Domain Name System Operations J. Livingood
Internet-Draft Comcast
Intended status: Informational August 13, 2019
Expires: February 14, 2020
Responsibility for Authoritative DNS and DNSSEC Mistakes
draft-livingood-dnsop-auth-dnssec-mistakes-05
Abstract
DNS Security Extensions (DNSSEC) validation by recursive DNS
resolvers has been deployed at scale. 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. This
sometimes results in DNSSEC-validation failures, for which operators
of validating resolvers are often blamed. This is similar to other,
non-DNSSEC-related authoritative DNS errors, for which individual
recursive DNS operators are sometimes incorrectly blamed. This
document makes clear that responsibility for any and all
authoritative DNS failures rests squarely with authoritative domain
name operators, who are the only party that can properly maintain
their domain names and rectify associated authoritative DNS errors.
Status of This Memo
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This Internet-Draft will expire on February 14, 2020.
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Domain Validation Failures . . . . . . . . . . . . . . . . . 3
3. Responsibility for Failures . . . . . . . . . . . . . . . . . 4
4. Comparison to Other DNS Misconfigurations . . . . . . . . . . 5
5. Other Considerations . . . . . . . . . . . . . . . . . . . . 5
5.1. Security Considerations . . . . . . . . . . . . . . . . . 5
5.2. Privacy Considerations . . . . . . . . . . . . . . . . . 5
5.3. IANA Considerations . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Appendix A. Document Change Log . . . . . . . . . . . . . . . . 7
Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
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].
DNS Security Extensions (DNSSEC) validation by recursive DNS
resolvers has been deployed at scale. 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. This
sometimes results in DNSSEC-validation failures, for which operators
of validating resolvers are often blamed. This is similar to other,
non-DNSSEC-related authoritative DNS errors, for which individual
recursive DNS operators are sometimes incorrectly blamed. This
documents makes clear that responsibility for any and all
authoritative DNS failures rests squarely with authoritative domain
name operators, who are the only party that can properly maintain
their domain names and rectify associated authoritative DNS errors.
Operators of DNS recursive resolvers, including Internet Service
Providers (ISPs) and cloud-based DNS resolvers, occasionally observe
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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.
Similarly, errors in non-DNSSEC-related authoritative DNS resource
records result in failures, from NXDOMAIN responses to valid
responses containing outdated or unreachable hosts.
Many end users, as well as reporters, policymakers, regulators, and
others often interpret this as a failure of particular recursive DNS
resolvers. Rather than seeing this as a failure on the part of the
domain they wanted to reach, they may themselves and/or recommend to
others that they switch to a non-validating resolver (which reduces
their security), switch to a different DNS resolver (which can reduce
non-DNS application layer performance), or contact their ISP or DNS
resolver operator to complain.
This document makes clear, however, that responsibility for these
types of authoritative DNS failures rests squarely with authoritative
domain name operators, as noted in Section 3.
2. 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 or other error or
omission on the part of an domain administrator. As domains
transition to DNSSEC the most likely reason for a validation failure
during and shortly after the transition is likely 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 validation failures.
In one 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
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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 a non-DNSSEC-related example, a domain administrator may add a new
host with an A and AAAA resource record pointing the name to the IP
addresses of new servers with a Time To Live (TTL) of two days. But
they may turn down the old servers with a similar two day TTL before
that TTL has expired. As a result, some number of users are likely
to continue to attempt to connect to the old IP addresses that are no
longer reachable. While a best practice is to reduce the TTL to a
matter of seconds or minutes before such a shift, many domains
continue to forget the impact that the TTL can have, or make
countless other errors in their domain name, server, and network
administration that negatively impacts domain name-based
reachability.
3. Responsibility for Failures
An authoritative domain owner is solely and completely responsible
for managing their domain name(s) and associated DNS resource
records. This includes complete responsibility for the correctness
of those resource records, the proper functioning and reachability of
their authoritative DNS servers, and the correctness of DNS records
linking their domain to a top-level domain (TLD) or other higher
level domain. The domain owner is also responsible for selection of
the authoritative domain administrator, operator, or service
provider. Thus, 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,
Content Delivery Network (CDN), or other organization, these are all
parties that the domain owner 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 (and that
domain administrator may further delegate some sub-domains and/or
records to another party, such as a CDN). So no matter whether a
domain owner is also the domain administrator or not, the domain
owner and domain administrator are nevertheless operationally
responsible for the proper configuration and operation of the domain
name .
