draft-ietf-ipsecme-tcp-encaps-09.txt		draft-ietf-ipsecme-tcp-encaps-10.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: September 13, 2017 Ericsson		Expires: December 1, 2017 Ericsson
	R. Mantha		R. Mantha
	Cisco Systems		Cisco Systems
	March 12, 2017		May 30, 2017
	TCP Encapsulation of IKE and IPsec Packets		TCP Encapsulation of IKE and IPsec Packets
	draft-ietf-ipsecme-tcp-encaps-09		draft-ietf-ipsecme-tcp-encaps-10
	Abstract		Abstract
	This document describes a method to transport IKE and IPsec packets		This document describes a method to transport IKE and IPsec packets
	over a TCP connection for traversing network middleboxes that may		over a TCP connection for traversing network middleboxes that may
	block IKE negotiation over UDP. This method, referred to as TCP		block IKE negotiation over UDP. This method, referred to as TCP
	encapsulation, involves sending both IKE packets for Security		encapsulation, involves sending both IKE packets for Security
	Association establishment and ESP packets over a TCP connection.		Association establishment and ESP packets over a TCP connection.
	This method is intended to be used as a fallback option when IKE		This method is intended to be used as a fallback option when IKE
	cannot be negotiated over UDP.		cannot be negotiated over UDP.
	skipping to change at page 1, line 39 ¶		skipping to change at page 1, line 39 ¶
	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 September 13, 2017.		This Internet-Draft will expire on December 1, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Prior Work and Motivation . . . . . . . . . . . . . . . . 3		1.1. Prior Work and Motivation . . . . . . . . . . . . . . . . 3
	1.2. Terminology and Notation . . . . . . . . . . . . . . . . 4		1.2. Terminology and Notation . . . . . . . . . . . . . . . . 4
	2. Configuration . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Configuration . . . . . . . . . . . . . . . . . . . . . . . . 5
	3. TCP-Encapsulated Header Formats . . . . . . . . . . . . . . . 5		3. TCP-Encapsulated Header Formats . . . . . . . . . . . . . . . 5
	3.1. TCP-Encapsulated IKE Header Format . . . . . . . . . . . 6		3.1. TCP-Encapsulated IKE Header Format . . . . . . . . . . . 6
	3.2. TCP-Encapsulated ESP Header Format . . . . . . . . . . . 6		3.2. TCP-Encapsulated ESP Header Format . . . . . . . . . . . 6
	4. TCP-Encapsulated Stream Prefix . . . . . . . . . . . . . . . 7		4. TCP-Encapsulated Stream Prefix . . . . . . . . . . . . . . . 7
	5. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 7		5. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 7
	5.1. Recommended Fallback from UDP . . . . . . . . . . . . . . 8		5.1. Recommended Fallback from UDP . . . . . . . . . . . . . . 8
	6. Connection Establishment and Teardown . . . . . . . . . . . . 8		6. Connection Establishment and Teardown . . . . . . . . . . . . 8
	7. Interaction with NAT Detection Payloads . . . . . . . . . . . 10		7. Interaction with NAT Detection Payloads . . . . . . . . . . . 10
	8. Using MOBIKE with TCP encapsulation . . . . . . . . . . . . . 10		8. Using MOBIKE with TCP encapsulation . . . . . . . . . . . . . 10
	9. Using IKE Message Fragmentation with TCP encapsulation . . . 11		9. Using IKE Message Fragmentation with TCP encapsulation . . . 11
	10. Considerations for Keep-alives and DPD . . . . . . . . . . . 11		10. Considerations for Keep-alives and DPD . . . . . . . . . . . 11
	11. Middlebox Considerations . . . . . . . . . . . . . . . . . . 11		11. Middlebox Considerations . . . . . . . . . . . . . . . . . . 12
	12. Performance Considerations . . . . . . . . . . . . . . . . . 12		12. Performance Considerations . . . . . . . . . . . . . . . . . 12
	12.1. TCP-in-TCP . . . . . . . . . . . . . . . . . . . . . . . 12		12.1. TCP-in-TCP . . . . . . . . . . . . . . . . . . . . . . . 12
	12.2. Added Reliability for Unreliable Protocols . . . . . . . 12		12.2. Added Reliability for Unreliable Protocols . . . . . . . 13
	12.3. Quality of Service Markings . . . . . . . . . . . . . . 12		12.3. Quality of Service Markings . . . . . . . . . . . . . . 13
	12.4. Maximum Segment Size . . . . . . . . . . . . . . . . . . 12		12.4. Maximum Segment Size . . . . . . . . . . . . . . . . . . 13
	13. Security Considerations . . . . . . . . . . . . . . . . . . . 13		12.5. Tunnelling ECN in TCP . . . . . . . . . . . . . . . . . 14
	14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13		13. Security Considerations . . . . . . . . . . . . . . . . . . . 14
	15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14		14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
	16. References . . . . . . . . . . . . . . . . . . . . . . . . . 14		15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15
