< draft-ietf-ipsecme-split-dns-12.txt   draft-ietf-ipsecme-split-dns-13.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: February 7, 2019 Red Hat Expires: April 25, 2019 Red Hat
August 6, 2018 October 22, 2018
Split DNS Configuration for IKEv2 Split DNS Configuration for IKEv2
draft-ietf-ipsecme-split-dns-12 draft-ietf-ipsecme-split-dns-13
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".
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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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 February 7, 2019. This Internet-Draft will expire on April 25, 2019.
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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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 . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Protocol Exchange . . . . . . . . . . . . . . . . . . . . . . 3
3. Protocol Exchange . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Configuration Request . . . . . . . . . . . . . . . . . . 4
3.1. Configuration Request . . . . . . . . . . . . . . . . . . 4 2.2. Configuration Reply . . . . . . . . . . . . . . . . . . . 4
3.2. Configuration Reply . . . . . . . . . . . . . . . . . . . 4 2.3. Mapping DNS Servers to Domains . . . . . . . . . . . . . 5
3.3. Mapping DNS Servers to Domains . . . . . . . . . . . . . 5 2.4. Example Exchanges . . . . . . . . . . . . . . . . . . . . 5
3.4. Example Exchanges . . . . . . . . . . . . . . . . . . . . 5 2.4.1. Simple Case . . . . . . . . . . . . . . . . . . . . . 5
3.4.1. Simple Case . . . . . . . . . . . . . . . . . . . . . 5 2.4.2. Requesting Domains and DNSSEC trust anchors . . . . . 6
3.4.2. Requesting Domains and DNSSEC trust anchors . . . . . 6 3. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 6
4. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. 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 3.2. INTERNAL_DNSSEC_TA Configuration Attribute . . . . . . . 7
5. INTERNAL_DNS_DOMAIN Usage Guidelines . . . . . . . . . . . . 9 4. INTERNAL_DNS_DOMAIN Usage Guidelines . . . . . . . . . . . . 9
6. INTERNAL_DNSSEC_TA Usage Guidelines . . . . . . . . . . . . . 10 5. INTERNAL_DNSSEC_TA Usage Guidelines . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 13 8.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 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
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servers", and other DNS servers will be referred to as "external DNS servers", and other DNS servers will be referred to as "external DNS
servers". servers".
A client using these configuration payloads will be able to request A client using these configuration payloads will be able to request
and receive Split DNS configurations using the INTERNAL_DNS_DOMAIN and receive Split DNS configurations using the INTERNAL_DNS_DOMAIN
and INTERNAL_DNSSEC_TA configuration attributes. The client device and INTERNAL_DNSSEC_TA configuration attributes. The client device
can use the internal DNS server(s) for any DNS queries within the can use the internal DNS server(s) for any DNS queries within the
assigned domains. DNS queries for other domains SHOULD be sent to assigned domains. DNS queries for other domains SHOULD be sent to
the regular external DNS server. the regular external DNS server.
Other tunnel-establishment protocols already support the assignment
of Split DNS domains. For example, there are proprietary extensions
to IKEv1 that allow a server to assign Split DNS domains to a client.
However, the IKEv2 standard does not include a method to configure
this option. This document defines a standard way to negotiate this
option for IKEv2.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
captials, as shown here. captials, as shown here.
2. Background 2. Protocol Exchange
Split DNS is a common configuration for enterprise VPN deployments,
in which one or more private DNS domains are only accessible and
resolvable via an IPsec based VPN connection.
Other tunnel-establishment protocols already support the assignment
of Split DNS domains. For example, there are proprietary extensions
to IKEv1 that allow a server to assign Split DNS domains to a client.
However, the IKEv2 standard does not include a method to configure
this option. This document defines a standard way to negotiate this
option for IKEv2.
3. Protocol Exchange
In order to negotiate which domains are considered internal to an In order to negotiate which domains are considered internal to an
IKEv2 tunnel, initiators indicate support for Split DNS in their IKEv2 tunnel, initiators indicate support for Split DNS in their
CFG_REQUEST payloads, and responders assign internal domains (and CFG_REQUEST payloads, and responders assign internal domains (and
DNSSEC trust anchors) in their CFG_REPLY payloads. When Split DNS DNSSEC trust anchors) in their CFG_REPLY payloads. When Split DNS
has been negotiated, the existing DNS server configuration attributes has been negotiated, the existing DNS server configuration attributes
will be interpreted as internal DNS servers that can resolve will be interpreted as internal DNS servers that can resolve
hostnames within the internal domains. hostnames within the internal domains.
