DNS over Transport Layer Security announcements using DHCP or Router Advertisements
draft-peterson-dot-dhcp-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
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|
|---|---|---|---|
| Author | Thomast Peterson | ||
| Last updated | 2019-04-27 | ||
| RFC stream | (None) | ||
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| Consensus boilerplate | Unknown | ||
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draft-peterson-dot-dhcp-00
Network Working Group T. Peterson
Internet-Draft April 27, 2019
Intended status: Standards Track
Expires: October 29, 2019
DNS over Transport Layer Security announcements using DHCP or Router
Advertisements
draft-peterson-dot-dhcp-00
Abstract
This specification describes a DHCP option and Router Advertisement
(RA) extension to inform clients of the presence of DNS resolvers
with Transport Layer Security (TLS).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Task Force (IETF). Note that other groups may also distribute
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 29, 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 2
3. The DNS over TLS Option . . . . . . . . . . . . . . . . . . . 2
3.1. IPv4 DHCP Option . . . . . . . . . . . . . . . . . . . . 2
3.2. IPv6 DHCP Option . . . . . . . . . . . . . . . . . . . . 3
3.3. The DoT IPv6 RA Option . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . 4
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
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 DNS over TLS Option
3.1. IPv4 DHCP Option
The format of the IPv4 DoT 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 | Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
| DNS Servers |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code: The DoT DHCPv4 option (one octet)
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Length: Length of the DNS Servers list in octects
DNS Servers: One or more IPv4 addresses of DNS servers
3.2. IPv6 DHCP Option
The format of the IPv6 Captive-Portal 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| DNS Servers |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: TODO (two octets)
option-len: Length of the list of DNS servers in octects, which MUST
be a multiple of 16
DNS Servers: IPv6 addresses of DNS servers
3.3. The DoT IPv6 RA Option
The format of the DoT Router Advertisement 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
| DNS Servers |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TODO (one octet)
Length: 8-bit unsigned integer representing the entire length of all
fields, in units of 8 bytes. The minimum value is 3 if one DNS
server is contained in the option. Every additional DNS server
increases the length by 2. This field is used by the receiver to
determine the number of DNS server addresses in the option.
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DNS Servers: One or more IPv6 addresses of DNS servers. The number
of addresses is determined by the Length field. That is, the
number of addresses is equal to (Length - 1) / 2.
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>.
[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>.
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[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>.
Acknowledgments
TODO
Author's Address
Thomas Peterson
Email: nosretep.samoht@gmail.com
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