draft-ietf-dprive-phase2-requirements-01.txt   draft-ietf-dprive-phase2-requirements-02.txt 
DPRIVE J. Livingood DPRIVE J. Livingood
Internet-Draft Comcast Internet-Draft Comcast
Intended status: Informational A. Mayrhofer Intended status: Informational A. Mayrhofer
Expires: December 18, 2020 nic.at GmbH Expires: May 6, 2021 nic.at GmbH
B. Overeinder B. Overeinder
NLnet Labs NLnet Labs
June 16, 2020 November 02, 2020
DNS Privacy Requirements for Exchanges between Recursive Resolvers and DNS Privacy Requirements for Exchanges between Recursive Resolvers and
Authoritative Servers Authoritative Servers
draft-ietf-dprive-phase2-requirements-01 draft-ietf-dprive-phase2-requirements-02
Abstract Abstract
This document provides requirements for adding confidentiality to DNS This document describes requirements and considerations for adding
exchanges between recursive resolvers and authoritative servers. confidentiality to DNS exchanges between recursive resolvers and
authoritative servers. The intent of this document is to guide
Internet Drafts in the DNS Private Exchange (DPRIVE) Working Group
pertaining to recursive to authorized name servers, with the stated
requirements and considerations.
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
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 December 18, 2020. This Internet-Draft will expire on May 6, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 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
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 13 skipping to change at page 2, line 16
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 & Scope . . . . . . . . . . . . . . . . . . . . 2 1. Introduction & Scope . . . . . . . . . . . . . . . . . . . . 2
2. Document Work Via GitHub . . . . . . . . . . . . . . . . . . 3 2. Document Work Via GitHub . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Threat Model and Problem Statement . . . . . . . . . . . . . 3 4. Threat Model and Problem Statement . . . . . . . . . . . . . 3
5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Features to Provide Confidentiality . . . . . . . . . . . . . 4
5.1. Mandatory Requirements . . . . . . . . . . . . . . . . . 4 5.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 4
5.2. Optional Requirements . . . . . . . . . . . . . . . . . . 5 5.2. Optional Features . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9. APPENDIX: Perspectives and Use Cases . . . . . . . . . . . . 5 9. APPENDIX: Perspectives and Use Cases . . . . . . . . . . . . 6
9.1. The User Perspective and Use Cases . . . . . . . . . . . 6 9.1. The User Perspective and Use Cases . . . . . . . . . . . 6
9.2. The Operator Perspective and Use Cases . . . . . . . . . 6 9.2. The Operator Perspective and Use Cases . . . . . . . . . 7
9.3. The Implementor / Software Vendor Perspective and Use 9.3. The Implementor / Software Vendor Perspective and Use
Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 9 10.1. Normative References . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . 9 10.2. Informative References . . . . . . . . . . . . . . . . . 9
10.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9 10.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction & Scope 1. Introduction & Scope
The 2018 approved charter of the IETF DPRIVE Working Group [1] The 2018 approved charter of the IETF DPRIVE Working Group [1]
contains milestones related to confidentiality aspects of DNS contains milestones related to confidentiality aspects of DNS
transactions between the iterative resolver and authoritative name transactions between the recursive resolver and authoritative name
servers. servers.
This is also reflected in the DPRIVE milestones [2], which (as of This is also reflected in the DPRIVE milestones [2], which (as of
October 2019) contains two relevant milestones: October 2019) contains two relevant milestones:
Develop requirements for adding confidentiality to DNS exchanges Develop requirements for adding confidentiality to DNS exchanges
between recursive resolvers and authoritative servers (unpublished between recursive resolvers and authoritative servers (unpublished
document). document).
Investigate potential solutions for adding confidentiality to DNS Investigate potential solutions for adding confidentiality to DNS
skipping to change at page 4, line 5 skipping to change at page 4, line 7
are still possible when performed by the recursive resolver, which are still possible when performed by the recursive resolver, which
decrypts queries, serves a response from cache or performs recursion decrypts queries, serves a response from cache or performs recursion
to obtain a response (or synthesizes a response), and then encrypts to obtain a response (or synthesizes a response), and then encrypts
the response and sends it back to the user's stub resolver. the response and sends it back to the user's stub resolver.
But observation and modification threats still exist when a recursive But observation and modification threats still exist when a recursive
resolver must perform DNS recursion, from the root to TLD to resolver must perform DNS recursion, from the root to TLD to
authoritative servers. This document specifies requirements for authoritative servers. This document specifies requirements for
filling those gaps. filling those gaps.
