< draft-ietf-ipsecme-ikev2-null-auth-03.txt		draft-ietf-ipsecme-ikev2-null-auth-04.txt >
	Network Working Group V. Smyslov		Network Working Group V. Smyslov
	Internet-Draft ELVIS-PLUS		Internet-Draft ELVIS-PLUS
	Intended status: Standards Track P. Wouters		Intended status: Standards Track P. Wouters
	Expires: August 1, 2015 Red Hat		Expires: August 24, 2015 Red Hat
	January 28, 2015		February 20, 2015
	The NULL Authentication Method in IKEv2 Protocol		The NULL Authentication Method in IKEv2 Protocol
	draft-ietf-ipsecme-ikev2-null-auth-03		draft-ietf-ipsecme-ikev2-null-auth-04
	Abstract		Abstract
	This document specifies the NULL Authentication method and the		This document specifies the NULL Authentication method and the
	ID_NULL Identification Payload ID Type for the IKEv2 Protocol. This		ID_NULL Identification Payload ID Type for the IKEv2 Protocol. This
	allows two IKE peers to establish single-side authenticated or mutual		allows two IKE peers to establish single-side authenticated or mutual
	unauthenticated IKE sessions for those use cases where a peer is		unauthenticated IKE sessions for those use cases where a peer is
	unwilling or unable to authenticate or identify itself. This ensures		unwilling or unable to authenticate or identify itself. This ensures
	IKEv2 can be used for Opportunistic Security (also known as		IKEv2 can be used for Opportunistic Security (also known as
	Opportunistic Encryption) to defend against Pervasive Monitoring		Opportunistic Encryption) to defend against Pervasive Monitoring
	skipping to change at page 1, line 38 ¶		skipping to change at page 1, line 38 ¶
	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 1, 2015.		This Internet-Draft will expire on August 24, 2015.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2015 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
	skipping to change at page 3, line 40 ¶		skipping to change at page 3, line 40 ¶
	authentication of the initiator.		authentication of the initiator.
	o Two peers without any trust relationship wish to defend against		o Two peers without any trust relationship wish to defend against
	widespread pervasive monitoring attacks as described in [RFC7258].		widespread pervasive monitoring attacks as described in [RFC7258].
	Without a trust relationship, the peers cannot authenticate each		Without a trust relationship, the peers cannot authenticate each
	other. Opportunistic Security [RFC7435] states that		other. Opportunistic Security [RFC7435] states that
	unauthenticated encrypted communication is preferred over		unauthenticated encrypted communication is preferred over
	cleartext communication. The peers want to use IKE to setup an		cleartext communication. The peers want to use IKE to setup an
	unauthenticated encrypted connection, that gives them protection		unauthenticated encrypted connection, that gives them protection
	against pervasive monitoring attacks. An attacker that is able		against pervasive monitoring attacks. An attacker that is able
	and willing to send packets can still launch an Man-in-the-Middle		and willing to send packets can still launch a Man-in-the-Middle
	attack to obtain access to the decrypted communication. This case		attack to obtain access to the decrypted communication. This case
	uses a fully unauthenticated key exchange.		uses a fully unauthenticated key exchange.
	To meet these needs this document introduces the NULL Authentication		To meet these needs this document introduces the NULL Authentication
	method, and the ID_NULL ID type. This allows an IKE peer to		method, and the ID_NULL ID type. This allows an IKE peer to
	explicitly indicate that it is unwilling or unable to certify its		explicitly indicate that it is unwilling or unable to certify its
	identity.		identity.
	1.1. Conventions Used in This Document		1.1. Conventions Used in This Document
	skipping to change at page 5, line 46 ¶		skipping to change at page 5, line 46 ¶
	2.2. Identification Payload		2.2. Identification Payload
	When a remote peer is not authenticated, any ID presented in the		When a remote peer is not authenticated, any ID presented in the
	Identification Data field of the ID payload cannot be validated. To		Identification Data field of the ID payload cannot be validated. To
	avoid the need of sending a bogus ID Type with placeholder data, this		avoid the need of sending a bogus ID Type with placeholder data, this
	specification defines a new ID Type, ID_NULL. The Identification		specification defines a new ID Type, ID_NULL. The Identification
	Data field of the ID payload for this ID Type MUST be empty.		Data field of the ID payload for this ID Type MUST be empty.