In the case of a domain name failing DNSSEC validation, even when
this is due to a misconfiguration of the domain, that is the sole
responsibility of the domain owner.
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Any assistance or mitigation responses undertaken by other parties to
mitigate the misconfiguration of a domain name by a domain owner and/
or administrator, especially operators of DNS recursive resolvers,
are optional and at the pleasure of those parties. This can the use
of a Negative Trust Anchor [RFC7646] and/or clearing the cache in
particular DNS resolvers.
4. Comparison to Other DNS Misconfigurations
As noted in Section 3 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 owners and
administrators from any misconfiguration of resource records is
therefore unrealistic and unreasonable, does not scale well, and is
strongly contrary to the delegated design of the DNS and could lead
to extensive operational instability and/or variation.
5. Other Considerations
5.1. Security Considerations
Authoritative domain name owners and/or administrators, in the case
of DNSSEC-related mistakes that cause validation failures to occur,
should focus on correcting the immediate authoritative DNS issue and
then improving their processes and tools in the future.
During the period of time that their domain cannot be resolved due to
a DNSSEC-related mistake, they SHOULD NOT encourage end users to
switch to non-validating resolvers [I-D.draft-livingood-dnsop-dont-
switch-resolvers] .
5.2. Privacy Considerations
In the case of a DNSSEC validation failure, if an end user changes to
a non-validating resolver they can subject themselves to increased
security risks and threats against which DNSSEC may have provided
protection. This can include threats to their privacy, such as by
unwittingly visiting a phishing site and sharing sensitive data or
other private information with a malicious party or some party other
than that which was originally intended.
As a result, in order to protect their privacy, users SHOULD NOT
switch to a non-validating resolver when a DNSSEC validation failure
occurs [I-D.draft-livingood-dnsop-dont-switch-resolvers].
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5.3. IANA Considerations
There are no IANA considerations in this document.
6. Acknowledgements
- William Brown
7. References
7.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, DOI 10.17487/RFC4033, March 2005,
<https://www.rfc-editor.org/info/rfc4033>.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, DOI 10.17487/RFC4034, March 2005,
<https://www.rfc-editor.org/info/rfc4034>.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
<https://www.rfc-editor.org/info/rfc4035>.
[RFC4398] Josefsson, S., "Storing Certificates in the Domain Name
System (DNS)", RFC 4398, DOI 10.17487/RFC4398, March 2006,
<https://www.rfc-editor.org/info/rfc4398>.
[RFC4509] Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer
(DS) Resource Records (RRs)", RFC 4509,
DOI 10.17487/RFC4509, May 2006,
<https://www.rfc-editor.org/info/rfc4509>.
[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
Security (DNSSEC) Hashed Authenticated Denial of
Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,
<https://www.rfc-editor.org/info/rfc5155>.
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[RFC6781] Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC
Operational Practices, Version 2", RFC 6781,
DOI 10.17487/RFC6781, December 2012,
<https://www.rfc-editor.org/info/rfc6781>.
[RFC7646] Ebersman, P., Kumari, W., Griffiths, C., Livingood, J.,
and R. Weber, "Definition and Use of DNSSEC Negative Trust
Anchors", RFC 7646, DOI 10.17487/RFC7646, September 2015,
<https://www.rfc-editor.org/info/rfc7646>.
7.2. 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>.
[I-D.livingood-dnsop-dont-switch-resolvers]
Livingood, J., "In Case of DNSSEC Validation Failures, Do
Not Change Resolvers", draft-livingood-dnsop-dont-switch-
resolvers-03 (work in progress), November 2015.
Appendix A. 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 nits identified by William Brown
Individual-02: Updated prior to IETF-91
WG-00: Renamed at request of DNSOP co-chairs
WG-01: Updated doc to keep it from expiring
WG-02: Removed RFC 2119 reference in XML
WG-03 to 04: Refreshed draft and broadened to all auth issues, not
just DNSSEC.
WG-05: Refreshed to buy time for me to write a combined document
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Appendix B. Open Issues
[RFC Editor: This section is to be removed before publication]
Fix I-D xref
Author's Address
Jason Livingood
Comcast
Email: jason_livingood@comcast.com
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