Internet DRAFT - draft-livingood-negative-trust-anchors
draft-livingood-negative-trust-anchors
Domain Name System Operations J. Livingood
Internet-Draft Comcast
Intended status: Informational C. Griffiths
Expires: March 28, 2015 Dyn
September 24, 2014
Definition and Use of DNSSEC Negative Trust Anchors
draft-livingood-negative-trust-anchors-07
Abstract
DNS Security Extensions (DNSSEC) is now entering widespread
deployment. However, domain signing tools and processes are not yet
as mature and reliable as is the case for non-DNSSEC-related domain
administration tools and processes. One potential technique to
mitigate this is to use a Negative Trust Anchor, which is defined in
this document.
This document discusses Trust Anchors for DNSSEC and defines a
Negative Trust Anchor, which is potentially useful during the
transition to ubiquitous DNSSEC deployment. These are configured
locally on a particular instance of a validating DNS recursive
resolver and can shield end users of such a resolver from the DNSSEC-
related authoritative name server operational errors that appear to
be somewhat typical during the transition to ubiquitous DNSSEC
deployment. 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 ad X.509.
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."
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This Internet-Draft will expire on March 28, 2015.
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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definition of a Negative Trust Anchor . . . . . . . . . . . . 4
3. Limited Time and Scope of Use . . . . . . . . . . . . . . . . 4
4. Domain Validation Failures . . . . . . . . . . . . . . . . . 5
5. End User Reaction . . . . . . . . . . . . . . . . . . . . . . 5
6. Switching to a Non-Validating Resolver is Not Recommended . . 6
7. Responsibility for Failures . . . . . . . . . . . . . . . . . 6
8. Use of a Negative Trust Anchor . . . . . . . . . . . . . . . 7
9. Managing Negative Trust Anchors . . . . . . . . . . . . . . . 8
10. Removal of a Negative Trust Anchor . . . . . . . . . . . . . 9
11. Comparison to Other DNS Misconfigurations . . . . . . . . . . 9
12. Intentionally Broken Domains . . . . . . . . . . . . . . . . 10
13. Other Considerations . . . . . . . . . . . . . . . . . . . . 10
13.1. Security Considerations . . . . . . . . . . . . . . . . 10
13.2. Privacy Considerations . . . . . . . . . . . . . . . . . 11
13.3. IANA Considerations . . . . . . . . . . . . . . . . . . 11
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
15.1. Normative References . . . . . . . . . . . . . . . . . . 12
15.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix A. Document Change Log . . . . . . . . . . . . . . . . 13
Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The Domain Name System (DNS), DNS Security Extensions (DNSSEC), and
related operational practices are defined extensively [RFC1034]
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[RFC1035] [RFC4033] [RFC4034] [RFC4035] [RFC4398] [RFC4509] [RFC6781]
[RFC5155].
This document discusses Trust Anchors for DNSSEC and defines a
Negative Trust Anchor, which is potentially useful during the
transition to ubiquitous DNSSEC deployment. These are configured
locally on a particular instance of a validating DNS recursive
resolver and can shield end users of such a resolver from the DNSSEC-
related authoritative name server operational errors that appear to
be somewhat typical during the transition to ubiquitous DNSSEC
deployment. 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 ad X.509. [REFERENCE NECESSARY?]
DNSSEC has now entered widespread deployment. However, domain
signing tools and processes are not yet as mature and reliable as is
the case for non-DNSSEC-related domain administration tools and
processes. 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 interpret this as a failure of their DNS servers, 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.
In the short-term, one potential way to address this is for DNS
operators to use a Negative Trust Anchor to temporarily disable
DNSSEC validation for a specific misconfigured domain name. This
immediately restores access for end users while that domain's
administrators fix their misconfiguration. While DNS operators
likely prefer not to use this tool, during the global transition to
DNSSEC it seems some tool is needed to reduce the negative impact on
such operators.
A Negative Trust Anchor should be considered a transitional and
temporary tactic which is not particularly scalable and should not be
used in the long-term. Over time, however, the use of Negative Trust
Anchors will become less necessary as DNSSEC-related domain
administration becomes more resilient.
