Split DNS Configuration for the Internet Key Exchange Protocol Version 2 (IKEv2)
RFC 8598

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Internet Engineering Task Force (IETF)                          T. Pauly
Request for Comments: 8598                                    Apple Inc.
Category: Standards Track                                     P. Wouters
ISSN: 2070-1721                                                  Red Hat
                                                                May 2019

                        Split DNS Configuration
        for the Internet Key Exchange Protocol Version 2 (IKEv2)

Abstract

   This document defines two Configuration Payload Attribute Types
   (INTERNAL_DNS_DOMAIN and INTERNAL_DNSSEC_TA) for the Internet Key
   Exchange Protocol version 2 (IKEv2).  These payloads add support for
   private (internal-only) DNS domains.  These domains are intended to
   be resolved using non-public DNS servers that are only reachable
   through the IPsec connection.  DNS resolution for other domains
   remains unchanged.  These Configuration Payloads only apply to split-
   tunnel configurations.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8598.

Pauly & Wouters              Standards Track                    [Page 1]
RFC 8598            Split DNS Configuration for IKEv2           May 2019

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Protocol Exchange . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Configuration Request . . . . . . . . . . . . . . . . . .   5
     3.2.  Configuration Reply . . . . . . . . . . . . . . . . . . .   6
     3.3.  Mapping DNS Servers to Domains  . . . . . . . . . . . . .   7
     3.4.  Example Exchanges . . . . . . . . . . . . . . . . . . . .   7
       3.4.1.  Simple Case . . . . . . . . . . . . . . . . . . . . .   7
       3.4.2.  Requesting Domains and DNSSEC Trust Anchors . . . . .   7
   4.  Payload Formats . . . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  INTERNAL_DNS_DOMAIN Configuration Attribute Type Request
           and Reply . . . . . . . . . . . . . . . . . . . . . . . .   9
     4.2.  INTERNAL_DNSSEC_TA Configuration Attribute  . . . . . . .   9
   5.  INTERNAL_DNS_DOMAIN Usage Guidelines  . . . . . . . . . . . .  11
   6.  INTERNAL_DNSSEC_TA Usage Guidelines . . . . . . . . . . . . .  12
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

Pauly & Wouters              Standards Track                    [Page 2]
RFC 8598            Split DNS Configuration for IKEv2           May 2019

1.  Introduction

   Split-tunnel Virtual Private Network (VPN) configurations only send
   packets with a specific destination IP range, usually chosen from
   [RFC1918], via the VPN.  All other traffic is not sent via the VPN.
   This allows an enterprise deployment to offer remote access VPN
   services without needing to accept and forward all the non-
   enterprise-related network traffic generated by their remote users.
   Resources within the enterprise can be accessed by the user via the
   VPN, while all other traffic generated by the user is not sent over
   the VPN.

   These internal resources tend to only have internal-only DNS names
   and require the use of special internal-only DNS servers to get
   resolved.  Split DNS [RFC2775] is commonly configured as part of