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Versions: 00 01

Domain Name System Operations                                P. Ebersman
Internet-Draft                                                   Comcast
Intended status: Informational                              C. Griffiths
Expires: April 26, 2015                                              Dyn
                                                               W. Kumari
                                                                  Google
                                                            J. Livingood
                                                                 Comcast
                                                                R. Weber
                                                                 Nominum
                                                        October 23, 2014


          Definition and Use of DNSSEC Negative Trust Anchors
            draft-livingood-dnsop-negative-trust-anchors-01

Abstract

   DNS Security Extensions (DNSSEC) is now entering widespread
   deployment.  However, domain signing tools and processes are not yet
   as mature and reliable as those for non-DNSSEC-related domain
   administration tools and processes.  Negative Trust Anchors
   (described in this document) can be used to mitigate DNSSEC
   validation failures.

   [ Editor note: This document was originally draft-livingood-negative-
   trust-anchors-07 - renamved at the request of the DNSOP chairs ]

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 26, 2015.







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Copyright Notice

   Copyright (c) 2014 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
   (http://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
   2.  Definition of a Negative Trust Anchor . . . . . . . . . . . .   3
   3.  delete  . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Domain Validation Failures  . . . . . . . . . . . . . . . . .   4
   5.  End User Reaction . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Switching to a Non-Validating Resolver is Not Recommended . .   5
   7.  Responsibility for Failures . . . . . . . . . . . . . . . . .   5
   8.  Use of a Negative Trust Anchor  . . . . . . . . . . . . . . .   6
   9.  Managing Negative Trust Anchors . . . . . . . . . . . . . . .   7
   10. Removal of a Negative Trust Anchor  . . . . . . . . . . . . .   7
   11. Comparison to Other DNS Misconfigurations . . . . . . . . . .   8
   12. Intentionally Broken Domains  . . . . . . . . . . . . . . . .   8
   13. Other Considerations  . . . . . . . . . . . . . . . . . . . .   8
     13.1.  Security Considerations  . . . . . . . . . . . . . . . .   8
     13.2.  Privacy Considerations . . . . . . . . . . . . . . . . .   9
     13.3.  IANA Considerations  . . . . . . . . . . . . . . . . . .   9
   14. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   15. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     15.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     15.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Appendix A.  Configuration Examples . . . . . . . . . . . . . . .  12
     A.1.  NLNet Labs Unbound  . . . . . . . . . . . . . . . . . . .  12
     A.2.  ISC BIND  . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.3.  Nominum Vantio  . . . . . . . . . . . . . . . . . . . . .  12
   Appendix B.  Document Change Log  . . . . . . . . . . . . . . . .  13
   Appendix C.  Open Issues  . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16







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1.  Introduction

   The Domain Name System (DNS), DNS Security Extensions (DNSSEC), and
   related operational practices are defined extensively [RFC1034]
   [RFC1035] [RFC4033] [RFC4034] [RFC4035] [RFC4398] [RFC4509] [RFC6781]
   [RFC5155].

   This document defines a Negative Trust Anchor, which can be used
   during the transition to ubiquitous DNSSEC deployment.  Negative
   Trust Anchors (NTAs) are configured locally on a validating DNS
   recursive resolver to shield end users from DNSSEC-related
   authoritative name server operational errors.  Negative Trust Anchors
   are intended to be temporary, and should not be distributed by IANA
   or any other organization outside of the administrative boundary of
   the organization locally implementing a Negative Trust Anchor.
   Finally, Negative Trust Anchors pertain only to DNSSEC and not to
   Public Key Infrastructures (PKI) such as X.509.

