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Versions: 00

Network Working Group                                        W. Hardaker
Internet-Draft                                                   USC/ISI
Intended status: Standards Track                       November 02, 2020
Expires: May 6, 2021


                     DNS Private Namespace Options
           draft-hardaker-dnsop-private-namespace-options-00

Abstract

   This document discusses the trade-offs between various options about
   creating a private namespace within top level domains within the root
   zone.

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 May 6, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
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   described in the Simplified BSD License.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Document state  . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements notation . . . . . . . . . . . . . . . . . .   3
   2.  Analysis of choices . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Assumptions . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  TLD choices . . . . . . . . . . . . . . . . . . . . . . .   4
       2.2.1.  Working state aside . . . . . . . . . . . . . . . . .   4
       2.2.2.  Analysis of an unsigned TLD (eg .internal)  . . . . .   5
       2.2.3.  Analysis of a special-use TLD (eg .zz)  . . . . . . .   5
   3.  Other considerations  . . . . . . . . . . . . . . . . . . . .   6
     3.1.  a unsigned delegated domain - .internal . . . . . . . . .   6
     3.2.  a special-use domain - .zz  . . . . . . . . . . . . . . .   6
   4.  Deployment considerations . . . . . . . . . . . . . . . . . .   7
   5.  Recommendation  . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Selecting good TLD names  . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   HATS: The author is not wearing any hats while writing this document.

   Deployed DNS clients within the Internet typically communicate with
   upstream resolvers using their own in-application stub resolver.
   These upstream resolvers may be run by ISPs, or may be a customer-
   premises equipment (CPE) that may or may not forward requests to its
   upstream ISP.

   In an entirely singular Internet DNS there would be no name
   collisions as all data is uniquely named.  However, the prevalence of
   local private name spaces within companies, organizations,
   governments, home LANs, etc have shown that existence of a single,
   unique naming system rarely exists.  The deployment of Internet of
   Things (IoT) devices is only accelerating this trend for private
   namespaces by devices that bootstrap their names with the easy
   solution of "just make one up until the customer provides us with a
   better one", followed by the customer never providing one.  This
   document makes no judgment on whether this is right or wrong, and
   takes this assumption as simply the state of the current world.





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   The for special use names is well spelled out in [RFC6761].
   [RFC8244] provides additional insight into areas that are still under
   discussion and where work is needed.  Recently ICANN's SSAC has
   issued [SAC113] entitled "SSAC Advisory on Private-Use TLDs", wherein
   it suggests the creation of a private-use DNS TLD.

   This document considers the aspects associated with DNSSEC and the
   potential choices for a private-use TLD (also see [RFC8244] bullet
   21).  Specifically, we consider the case where somewhere in the
   resolution path DNSSEC validation is in use, potentially at an end-
   device (phone, laptop, etc), a CPE, or at an ISP's resolver.

1.1.  Document state

   This document is not a fully complete analysis, but rather a starting
   point for discussion and continued analysis by both the author and
   others that wish to contribute.

1.2.  Requirements notation

   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.

2.  Analysis of choices

   Note that this analysis is not (yet) exhaustive.  It does describe
   some of the differences in the two approaches.

2.1.  Assumptions

   We make the following assumptions to begin:

   1.  A local environment needs to use both the Global Internet's DNS
       (GID), as well as at least one private name space as well.

   2.  A end-device, a CPE and/or a resolver may choose to validate DNS
       requests.

   3.  The validating resolver wishes to validate both responses from
       the GID as well as local names using DNSSEC.

   4.  The validating resolver will, thus, need Trust Anchors (TAs) for
       both the GID and all private namespaces, or will need a list of
       names which are assumed insecure and exemptions to the GID.




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   5.  The device may (unfortunately) move to another network where
       private namespace resolution is not available, and thus queries
       to it will leak to the GID.  This is extremely common today.

   6.  We take as accepted consensus that anything protocol needing a
       private name space that is not user visible can be properly
       housed under .arpa.  This document assumes a private-namespace
       TLD is needed, as discussed in other documents ([SAC113, etc]) to
       aid in user presentation and understanding.  This document does
       not make judgment on whether this or user-education may be the
       right approach to this problem.

2.2.  TLD choices

   Given these assumptions, we consider the cases where a private
   namespace TLD exists that is:

   1.  Is a special-use domain per [RFC6761], and does not (and will
       never) exist in the GID.  In this document, we refer to this as
       ".internal" for discussion purposes only following conventions in
       [draft-wkumari-dnsop-internal].

   2.  Is an unsigned delegation within the (GID's) DNS root, with NS
       records likely pointing eventually to something like 127.0.53.53.
       In this document, we refer to this as ".zz" following convention
       in [draft-ietf-dnsop-private-use-tld].  We note that [draft-ietf-
       dnsop-alt-tld] also proposed a private namespace (".alt") that
       also fits into this category.

   This document recognizes that .zz itself is actually not necessarily
   a normal special use domain, and [RFC6761] may not apply as its an
   ISO reversed name.  However, in other aspects it will behave like a
   special-use registered domain and its under current consideration by
   dnsop so we leave it in here as the example name.

   In summary:

   o  .internal is an unsigned TLD

   o  .zz is a special-use-like TLD that MUST never be assigned

2.2.1.  Working state aside

   The next two sections mix together DNSSEC validation at end-devices
   and resolvers; it would add significant more clarity to discuss them
   individually, which will be done in a future version.