3.1. Configuration Request 2.1. Configuration Request
To indicate support for Split DNS, an initiator includes one more To indicate support for Split DNS, an initiator includes one more
INTERNAL_DNS_DOMAIN attributes as defined in Section 4 as part of the INTERNAL_DNS_DOMAIN attributes as defined in Section 3 as part of the
CFG_REQUEST payload. If an INTERNAL_DNS_DOMAIN attribute is included CFG_REQUEST payload. If an INTERNAL_DNS_DOMAIN attribute is included
in the CFG_REQUEST, the initiator SHOULD also include one or more in the CFG_REQUEST, the initiator MUST also include one or more
INTERNAL_IP4_DNS and INTERNAL_IP6_DNS attributes in the CFG_REQUEST. INTERNAL_IP4_DNS and INTERNAL_IP6_DNS attributes in the CFG_REQUEST.
The INTERNAL_DNS_DOMAIN attribute sent by the initiator is usually The INTERNAL_DNS_DOMAIN attribute sent by the initiator is usually
empty but MAY contain a suggested domain name. empty but MAY contain a suggested domain name.
The absence of INTERNAL_DNS_DOMAIN attributes in the CFG_REQUEST The absence of INTERNAL_DNS_DOMAIN attributes in the CFG_REQUEST
payload indicates that the initiator does not support or is unwilling payload indicates that the initiator does not support or is unwilling
to accept Split DNS configuration. to accept Split DNS configuration.
To indicate support for DNSSEC, an initiator includes one or more To indicate support for DNSSEC, an initiator includes one or more
INTERNAL_DNSSEC_TA attributes as defined in Section 4 as part of the INTERNAL_DNSSEC_TA attributes as defined in Section 3 as part of the
CFG_REQUEST payload. If an INTERNAL_DNSSEC_TA attribute is included CFG_REQUEST payload. If an INTERNAL_DNSSEC_TA attribute is included
in the CFG_REQUEST, the initiator SHOULD also include one or more in the CFG_REQUEST, the initiator MUST also include one or more
INTERNAL_DNS_DOMAIN attributes in the CFG_REQUEST. If the initiator INTERNAL_DNS_DOMAIN attributes in the CFG_REQUEST. If the initiator
includes an INTERNAL_DNSSEC_TA attribute, but does not inclue an includes an INTERNAL_DNSSEC_TA attribute, but does not inclue an
INTERNAL_DNS_DOMAIN attribute, the responder MAY still respond with INTERNAL_DNS_DOMAIN attribute, the responder MAY still respond with
both INTERNAL_DNSSEC_TA and INTERNAL_DNS_DOMAIN attributes. both INTERNAL_DNSSEC_TA and INTERNAL_DNS_DOMAIN attributes.
An initiator MAY convey its current DNSSEC trust anchors for the An initiator MAY convey its current DNSSEC trust anchors for the
domain specified in the INTERNAL_DNS_DOMAIN attribute. If it does domain specified in the INTERNAL_DNS_DOMAIN attribute. If it does
not wish to convey this information, it MUST use a length of 0. not wish to convey this information, it MUST use a length of 0.
The absence of INTERNAL_DNSSEC_TA attributes in the CFG_REQUEST The absence of INTERNAL_DNSSEC_TA attributes in the CFG_REQUEST
payload indicates that the initiator does not support or is unwilling payload indicates that the initiator does not support or is unwilling
to accept DNSSEC trust anchor configuration. to accept DNSSEC trust anchor configuration.
3.2. Configuration Reply 2.2. Configuration Reply
Responders MAY send one or more INTERNAL_DNS_DOMAIN attributes in Responders MAY send one or more INTERNAL_DNS_DOMAIN attributes in
their CFG_REPLY payload. If an INTERNAL_DNS_DOMAIN attribute is their CFG_REPLY payload. If an INTERNAL_DNS_DOMAIN attribute is
included in the CFG_REPLY, the responder MUST also include one or included in the CFG_REPLY, the responder MUST also include one or
both of the INTERNAL_IP4_DNS and INTERNAL_IP6_DNS attributes in the both of the INTERNAL_IP4_DNS and INTERNAL_IP6_DNS attributes in the
CFG_REPLY. These DNS server configurations are necessary to define CFG_REPLY. These DNS server configurations are necessary to define
which servers can receive queries for hostnames in internal domains. which servers can receive queries for hostnames in internal domains.
