< draft-ietf-ipsecme-split-dns-07.txt		draft-ietf-ipsecme-split-dns-08.txt >
	Network T. Pauly		Network T. Pauly
	Internet-Draft Apple Inc.		Internet-Draft Apple Inc.
	Intended status: Standards Track P. Wouters		Intended status: Standards Track P. Wouters
	Expires: August 31, 2018 Red Hat		Expires: December 20, 2018 Red Hat
	February 27, 2018		June 18, 2018
	Split DNS Configuration for IKEv2		Split DNS Configuration for IKEv2
	draft-ietf-ipsecme-split-dns-07		draft-ietf-ipsecme-split-dns-08
	Abstract		Abstract
	This document defines two Configuration Payload Attribute Types for		This document defines two Configuration Payload Attribute Types for
	the IKEv2 protocol that add support for private DNS domains. These		the IKEv2 protocol that add support for private DNS domains. These
	domains are intended to be resolved using DNS servers reachable		domains are intended to be resolved using DNS servers reachable
	through an IPsec connection, while leaving all other DNS resolution		through an IPsec connection, while leaving all other DNS resolution
	unchanged. This approach of resolving a subset of domains using non-		unchanged. This approach of resolving a subset of domains using non-
	public DNS servers is referred to as "Split DNS".		public DNS servers is referred to as "Split DNS".
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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
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	This Internet-Draft will expire on August 31, 2018.		This Internet-Draft will expire on December 20, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 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
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	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 . . . . . . . . . . . . . . . . . . . . . . . . 2
	skipping to change at page 2, line 23 ¶		skipping to change at page 2, line 23 ¶
	3.1. Configuration Request . . . . . . . . . . . . . . . . . . 4		3.1. Configuration Request . . . . . . . . . . . . . . . . . . 4
	3.2. Configuration Reply . . . . . . . . . . . . . . . . . . . 4		3.2. Configuration Reply . . . . . . . . . . . . . . . . . . . 4
	3.3. Mapping DNS Servers to Domains . . . . . . . . . . . . . 5		3.3. Mapping DNS Servers to Domains . . . . . . . . . . . . . 5
	3.4. Example Exchanges . . . . . . . . . . . . . . . . . . . . 5		3.4. Example Exchanges . . . . . . . . . . . . . . . . . . . . 5
	3.4.1. Simple Case . . . . . . . . . . . . . . . . . . . . . 5		3.4.1. Simple Case . . . . . . . . . . . . . . . . . . . . . 5
	3.4.2. Requesting Domains and DNSSEC trust anchors . . . . . 6		3.4.2. Requesting Domains and DNSSEC trust anchors . . . . . 6
	4. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 6		4. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 6
	4.1. INTERNAL_DNS_DOMAIN Configuration Attribute Type Request		4.1. INTERNAL_DNS_DOMAIN Configuration Attribute Type Request
	and Reply . . . . . . . . . . . . . . . . . . . . . . . . 7		and Reply . . . . . . . . . . . . . . . . . . . . . . . . 7
	4.2. INTERNAL_DNSSEC_TA Configuration Attribute . . . . . . . 7		4.2. INTERNAL_DNSSEC_TA Configuration Attribute . . . . . . . 7
	5. Split DNS Usage Guidelines . . . . . . . . . . . . . . . . . 8		5. INTERNAL_DNS_DOMAIN Usage Guidelines . . . . . . . . . . . . 9
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 10		6. INTERNAL_DNSSEC_TA Usage Guidelines . . . . . . . . . . . . . 10
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10		7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
	8.1. Normative References . . . . . . . . . . . . . . . . . . 11		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
	8.2. Informative References . . . . . . . . . . . . . . . . . 11		9.1. Normative References . . . . . . . . . . . . . . . . . . 12
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12		9.2. Informative References . . . . . . . . . . . . . . . . . 12
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
	1. Introduction		1. Introduction
	Split DNS is a common configuration for secure tunnels, such as		Split DNS is a common configuration for secure tunnels, such as
	Virtual Private Networks in which host machines private to an		Virtual Private Networks in which host machines private to an
	organization can only be resolved using internal DNS resolvers		organization can only be resolved using internal DNS resolvers
	[RFC2775]. In such configurations, it is often desirable to only		[RFC2775]. In such configurations, it is often desirable to only
	resolve hosts within a set of private domains using the tunnel, while		resolve hosts within a set of private domains using the tunnel, while
	letting resolutions for public hosts be handled by a device's default		letting resolutions for public hosts be handled by a device's default
	DNS configuration.		DNS configuration.