   DNSSEC has now entered widespread deployment.  However, the DNSSEC
   signing tools and processes are less mature and reliable than those
   for non-DNSSEC-related administration.  As a result, operators of DNS
   recursive resolvers, such as Internet Service Providers (ISPs),
   occasionally observe domains incorrectly managing DNSSEC-related
   resource records.  This mismanagement triggers DNSSEC validation
   failures, and then causes large numbers of end users to be unable to
   reach a domain.  Many end users tend to interpret this as a failure
   of their ISP or resolver operator, and may switch to a non-validating
   resolver or contact their ISP to complain, rather than seeing this as
   a failure on the part of the domain they wanted to reach.  Without
   the techniques in this document, this pressure may cause the resolver
   operator to disable (or simply not deploy) DNSSEC validation.  Use of
   a Negative Trust Anchor to temporarily disable DNSSEC validation for
   a specific misconfigured domain name immediately restores access for
   end users.  This allows the domain's administrators to fix their
   misconfiguration, while also allowing the organization using the
   Negative Trust Anchor to keep DNSSEC validation enabled and still
   reach the misconfigured domain.

2.  Definition of a Negative Trust Anchor

   Trust Anchors are defined in [RFC5914].  A trust anchor should be
   used by a validating caching resolver as a starting point for
   building the authentication chain for a signed DNS response.  The
   inverse of this is a Negative Trust Anchor, which creates a stopping
   point for a caching resolver to end validation of the authentication
   chain.  Instead, the resolver sends the response as if the zone is
   unsigned and does not set the AD bit.  This Negative Trust Anchor can




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   potentially be placed at any level within the chain of trust and
   would stop validation from that point in the chain down.

3.  delete

4.  Domain Validation Failures

   A domain name can fail validation for two general reasons: a
   legitimate security failure such as due to an attack or compromise of
   some sort, or as a result of misconfiguration on the part of an
   domain administrator.  As domains transition to DNSSEC the most
   likely reason for a validation failure will be misconfiguration.
   Thus, domain administrators should be sure to read [RFC6781] in full.
   They should also pay special attention to Section 4.2, pertaining to
   key rollovers, which appear to be the cause of many recent validation
   failures.

   It is also possible that some DNSSEC validation failures could arise
   due to differences in how different software developers interpret
   DNSSEC standards and/or how those developers choose to implement
   support for DNSSEC.  For example, it is conceivable that a domain may
   be DNSSEC signed properly, and one vendor's DNS recursive resolvers
   will validate the domain but other vendors' software may fail to
   validate the domain.

5.  End User Reaction

   End users generally do not know what DNSSEC is, nor should they be
   expected to at the current time (especially absent widespread
   integration of DNSSEC indicators in end user software such as web
   browsers).  As a result, end users may misinterpret the failure to
   reach a domain due to DNSSEC-related misconfiguration . They may
   (incorrectly) assume that their ISP is purposely blocking access to
   the domain or that it is a performance failure on the part of their
   ISP (especially of the ISP's DNS servers).  They may contact their
   ISP to complain, which will incur cost for their ISP.  In addition,
   they may use online tools and sites to complain of this problem, such
   as via a blog, web forum, or social media site, which may lead to
   dissatisfaction on the part of other end users or general criticism
   of an ISP or operator of a DNS recursive resolver.

   As end users publicize these failures, others may recommend they
   switch from security-aware DNS resolvers to resolvers not performing
   DNSSEC validation.  This is a shame since the ISP or other DNS
   recursive resolver operator is actually doing exactly what they are
   supposed to do in failing to resolve a domain name, as this is the
   expected result when a domain can no longer be validated, protecting
   end users from a potential security threat.  Use of a Negative Trust



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   Anchor would allow the ISP to specifically remedy the failure to
   reach that domain, without compromising security for other sites.
   This would result in a satisfied end user, with minimal impact to the
   ISP, while maintaining the security of DNSSEC for correctly
   maintained domains.

6.  Switching to a Non-Validating Resolver is Not Recommended

   As noted in Section 5 some people may consider switching to an
   alternative, non-validating resolver themselves, or may recommend
   that others do so.  But if a domain fails DNSSEC validation and is
   inaccessible, this could very well be due to a security-related
   issue.  In order to be as safe and secure as possible, end users
   should not change to DNS servers that do not perform DNSSEC
   validation as a workaround, and people should not recommend that
   others do so either.  Domains that fail DNSSEC for legitimate reasons
   (versus misconfiguration) may be in control of hackers or there could
   be other significant security issues with the domain.