	16.1. Normative References . . . . . . . . . . . . . . . . . . 14		16. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
	16.2. Informative References . . . . . . . . . . . . . . . . . 14		16.1. Normative References . . . . . . . . . . . . . . . . . . 15
	Appendix A. Using TCP encapsulation with TLS . . . . . . . . . . 15		16.2. Informative References . . . . . . . . . . . . . . . . . 16
	Appendix B. Example exchanges of TCP Encapsulation with TLS . . 16		Appendix A. Using TCP encapsulation with TLS . . . . . . . . . . 17
	B.1. Establishing an IKE session . . . . . . . . . . . . . . . 16		Appendix B. Example exchanges of TCP Encapsulation with TLS . . 17
	B.2. Deleting an IKE session . . . . . . . . . . . . . . . . . 17		B.1. Establishing an IKE session . . . . . . . . . . . . . . . 17
	B.3. Re-establishing an IKE session . . . . . . . . . . . . . 18		B.2. Deleting an IKE session . . . . . . . . . . . . . . . . . 19
	B.4. Using MOBIKE between UDP and TCP Encapsulation . . . . . 19		B.3. Re-establishing an IKE session . . . . . . . . . . . . . 20
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21		B.4. Using MOBIKE between UDP and TCP Encapsulation . . . . . 21
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
	1. Introduction		1. Introduction
	IKEv2 [RFC7296] is a protocol for establishing IPsec Security		IKEv2 [RFC7296] is a protocol for establishing IPsec Security
	Associations (SAs), using IKE messages over UDP for control traffic,		Associations (SAs), using IKE messages over UDP for control traffic,
	and using Encapsulating Security Payload (ESP) messages for encrypted		and using Encapsulating Security Payload (ESP) messages for encrypted
	data traffic. Many network middleboxes that filter traffic on public		data traffic. Many network middleboxes that filter traffic on public
	hotspots block all UDP traffic, including IKE and IPsec, but allow		hotspots block all UDP traffic, including IKE and IPsec, but allow
	TCP connections through since they appear to be web traffic. Devices		TCP connections through since they appear to be web traffic. Devices
	on these networks that need to use IPsec (to access private		on these networks that need to use IPsec (to access private
	skipping to change at page 4, line 16 ¶		skipping to change at page 4, line 21 ¶
	to create secure connections to cellular carrier networks for		to create secure connections to cellular carrier networks for
	making voice calls and accessing other network services over		making voice calls and accessing other network services over
	Wi-Fi networks. 3GPP has recommended that IKEv2 and ESP packets		Wi-Fi networks. 3GPP has recommended that IKEv2 and ESP packets
	be sent within a TLS connection to be able to establish		be sent within a TLS connection to be able to establish
	connections on restrictive networks.		connections on restrictive networks.
	ISAKMP over TCP Various non-standard extensions to ISAKMP have been		ISAKMP over TCP Various non-standard extensions to ISAKMP have been
	deployed that send IPsec traffic over TCP or TCP-like packets.		deployed that send IPsec traffic over TCP or TCP-like packets.
	SSL VPNs Many proprietary VPN solutions use a combination of TLS and		SSL VPNs Many proprietary VPN solutions use a combination of TLS and
	IPsec in order to provide reliability.		IPsec in order to provide reliability. These often run on TCP
			port 443.
	IKEv2 over TCP IKEv2 over TCP as described in		IKEv2 over TCP IKEv2 over TCP as described in
	[I-D.nir-ipsecme-ike-tcp] is used to avoid UDP fragmentation.		[I-D.nir-ipsecme-ike-tcp] is used to avoid UDP fragmentation.
	The goal of this specification is to provide a standardized method		The goal of this specification is to provide a standardized method
	for using TCP streams to transport IPsec that is compatible with the		for using TCP streams to transport IPsec that is compatible with the
	current IKE standard, and avoids the overhead of other alternatives		current IKE standard, and avoids the overhead of other alternatives
	that always rely on TCP or TLS.		that always rely on TCP or TLS.
	1.2. Terminology and Notation		1.2. Terminology and Notation
	skipping to change at page 5, line 5 ¶		skipping to change at page 5, line 13 ¶
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	2. Configuration		2. Configuration
	One of the main reasons to use TCP encapsulation is that UDP traffic		One of the main reasons to use TCP encapsulation is that UDP traffic
	may be entirely blocked on a network. Because of this, support for		may be entirely blocked on a network. Because of this, support for
	TCP encapsulation is not specifically negotiated in the IKE exchange.		TCP encapsulation is not specifically negotiated in the IKE exchange.