	skipping to change at page 8, line 47 ¶		skipping to change at page 8, line 47 ¶
	o DNSKEY Algorithm (0 or 1 octet) - DNSKEY algorithm value from the		o DNSKEY Algorithm (0 or 1 octet) - DNSKEY algorithm value from the
	IANA DNS Security Algorithm Numbers Registry.		IANA DNS Security Algorithm Numbers Registry.
	o Digest Type (0 or 1 octet) - DS algorithm value from the IANA		o Digest Type (0 or 1 octet) - DS algorithm value from the IANA
	Delegation Signer (DS) Resource Record (RR) Type Digest Algorithms		Delegation Signer (DS) Resource Record (RR) Type Digest Algorithms
	Registry.		Registry.
	o Digest Data (0 or more octets) - The DNSKEY digest as specified in		o Digest Data (0 or more octets) - The DNSKEY digest as specified in
	[RFC4034] Section 5.1 in presentation format.		[RFC4034] Section 5.1 in presentation format.
	5. Split DNS Usage Guidelines		INTERNAL_DNSSEC_TA payloads MUST immediately follow an
			INTERNAL_DNS_DOMAIN payload. As the INTERNAL_DNSSEC_TA format itself
			does not contain the domain name, it relies on the preceding
			INTERNAL_DNS_DOMAIN to provide the domain for which it specifies the
			trust anchor.
			5. INTERNAL_DNS_DOMAIN Usage Guidelines
	If a CFG_REPLY payload contains no INTERNAL_DNS_DOMAIN attributes,		If a CFG_REPLY payload contains no INTERNAL_DNS_DOMAIN attributes,
	the client MAY use the provided INTERNAL_IP4_DNS or INTERNAL_IP6_DNS		the client MAY use the provided INTERNAL_IP4_DNS or INTERNAL_IP6_DNS
	servers as the default DNS server(s) for all queries.		servers as the default DNS server(s) for all queries.
	If a client is configured by local policy to only accept a limited		If a client is configured by local policy to only accept a limited
	number of INTERNAL_DNS_DOMAIN values, the client MUST ignore any		number of INTERNAL_DNS_DOMAIN values, the client MUST ignore any
	other INTERNAL_DNS_DOMAIN values.		other INTERNAL_DNS_DOMAIN values.
	For each INTERNAL_DNS_DOMAIN entry in a CFG_REPLY payload that is not		For each INTERNAL_DNS_DOMAIN entry in a CFG_REPLY payload that is not
	skipping to change at page 9, line 44 ¶		skipping to change at page 9, line 50 ¶
	and "ample.com" SHOULD NOT be resolved using the internal resolver		and "ample.com" SHOULD NOT be resolved using the internal resolver
	and SHOULD use the system's external DNS resolver(s).		and SHOULD use the system's external DNS resolver(s).
	When an IKE SA is terminated, the DNS forwarding MUST be		When an IKE SA is terminated, the DNS forwarding MUST be
	unconfigured. This includes deleting the DNS forwarding rules;		unconfigured. This includes deleting the DNS forwarding rules;
	flushing all cached data for DNS domains provided by the		flushing all cached data for DNS domains provided by the
	INTERNAL_DNS_DOMAIN attribute, including negative cache entries;		INTERNAL_DNS_DOMAIN attribute, including negative cache entries;
	removing any obtained DNSSEC trust anchors from the list of trust		removing any obtained DNSSEC trust anchors from the list of trust
	anchors; and clearing the outstanding DNS request queue.		anchors; and clearing the outstanding DNS request queue.
	INTERNAL_DNS_DOMAIN and INTERNAL_DNSSEC_TA attributes SHOULD only be		INTERNAL_DNS_DOMAIN attributes SHOULD only be used on split tunnel
	used on split tunnel configurations where only a subset of traffic is		configurations where only a subset of traffic is routed into a
	routed into a private remote network using the IPsec connection. If		private remote network using the IPsec connection. If all traffic is
	all traffic is routed over the IPsec connection, the existing global		routed over the IPsec connection, the existing global
	INTERNAL_IP4_DNS and INTERNAL_IP6_DNS can be used without creating		INTERNAL_IP4_DNS and INTERNAL_IP6_DNS can be used without creating
	specific DNS exemptions.		specific DNS exemptions.