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2.2.2.  Analysis of an unsigned TLD (eg .internal)

   An unsigned TLD such as .internal will:

   o  Exist within the DNS root

   o  have NS records pointing to something.arpa with on A/AAAA
      resolution

2.2.2.1.  non-validating end-devices querying within .internal will:

   o  inside the private network the client will:

      *  Believe the upstream resolver's responses

   o  outside the private network the client will:

      *  Believe the upstream resolver's NXDOMAIN responses for anything
         deeper than .internal itself (IE, api.example.internal/A will
         return NXDOMAIN)

2.2.2.2.  validating end-devices querying within .internal will:

   o  inside the private network the client will:

      *  must be configured with a private TA to enable DNSSEC within
         the private network (creating an island of trust)

      *  If unconfigured, it will believe the upstream resolver's
         responses because its delegated insecure, and therefore has no
         basis to distrust the answers

   o  outside the private network the client will:

      *  if not configured with a TA, all answers to .internal will
         either be NXDOMAIN or spoofable

      *  if configured with a TA, all answers will be detected as BOGUS

2.2.3.  Analysis of a special-use TLD (eg .zz)

   A special-use TLD will:

   o  Not exist within the DNS root

   o  Proven by the root's NSEC chain





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2.2.3.1.  non-validating end-devices querying within .zz will:

   o  inside the private network the client will:

      *  Believe the upstream resolver's responses

   o  outside the private network the client will:

      *  Believe the upstream resolver's NXDOMAIN or spoofed answers for
         all data within the .zz domain.

2.2.3.2.  validating end-devices querying within .zz will:

   o  inside the private network the client will:

      *  with an upstream resolver

      *  self-resolving:

         +  needs a configured TA or a configured negative trust anchor

         +  possibly automatically obtained configuration with a
            bootstrapping mechanism, or-preconfigured in a ROM image

   o  outside the private network the client will:

      *  if not configured with a TA, all answers to .internal will
         either be NXDOMAIN or spoofable

      *  if configured with a TA, all answers will be detected as BOGUS

3.  Other considerations

3.1.  a unsigned delegated domain - .internal

   o  configuration of new TAs

   o  requires collaboration between the IETF and ICANN , since the TLD
      will exist and falls outside the scope of [RFC6761].  This process
      can be slow.

3.2.  a special-use domain - .zz

   o  May require invoking [RFC6761] (depending on .zz or not .zz)

   o  may require more configuration per-device





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4.  Deployment considerations

   During initial deployment of either of these, there is a fundamental
   difference for validating resolvers.

   Specifically, until all validating resolvers are updated with a new
   TA for specific instances under a special-use TLD (e.g. .zz), the
   resolvers will fail to validate any names underneath as .zz is
   provable insecure.  This could take a while to update all deployed
   validating resolvers.

   On the other hand, deploying a newly allocated, unsigned TLD will
   take a long time in process both within the IETF and within ICANN.

   And each may have impacts on what error processing results, based on
   the differing resolution characteristics (Section 2.2.2,
   Section 2.2.3).

5.  Recommendation

   This author recommends that the IETF take on both tracks
   simultaneously, and:

   1.  starts the process of communicating with ICANN and ISO about the
       use of .zz, or selects another name to use under [RFC6761] as a
       special-use name.

   2.  Issues a request to the ICANN board via the IAB to follow the
       guidance of [SAC113] and reserve a string or set of strings for
       use as a private-namespace(s) as an unsigned TLD.  The ICANN
       board can not act on their own, based on ICANN bilaws, but can
       take requests from the IETF via the IAB to act.

   This leaves vendors the freedom to chose that path that best meets
   their specific requirements.  Recommendations about how to best
   select one given their situation is hinted above, but should be more
   formally written down in this document or others.

5.1.  Selecting good TLD names

   Unfortunately, here be dragons.  Selecting a good name has been
   discussed multiple times in the IETF, and has always resulted in a
   lack of consensus.  In part, this is because the IETF doesn't have
   the skillsets needed to hold a discussion about what language
   element(s) would be best for universal adoption and usage.

   Instead, this author recommends that we direct ICANN to select the
   names that should be used for both of these cases.  ICANN has



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   significant more skill breadth in the area of selecting names best
   suited to be understood by end-users.  This discussion will not be
   faster, however, within ICANN but this author believes a resolution
   in that SDO will be more likely successful.

   Thus, the IETF can make the technical recommendation and ICANN can
   implement these two choices.

6.  Security Considerations

   TBD

   (though much of this draft is a security considerations itself)

7.  IANA Considerations

   TBD

8.  References

8.1.  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>.

   [RFC6761]  Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
              RFC 6761, DOI 10.17487/RFC6761, February 2013,
              <https://www.rfc-editor.org/info/rfc6761>.

8.2.  Informative References

   [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>.

   [RFC8244]  Lemon, T., Droms, R., and W. Kumari, "Special-Use Domain
              Names Problem Statement", RFC 8244, DOI 10.17487/RFC8244,
              October 2017, <https://www.rfc-editor.org/info/rfc8244>.

Appendix A.  Acknowledgments

   Large portions of the technical analysis in this document derives
   from a discussion with Roy Arends and Warren Kumari (back when we
   could stand in front of a whiteboard together).





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Author's Address

   Wes Hardaker
   USC/ISI

   Email: ietf@hardakers.net













































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