   Thus, switching to a non-validating resolver to restore access to a
   domain that fails DNSSEC validation is not a recommended practice, is
   bad advice to others, is potentially harmful to end user security,
   and is potentially harmful to DNSSEC adoption.

7.  Responsibility for Failures

   A domain administrator is solely and completely responsible for
   managing their domain name(s) and DNS resource records.  This
   includes complete responsibility for the correctness of those
   resource records, the proper functioning of their DNS authoritative
   servers, and the correctness of DNS records linking their domain to a
   top-level domain (TLD) or other higher level domain.  Even in cases
   where some error may be introduced by a third party, whether that is
   due to an authoritative server software vendor, software tools
   vendor, domain name registrar, or other organization, these are all
   parties that the domain administrator has selected or approved, and
   therefore is responsible for managing successfully.

   There are some cases in which the domain administrator is not the
   same as the domain owner.  In those cases, a domain owner has
   delegated operational responsibility to the domain administrator.  So
   no matter whether a domain owner is also the domain administrator or
   not, the domain administrator is operationally responsible for the
   proper configuration operation of the domain.

   So in the case of a domain name failing to successfully validate,
   when this is due to a misconfiguration of the domain, that is the
   sole responsibility of the domain administrator.



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   Any assistance or mitigation responses undertaken by other parties to
   mitigate the misconfiguration of a domain name by a domain
   administrator, especially operators of DNS recursive resolvers, are
   optional and at the pleasure of those parties.

8.  Use of a Negative Trust Anchor

   Technical personnel trained in the operation of DNS servers MUST
   confirm that a failure is due to misconfiguration, as a similar
   breakage could have occurred if an attacker gained access to a
   domain's authoritative servers and modified those records or had the
   domain pointed to their own rogue authoritative servers.  They should
   also confirm that the domain is not intentionally broken, such as for
   testing purposes as noted in Section 12.  Finally, they should make a
   reasonable attempt to contact the domain owner of the misconfigured
   zone, preferably prior to implementing the Negative Trust Anchor.

   In the case of a validation failure due to misconfiguration of a TLD
   or popular domain name (such as a top 100 website), this could make
   content or services in the affected TLD or domain inaccessible for a
   large number of users.  In such cases, it may be appropriate to use a
   Negative Trust Anchor as soon as the misconfiguration is confirmed.

   Once a domain has been confirmed to fail DNSSEC validation due to a
   DNSSEC-related misconfiguration, an ISP or other DNS recursive
   resolver operator may elect to use a Negative Trust Anchor for that
   domain or sub-domain.  This instructs their DNS recursive resolver to
   temporarily NOT perform DNSSEC validation at or in the misconfigured
   domain.  This immediately restores access to the domain for end users
   while the domain's administrator corrects the misconfiguration(s).
   It does not and should not involve turning off validation more
   broadly.

   A Negative Trust Anchor MUST only be used for a limited duration.
   Implementors SHOULD allow the operator using the Negative Trust
   Andhor to set an end time and date associated with any Negative Trust
   Anchor.  Optimally this time and date is set in a DNS recursive
   resolver's configuration, though in the short-term this may also be
   achieved via other systems or supporting processes.  Use of a
   Negative Trust Anchor MUST NOT be automatic.

   Finally, a Negative Trust Anchor SHOULD be used only in a specific
   domain or sub-domain and MUST NOT affect validation of other names up
   the authentication chain.  For example, a Negative Trust Anchor for
   zone1.example.com would affect only names at or below
   zone1.example.com, and validation would still be performed on
   example.com, .com, and the root (".").  In another example, a
   Negative Trust Anchor for example.com would affect only names within



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   example.com, and validation would still be performed on .com, and the
   root (".")

        Root (.)              <======
            |                       ||
            |                       ||<======>+----+----+    DNSSEC
            |                       ||        |Recursive|   Validation
        TLD (com)             <=====||        |Resolver |<============>
            |                        +<------>+---------+
            |                        |                     DNS NTA
            |                        |                   (example.com)
    SUB TLD (example.com)     <------|                 <-------------->
            |                        |
            |                        |
            |                        |
            (zone1.example.com <-----|

                  Figure 1: Negative Trust Anchor Diagram

9.  Managing Negative Trust Anchors

   While Negative Trust Anchors have proven useful during the early
   stages of DNSSEC adoption, domain owners are ultimately responsible
   for managing and ensuring their DNS records are configured correctly
   Section 7.