	6. Security Considerations		6. INTERNAL_DNSSEC_TA Usage Guidelines
			Installing an INTERNAL_DNSSEC_TA trust anchor can be seen as the
			equivalent of installing an Enterprise Certificate Agency (CA)
			certificate. It allows the remote IKE/IPsec server to modify DNS
			answers including its DNSSEC cryptographic signatures by overriding
			existing DNS information with trust anchor conveyed via IKE and
			(temporarilly) installed on the IKE client. Of specific concern is
			the overriding of [RFC6698] based TLSA records, which represent a
			confirmation or override of an existing WebPKI TLS certificate.
			Other DNS record types that convey cryptographic materials (public
			keys or fingerprints) are OPENPGPKEY, SMIMEA, SSHP and IPSECKEY
			records.
			IKE clients MUST ignore any received INTERNAL_DNSSEC_TA requests for
			a FDQN for which it did not receive and accept an INTERNAL_DNS_DOMAIN
			Configuration Payload.
			DNS records can be used to publish specific records containing trust
			anchors for applications. The most common record type is the TLSA
			record specified in [RFC6698]. This DNS record type publishes which
			CA certificate or EE certificate to expect for a certain host name.
			These records are protected by DNSSEC and thus can be trusted by the
			application. Whether to trust TLSA records instead of the
			traditional WebPKI depends on the local policy of the client. By
			accepting an INTERNAL_DNSSEC_TA trust anchor via IKE from the remote
			IKE server, the IPsec client might be allowing the remote IKE server
			to override the trusted certificates for TLS. The same applies to
			other public key or fingerprint based DNS records, such as
			OPENPGPKEY, SMIMEA or IPSECKEY records.
			In most deployment scenario's, the IKE client has an expectation that
			it is connecting, using a split-network setup, to a specific
			organisation or enterprise. A recommended policy would be to only
			accept INTERNAL_DNSSEC_TA directives from that organization's DNS
			names. However, this might not be possible in all deployment
			scenarios, such as one where the IKE server is handing out a number
			of domains that are not within one parent domain.
			7. Security Considerations
	The use of Split DNS configurations assigned by an IKEv2 responder is		The use of Split DNS configurations assigned by an IKEv2 responder is
	predicated on the trust established during IKE SA authentication.		predicated on the trust established during IKE SA authentication.
	However, if IKEv2 is being negotiated with an anonymous or unknown		However, if IKEv2 is being negotiated with an anonymous or unknown
	endpoint (such as for Opportunistic Security [RFC7435]), the		endpoint (such as for Opportunistic Security [RFC7435]), the
	initiator MUST ignore Split DNS configurations assigned by the		initiator MUST ignore Split DNS configurations assigned by the
	responder.		responder.
	If a host connected to an authenticated IKE peer is connecting to		If a host connected to an authenticated IKE peer is connecting to
	another IKE peer that attempts to claim the same domain via the		another IKE peer that attempts to claim the same domain via the
	INTERNAL_DNS_DOMAIN attribute, the IKE connection SHOULD only process		INTERNAL_DNS_DOMAIN attribute, the IKE connection SHOULD only process
	the DNS information if the two connections are part of the same		the DNS information if the two connections are part of the same
	logical entity. Otherwise, the client SHOULD refuse the DNS		logical entity. Otherwise, the client SHOULD refuse the DNS
	information and potentially warn the end-user.		information and potentially warn the end-user.
	INTERNAL_DNSSEC_TA payloads MUST immediately follow an
	INTERNAL_DNS_DOMAIN payload. As the INTERNAL_DNSSEC_TA format itself
	does not contain the domain name, it relies on the preceding
	INTERNAL_DNS_DOMAIN to provide the domain for which it specifies the
	trust anchor.
	If the initiator is using DNSSEC validation for a domain in its		If the initiator is using DNSSEC validation for a domain in its
	public DNS view, and it requests and receives an INTERNAL_DNS_DOMAIN		public DNS view, and it requests and receives an INTERNAL_DNS_DOMAIN
	attribute without an INTERNAL_DNSSEC_TA, it will need to reconfigure		attribute without an INTERNAL_DNSSEC_TA, it will need to reconfigure
	its DNS resolver to allow for an insecure delegation. It SHOULD NOT		its DNS resolver to allow for an insecure delegation. It SHOULD NOT
	accept insecure delegations for domains that are DNSSEC signed in the		accept insecure delegations for domains that are DNSSEC signed in the
	public DNS view, for which it has not explicitely requested such		public DNS view, for which it has not explicitely requested such
	deletation by specifying the domain specifically using a		deletation by specifying the domain specifically using a
	INTERNAL_DNS_DOMAIN(domain) request.		INTERNAL_DNS_DOMAIN(domain) request.