If the CFG_REQUEST included an INTERNAL_DNS_DOMAIN attribute, but the If the CFG_REQUEST included an INTERNAL_DNS_DOMAIN attribute, but the
CFG_REPLY does not include an INTERNAL_DNS_DOMAIN attribute, the CFG_REPLY does not include an INTERNAL_DNS_DOMAIN attribute, the
initiator SHOULD behave as if Split DNS configurations are not initiator MUST behave as if Split DNS configurations are not
supported by the server. supported by the server, unless the initiator has been configured
with local polict to define a set of Split DNS domains to use by
default.
Each INTERNAL_DNS_DOMAIN represents a domain that the DNS servers Each INTERNAL_DNS_DOMAIN represents a domain that the DNS servers
address listed in INTERNAL_IP4_DNS and INTERNAL_IP6_DNS can resolve. address listed in INTERNAL_IP4_DNS and INTERNAL_IP6_DNS can resolve.
If the CFG_REQUEST included INTERNAL_DNS_DOMAIN attributes with non- If the CFG_REQUEST included INTERNAL_DNS_DOMAIN attributes with non-
zero lengths, the content MAY be ignored or be interpreted as a zero lengths, the content MAY be ignored or be interpreted as a
suggestion by the responder. suggestion by the responder.
For each DNS domain specified in an INTERNAL_DNS_DOMAIN attribute, For each DNS domain specified in an INTERNAL_DNS_DOMAIN attribute,
one or more INTERNAL_DNSSEC_TA attributes MAY be included by the one or more INTERNAL_DNSSEC_TA attributes MAY be included by the
responder. This attribute lists the corresponding internal DNSSEC responder. This attribute lists the corresponding internal DNSSEC
trust anchor in the DNS presentation format of a DS record as trust anchor in the DNS presentation format of a DS record as
specified in [RFC4034]. The INTERNAL_DNSSEC_TA attribute MUST specified in [RFC4034]. The INTERNAL_DNSSEC_TA attribute MUST
immediately follow the INTERNAL_DNS_DOMAIN attribute that it applies immediately follow the INTERNAL_DNS_DOMAIN attribute that it applies
to. to.
3.3. Mapping DNS Servers to Domains 2.3. Mapping DNS Servers to Domains
All DNS servers provided in the CFG_REPLY MUST support resolving All DNS servers provided in the CFG_REPLY MUST support resolving
hostnames within all INTERNAL_DNS_DOMAIN domains. In other words, hostnames within all INTERNAL_DNS_DOMAIN domains. In other words,
the INTERNAL_DNS_DOMAIN attributes in a CFG_REPLY payload form a the INTERNAL_DNS_DOMAIN attributes in a CFG_REPLY payload form a
single list of Split DNS domains that applies to the entire list of single list of Split DNS domains that applies to the entire list of
INTERNAL_IP4_DNS and INTERNAL_IP6_DNS attributes. INTERNAL_IP4_DNS and INTERNAL_IP6_DNS attributes.
3.4. Example Exchanges 2.4. Example Exchanges
3.4.1. Simple Case 2.4.1. Simple Case
In this example exchange, the initiator requests INTERNAL_IP4_DNS and In this example exchange, the initiator requests INTERNAL_IP4_DNS and
INTERNAL_DNS_DOMAIN attributes in the CFG_REQUEST, but does not INTERNAL_DNS_DOMAIN attributes in the CFG_REQUEST, but does not
specify any value for either. This indicates that it supports Split specify any value for either. This indicates that it supports Split
DNS, but has no preference for which DNS requests will be routed DNS, but has no preference for which DNS requests will be routed
through the tunnel. through the tunnel.
The responder replies with two DNS server addresses, and two internal The responder replies with two DNS server addresses, and two internal
domains, "example.com" and "city.other.com". domains, "example.com" and "city.other.com".