   Most current implementations of DNS validating resolvers currently
   follow [RFC4033] on defining the implementation of Trust Anchor as
   either using Delegation Signer (DS), Key Signing Key (KSK), or Zone
   Signing Key (ZSK).  A Negative Trust Anchor should use domain name
   formatting that signifies where in a delegation a validation process
   should be stopped.

   Different DNS recursive resolvers may have different configuration
   names for a Negative Trust Anchor.  For example, Unbound calls their
   configuration "domain-insecure."

   [need to update reference to full Appendix A, not just unbound]

   [Unbound-Configuration]

10.  Removal of a Negative Trust Anchor

   As explored in Section 13.1, using an NTA once the zone correctly
   validates can have security considerations.  It is therefore
   recommended that NTA implementors should periodically attempt to
   validate the domain in question, for the period of time that the
   Negative Trust Anchor is in place, until such validation is again



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   successful.  Before removing the Negative Trust Anchor, all
   authoritive resolvers listed in the zone should be checked.  Due to
   AnyCast or load balancers, this may not be possible.

   Once all testing succeeds, a Negative Trust Anchor should be removed
   as soon as is reasonably possible.  Optimally this is automatic,
   though it may also be achieved via other systems or supporting
   processes.

11.  Comparison to Other DNS Misconfigurations

   As noted in Section 7 domain administrators are ultimately
   responsible for managing and ensuring their DNS records are
   configured correctly.  ISPs or other DNS recursive resolver operators
   cannot and should not correct misconfigured A, CNAME, MX, or other
   resource records of domains for which they are not authoritative.
   Expecting non-authoritative entities to protect domain administrators
   from any misconfiguration of resource records is therefore
   unrealistic and unreasonable, and in the long-term is harmful to the
   delegated design of the DNS and could lead to extensive operational
   instability and/or variation.

12.  Intentionally Broken Domains

   Some domains, such as dnssec-failed.org, have been intentionally
   broken for testing purposes
   [Measuring-DNSSEC-Validation-of-Website-Visitors] [Netalyzr].  For
   example, dnssec-failed.org is a DNSSEC-signed domain that is broken.
   If an end user is querying a validating DNS recursive resolver, then
   this or other similarly intentionally broken domains should fail to
   resolve and should result in a SERVFAIL error.  If such a domain
   resolved successfully, then it is a sign that the DNS recursive
   resolver is not fully validating.

   Organizations that utilize Negative Trust Anchors should not add a
   Negative Trust Anchor for any intentionally broken domain.

   Organizations operating an intentionally broken domain may wish to
   consider adding a TXT record for the domain to the effect of "This
   domain is purposely DNSSEC broken for testing purposes".

13.  Other Considerations

13.1.  Security Considerations

   End to end DNSSEC validation will be disabled during the time that a
   Negative Trust Anchor is used.  In addition, the Negative Trust
   Anchor may be in place after the point in time when the DNS



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   misconfiguration that caused validation to break has been fixed.
   Thus, there may be a gap between when a domain has have been re-
   secured and when a Negative Trust Anchor is removed.  In addition, a
   Negative Trust Anchor may be put in place by DNS recursive resolver
   operators without the knowledge of the authoritative domain
   administrator for a given domain name.  However, attempts SHOULD be
   made to contact and inform the domain administrator prior to putting
   the NTA in place.

   End users of a DNS recursive resolver or other people may wonder why
   a domain that fails DNSSEC validation resolves with a supposedly
   validating resolver.  As a result, implementors should consider
   transparently disclosing those Negative Trust Anchors which are
   currently in place or were in place in the past, such as on a website
   [Disclosure-Example].  This is particularly important since there is
   currently no special DNS query response code that could indicate to
   end users or applications that a Negative Trust Anchor is in place.
   Such disclosures should optimally include both the data and time that
   the Negative Trust Anchor was put in place and when it was removed.

