draft-ietf-dnsop-qname-minimisation-05.txt   draft-ietf-dnsop-qname-minimisation-06.txt 
Domain Name System Operations (dnsop) Working Group S. Bortzmeyer Domain Name System Operations (dnsop) Working Group S. Bortzmeyer
Internet-Draft AFNIC Internet-Draft AFNIC
Intended status: Experimental August 1, 2015 Intended status: Experimental October 5, 2015
Expires: February 2, 2016 Expires: April 7, 2016
DNS query name minimisation to improve privacy DNS query name minimisation to improve privacy
draft-ietf-dnsop-qname-minimisation-05 draft-ietf-dnsop-qname-minimisation-06
Abstract Abstract
This document describes one of the techniques that could be used to This document describes one of the techniques that could be used to
improve DNS privacy (see [I-D.ietf-dprive-problem-statement]), a improve DNS privacy (see [RFC7626]), a technique called "QNAME
technique called "QNAME minimisation", where the DNS resolver no minimisation", where the DNS resolver no longer sends the full
longer sends the full original QNAME to the upstream name server. original QNAME to the upstream name server.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 2, 2016. This Internet-Draft will expire on April 7, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 8 10.1. Normative References . . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . 8 10.2. Informative References . . . . . . . . . . . . . . . . . 8
10.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9 10.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix A. An algorithm to find the zone cut . . . . . . . . . 9 Appendix A. An algorithm to find the zone cut . . . . . . . . . 9
Appendix B. Alternatives . . . . . . . . . . . . . . . . . . . . 10 Appendix B. Alternatives . . . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction and background 1. Introduction and background
The problem statement is exposed in The problem statement is exposed in [RFC7626]. The terminology
[I-D.ietf-dprive-problem-statement]. The terminology ("QNAME", ("QNAME", "resolver", etc) is also defined in this companion
"resolver", etc) is also defined in this companion document. This document. This specific solution is not intended to fully solve the
specific solution is not intended to fully solve the DNS privacy DNS privacy problem; instead, it should be viewed as one tool amongst
problem; instead, it should be viewed as one tool amongst many. many.
It follows the principle explained in section 6.1 of [RFC6973]: the It follows the principle explained in section 6.1 of [RFC6973]: the
less data you send out, the fewer privacy problems you'll get. less data you send out, the fewer privacy problems you'll get.
Under current practice, when a resolver receives the query "What is Under current practice, when a resolver receives the query "What is
the AAAA record for www.example.com?", it sends to the root (assuming the AAAA record for www.example.com?", it sends to the root (assuming
a cold resolver, whose cache is empty) the very same question. a cold resolver, whose cache is empty) the very same question.
Sending the full QNAME to the authoritative name server is a Sending the full QNAME to the authoritative name server is a
tradition, not a protocol requirement. This tradition tradition, not a protocol requirement. This tradition comes
comes[mockapetris-history] from a desire to optimize the number of [mockapetris-history] from a desire to optimize the number of
requests, when the same name server is authoritative for many zones requests, when the same name server is authoritative for many zones
in a given name (something which was more common in the old days, in a given name (something which was more common in the old days,
where the same name servers served .com and the root) or when the where the same name servers served .com and the root) or when the
same name server is both recursive and authoritative (something which same name server is both recursive and authoritative (something which
is strongly discouraged now). Whatever the merits of this choice at is strongly discouraged now). Whatever the merits of this choice at
this time, the DNS is quite different now. this time, the DNS is quite different now.
2. QNAME minimisation 2. QNAME minimisation
The idea is to minimise the amount of data sent from the DNS resolver The idea is to minimise the amount of data sent from the DNS resolver
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Note that DNSSEC-validating resolvers already have access to this Note that DNSSEC-validating resolvers already have access to this
information, since they have to know the zone cut (the DNSKEY record information, since they have to know the zone cut (the DNSKEY record
set is just below, the DS record set just above). set is just below, the DS record set just above).