	Instead, support for TCP encapsulation must be pre-configured on both		Instead, support for TCP encapsulation must be pre-configured on both
	the TCP Originator and the TCP Responder.		the TCP Originator and the TCP Responder.
	The configuration defined on each peer should include the following		Implementations MUST support TCP encapsulation on TCP port 4500,
	parameters:		which is reserved for IPsec NAT Traversal.
	o One or more TCP ports on which the TCP Responder will listen for		Beyond a flag indicating support for TCP encapsulation, the
	incoming connections. Note that the TCP Originator may initiate		configuration for each peer can include the following optional
	TCP connections to the TCP Responder from any local port. The		parameters:
	ports on which the TCP Responder listens will likely be based on
	the ports commonly allowed on restricted networks.
	o Optionally, an extra framing protocol to use on top of TCP to		o Alternate TCP ports on which the specific TCP Responder listens
	further encapsulate the stream of IKE and IPsec packets. See		for incoming connections. Note that the TCP Originator may
	Appendix A for a detailed discussion.		initiate TCP connections to the TCP Responder from any local port.
	This document leaves the selection of TCP ports up to		o An extra framing protocol to use on top of TCP to further
	implementations. It is suggested to use TCP port 4500, which is		encapsulate the stream of IKE and IPsec packets. See Appendix A
	allocated for IPsec NAT Traversal.		for a detailed discussion.
	Since TCP encapsulation of IKE and IPsec packets adds overhead and		Since TCP encapsulation of IKE 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 SAs (as described in Performance Considerations,		encapsulated SAs (as described in Performance Considerations,
	Section 12), implementations SHOULD prefer ESP direct or UDP		Section 12), implementations SHOULD prefer ESP direct or UDP
	encapsulated SAs over TCP encapsulated SAs when possible.		encapsulated SAs over TCP encapsulated SAs when possible.
	3. TCP-Encapsulated Header Formats		3. TCP-Encapsulated Header Formats
	Like UDP encapsulation, TCP encapsulation uses the first four bytes		Like UDP encapsulation, TCP encapsulation uses the first four bytes
	skipping to change at page 7, line 9 ¶		skipping to change at page 7, line 14 ¶
	The SPI field in the ESP header MUST NOT be a zero value.		The SPI field in the ESP header MUST NOT be a zero value.
	o Length (2 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. TCP-Encapsulated Stream Prefix		4. TCP-Encapsulated Stream Prefix
	Each stream of bytes used for IKE and IPsec encapsulation MUST begin		Each stream of bytes used for IKE and IPsec encapsulation MUST begin
	with a fixed sequence of six bytes as a magic value, containing the		with a fixed sequence of six bytes as a magic value, containing the
	characters "IKETCP" as ASCII values. This allows peers to		characters "IKETCP" as ASCII values. This value is intended to
	differentiate this protocol from other protocols that may be run over		identify and validate that the TCP connection is being used for TCP
	the same TCP port. Since TCP encapsulated IPsec is not assigned to a		encapsulation as defined in this document, to avoid conflicts with
	specific port, TCP Responders may be able to receive multiple		the prevalence of previous non-standard protocols that used TCP port
	protocols on the same port. The bytes of the stream prefix do not		4500. This value is only sent once, by the TCP Originator only, at
	overlap with the valid start of any other known stream protocol.		the beginning of any stream of IKE and ESP messages.
	This value is only sent once, by the TCP Originator only, at the
	beginning of any stream of IKE and ESP messages.
	If other framing protocols are used within TCP to further encapsulate		If other framing protocols are used within TCP to further encapsulate
	or encrypt the stream of IKE and ESP messages, the Stream Prefix must		or encrypt the stream of IKE and ESP messages, the Stream Prefix must
	be at the start of the TCP Originator's IKE and ESP message stream		be at the start of the TCP Originator's IKE and ESP message stream
	within the added protocol layer [Appendix A]. Although some framing		within the added protocol layer [Appendix A]. Although some framing
	protocols do support negotiating inner protocols, the stream prefix		protocols do support negotiating inner protocols, the stream prefix
	should always be used in order for implementations to be as generic		should always be used in order for implementations to be as generic
	as possible and not rely on other framing protocols on top of TCP.		as possible and not rely on other framing protocols on top of TCP.
	0 1 2 3 4 5		0 1 2 3 4 5
	skipping to change at page 9, line 23 ¶		skipping to change at page 9, line 26 ¶
	an existing IKE SA, it MUST send the stream prefix first, before any		an existing IKE SA, it MUST send the stream prefix first, before any
	IKE or ESP messages. This follows the same behavior as the initial		IKE or ESP messages. This follows the same behavior as the initial
	TCP connection.		TCP connection.