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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. This Negative Trust Anchor can potentially be placed at any
level within the chain of trust and would stop validation at that
point in the chain.
3. Limited Time and Scope of Use
As noted in Section 1, the use of Negative Trust Anchors should be
temporary. These are key recommendations pertaining to this
practice:
1. The general practice of using Negative Trust Anchors should be
limited to the transition to widespread deployment of DNSSEC
(including signing of domain names and validation in DNS
recursive resolvers). Thus, the practice of using Negative Trust
Anchors should not be permanent.
2. During this transition phase when Negative Trust Anchors may be
useful, the use of a particular Negative Trust Anchor should be
temporary and in most cases limited to no more than 1 day. Thus,
the use of an individual Negative Trust Anchor should be strictly
time limited and very short in duration.
3. So that the use of Negative Trust Anchors remains temporary and
useful only during a transition to widespread DNSSEC deployment,
the use and distribution of individual Negative Trust Anchors
should not be centralized, beyond the borders of one
organization's operational unit. Thus, no organization should
endeavor to create and centrally distribute Negative Trust
Anchors to other organizations as was the case with positive
Trust Anchors prior to the signing of the root.
4. As noted in Section 12, organizations that utilize Negative Trust
Anchors should not add a Negative Trust Anchor for any
intentionally broken domain.
5. As noted in Section 8, use of a Negative Trust Anchor should not
be automatic in any way, and must involve investigation by
technical personnel trained in the operation of DNS servers.
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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 due to
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 appears to be the
cause of many recent validation failures.
In one recent example [DNSSEC-Validation-Failure-Analysis], a
specific domain name failed to validate. An investigation revealed
that the domain's administrators performed a Key Signing Key (KSK)
rollover by (1) generating a new key and (2) signing the domain with
the new key. However, they did not use a double-signing procedure
for the KSK and a pre-publish procedure for the ZSK. Double-signing
refers to signing a zone with two KSKs and then updating the parent
zone with the new DS record so that both keys are valid at the same
time. This meant that the domain name was signed with the new KSK,
but it was not double-signed with the old KSK. So, the new key was
used for signing the zone but the old key was not. As a result, the
domain could not be trusted and returned an error when trying to
reach the domain. Thus, the domain was in a situation where the
DNSSEC chain of trust was broken because the Delegation Signer (DS)
record pointed to the old KSK, which was no longer used for signing
the zone. (A DS record provides a link in the chain of trust for
DNSSEC from the parent zone to the child zone - in this case between
TLD and domain name.)
In addition, it is 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
some domain may be DNSSEC signed properly, and Unbound-based DNS
recursive resolvers will validate the domain but those using BIND or
Nominum's Vantio software may fail to validate a 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 incorrectly interpret the
failure to reach a domain due to DNSSEC-related misconfiguration as
their ISP purposely blocking access to the domain or as a performance
failure on the part of their ISP (especially of the ISP's DNS
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servers). End users may feel less satisfied with their ISP's
service, which may make them more likely to switch to a competing
ISP. They may also contact their ISP to complain, which of course
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.
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. Even if a website in a domain seems to look
"normal" and valid, according to the DNSSEC protocol, that domain is
not secure. Domains that fail DNSSEC for legitimate reasons 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
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parties that the domain administrator has selected and is responsible
for managing successfully.
There are some cases where the domain administrator is different than
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 nevertheless 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.
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
When a domain has been confirmed to fail DNSSEC validation due to a
DNSSEC-related misconfiguration, an ISP or other DNS recursive
resolver operator may in some cases use a Negative Trust Anchor for a
domain or sub-domain. This instructs a DNS recursive resolver to
temporarily NOT perform DNSSEC validation for a specific domain name.
This immediately restores access to the domain for end users while
the domain's administrator corrects the misconfiguration(s).
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 to be inaccessible
for a large number of users. A Negative Trust Anchor can therefore
be useful in the short-term when used on a targeted and time-limited
basis. It does not and should not involve turning off validation
more broadly, and helps during the transition to DNSSEC as
organizations that are new to signing their domains are still
maturing their DNSSEC operational practices, alleviating end user
issues as noted in Section 5 and restoring end user access. However,
use of a Negative Trust Anchor should not be automatic in any way,
and must involve investigation by technical personnel trained in the
operation of DNS servers.