3. Possible issues 3. Possible issues
QNAME minimisation is legal, since the original DNS RFC do not QNAME minimisation is legal, since the original DNS RFC do not
mandate sending the full QNAME. So, in theory, it should work mandate sending the full QNAME. So, in theory, it should work
without any problems. However, in practice, some problems may occur without any problems. However, in practice, some problems may occur
(see an analysis in [huque-qnamemin]). (see an analysis in [huque-qnamemin] and an interesting discussion in
[huque-qnamestorify]).
Some broken name servers do not react properly to qtype=NS requests. Some broken name servers do not react properly to qtype=NS requests.
For instance, some authoritative name servers embedded in load For instance, some authoritative name servers embedded in load
balancers reply properly to A queries but send REFUSED to NS queries. balancers reply properly to A queries but send REFUSED to NS queries.
This behaviour is a gross protocol violation, and there is no need to This behaviour is a gross protocol violation, and there is no need to
stop improving the DNS because of such brokenness. However, QNAME stop improving the DNS because of such brokenness. However, QNAME
minimisation may still work with such domains since they are only minimisation may still work with such domains since they are only
leaf domains (no need to send them NS requests). Such setup breaks leaf domains (no need to send them NS requests). Such setup breaks
more than just QNAME minimisation. It breaks negative answers, since more than just QNAME minimisation. It breaks negative answers, since
the servers don't return the correct SOA, and it also breaks anything the servers don't return the correct SOA, and it also breaks anything
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advantages (besides privacy) to QNAME minimisation. Thanks to advantages (besides privacy) to QNAME minimisation. Thanks to
Phillip Hallam-Baker for the fallback on A queries, to deal with Phillip Hallam-Baker for the fallback on A queries, to deal with
broken servers. Thanks to Robert Edmonds for an interesting anti- broken servers. Thanks to Robert Edmonds for an interesting anti-
pattern. pattern.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987. STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<http://www.rfc-editor.org/info/rfc1034>.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <http://www.rfc-editor.org/info/rfc1035>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973, July Considerations for Internet Protocols", RFC 6973, DOI
2013. 10.17487/RFC6973, July 2013,
<http://www.rfc-editor.org/info/rfc6973>.
[I-D.ietf-dprive-problem-statement] [RFC7626] Bortzmeyer, S., "DNS Privacy Considerations", RFC 7626,
Bortzmeyer, S., "DNS privacy considerations", draft-ietf- DOI 10.17487/RFC7626, August 2015,
dprive-problem-statement-06 (work in progress), June 2015. <http://www.rfc-editor.org/info/rfc7626>.
10.2. Informative References 10.2. Informative References
[RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS [RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS
Specification", RFC 2181, July 1997. Specification", RFC 2181, DOI 10.17487/RFC2181, July 1997,
<http://www.rfc-editor.org/info/rfc2181>.
[RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running [RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", RFC 6982, July Code: The Implementation Status Section", RFC 6982, DOI
2013. 10.17487/RFC6982, July 2013,
<http://www.rfc-editor.org/info/rfc6982>.
[I-D.wkumari-dnsop-hammer] [I-D.wkumari-dnsop-hammer]
Kumari, W., Arends, R., Woolf, S., and D. Migault, "Highly Kumari, W., Arends, R., Woolf, S., and D. Migault, "Highly
Automated Method for Maintaining Expiring Records", draft- Automated Method for Maintaining Expiring Records", draft-
wkumari-dnsop-hammer-01 (work in progress), July 2014. wkumari-dnsop-hammer-01 (work in progress), July 2014.
[I-D.vixie-dnsext-resimprove] [I-D.vixie-dnsext-resimprove]
Vixie, P., Joffe, R., and F. Neves, "Improvements to DNS Vixie, P., Joffe, R., and F. Neves, "Improvements to DNS
Resolvers for Resiliency, Robustness, and Responsiveness", Resolvers for Resiliency, Robustness, and Responsiveness",
draft-vixie-dnsext-resimprove-00 (work in progress), June draft-vixie-dnsext-resimprove-00 (work in progress), June
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