	If NULL Authentication is in use and an anonymity is a concern then		If NULL Authentication is in use and an anonymity is a concern then
	ID_NULL SHOULD be used in Identification payload. In some cases		ID_NULL SHOULD be used in the Identification payload. Some examples
	there may be good reasons to use non-null identities (and ID Types		of acceptable cases to use a non-null identity type and value with
	other than ID_NULL) with NULL Authentication. The identities may be		NULL Authentication are logging, troubleshooting or in scenarios
	used for logging, troubleshooting or in scenarios when authentication		where authentication takes place out of band after the IKE SA is
	takes place out of band after the IKE SA is created (like in		created (like in [AUTOVPN]). The content of the Identification
	[AUTOVPN]). In any case, when NULL Authentication is employed, the		payload MUST NOT be used for any trust and policy checking in
	content of Identification payload MUST NOT be used for any trust and		IKE_AUTH exchange when NULL Authentication is employed (see Section
	policy checking in IKE_AUTH exchange.		2.4 for details).
	ID_NULL is primarily intended to be used with the NULL		ID_NULL is primarily intended to be used with NULL Authentication but
	Authentication, but it MAY also be used in other situations, when the		could be used in other situations where the content of the
	content of Identification payload does not matter. For example,		Identification Payload is not used. For example, ID_NULL could be
	ID_NULL can be used when authentication is performed via raw public		used when authentication is performed via raw public keys and the
	keys and the identities are these keys themselves. Another example		identities are the keys themselves. These alternative uses of
	is EAP authentication when the client identity in ID payload is not		ID_NULL should be described in their own respective documents.
	used.
	The IKEv2 Identification Payload ID Type for ID_NULL is 13.		The IKEv2 Identification Payload ID Type for ID_NULL is 13.
	2.3. INITIAL_CONTACT Notification		2.3. INITIAL_CONTACT Notification
	The identity of a peer using NULL Authentication cannot be used to		The identity of a peer using NULL Authentication cannot be used to
	distinguish from IKE SAs created by other peers using the NULL		find existing IKE SAs created by the same peer, as the peer identity
	Authentication method. For that reason the INITIAL_CONTACT		is not authenticated. For that reason the INITIAL_CONTACT
	notifications MUST be ignored for IKE SAs using NULL Authentication.		notifications MUST NOT be used to delete any other IKE SAs based on
			the same peer identity without additional verification that the
			existing IKE SAs with matching identity are actually stale.
	The standard IKE Liveness Check procedure, decribed in Section 2.4 of		The standard IKE Liveness Check procedure, described in Section 2.4
	[RFC7296], can be used to detect stale IKE SAs created by peers using		of [RFC7296], can be used to detect stale IKE SAs created by peers
	NULL Authentication. Inactive unauthenticated IKE SAs should be		using NULL Authentication. Inactive unauthenticated IKE SAs should
	checked periodically. Additionally, the event of creating a new		be checked periodically. Additionally, the event of creating a new
	unauthenticated IKE SA can be used to trigger an out-of-order check		unauthenticated IKE SA can be used to trigger an out-of-order check
	on existing unauthenticated IKE SAs, possibly limited to identical or		on existing unauthenticated IKE SAs, possibly limited to identical or
	close-by IP addresses or to identical identities of the just created		close-by IP addresses or to identical identities of the just created
	IKE SA.		IKE SA.
	Implementations should weight the resource consumption of sending		Implementations should weight the resource consumption of sending
	Liveness Checks against the memory usage of possible orphaned IKE		Liveness Checks against the memory usage of possible orphaned IKE
	SAs. Implementations may choose to handle situations with thousands		SAs. Implementations may choose to handle situations with thousands
	of unauthenticated IKE SAs differently from situations with very few		of unauthenticated IKE SAs differently from situations with very few
	such SAs.		such SAs.