	If a TCP connection is being used to resume a previous IKE session,		If a TCP connection is being used to resume a previous IKE session,
	the TCP Responder can recognize the session using either the IKE SPI		the TCP Responder can recognize the session using either the IKE SPI
	from an encapsulated IKE message or the ESP SPI from an encapsulated		from an encapsulated IKE message or the ESP SPI from an encapsulated
	ESP message. If the session had been fully established previously,		ESP message. If the session had been fully established previously,
	it is suggested that the TCP Originator send an UPDATE_SA_ADDRESSES		it is suggested that the TCP Originator send an UPDATE_SA_ADDRESSES
	message if MOBIKE is supported, or an INFORMATIONAL message (a		message if MOBIKE is supported, or an INFORMATIONAL message (a
	keepalive) otherwise. If either TCP Originator or TCP Responder		keepalive) otherwise.
	receives a stream that cannot be parsed correctly (for example, if
	the TCP Originator stream is missing the stream prefix, or message		The TCP Responder MUST NOT accept any messages for the existing IKE
	frames are not parsable as IKE or ESP messages), it MUST close the		session on a new incoming connection unless that connection begins
	TCP connection. If there is instead a syntax issue within an IKE		with the stream prefix. If either the TCP Originator or TCP
	message, an implementation MUST send the INVALID_SYNTAX notify		Responder detects corruption on a connection that was started with a
	payload and tear down the IKE SA as usual, rather than tearing down		valid stream prefix, it SHOULD close the TCP connection. The
	the TCP connection directly.		connection can be determined as corrupted if there are too many
			subsequent messages that cannot be parsed as valid IKE messages or
			ESP messages with known SPIs, or if the authentication check for an
			ESP message with a known SPI fails. Implementations SHOULD NOT tear
			down a connection if only a single ESP message has an unknown SPI,
			since the SPI databases may be momentarily out of sync. If there is
			instead a syntax issue within an IKE message, an implementation MUST
			send the INVALID_SYNTAX notify payload and tear down the IKE SA as
			usual, rather than tearing down the TCP connection directly.
	An TCP Originator SHOULD only open one TCP connection per IKE SA,		An TCP Originator SHOULD only open one TCP connection per IKE SA,
	over which it sends all of the corresponding IKE and ESP messages.		over which it sends all of the corresponding IKE and ESP messages.
	This helps ensure that any firewall or NAT mappings allocated for the		This helps ensure that any firewall or NAT mappings allocated for the
	TCP connection apply to all of the traffic associated with the IKE SA		TCP connection apply to all of the traffic associated with the IKE SA
	equally.		equally.
	Similarly, a TCP Responder SHOULD at any given time send packets for		Similarly, a TCP Responder SHOULD at any given time send packets for
	an IKE SA and its Child SAs over only one TCP connection. It SHOULD		an IKE SA and its Child SAs over only one TCP connection. It SHOULD
	choose the TCP connection on which it last received a valid and		choose the TCP connection on which it last received a valid and
	skipping to change at page 11, line 48 ¶		skipping to change at page 12, line 14 ¶
	11. 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. While many of these devices will be more likely to pass
			TCP-encapsulated traffic as opposed to UDP-encapsulated traffic, some
	A network device that monitors up to the application layer will		may still block or interfere with TCP-encapsulated IKE and IPsec.
	commonly expect to see HTTP traffic within a TCP socket running over
	port 80, if non-HTTP traffic is seen (such as TCP encapsulated IKE),
	this could be dropped by the security device.
	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 IKE should therefore use standard TCP behaviors to		encapsulation of IKE should therefore use standard TCP behaviors to
	avoid being dropped by middleboxes.		avoid being dropped by middleboxes.
	12. Performance Considerations		12. Performance Considerations
	Several aspects of TCP encapsulation for IKE and IPsec packets may		Several aspects of TCP encapsulation for IKE and IPsec packets may
	negatively impact the performance of connections within a tunnel-mode		negatively impact the performance of connections within a tunnel-mode
	IPsec SA. Implementations should be aware of these and take these		IPsec SA. Implementations should be aware of these performance
	into consideration when determining when to use TCP encapsulation.		impacts and take these into consideration when determining when to
			use TCP encapsulation. Implementations SHOULD favor using direct ESP
			or UDP encapsulation over TCP encapsulation whenever possible.