	Deployments that configure INTERNAL_DNS_DOMAIN domains should pay		Deployments that configure INTERNAL_DNS_DOMAIN domains should pay
	close attention to their use of indirect reference RRtypes such as		close attention to their use of indirect reference RRtypes such as
	CNAME, DNAME, MX or SRV records so that resolving works as intended		CNAME, DNAME, MX or SRV records so that resolving works as intended
	when all, some, or none of the IPsec connections are established.		when all, some, or none of the IPsec connections are established.
	The content of INTERNAL_DNS_DOMAIN and INTERNAL_DNSSEC_TA may be		The content of INTERNAL_DNS_DOMAIN and INTERNAL_DNSSEC_TA may be
	passed to another (DNS) program for processing. As with any network		passed to another (DNS) program for processing. As with any network
	input, the content SHOULD be considered untrusted and handled		input, the content SHOULD be considered untrusted and handled
	accordingly.		accordingly.
	7. IANA Considerations		8. IANA Considerations
	This document defines two new IKEv2 Configuration Payload Attribute		This document defines two new IKEv2 Configuration Payload Attribute
	Types, which are allocated from the "IKEv2 Configuration Payload		Types, which are allocated from the "IKEv2 Configuration Payload
	Attribute Types" namespace.		Attribute Types" namespace.
	Multi-		Multi-
	Value Attribute Type Valued Length Reference		Value Attribute Type Valued Length Reference
	------ ------------------- ------ ---------- ---------------		------ ------------------- ------ ---------- ---------------
	25 INTERNAL_DNS_DOMAIN YES 0 or more [this document]		25 INTERNAL_DNS_DOMAIN YES 0 or more [this document]
	26 INTERNAL_DNSSEC_TA YES 0 or more [this document]		26 INTERNAL_DNSSEC_TA YES 0 or more [this document]
	Figure 1		Figure 1
	8. References		9. References
	8.1. Normative References		9.1. Normative References
	[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,		[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
	and E. Lear, "Address Allocation for Private Internets",		and E. Lear, "Address Allocation for Private Internets",
	BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,		BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,
	<https://www.rfc-editor.org/info/rfc1918>.		<https://www.rfc-editor.org/info/rfc1918>.
	[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, <https://www.rfc-
	<https://www.rfc-editor.org/info/rfc2119>.		editor.org/info/rfc2119>.
	[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.		[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
	Rose, "Resource Records for the DNS Security Extensions",		Rose, "Resource Records for the DNS Security Extensions",
	RFC 4034, DOI 10.17487/RFC4034, March 2005,		RFC 4034, DOI 10.17487/RFC4034, March 2005,
	<https://www.rfc-editor.org/info/rfc4034>.		<https://www.rfc-editor.org/info/rfc4034>.
	[RFC5890] Klensin, J., "Internationalized Domain Names for		[RFC5890] Klensin, J., "Internationalized Domain Names for
	Applications (IDNA): Definitions and Document Framework",		Applications (IDNA): Definitions and Document Framework",
	RFC 5890, DOI 10.17487/RFC5890, August 2010,		RFC 5890, DOI 10.17487/RFC5890, August 2010,
	<https://www.rfc-editor.org/info/rfc5890>.		<https://www.rfc-editor.org/info/rfc5890>.
			[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
			of Named Entities (DANE) Transport Layer Security (TLS)
			Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
			2012, <https://www.rfc-editor.org/info/rfc6698>.
	[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, <https://www.rfc-editor.org/info/rfc7296>.		2014, <https://www.rfc-editor.org/info/rfc7296>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	8.2. Informative References		9.2. Informative References
	[RFC2775] Carpenter, B., "Internet Transparency", RFC 2775,		[RFC2775] Carpenter, B., "Internet Transparency", RFC 2775,
	DOI 10.17487/RFC2775, February 2000,		DOI 10.17487/RFC2775, February 2000, <https://www.rfc-
	<https://www.rfc-editor.org/info/rfc2775>.		editor.org/info/rfc2775>.
	[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection		[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
	Most of the Time", RFC 7435, DOI 10.17487/RFC7435,		Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
	December 2014, <https://www.rfc-editor.org/info/rfc7435>.		December 2014, <https://www.rfc-editor.org/info/rfc7435>.
	Authors' Addresses		Authors' Addresses
	Tommy Pauly		Tommy Pauly
	Apple Inc.		Apple Inc.
	One Apple Park Way		One Apple Park Way
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