	skipping to change at page 6, line 49 ¶		skipping to change at page 6, line 50 ¶
	Section 4.4.3 of [RFC4301] defines the Peer Authorization Database		Section 4.4.3 of [RFC4301] defines the Peer Authorization Database
	(PAD), which provides the link between Security Policy Database (SPD)		(PAD), which provides the link between Security Policy Database (SPD)
	and the IKEv2. The PAD contains an ordered list of records, with		and the IKEv2. The PAD contains an ordered list of records, with
	peers' identities along with corresponding authentication data and		peers' identities along with corresponding authentication data and
	Child SA authorization data. When the IKE SA is being established		Child SA authorization data. When the IKE SA is being established
	the PAD is consulted to determine how the peer should be		the PAD is consulted to determine how the peer should be
	authenticated and what Child SAs it is authorized to create.		authenticated and what Child SAs it is authorized to create.
	When using NULL Authentication, the peer identity is not		When using NULL Authentication, the peer identity is not
	authenticated and cannot be used. If ID_NULL is used with NULL		authenticated and cannot be trusted. If ID_NULL is used with NULL
	Authentication, there is no ID at all. The processing of PAD		Authentication, there is no ID at all. The processing of PAD
	described in Section 4.4.3.4 of [RFC4301] must be updated.		described in Section 4.4.3.4 of [RFC4301] must be updated.
	If NULL Authentication is supported and allowed, then a special entry		The NULL authentication needs to be added as one of supported
	MUST be included in the PAD. This entry MUST contain no		authentication methods. This method does not have any authentication
	authentication data. It MAY contain a set of constraints for		data. To add support for ID_NULL, it needs to be included into the
	creating Child SAs as described in Section 4.4.3 of [RFC4301]. When		list of ID types, specified in Section 4.4.3.1 of [RFC4301]. The
	a peer uses NULL Authentication, regular matching rules for the PAD		matching rule for ID_NULL is just whether this type is used, i.e. no
	MUST be ignored and this special entry MUST be selected regardless of		actual ID matching is done, as ID_NULL contains no identity data.
	the peer identity. Likewise, if a peer uses any other authentication
	method, then this special entry MUST NOT be selected regardless of
	the peer identity and the regular search of the PAD described in
	Section 4.4.3.4 of [RFC4301] MUST be performed.
	Implementations SHOULD allow to be configured so, that when a peer		Section 4.4.3.3 of the [RFC4301] describes how the IKE ID is matched
	requests NULL Authentication, then regular PAD entries are searched		against the SPD entries. When using the NULL authentication method
	before selecting the special entry, to ensure that there is no entry,		those matching rules MUST include matching of a new flag in the SPD
	containing peer's IP address. In this case implementations MUST		entry specifying whether unauthenticated users are allowed to use
	reject the IKE_AUTH exchange by sending an AUTHENTICATION_FAILED		that entry. I.e. each SPD entry needs to be augmented to have flag
	notification if such an entry is found.		specifying whether it can be used with NULL authentication or not,
			and only those rules explictly having that flag turned on can be used
			with unauthenticated connections.
	2.5. Traffic Selectors		2.5. Traffic Selectors
	Traffic Selectors and narrowing allow two IKE peers to mutually agree		Traffic Selectors and narrowing allow two IKE peers to mutually agree
	on a traffic range for an IPsec SA. An unauthenticated peer must not		on a traffic range for an IPsec SA. An unauthenticated peer must not
	be allowed to use this mechanism to steal traffic that an IKE peer		be allowed to use this mechanism to steal traffic that an IKE peer
	intended to be for another host. This is especially problematic when		intended to be for another host. This is especially problematic when
	supporting anonymous IKE peers behind NAT, as such IKE peers build an		supporting anonymous IKE peers behind NAT, as such IKE peers build an
	IPsec SA using their pre-NAT IP address that are different from the		IPsec SA using their pre-NAT IP address that are different from the
	source IP of their IKE packets. A rogue IKE peer could use malicious		source IP of their IKE packets. A rogue IKE peer could use malicious
	skipping to change at page 8, line 7 ¶		skipping to change at page 8, line 7 ¶
	internal NAT and connection tracking.		internal NAT and connection tracking.