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INTERNAL_IP4_DNS() INTERNAL_IP4_DNS()
INTERNAL_DNS_DOMAIN() INTERNAL_DNS_DOMAIN()
CP(CFG_REPLY) = CP(CFG_REPLY) =
INTERNAL_IP4_ADDRESS(198.51.100.234) INTERNAL_IP4_ADDRESS(198.51.100.234)
INTERNAL_IP4_DNS(198.51.100.2) INTERNAL_IP4_DNS(198.51.100.2)
INTERNAL_IP4_DNS(198.51.100.4) INTERNAL_IP4_DNS(198.51.100.4)
INTERNAL_DNS_DOMAIN(example.com) INTERNAL_DNS_DOMAIN(example.com)
INTERNAL_DNS_DOMAIN(city.other.com) INTERNAL_DNS_DOMAIN(city.other.com)
3.4.2. Requesting Domains and DNSSEC trust anchors 2.4.2. Requesting Domains and DNSSEC trust anchors
In this example exchange, the initiator requests INTERNAL_IP4_DNS, In this example exchange, the initiator requests INTERNAL_IP4_DNS,
INTERNAL_DNS_DOMAIN and INTERNAL_DNSSEC_TA attributes in the INTERNAL_DNS_DOMAIN and INTERNAL_DNSSEC_TA attributes in the
CFG_REQUEST. CFG_REQUEST.
Any subsequent DNS queries from the initiator for domains such as Any subsequent DNS queries from the initiator for domains such as
"www.example.com" or "city.other.com" would be DNSSEC validated using "www.example.com" or "city.other.com" would be DNSSEC validated using
the DNSSEC trust anchor received in the CFG_REPLY. the DNSSEC trust anchor received in the CFG_REPLY.
In this example, the initiator has no existing DNSSEC trust anchors In this example, the initiator has no existing DNSSEC trust anchors
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CP(CFG_REPLY) = CP(CFG_REPLY) =
INTERNAL_IP4_ADDRESS(198.51.100.234) INTERNAL_IP4_ADDRESS(198.51.100.234)
INTERNAL_IP4_DNS(198.51.100.2) INTERNAL_IP4_DNS(198.51.100.2)
INTERNAL_IP4_DNS(198.51.100.4) INTERNAL_IP4_DNS(198.51.100.4)
INTERNAL_DNS_DOMAIN(example.com) INTERNAL_DNS_DOMAIN(example.com)
INTERNAL_DNSSEC_TA(43547,8,1,B6225AB2CC613E0DCA7962BDC2342EA4...) INTERNAL_DNSSEC_TA(43547,8,1,B6225AB2CC613E0DCA7962BDC2342EA4...)
INTERNAL_DNSSEC_TA(31406,8,2,F78CF3344F72137235098ECBBD08947C...) INTERNAL_DNSSEC_TA(31406,8,2,F78CF3344F72137235098ECBBD08947C...)
INTERNAL_DNS_DOMAIN(city.other.com) INTERNAL_DNS_DOMAIN(city.other.com)
4. Payload Formats 3. Payload Formats
All multi-octet fields representing integers are laid out in big All multi-octet fields representing integers are laid out in big
endian order (also known as "most significant byte first", or endian order (also known as "most significant byte first", or
"network byte order"). "network byte order").
4.1. INTERNAL_DNS_DOMAIN Configuration Attribute Type Request and Reply 3.1. INTERNAL_DNS_DOMAIN Configuration Attribute Type Request and Reply
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
+-+-----------------------------+-------------------------------+ +-+-----------------------------+-------------------------------+
|R| Attribute Type | Length | |R| Attribute Type | Length |
+-+-----------------------------+-------------------------------+ +-+-----------------------------+-------------------------------+
| | | |
~ Domain Name in DNS presentation format ~ ~ Domain Name in DNS presentation format ~
| | | |
+---------------------------------------------------------------+ +---------------------------------------------------------------+
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o Attribute Type (15 bits) set to value 25 for INTERNAL_DNS_DOMAIN. o Attribute Type (15 bits) set to value 25 for INTERNAL_DNS_DOMAIN.
o Length (2 octets) - Length of domain name. o Length (2 octets) - Length of domain name.
o Domain Name (0 or more octets) - A Fully Qualified Domain Name o Domain Name (0 or more octets) - A Fully Qualified Domain Name
used for Split DNS rules, such as "example.com", in DNS used for Split DNS rules, such as "example.com", in DNS
presentation format and optionally using IDNA [RFC5890] for presentation format and optionally using IDNA [RFC5890] for
Internationalized Domain Names. Implementors need to be careful Internationalized Domain Names. Implementors need to be careful
that this value is not null-terminated. that this value is not null-terminated.