5. Requirements 5. Features to Provide Confidentiality
The requirements of different interested stakeholders are outlined Confidentialty can be provided using a combination of techniques.
below. This section describes the protocol implementation requirements and
optional features that can be used to provide confidentiality.
5.1. Mandatory Requirements 5.1. Requirements
1. Each implementing party should be able to independently take 1. Each implementing party MUST be able to independently take
incremental steps to meet requirements without the need for incremental steps to meet requirements without the need for
close coordination (e.g. loosely coupled) close coordination (e.g. loosely coupled)
2. Use a secure transport protocol between a recursive resolver and 2. A recursive resolver that supports recursive-to-authoritative
authoritative servers DNS encryption MUST be able to determine whether or not a given
authoritative name server to which it intends to connect also
supports recursive-to-authoritative DNS encryption.
3. Use a secure transport protocol between a recursive resolver and 3. An authoritative name server that supports recursive-to-
TLD servers authoritative DNS encryption MUST be able to indicate that it
supports recursive-to-authoritative DNS encryption in a way that
facilitates (2).
4. Use a secure transport protocol between a recursive resolver and 4. An authoritative name server that does not support recursive-to-
the root servers authoritative MUST NOT have to make any changes to facilitate
(2).
5. The secure transport MUST only be established when referential 5. The secure transport MUST only be established when referential
integrity can be verified, MUST NOT have circular dependencies, integrity can be verified, MUST NOT have circular dependencies,
and MUST be easily analyzed for diagnostic purposes. and MUST be easily analyzed for diagnostic purposes.
6. Use a secure transport protocol or other DNS privacy protections 6. Each implementing party MUST be able to negotiate use of a
in a manner that enables operators to perform appropriate secure transport protocol or other DNS privacy protections in a
performance and security monitoring, conduct relevant research, manner that enables operators to perform appropriate performance
etc. and security monitoring, conduct relevant research, etc.
7. The authoritative domain owner or their administrator MUST have 7. The authoritative domain owner or their administrator MUST have
the option to specify their secure transport preferences (e.g. the option to specify their secure transport preferences (e.g.
what specific protocols are supported). This SHALL include a what specific protocols are supported). This SHALL include a
method to publish a list of secure transport protocols (e.g. method to publish a list of secure transport protocols (e.g.
DoH, DoT and other future protocols not yet developed). In DoH, DoT and other future protocols not yet developed). In
addition this SHALL include whether a secure transport protocol addition this SHALL include whether a secure transport protocol
MUST always be used (non-downgradable) or whether a secure MUST always be used (non-downgradable) or whether a secure
transport protocol MAY be used on an opportunistic (not strict) transport protocol MAY be used on an opportunistic (not strict)
basis. basis in recognition that some servers for a domain might use a
secure transport protocol and others might not.
8. The authoritative domain owner or their administrator MUST have 8. The authoritative domain owner or their administrator MUST have
the option to vary their preferences on an authoritative the option to vary their preferences on an authoritative
nameserver to nameserver basis, due to the fact that nameserver to nameserver basis, due to the fact that
administration of a particular DNS zone may be delegated to administration of a particular DNS zone may be delegated to
multiple parties (such as several CDNs), each of which may have multiple parties (such as several CDNs), each of which may have
different technical capabilities. different technical capabilities. This includes that some
servers for a domain may use secure transport and others may
not, as it is common for a given name server to be authoritative
for multiple zones.
9. The specification of secure transport preferences MUST be 9. A given name server may be authoritative for multiple zones. As
such, a name server MAY support use of a secure transport
protocol for one zone, but not for another.
10. The specification of secure transport preferences MUST be
performed using the DNS and MUST NOT depend on non-DNS performed using the DNS and MUST NOT depend on non-DNS
protocols. protocols.
10. For the secure transport, TLS 1.3 (or later versions) MUST be 11. For secure transports using TLS, TLS 1.3 (or later versions)
supported and downgrades from TLS 1.3 to prior versions MUST not MUST be supported and downgrades from TLS 1.3 to prior versions
occur. MUST not occur.
