. SA deletion.
2. Client and server negotiate TLS session deletion using TLS 2. Client and server negotiate TLS session deletion using TLS
CLOSE_NOTIFY. CLOSE_NOTIFY.
3. The TCP connection is torn down. 3. The TCP connection is torn down.
Unless the TCP connection and/or TLS session are being used for Unless the TCP connection and/or TLS session are being used for
multiple IKE SAs, the deletion of the IKE SA should lead to the multiple IKE SAs, the deletion of the IKE SA should lead to the
disposal of the underlying TLS and TCP state. disposal of the underlying TLS and TCP state.
A.3. Re-establishing an IKEv2 session B.3. Re-establishing an IKEv2 session
Client Server Client Server
---------- ---------- ---------- ----------
-------------------- TCP Connection ------------------- -------------------- TCP Connection -------------------
1) (IP_I:Port_I -> IP_R:TCP443 or TCP4500) 1) (IP_I:Port_I -> IP_R:TCP443 or TCP4500)
TcpSyn ----------> TcpSyn ---------->
<---------- TcpSyn,Ack <---------- TcpSyn,Ack
TcpAck ----------> TcpAck ---------->
--------------------- TLS Session --------------------- --------------------- TLS Session ---------------------
2) ClientHello ----------> 2) ClientHello ---------->
<---------- ServerHello <---------- ServerHello
[ChangeCipherSpec] [ChangeCipherSpec]
Finished Finished
[ChangeCipherSpec] ----------> [ChangeCipherSpec] ---------->
Finished Finished
3) <--------------------> IKEv2/ESP flow <-----------------> 3) <--------------------> IKEv2/ESP flow <----------------->
Figure 5 Figure 6
1. If a previous TCP connection was broken (for example, due to a 1. If a previous TCP connection was broken (for example, due to a
RST), the client is responsible for re-initiating the TCP RST), the client is responsible for re-initiating the TCP
connection. The initiator's address and port (IP_I and Port_I) connection. The initiator's address and port (IP_I and Port_I)
may be different from the previous connection's address and may be different from the previous connection's address and
port. port.
2. In ClientHello TLS message, the client SHOULD send the Session 2. In ClientHello TLS message, the client SHOULD send the Session
ID it received in the previous TLS handshake if available. It ID it received in the previous TLS handshake if available. It
is up to the server to perform either an abbreviated handshake is up to the server to perform either an abbreviated handshake
or full handshake based on the session ID match. or full handshake based on the session ID match.
3. After TCP and TLS are complete, the IKEv2 and ESP packet flow 3. After TCP and TLS are complete, the IKEv2 and ESP packet flow
can resume. If MOBIKE is being used, the initiator SHOULD send can resume. If MOBIKE is being used, the initiator SHOULD send
UPDATE_SA_ADDRESSES. UPDATE_SA_ADDRESSES.
A.4. Using MOBIKE between UDP and TCP Encapsulation B.4. Using MOBIKE between UDP and TCP Encapsulation
Client Server Client Server
---------- ---------- ---------- ----------
(IP_I1:UDP500 -> IP_R:UDP500) (IP_I1:UDP500 -> IP_R:UDP500)
1) ----------------- IKE_SA_INIT Exchange ----------------- 1) ----------------- IKE_SA_INIT Exchange -----------------
(IP_I1:UDP4500 -> IP_R:UDP4500) (IP_I1:UDP4500 -> IP_R:UDP4500)
Intial IKE_AUTH -----------> Intial IKE_AUTH ----------->
HDR, SK { IDi, CERT, AUTH, HDR, SK { IDi, CERT, AUTH,
CP(CFG_REQUEST), CP(CFG_REQUEST),
SAi2, TSi, TSr, SAi2, TSi, TSr,
skipping to change at page 17, line 48 skipping to change at page 17, line 48
INFORMATIONAL -----------> INFORMATIONAL ----------->
HDR, SK { N(UPDATE_SA_ADDRESSES), HDR, SK { N(UPDATE_SA_ADDRESSES),
N(NAT_DETECTION_SOURCE_IP), N(NAT_DETECTION_SOURCE_IP),
N(NAT_DETECTION_DESTINATION_IP) } N(NAT_DETECTION_DESTINATION_IP) }
<----------- INFORMATIONAL <----------- INFORMATIONAL
HDR, SK { N(NAT_DETECTION_SOURCE_IP), HDR, SK { N(NAT_DETECTION_SOURCE_IP),
N(NAT_DETECTION_DESTINATION_IP) } N(NAT_DETECTION_DESTINATION_IP) }
6) <---------------- IKEv2/ESP data flow ------------------> 6) <---------------- IKEv2/ESP data flow ------------------>
Figure 6 Figure 7
1. During the IKE_SA_INIT exchange, the client and server exchange 1. During the IKE_SA_INIT exchange, the client and server exchange
MOBIKE_SUPPORTED notify payloads to indicate support for MOBIKE_SUPPORTED notify payloads to indicate support for
MOBIKE. MOBIKE.
2. The client changes its point of attachment to the network, and 2. The client changes its point of attachment to the network, and
receives a new IP address. The client attempts to re-establish receives a new IP address. The client attempts to re-establish
the IKEv2 session using the UPDATE_SA_ADDRESSES notify payload, the IKEv2 session using the UPDATE_SA_ADDRESSES notify payload,
but the server does not respond because the network blocks UDP but the server does not respond because the network blocks UDP
traffic. traffic.
 End of changes. 56 change blocks. 
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