	12.1. TCP-in-TCP		12.1. TCP-in-TCP
	If the outer connection between IKE peers is over TCP, inner TCP		If the outer connection between IKE 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. Running
	particular, the inner TCP's round-trip-time estimation will be		TCP within TCP is discouraged, since the TCP algorithms generally
	affected by the burstiness of the outer TCP. This will make loss-		assume that they are running over an unreliable datagram layer.
	recovery of the inner TCP traffic less reactive and more prone to
	spurious retransmission timeouts.		If the outer (tunnel) TCP connection experiences packet loss, this
			loss will be hidden from any inner TCP connections, since the outer
			connection will retransmit to account for the losses. Since the
			outer TCP connection will deliver the inner messages in order, any
			messages after a lost packet may have to wait until the loss is
			recovered. This means that loss on the outer connection will be
			interpreted only as delay by inner connections. The burstiness of
			inner traffic can increase, since a large number of inner packets may
			be delivered across the tunnel at once. The inner TCP connection may
			interpret a long period of delay as a transmission problem,
			triggering a retransmission timeout, which will cause spurious
			retransmissions. The sending rate of the inner connection may be
			unnecessarily reduced if the retransmissions are not detected as
			spurious in time.
			The inner TCP connection's round-trip-time estimation will be
			affected by the burstiness of the outer TCP connection if there are
			long delays when packets are retransmitted by the outer TCP
			connection. This will make the congestion control loop of the inner
			TCP traffic less reactive, potentially permanently leading to a lower
			sending rate than the outer TCP would allow for.
			TCP-in-TCP can also lead to increased buffering, or bufferbloat.
			This can occur when the window size of the outer TCP connection is
			reduced, and becomes smaller than the window sizes of the inner TCP
			connections. This can lead to packets backing up in the outer TCP
			connection's send buffers. In order to limit this effect, the outer
			TCP connection should have limits on its send buffer size, and on the
			rate at which it reduces its window size.
			Note that any negative effects will be shared between all flows going
			through the outer TCP connection. This is of particular concern for
			any latency-sensitive or real-time applications using the tunnel. If
			such traffic is using a TCP encapsulated IPsec connection, it is
			recommended that the number of inner connections sharing the tunnel
			be limited as much as possible.
	12.2. 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.
	skipping to change at page 13, line 5 ¶		skipping to change at page 14, line 5 ¶
	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.
	12.4. Maximum Segment Size		12.4. Maximum Segment Size
	A TCP connection used for IKE encapsulation SHOULD negotiate its		A TCP connection used for IKE 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.
			12.5. Tunnelling ECN in TCP
			Since there is not a one-to-one relationship between outer IP packets
			and inner ESP/IP messages when using TCP encapsulation, the markings
			for Explicit Congestion Notification (ECN) [RFC3168] cannot be simply
			mapped. However, any ECN Congestion Experienced (CE) marking on
			inner messages should be preserved through the tunnel.
			Implementations SHOULD follow the ECN compatibility mode as described
			in [RFC6040]. In compatibility mode, the outer TCP connection SHOULD
			mark its packets as not ECN-capable, and MUST NOT clear any ECN
			markings on inner packets. Note that outer packets may be ECN marked
			even though the outer connection did not negotiate support for ECN.
			If an implementation receives such an outer packet, it MAY propagate
			the markings as described in the Default Tunnel Egress Behaviour
			[RFC6040] for any inner packet contained within a single outer TCP
			packet, or simply apply the rules as if the outer packet were Not-ECT
			if the inner packet spans multiple outer packets.
	13. Security Considerations		13. Security Considerations
	IKE Responders that support TCP encapsulation may become vulnerable		IKE 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. TCP Responders should be aware of this		as SYN-flooding attacks. TCP Responders should be aware of this
	additional attack-surface.		additional attack-surface.
	TCP Responders should be careful to ensure that the stream prefix		TCP Responders should be careful to ensure that the stream prefix
	"IKETCP" uniquely identifies streams using the TCP encapsulation		"IKETCP" uniquely identifies incoming streams as ones that use the
	protocol. The prefix was chosen to not overlap with the start of any		TCP encapsulation protocol, and they are not running any other
	known valid protocol over TCP, but implementations should make sure		protocols on the same listening port that could conflict with this.
	to validate this assumption in order to avoid unexpected processing
	of TCP connections.
	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 MOBIKE is being used, all of the security considerations outlined		If MOBIKE is being used, all of the security considerations outlined
	for MOBIKE apply [RFC4555].		for MOBIKE apply [RFC4555].
	Similarly to MOBIKE, TCP encapsulation requires a TCP Responder to		Similarly to MOBIKE, TCP encapsulation requires a TCP Responder to
	skipping to change at page 13, line 44 ¶		skipping to change at page 15, line 12 ¶
	packets take. For this reason, the validation of messages on the TCP		packets take. For this reason, the validation of messages on the TCP
	Responder must include decryption, authentication, and replay checks.		Responder must include decryption, authentication, and replay checks.
	Since TCP provides a reliable, in-order delivery of ESP messages, the		Since TCP provides a reliable, in-order delivery of ESP messages, the
	ESP Anti-Replay Window size SHOULD be set to 1. See [RFC4303] for a		ESP Anti-Replay Window size SHOULD be set to 1. See [RFC4303] for a
	complete description of the ESP Anti-Replay Window. This increases		complete description of the ESP Anti-Replay Window. This increases
	the protection of implementations against replay attacks.		the protection of implementations against replay attacks.