5.2. Optional Requirements 5.2. Optional Features
1. QNAME minimisation SHOULD be implemented in all steps of 1. QNAME minimisation SHOULD be implemented in all steps of
recursion recursion
2. DNSSEC validation SHOULD be performed 2. DNSSEC validation SHOULD be performed
3. If an authoritative domain owner or their administrator indicates 3. If an authoritative domain owner or their administrator indicates
that (1) multiple secure transport protocols are available or that (1) multiple secure transport protocols are available, or
that (2) a secure transport and insecure transport are available, that (2) a secure transport and insecure transport are available,
then per the recommendations in [RFC8305] (aka Happy Eyeballs) a or that (3) no secure transport is available, then a recursive
recursive server SHOULD initiate concurrent connections to server SHOULD negotiate selection of an available transport
available protocols. Consistent with Section 2 of [RFC8305] this protocol.
would be: (1) Initiation of asynchronous DNS queries to determine
what transport protocols are supported, (2) Sorting of resolved
destination transport protocols, (3) Initiation of asynchronous
connection attempts, and (4) Establishment of one connection,
which cancels all other attempts.
6. Security Considerations 6. Security Considerations
This entire document concerns the security of DNS traffic, so a Authoritative name servers will need to perform additional processing
specific section on security is superfluous. steps, such as completing key exchanges and maintaining persistent
connections, when responding to queries from a recursive resolver
that requests use of a secure transport protocol. These additional
processing steps can have an impact on server availability if they
are abused. As such, negotiation and use of a secure transport
protocol should be done in a manner that does not increase the risk
of an authoritative name server outage or lead a recursive server to
fail to communicate with an authoritative name server.
7. IANA Considerations 7. IANA Considerations
This document has no actions for IANA. This document has no actions for IANA.
8. Changelog 8. Changelog
Version 00: Updated prior individual draft following IETF-106 Version 00: Updated prior individual draft following IETF-106
feedback feedback Version 01: Small editorial changes Version 02: Incorporate
feedback and suggestions from Scott Hollenbeck, Duane Wessels and
email discussions.
9. APPENDIX: Perspectives and Use Cases 9. APPENDIX: Perspectives and Use Cases
The DNS resolving process involves several entities. These entities The DNS resolving process involves several entities. These entities
have different interests/requirements, and hence it does make sense have different interests/requirements, and hence it does make sense
to examine the interests of those entities separately - though in to examine the interests of those entities separately - though in
many cases their interests are aligned. Four different entities can many cases their interests are aligned. Four different entities can
be identified, and their interests are described in the following be identified, and their interests are described in the following
sections: sections:
skipping to change at page 9, line 40 skipping to change at page 10, line 13
2012, <https://www.rfc-editor.org/info/rfc6698>. 2012, <https://www.rfc-editor.org/info/rfc6698>.
[RFC7816] Bortzmeyer, S., "DNS Query Name Minimisation to Improve [RFC7816] Bortzmeyer, S., "DNS Query Name Minimisation to Improve
Privacy", RFC 7816, DOI 10.17487/RFC7816, March 2016, Privacy", RFC 7816, DOI 10.17487/RFC7816, March 2016,
<https://www.rfc-editor.org/info/rfc7816>. <https://www.rfc-editor.org/info/rfc7816>.
[RFC8198] Fujiwara, K., Kato, A., and W. Kumari, "Aggressive Use of [RFC8198] Fujiwara, K., Kato, A., and W. Kumari, "Aggressive Use of
DNSSEC-Validated Cache", RFC 8198, DOI 10.17487/RFC8198, DNSSEC-Validated Cache", RFC 8198, DOI 10.17487/RFC8198,
July 2017, <https://www.rfc-editor.org/info/rfc8198>. July 2017, <https://www.rfc-editor.org/info/rfc8198>.
[RFC8305] Schinazi, D. and T. Pauly, "Happy Eyeballs Version 2:
Better Connectivity Using Concurrency", RFC 8305,
DOI 10.17487/RFC8305, December 2017,
<https://www.rfc-editor.org/info/rfc8305>.
10.3. URIs 10.3. URIs
[1] https://datatracker.ietf.org/doc/charter-ietf-dprive/ [1] https://datatracker.ietf.org/doc/charter-ietf-dprive/
[2] https://datatracker.ietf.org/wg/dprive/about/ [2] https://datatracker.ietf.org/wg/dprive/about/
Acknowledgments Acknowledgments
TODO The authors would like to thank Scott Hollenbeck for his early
feedback and providing text for the Internet Draft. We would also
like to thank Duane Wessels for the feedback on the mailing list, and
Peter van Dijk for his comments in personal conversations.
Authors' Addresses Authors' Addresses
Jason Livingood Jason Livingood
Comcast Comcast
Email: Jason_Livingood@comcast.com Email: Jason_Livingood@comcast.com
Alexander Mayrhofer Alexander Mayrhofer
nic.at GmbH nic.at GmbH
 End of changes. 30 change blocks. 
56 lines changed or deleted 76 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/