	Implementations MAY force unauthenticated IKE peers to single host-		Implementations MAY force unauthenticated IKE peers to single host-
	to-host IPsec SAs. When using IPv6 it is not always possible, so in		to-host IPsec SAs. When using IPv6 it is not always possible, so in
	this case implementations MUST be able to assign full /64 address		this case implementations MUST be able to assign full /64 address
	block to the peer as described in [RFC5739], even if it is not		block to the peer as described in [RFC5739], even if it is not
	authenticated.		authenticated.
	3. Security Considerations		3. Security Considerations
	If authenticated IKE sessions are possible between the peers, then		If authenticated IKE sessions are possible for a certain traffic
	unauthenticated IKE SHOULD NOT be used, unless implementations make		selector range between the peers, then unauthenticated IKE SHOULD NOT
	sure to keep authenticated and unauthenticated IKE sessions separate,		be used for that traffic selector range. When mixing authenticated
	and has policy rules to specify when to use which IKE session. See		and unauthenticated IKE with the same peer, policy rules should
	[RFC7435] for details.		ensure the highest level of security will be used to protect the
			communication between the two peers. See [RFC7435] for details.
	If both peers use NULL Authentication, the entire key exchange		If both peers use NULL Authentication, the entire key exchange
	becomes unauthenticated. This makes the IKE session vulnerable to		becomes unauthenticated. This makes the IKE session vulnerable to
	active Man-in-the-Middle Attacks.		active Man-in-the-Middle Attacks.
	Using an ID Type other than ID_NULL with the NULL Authentication		Using an ID Type other than ID_NULL with the NULL Authentication
	Method may compromise the client's anonimity in case of an active		Method may compromise the client's anonymity in case of an active
	MITM attack.		MITM attack.
	IKE implementations without NULL Authentication have always performed		IKE implementations without NULL Authentication have always performed
	mutual authentication and were not designed for use with		mutual authentication and were not designed for use with
	unauthenticated IKE peers. Implementations might have made		unauthenticated IKE peers. Implementations might have made
	assumptions that are no longer valid. Furthermore, the host itself		assumptions that are no longer valid. Furthermore, the host itself
	might have made trust assumptions or may not be aware of the network		might have made trust assumptions or may not be aware of the network
	topology changes that resulted from IPsec SAs from unauthenticated		topology changes that resulted from IPsec SAs from unauthenticated
	IKE peers.		IKE peers.
	skipping to change at page 9, line 28 ¶		skipping to change at page 9, line 29 ¶
	peer.		peer.
	3.4. Networking topology changes		3.4. Networking topology changes
	When a host relies on packet filters or firewall software to protect		When a host relies on packet filters or firewall software to protect
	itself, establishing an IKE SA and installing an IPsec SA might		itself, establishing an IKE SA and installing an IPsec SA might
	accidentally circumvent these packet filters and firewall		accidentally circumvent these packet filters and firewall
	restrictions, as the encrypted ESP (protocol 50) or ESPinUDP (UDP		restrictions, as the encrypted ESP (protocol 50) or ESPinUDP (UDP
	port 4500) packets do not match the packet filters defined. IKE		port 4500) packets do not match the packet filters defined. IKE
	peers supporting unauthenticated IKE MUST pass all decrypted traffic		peers supporting unauthenticated IKE MUST pass all decrypted traffic
	through the same packet filters and security mechanisms as plaintext		through the same packet filters and security mechanisms as incoming
	traffic.		plaintext traffic.
	4. Acknowledgments		4. Acknowledgments
	The authors would like to thank Yaron Sheffer and Tero Kivinen for		The authors would like to thank Yaron Sheffer and Tero Kivinen for
	their reviews and valuable comments.		their reviews, valuable comments and contributed text.
	5. IANA Considerations		5. IANA Considerations
	This document defines a new entry in the "IKEv2 Authentication		This document defines a new entry in the "IKEv2 Authentication
	Method" registry:		Method" registry:
	13 NULL Authentication		13 NULL Authentication
	This document also defines a new entry in the "IKEv2 Identification		This document also defines a new entry in the "IKEv2 Identification
	Payload ID Types" registry:		Payload ID Types" registry:
End of changes. 15 change blocks.
	53 lines changed or deleted		53 lines changed or added
This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/