	14. IANA Considerations		14. IANA Considerations
	This memo includes no request to IANA.		TCP port 4500 is already allocated to IPsec for NAT Traversal. This
			port SHOULD be used for TCP encapsulated IKE and ESP as described in
			this document.
	TCP port 4500 is already allocated to IPsec. This port MAY be used		This document updates the reference for TCP port 4500:
	for the protocol described in this document, but implementations MAY
	prefer to use other ports based on local policy.		Keyword Decimal Description Reference
			------- ------- ----------- ---------
			ipsec-nat-t 4500/tcp IPsec NAT-Traversal [RFC-this-rfc]
			Figure 4
	15. 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,
	Kingwel Xie, Valery Smyslov, Jun Hu, and Tero Kivinen. Special		Kingwel Xie, Valery Smyslov, Jun Hu, and Tero Kivinen. Special
	thanks to Eric Kinnear for his implementation work.		thanks to Eric Kinnear for his implementation work.
	16. References		16. References
	skipping to change at page 14, line 31 ¶		skipping to change at page 15, line 50 ¶
	[RFC3948] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.		[RFC3948] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.
	Stenberg, "UDP Encapsulation of IPsec ESP Packets",		Stenberg, "UDP Encapsulation of IPsec ESP Packets",
	RFC 3948, DOI 10.17487/RFC3948, January 2005,		RFC 3948, DOI 10.17487/RFC3948, January 2005,
	<http://www.rfc-editor.org/info/rfc3948>.		<http://www.rfc-editor.org/info/rfc3948>.
	[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",		[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
	RFC 4303, DOI 10.17487/RFC4303, December 2005,		RFC 4303, DOI 10.17487/RFC4303, December 2005,
	<http://www.rfc-editor.org/info/rfc4303>.		<http://www.rfc-editor.org/info/rfc4303>.
			[RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion
			Notification", RFC 6040, DOI 10.17487/RFC6040, November
			2010, <http://www.rfc-editor.org/info/rfc6040>.
	[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>.
	16.2. 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
	skipping to change at page 15, line 5 ¶		skipping to change at page 16, line 26 ¶
	[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>.
			[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
			of Explicit Congestion Notification (ECN) to IP",
			RFC 3168, DOI 10.17487/RFC3168, September 2001,
			<http://www.rfc-editor.org/info/rfc3168>.
	[RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol		[RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol
	(MOBIKE)", RFC 4555, DOI 10.17487/RFC4555, June 2006,		(MOBIKE)", RFC 4555, DOI 10.17487/RFC4555, June 2006,
	<http://www.rfc-editor.org/info/rfc4555>.		<http://www.rfc-editor.org/info/rfc4555>.
	[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security		[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
	(TLS) Protocol Version 1.2", RFC 5246,		(TLS) Protocol Version 1.2", RFC 5246,
	DOI 10.17487/RFC5246, August 2008,		DOI 10.17487/RFC5246, August 2008,
	<http://www.rfc-editor.org/info/rfc5246>.		<http://www.rfc-editor.org/info/rfc5246>.
	[RFC6520] Seggelmann, R., Tuexen, M., and M. Williams, "Transport		[RFC6520] Seggelmann, R., Tuexen, M., and M. Williams, "Transport
	skipping to change at page 15, line 27 ¶		skipping to change at page 17, line 7 ¶
	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. Using TCP encapsulation with TLS		Appendix A. Using TCP encapsulation with TLS
	This section provides recommendations on the support of TLS with the		This section provides recommendations on how to use TLS in addition
	TCP encapsulation.		to TCP encapsulation.
	When using TCP encapsulation, implementations may choose to use TLS		When using TCP encapsulation, implementations may choose to use TLS
	[RFC5246], to be able to traverse middle-boxes, which may block non-		[RFC5246] on the TCP connection to be able to traverse middle-boxes,
	HTTP traffic.		which may otherwise block the traffic.
	If a web proxy is applied to the ports for the TCP connection, and		If a web proxy is applied to the ports used for the TCP connection,
	TLS is being used, the TCP Originator can send an HTTP CONNECT		and TLS is being used, the TCP Originator can send an HTTP CONNECT
	message to establish an SA through the proxy [RFC2817].		message to establish an SA through the proxy [RFC2817].