13.2.  Privacy Considerations

   There are no privacy considerations in this document.

13.3.  IANA Considerations

   There are no IANA considerations in this document.

14.  Acknowledgements

   Several people made contributions of text to this document and/or
   played an important role in the development and evolution of this
   document.  This in some cases included performing a detailed review
   of this document and then providing feedback and constructive
   criticism for future revisions, or engaging in a healthy debate over
   the subject of the document.  All of this was helpful and therefore
   the following individuals merit acknowledgement:

   - Joe Abley

   - John Barnitz

   - Tom Creighton

   - Marco Davids

   - Brian Dickson




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   - Patrik Falstrom

   - Tony Finch

   - Chris Ganster

   - Olafur Gudmundsson

   - Peter Hagopian

   - Wes Hardaker

   - Paul Hoffman

   - Shane Kerr

   - Murray Kucherawy

   - Warren Kumari

   - Rick Lamb

   - Marc Lampo

   - Ted Lemon

   - Ed Lewis

   - Antoin Verschuren

   - Paul Vixie

   - Patrik Wallstrom

   - Nick Weaver

   - Ralf Weber

15.  References

15.1.  Normative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.




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   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements", RFC
              4033, March 2005.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, March 2005.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, March 2005.

   [RFC4398]  Josefsson, S., "Storing Certificates in the Domain Name
              System (DNS)", RFC 4398, March 2006.

   [RFC4509]  Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer
              (DS) Resource Records (RRs)", RFC 4509, May 2006.

   [RFC5155]  Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
              Security (DNSSEC) Hashed Authenticated Denial of
              Existence", RFC 5155, March 2008.

   [RFC5914]  Housley, R., Ashmore, S., and C. Wallace, "Trust Anchor
              Format", RFC 5914, June 2010.

   [RFC6781]  Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC
              Operational Practices, Version 2", RFC 6781, December
              2012.

15.2.  Informative References

   [DNSSEC-Validation-Failure-Analysis]
              Barnitz, J., Creighton, T., Ganster, C., Griffiths, C.,
              and J. Livingood, "Analysis of DNSSEC Validation Failure -
              NASA.GOV", Comcast , January 2012,
              <http://www.dnssec.comcast.net/
              DNSSEC_Validation_Failure_NASAGOV_20120118_FINAL.pdf>.

   [Disclosure-Example]
              Comcast, "faa.gov Failing DNSSEC Validation (Fixed)",
              Comcast , February 2013, <http://dns.comcast.net/index
              .php/entry/faa-gov-failing-dnssec-validation-fixed>.

   [Measuring-DNSSEC-Validation-of-Website-Visitors]
              Mens, J., "Is my Web site being used via a DNSSEC-
              validator?", July 2012, <http://jpmens.net/2012/07/30/
              is-my-web-site-being-used-via-dnssec-validator/>.




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   [Netalyzr]
              Weaver, N., Kreibich, C., Nechaev, B., and V. Paxson,
              "Implications of Netalyzr's DNS Measurements", Securing
              and Trusting Internet Names, SATIN 2011 SATIN 2011, April
              2011, <http://conferences.npl.co.uk/satin/presentations/
              satin2011slides-Weaver.pdf>.

   [Unbound-Configuration]
              Wijngaards, W., "Unbound: How to Turn Off DNSSEC", June
              2010, <http://unbound.net/documentation/
              howto_turnoff_dnssec.html>.

Appendix A.  Configuration Examples

   The section contains example configurations to achive Negative Trust
   Anchor funcationality for the zone foo.example.com.

   Please note: These are simply examples - nameserver operators are
   expected to test and understand the implications of these operations.

A.1.  NLNet Labs Unbound

   Unbound lets us simply disable validation eching for a specific zone.
   See: <http://unbound.net/documentation/howto_turnoff_dnssec.html> [
   TODO(WK): Make this a "real" reference ]

   server:
           domain-insecure: "foo.example.com"

A.2.  ISC BIND

   Use the "rndc" command:

   _rndc nta [-lifetime duration] [-force] foo.example.com [view]_

   Set a negative trust anchor, disabling DNSSEC validation for the
   given domain.  Using -lifetime specifies the duration of the NTA, up
   to one day.  Using -force prevents the NTA from expiring before its
   full lifetime, even if the domain can validate sooner.

