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Versions: 00 01

Network Working Group                                        T. Peterson
Internet-Draft                                          October 20, 2019
Intended status: Standards Track
Expires: April 22, 2020


DNS over HTTP resolver announcement Using DHCP or Router Advertisements
                       draft-peterson-doh-dhcp-01

Abstract

   This specification describes a DHCP option and Router Advertisement
   (RA) extension to inform clients of the presence of a DNS over HTTP
   (DoH) service to be used for DNS queries.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on April 22, 2020.

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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   2
   3.  The DoH Option  . . . . . . . . . . . . . . . . . . . . . . .   2
     3.1.  IPv4 DHCP Option  . . . . . . . . . . . . . . . . . . . .   3
     3.2.  IPv6 DHCP Option  . . . . . . . . . . . . . . . . . . . .   3
     3.3.  The DoH IPv6 RA Option  . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   DHCPv4 [RFC2131], DHCPv6 [RFC3646], and IPv6 Router Announcements
   [RFC8106] all provide means to inform clients of available resolvers
   using the incumbent DNS protocol for querying, however there is no
   means of specifying alternate protocols to perform DNS queries.

2.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  The DoH Option

   The DoH DHCP/RA option informs the client that a DoH service is
   available for use for answering DNS queries.  In order to support
   multiple "classes" of clients, the network operator can provide the
   URI template [RFC6570] which describes how a client can construct the
   URL to use for resolution.  Whilst DoH servers may support multiple
   URI Templates, only one template MUST be transmitted.

   URI Templates that contain a host name SHOULD only be sent where a
   DHCP server or Router provide name servers, as name resolution of any
   host name in the template will require clients to use the non-DoH
   servers provided or manual configuration.  URI Templates that are
   over 255 bytes in length MUST implement long option encoding as
   defined in [RFC3396].





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3.1.  IPv4 DHCP Option

   The format of the IPv4 DoH DHCP option is shown below.

    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Code      |     Length    |      URI Template             .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Code:  The DoH DHCPv4 option (one octet).

   Length:  The length, in octets of the URI template.

   URI Template:  The DoH server available, encoded following the rules
      of [RFC3986].

3.2.  IPv6 DHCP Option

   The format of the IPv6 DHCP option is shown below.

    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          option-code          |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                                                               .
   .                          URI Template                         .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   option-code:  TODO (two octets)

   option-len:  The length, in octects of the URI Template.

   URI Template:  The DoH server

3.3.  The DoH IPv6 RA Option

   The format of the DoH Router Advertisement option is shown below.









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    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |     Length    |      URI Template             .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               .
   .                                                               .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:  TODO (one octet)

   Length:  8-bit unsigned integer representing the entire length of all
      fields, in units of 8 bytes.

   URI Template:  The DoH server available for use.  This should be
      padded with NULL (0x0) to make the total option length (including
      the Type and Length fields) a multiple of 8 bytes.

4.  Security Considerations

   An attacker with the ability to inject DHCP messages could include
   this option and present a malicious resolver.

   TODO: Further risk and threat assessments.

5.  IANA Considerations

   TODO: This section must be updated after assignments have been
   issued.

   This document requires the assignment of an option code assigned
   under the "BOOTP Vendor Extensions and DHCP Options"
   [bootp-registry], in addition to an option code assigned under the
   "Option Codes" registry under DHCPv6 parameters [dhcpv6-registry].

   Also, an assignment for an IPv6 RA Option Type from the "IPv6
   Neighbor Discovery Option Formats" registry under ICMPv6 paramters
   [icmpv6-registry].

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.




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   [RFC3396]  Lemon, T. and S. Cheshire, "Encoding Long Options in the
              Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
              DOI 10.17487/RFC3396, November 2002,
              <https://www.rfc-editor.org/info/rfc3396>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC6570]  Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
              and D. Orchard, "URI Template", RFC 6570,
              DOI 10.17487/RFC6570, March 2012,
              <https://www.rfc-editor.org/info/rfc6570>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

6.2.  Informative References

   [bootp-registry]
              "Dynamic Host Configuration Protocol (DHCP) and Bootstrap
              Protocol (BOOTP) Parameters", n.d.,
              <http://www.iana.org/assignments/bootp-dhcp-parameters>.

   [dhcpv6-registry]
              "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
              n.d., <http://www.iana.org/assignments/dhcpv6-parameters>.

   [icmpv6-registry]
              "Internet Control Message Protocol version 6 (ICMPv6)
              Parameters", n.d.,
              <http://www.iana.org/assignments/icmpv6-parameters>.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, DOI 10.17487/RFC2131, March 1997,
              <https://www.rfc-editor.org/info/rfc2131>.

   [RFC3646]  Droms, R., Ed., "DNS Configuration options for Dynamic
              Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
              DOI 10.17487/RFC3646, December 2003,
              <https://www.rfc-editor.org/info/rfc3646>.

   [RFC8106]  Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
              "IPv6 Router Advertisement Options for DNS Configuration",
              RFC 8106, DOI 10.17487/RFC8106, March 2017,
              <https://www.rfc-editor.org/info/rfc8106>.



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Acknowledgments

   TODO

Author's Address

   Thomas Peterson

   Email: nosretep.samoht@gmail.com










































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