	The use of TLS should be configurable on the peers, and may be used		The use of TLS should be configurable on the peers, and may be used
	as the default when using TCP encapsulation, or else be a fallback		as the default when using TCP encapsulation, or else be a fallback
	when basic TCP encapsulation fails. The TCP Responder may expect to		when basic TCP encapsulation fails. The TCP Responder may expect to
	read encapsulated IKE and ESP packets directly from the TCP		read encapsulated IKE and ESP packets directly from the TCP
	connection, or it may expect to read them from a stream of TLS data		connection, or it may expect to read them from a stream of TLS data
	packets. The TCP Originator should be pre-configured to use TLS or		packets. The TCP Originator should be pre-configured to use TLS or
	not when communicating with a given port on the TCP Responder.		not when communicating with a given port on the TCP Responder.
	skipping to change at page 16, line 22 ¶		skipping to change at page 17, line 51 ¶
	in situations in which TLS is not required in order to traverse		in situations in which TLS is not required in order to traverse
	middle-boxes.		middle-boxes.
	Appendix B. Example exchanges of TCP Encapsulation with TLS		Appendix B. Example exchanges of TCP Encapsulation with TLS
	B.1. Establishing an IKE session		B.1. Establishing an IKE session
	Client Server		Client Server
	---------- ----------		---------- ----------
	1) -------------------- TCP Connection -------------------		1) -------------------- TCP Connection -------------------
	(IP_I:Port_I -> IP_R:TCP443 or TCP4500)		(IP_I:Port_I -> IP_R:Port_R)
	TcpSyn ---------->		TcpSyn ---------->
	<---------- TcpSyn,Ack		<---------- TcpSyn,Ack
	TcpAck ---------->		TcpAck ---------->
	2) --------------------- TLS Session ---------------------		2) --------------------- TLS Session ---------------------
	ClientHello ---------->		ClientHello ---------->
	ServerHello		ServerHello
	Certificate*		Certificate*
	ServerKeyExchange*		ServerKeyExchange*
	<---------- ServerHelloDone		<---------- ServerHelloDone
	skipping to change at page 17, line 24 ¶		skipping to change at page 19, line 4 ¶
	repeat 1..N times		repeat 1..N times
	<------ Length + Non-ESP Marker		<------ Length + Non-ESP Marker
	IKE_AUTH + EAP		IKE_AUTH + EAP
	Length + Non-ESP Marker ---------->		Length + Non-ESP Marker ---------->
	final IKE_AUTH		final IKE_AUTH
	HDR, SK {AUTH}		HDR, SK {AUTH}
	<------ Length + Non-ESP Marker		<------ Length + Non-ESP Marker
	final IKE_AUTH		final IKE_AUTH
	HDR, SK {AUTH, CP(CFG_REPLY),		HDR, SK {AUTH, CP(CFG_REPLY),
	SA, TSi, TSr, ...}		SA, TSi, TSr, ...}
	-------------- IKE and IPsec SAs Established ------------		-------------- IKE and IPsec SAs Established ------------
	Length + ESP frame ---------->		Length + ESP frame ---------->
	Figure 4		Figure 5
	1. Client establishes a TCP connection with the server on port 443		1. Client establishes a TCP connection with the server on port
	or 4500.		4500, or an alternate pre-configured port that the server is
			listening on.
	2. Client initiates TLS handshake. During TLS handshake, the		2. If configured to use TLS, the client initiates a TLS handshake.
	server SHOULD NOT request the client's' certificate, since		During the TLS handshake, the server SHOULD NOT request the
	authentication is handled as part of IKE negotiation.		client's certificate, since authentication is handled as part
			of IKE negotiation.
	3. Client send the Stream Prefix for TCP encapsulated IKE		3. Client send the Stream Prefix for TCP encapsulated IKE
	Section 4 traffic to signal the beginning of IKE negotiation.		Section 4 traffic to signal the beginning of IKE negotiation.
	4. Client and server establish an IKE connection. This example		4. Client and server establish an IKE 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.
	B.2. Deleting an IKE session		B.2. Deleting an IKE session
	Client Server		Client Server
	---------- ----------		---------- ----------
	1) ----------------------- IKE Session ---------------------		1) ----------------------- IKE Session ---------------------
	Length + Non-ESP Marker ---------->		Length + Non-ESP Marker ---------->
	INFORMATIONAL		INFORMATIONAL
	HDR, SK {[N,] [D,]		HDR, SK {[N,] [D,]
	[CP,] ...}		[CP,] ...}
	<------ Length + Non-ESP Marker		<------ Length + Non-ESP Marker
	INFORMATIONAL		INFORMATIONAL
	HDR, SK {[N,] [D,]		HDR, SK {[N,] [D,]
	skipping to change at page 18, line 26 ¶		skipping to change at page 19, line 50 ¶
	2) --------------------- TLS Session ---------------------		2) --------------------- TLS Session ---------------------
	close_notify ---------->		close_notify ---------->
	<---------- close_notify		<---------- close_notify
	3) -------------------- TCP Connection -------------------		3) -------------------- TCP Connection -------------------
	TcpFin ---------->		TcpFin ---------->
	<---------- Ack		<---------- Ack
	<---------- TcpFin		<---------- TcpFin
	Ack ---------->		Ack ---------->
	--------------------- IKE SA Deleted -------------------		--------------------- IKE SA Deleted -------------------
	Figure 5		Figure 6
	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.