A.3.  Nominum Vantio

   **

   *negative-trust-anchors*

   _Format_: name




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   _Command Channel_: view.update name=world negative-trust-
   anchors=(foo.example.com)

   _Command Channel_: resolver.update name=res1 negative-trust-
   anchors=(foo.example.com)

   *Description*: Disables DNSSEC validation for a domain, even if the
   domain is under an existing security root.

Appendix B.  Document Change Log

   [RFC Editor: This section is to be removed before publication]

   Individual-00: First version published as an individual draft.

   Individual-01: Fixed minor typos and grammatical nits.  Closed all
   open editorial items.

   Individual-02: Simple date change to keep doc from expiring.
   Substantive updates planned.

   Individual-03: Changes to address feedback from Paul Vixie, by adding
   a new section "Limited Time and Scope of Use".  Changes to address
   issues raised by Antoin Verschuren and Patrik Wallstrom, by adding a
   new section "Intentionally Broken Domains" and added two related
   references.  Added text to address the need for manual investigation,
   as suggested by Patrik Falstrom.  Added a suggestion on notification
   as suggested by Marc Lampo.  Made several additions and changes
   suggested by Ralf Weber, Wes Hardaker, Nick Weaver, Tony Finch, Shane
   Kerr, Joe Abley, Murray Kucherawy, Olafur Gudmundsson.

   Individual-04: Moved the section defining a NTA forward, and added
   new text to the Abstract and Introduction per feedback from Paul
   Hoffman.

   Individual-05: Incorporated feedback from the DNSOP WG list received
   on 2/17/13 and 2/18/13.  This is likely the final version before the
   IETF 86 draft cutoff date.  Updated references to RFC6781 to RFC6781,
   per March Davids.

   Individual-06: Added more OPEN issues to continue tracking WG
   discussion.  No changes in the main document - just expanded issue
   tracking.

   Individual-07: Refresh document - needs revision and rework before
   IETF-91.  Planning to add more contributors.

   WG-00: Renamed at request of DNSOP co-chairs, added co-authors



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   WG-00 (cont):

   o  Using github issue tracker - go see https://github.com/wkumari/
      draft-livingood-dnsop-negative-trust-anchors/issues for more
      details.

   o  A bunch of readability improvments.

   o  Issue: Notify the domain owner of the validation failure -
      resolved.

   o  Issue: Make the NTA as specific as possible - resolved.

Appendix C.  Open Issues

   [RFC Editor: This section is to be removed before publication]

   Determine whether RFC 2119 language should be used or not when
   describing things like the duration of a NTA.

   The DNSOP WG should discuss whether a 1 day limit is reasonable,
   whether a different time (more or less than 1 day, such as 1 hour or
   1 week) should be specified, or whether no time should be specified
   (just a recommendation that it SHOULD generally be limited to X).

   Olafur Gudmundsson has suggested that we may want to consider whether
   a non validatable RRSIG should be returned or not when a NTA is in
   place.  This was raised in the context of NLnet Labs' DNSSEC-Trigger,
   which apparently acts like forwarding stub-validator.  He said, "The
   reason for this is if NTA strips signatures the stub-validator thinks
   it is under attack and may a) go into recursive mode to try to
   resolve the domain, getting to the right answer the long way. b) Give
   the wrong error "Missing signatures" instead of the real error.  If
   all the validator does is not to set the AD bit for RRsets at and
   below the NTA, stub-resolvers (and cascading resolvers) should be
   happy."

   Determine whether an informative reference to X.509 in the
   Introduction is necessary.

   Is it desirable to say that NTAs should not be distributed across
   organizational boundaries?

   Per Warren Kumari, add examples to appendix. "it would be very
   helpful to actually show how this is used, with e.g and example in an
   Appendix, for -insert favorite resolver here-. The document contains
   a lot of really useful content about why you might use one, how to
   minimize damage, etc but (IMO) does't do a great job of explaining



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   how to actually do so".  Rick Lamb and Joe Abley also agreed on the
   need for this.