4.2. INTERNAL_DNSSEC_TA Configuration Attribute 3.2. INTERNAL_DNSSEC_TA Configuration Attribute
An INTERNAL_DNSSEC_TA Configuration Attribute can either be empty, or An INTERNAL_DNSSEC_TA Configuration Attribute can either be empty, or
it can contain one Trust Anchor by containing a non-zero Length with it can contain one Trust Anchor by containing a non-zero Length with
a DNSKEY Key Tag, DNSKEY Algorithm, Digest Type and Digest Data a DNSKEY Key Tag, DNSKEY Algorithm, Digest Type and Digest Data
fields. fields.
An empty INTERNAL_DNSSEC_TA CFG attribute: An empty INTERNAL_DNSSEC_TA CFG attribute:
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
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Each INTERNAL_DNSSEC_TA attribute in the CFG_REPLY payload MUST Each INTERNAL_DNSSEC_TA attribute in the CFG_REPLY payload MUST
immediately follow a corresponding INTERNAL_DNS_DOMAIN attribute. As immediately follow a corresponding INTERNAL_DNS_DOMAIN attribute. As
the INTERNAL_DNSSEC_TA format itself does not contain the domain the INTERNAL_DNSSEC_TA format itself does not contain the domain
name, it relies on the preceding INTERNAL_DNS_DOMAIN to provide the name, it relies on the preceding INTERNAL_DNS_DOMAIN to provide the
domain for which it specifies the trust anchor. Any domain for which it specifies the trust anchor. Any
INTERNAL_DNSSEC_TA attribute that is not immediately preceded by an INTERNAL_DNSSEC_TA attribute that is not immediately preceded by an
INTERNAL_DNS_DOMAIN or another INTERNAL_DNSSEC_TA attribute applying INTERNAL_DNS_DOMAIN or another INTERNAL_DNSSEC_TA attribute applying
to the same domain name MUST be ignored and treated as a protocol to the same domain name MUST be ignored and treated as a protocol
error. error.
5. INTERNAL_DNS_DOMAIN Usage Guidelines 4. 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
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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 attributes SHOULD only be used on split tunnel INTERNAL_DNS_DOMAIN attributes SHOULD only be used on split tunnel
configurations where only a subset of traffic is routed into a configurations where only a subset of traffic is routed into a
private remote network using the IPsec connection. If all traffic is private remote network using the IPsec connection. If 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. INTERNAL_DNSSEC_TA Usage Guidelines 5. INTERNAL_DNSSEC_TA Usage Guidelines
DNS records can be used to publish specific records containing trust DNS records can be used to publish specific records containing trust
anchors for applications. The most common record type is the TLSA anchors for applications. The most common record type is the TLSA
record specified in [RFC6698]. This DNS record type publishes which record specified in [RFC6698]. This DNS record type publishes which
CA certificate or EE certificate to expect for a certain host name. 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 These records are protected by DNSSEC and thus can be trusted by the
application. Whether to trust TLSA records instead of the application. Whether to trust TLSA records instead of the
traditional WebPKI depends on the local policy of the client. By traditional WebPKI depends on the local policy of the client. By
accepting an INTERNAL_DNSSEC_TA trust anchor via IKE from the remote accepting an INTERNAL_DNSSEC_TA trust anchor via IKE from the remote
IKE server, the IPsec client might be allowing the remote IKE server IKE server, the IPsec client might be allowing the remote IKE server
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Configuration Payload. Configuration Payload.
In most deployment scenario's, the IKE client has an expectation that In most deployment scenario's, the IKE client has an expectation that
it is connecting, using a split-network setup, to a specific it is connecting, using a split-network setup, to a specific
organisation or enterprise. A recommended policy would be to only organisation or enterprise. A recommended policy would be to only
accept INTERNAL_DNSSEC_TA directives from that organization's DNS accept INTERNAL_DNSSEC_TA directives from that organization's DNS
names. However, this might not be possible in all deployment names. However, this might not be possible in all deployment
scenarios, such as one where the IKE server is handing out a number scenarios, such as one where the IKE server is handing out a number
of domains that are not within one parent domain. of domains that are not within one parent domain.
7. Security Considerations 6. 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
skipping to change at page 12, line 12 skipping to change at page 12, line 12
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.
8. IANA Considerations 7. 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
9. References 8. References
9.1. Normative References 8.1. 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-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 13, line 19 skipping to change at page 13, line 19
[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>.
9.2. Informative References 8.2. 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-editor.org/info/rfc2775>. <https://www.rfc-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
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