	The deletion of the IKE SA should lead to the disposal of the		The deletion of the IKE SA should lead to the disposal of the
	skipping to change at page 19, line 4 ¶		skipping to change at page 20, line 17 ¶
	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.
	The deletion of the IKE SA should lead to the disposal of the		The deletion of the IKE SA should lead to the disposal of the
	underlying TLS and TCP state.		underlying TLS and TCP state.
	B.3. Re-establishing an IKE session		B.3. Re-establishing an IKE session
	Client Server		Client Server
	---------- ----------		---------- ----------
	1) -------------------- TCP Connection -------------------		1) -------------------- TCP Connection -------------------
	(IP_I:Port_I -> IP_R:TCP443 or TCP4500)		(IP_I:Port_I -> IP_R:Port_R)
	TcpSyn ---------->		TcpSyn ---------->
	<---------- TcpSyn,Ack		<---------- TcpSyn,Ack
	TcpAck ---------->		TcpAck ---------->
	2) --------------------- TLS Session ---------------------		2) --------------------- TLS Session ---------------------
	ClientHello ---------->		ClientHello ---------->
	<---------- ServerHello		<---------- ServerHello
	[ChangeCipherSpec]		[ChangeCipherSpec]
	Finished		Finished
	[ChangeCipherSpec] ---------->		[ChangeCipherSpec] ---------->
	Finished		Finished
	3) ---------------------- Stream Prefix --------------------		3) ---------------------- Stream Prefix --------------------
	"IKETCP" ---------->		"IKETCP" ---------->
	4) <---------------------> IKE/ESP flow <------------------>		4) <---------------------> IKE/ESP flow <------------------>
	Length + ESP frame ---------->		Length + ESP frame ---------->
	Figure 6		Figure 7
	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 TCP Originator's address and port (IP_I and		connection. The TCP Originator's address and port (IP_I and
	Port_I) may be different from the previous connection's address		Port_I) may be different from the previous connection's address
	and port.		and 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
	skipping to change at page 20, line 25 ¶		skipping to change at page 21, line 40 ¶
	2) ------------ MOBIKE Attempt on new network --------------		2) ------------ MOBIKE Attempt on new network --------------
	(IP_I2:UDP4500 -> IP_R:UDP4500)		(IP_I2:UDP4500 -> IP_R:UDP4500)
	Non-ESP Marker ----------->		Non-ESP Marker ----------->
	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) }
	3) -------------------- TCP Connection -------------------		3) -------------------- TCP Connection -------------------
	(IP_I2:PORT_I -> IP_R:TCP443 or TCP4500)		(IP_I2:Port_I -> IP_R:Port_R)
	TcpSyn ----------->		TcpSyn ----------->
	<----------- TcpSyn,Ack		<----------- TcpSyn,Ack
	TcpAck ----------->		TcpAck ----------->
	4) --------------------- TLS Session ---------------------		4) --------------------- TLS Session ---------------------
	ClientHello ----------->		ClientHello ----------->
	ServerHello		ServerHello
	Certificate*		Certificate*
	ServerKeyExchange*		ServerKeyExchange*
	<----------- ServerHelloDone		<----------- ServerHelloDone
	skipping to change at page 21, line 4 ¶		skipping to change at page 22, line 20 ¶
	<----------- Finished		<----------- Finished
	5) ---------------------- Stream Prefix --------------------		5) ---------------------- Stream Prefix --------------------
	"IKETCP" ---------->		"IKETCP" ---------->
	6) ----------------------- IKE Session ---------------------		6) ----------------------- IKE Session ---------------------
	Length + Non-ESP Marker ----------->		Length + Non-ESP Marker ----------->
	INFORMATIONAL (Same as step 2)		INFORMATIONAL (Same as step 2)
	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) }
	<------- Length + Non-ESP Marker		<------- Length + Non-ESP Marker
	HDR, SK { N(NAT_DETECTION_SOURCE_IP),		HDR, SK { N(NAT_DETECTION_SOURCE_IP),
	N(NAT_DETECTION_DESTINATION_IP) }		N(NAT_DETECTION_DESTINATION_IP) }
	7) <----------------- IKE/ESP data flow ------------------->		7) <----------------- IKE/ESP data flow ------------------->
	Figure 7		Figure 8
	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 IKE session using the UPDATE_SA_ADDRESSES notify payload,		the IKE 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. 40 change blocks.
	93 lines changed or deleted		171 lines changed or added
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