   Per Rick Lamb, "it might be useful to have section 2 "Definition .."
   make that clear for slow people like me - that the NTA is not an RR
   and is more of a configuration.  Maybe simply replacing "placed" with
   "implemented" in section 2?  "This NTA can potentially be -placed/
   implemented- at any level within the chain of trust"

   Per Olafur Gudmundsson, address fact that ALL authoritative name
   servers must be working. "section 10 you talk about possible early
   removal the NTA when validation succeeds but there may be instances
   where validation succeeds when using a sub-set of the authoritative
   servers thus NTA should only be removed if all servers are providing
   "good" signatures."

   Per Olafur Gudmundsson, "Furthermore what to do if some names work
   but others do not, for example I remember a case where the records at
   the apex worked but all names below the apex were signed by a key not
   in the DNSKEY RRset, thus it is possible that either human or
   automated checks may assume there is no problem when there actually
   is one.  What this is bringing to my mind is maybe you want a new
   section with guidelines on how to test for failures and in what cases
   failure justifies NTA and what tests MUST pass before preemttive
   removal of an NTA."

   Per Olafur Gudmundsson, "Also should there be guidance that removal
   of NTA should include cleaning the caches of all RRsets below the
   name?"

   Reference and text per Ed Lewis: One thing that seems to need
   repeating from time to time is this passage in RFC 4033. ... In the
   final analysis, however, authenticating both DNS keys and data is a
   matter of local policy, which may extend or even override the
   protocol extensions defined in this document set.  See Section 5 for
   further discussion.  A responsibility (one of many) of a caching
   server operator is to "protect the integrity of the cache."  DNSSEC
   is just a tool to help accomplish that.  It carries ancillary data
   that a local cache administrator may use to filter out undesired
   responses.  DNSSEC is not an enforcement mechanism, it's a resource.
   When I see folks voice opinions that DNSSEC's recommended operation
   has to strictly followed, my gut reaction is that these folks have
   forgotten the purpose of all of our efforts.  We don't secure
   protocols to make things work better.  We don't operate the DNS
   because we like to run a well run machine.  We don't run the Internet
   for the fun of it.  (Some might enjoy running it, that's job
   satisfaction to some extent.)  At the end of the day all that matters
   is that what is being done benefits society.  We run the Internet to



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   enrich society.  We prefer a well run DNS because it saps less
   resources than a poorly run DNS.  We prefer secure protocols so that
   people don't become victims (in some sense of the word).  Make it
   work.  Do what it takes to make it work.  "Local policy" rules.

   Per David Conrad: I'd suggest that in the BCP/RFC/whatever, in
   addition to recommending that NTAs be time capped and not written to
   permanent storage, it should also recommend NTAs be written as
   specifically as possible.  (Should be obvious, but doesn't hurt to
   reiterate I suppose).

   Per Ralf Weber: Informing the domain owner on the validation failure.
   There should be a section in the document that the operator deploying
   an NTA has to inform the domain owner of the problem.  (JL note:
   would prefer to say operator SHOULD take reasonable steps to notify
   the domain owner, etc.)

Authors' Addresses

   Paul Ebersman
   Comcast
   One Comcast Center
   1701 John F. Kennedy Boulevard
   Philadelphia, PA  19103
   US

   Email: ebersman-ietf@dragon.net


   Chris Griffiths
   Dyn
   150 Dow Street
   Tower Two
   Manchester, NH  03101
   US

   Email: cgriffiths@gmail.com
   URI:   http://www.dyn.com


   Warren Kumari
   Google
   1600 Amphitheatre Parkway
   Mountain View, CA  94043
   US

   Email: warren@kumari.net
   URI:   http://www.google.com



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   Jason Livingood
   Comcast
   One Comcast Center
   1701 John F. Kennedy Boulevard
   Philadelphia, PA  19103
   US

   Email: jason_livingood@cable.comcast.com
   URI:   http://www.comcast.com


   Ralf Weber
   Nominum

   Email: Ralf.Weber@nominum.com
   URI:   http://www.nominum.com



































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