Technical personnel should also confirm that the domain is not
intentionally broken, such as for testing purposes as noted in
Section 12. Such an investigation 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
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modified those records or had the domain pointed to their own rogue
authoritative servers. In addition, personnel should make a
reasonable attempt to contact a domain for which a Negative Trust
Anchor may be used, and preferably prior to implementing it.
Furthermore, a Negative Trust Anchor MUST only be used for a short
duration, such as for a day or less. Implementors SHOULD set an end
time and date associated with any Negative Trust Anchor.
Implementors SHOULD in most cases limit the maximum duration to one
day, meaning the Negative Trust Anchor will be removed or invalidated
from the point of implementation, plus 86,400 seconds. However,
there may be corner cases where a Negative Trust Anchor is needed for
a longer period of time. 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.
Finally, a Negative Trust Anchor is used only in a specific domain or
sub-domain and would not affect validation at other names up the
authentication chain. For example, a Negative Trust Anchor for
zone1.example.com would affect only names within 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 example.com, and
validation would still be performed on .com, and the root (".")
Root (.) <======
| ||
| ||<======>+----+----+ DNSSEC
| || |Recursive| Validation
TLD (com) <=====|| |Resolver | <==============>
| +<------>+---------+
| | DNS NTA
| | (zone1.example.com)
SUB TLD (example.com) <------| <-------------->
| |
| |
| |
(zone1.example.com <-----|
Figure 1: Negative Trust Anchor Diagram
9. Managing Negative Trust Anchors
This tool is unlikely to be and probably should not be used over the
long-term since DNSSEC-related domain administration practices will
naturally improve over time. In addition, however, continued and
frequent use of Negative Trust Anchors is not scalable since it
requires investigation by technical personnel and may involve manual
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processes, resulting in increased operational overhead (and therefore
cost).
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" [Unbound-Configuration]
10. Removal of a Negative Trust Anchor
As explored in Section 13.1, if a Negative Trust Anchor is still in
place after the point in time when the DNS misconfiguration that
caused validation to break has been fixed, this could be problematic.
It is therefore recommended that implementors should periodically or
even continuously 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 successful. (Obviously a Negative Trust Anchor
could be removed prior to validation succeeding again, alleviating an
implementor of the need to continuing to test validation separate
from their normal operations.)
Once validation is again successful, 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
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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
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.
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.
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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
- Patrik Falstrom
- Tony Finch
- Chris Ganster
- Olafur Gudmundsson
- Peter Hagopian
- Wes Hardaker
- Paul Hoffman
- Shane Kerr
- Murray Kucherawy
- Warren Kumari
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- 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.
[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.
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[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/>.
[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. Document Change Log
[RFC Editor: This section is to be removed before publication]
-00: First version published as an individual draft.
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-01: Fixed minor typos and grammatical nits. Closed all open
editorial items.
-02: Simple date change to keep doc from expiring. Substantive
updates planned.
-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.
-04: Moved the section defining a NTA forward, and added new text to
the Abstract and Introduction per feedback from Paul Hoffman.
-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.
-06: Added more OPEN issues to continue tracking WG discussion. No
changes in the main document - just expanded issue tracking.
-07: Refresh document - needs revision and rework before IETF-91.
Planning to add more contributors.
Appendix B. 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
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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 on 2/19/2013, 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 how to actually do so". Rick Lamb and Joe Abley also
agreed on the need for this.
Per Rick Lamb on 2/20/2013, "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 on 2/18/2013, 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 on 2/18/2013, "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 on 2/18/2013, "Also should there be guidance
that removal of NTA should include cleaning the caches of all RRsets
below the name?"
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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
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
Jason Livingood
Comcast Cable Communications
One Comcast Center
1701 John F. Kennedy Boulevard
Philadelphia, PA 19103
US
Email: jason_livingood@cable.comcast.com
URI: http://www.comcast.com
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Chris Griffiths
Dyn
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