< draft-hzpa-dprive-xfr-over-tls-00.txt   draft-hzpa-dprive-xfr-over-tls-01.txt >
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Intended status: Standards Track Salesforce Intended status: Standards Track Salesforce
Expires: September 12, 2019 W. Toorop Expires: September 12, 2019 W. Toorop
NLnet Labs NLnet Labs
S. Dickinson S. Dickinson
Sinodun IT Sinodun IT
A. Mankin A. Mankin
Salesforce Salesforce
March 11, 2019 March 11, 2019
DNS Zone Transfer over TLS DNS Zone Transfer over TLS
draft-hzpa-dprive-xfr-over-tls-00 draft-hzpa-dprive-xfr-over-tls-01
Abstract Abstract
DNS zone transfers are transmitted in clear text, which gives DNS zone transfers are transmitted in clear text, which gives
attackers the opportunity to collect the content of a zone by attackers the opportunity to collect the content of a zone by
eavesdropping on links. The DNS Transaction Signature (TSIG) is eavesdropping on network connections. The DNS Transaction Signature
specified to restrict direct zone transfer to authorized clients, but (TSIG) mechanism is specified to restrict direct zone transfer to
it does not add confidentiality. This document specifies use of TLS authorized clients only, but it does not add confidentiality. This
to prevent zone collection document specifies use of DNS-over-TLS to prevent zone contents
collection via passive monitoring of zone transfers.
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 https://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 September 12, 2019. This Internet-Draft will expire on September 12, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 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
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Zone Transfer Confidentiality Overview . . . . . . . . . . . 3 3. Zone Transfer Confidentiality Overview . . . . . . . . . . . 4
4. Zone Transfer with DOT - Authentication . . . . . . . . . . . 3 4. Zone Transfer with DoT - Authentication . . . . . . . . . . . 4
4.1. TSIG . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Mutual TLS . . . . . . . . . . . . . . . . . . . . . . . 4
5. Session Establishment and Closing . . . . . . . . . . . . . . 4 5. Session Establishment and Closing . . . . . . . . . . . . . . 4
5.1. AXFR Sessions . . . . . . . . . . . . . . . . . . . . . . 4
5.2. IXFR Sessions . . . . . . . . . . . . . . . . . . . . . . 4
5.3. Policies for Both AXFR and IXFR . . . . . . . . . . . . . 5
5.4. Next Steps . . . . . . . . . . . . . . . . . . . . . . . 5
6. Performance Considerations . . . . . . . . . . . . . . . . . 5 6. Performance Considerations . . . . . . . . . . . . . . . . . 5
7. Implementation Considerations . . . . . . . . . . . . . . . . 5 7. Implementation Considerations . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . 5 9. Security Considerations . . . . . . . . . . . . . . . . . . . 5
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
12. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 5 12. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 6
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 13. Normative References . . . . . . . . . . . . . . . . . . . . 6
13.1. Normative References . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
13.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
DNS has a number of privacy vulnerabilities, as discussed in detail DNS has a number of privacy vulnerabilities, as discussed in detail
in [RFC7626]. Query privacy has received the most attention. There in [I-D.bortzmeyer-dprive-rfc7626-bis]. Stub client to recursive
are now standards for three encryption capabilities for queries and resolver query privacy has received the most attention to date.
more work going on to guide deployment [RFC7858] [RFC8484]. There are now standards track documents for three encryption
capabilities for stub to recursive queries and more work going on to
guide deployment of specifically DNS-over-TLS (DoT) [RFC7858] and
DNS-over-HTTPS (DoH) [RFC8484].
[RFC7626] established that the query transactions are not public and [I-D.bortzmeyer-dprive-rfc7626-bis] established that stub client DNS
needed protection, but on zone transfer it says only: Privacy risks query transactions are not public and needed protection, but on zone
for the holder of a zone (the risk that someone gets the data) are transfer [RFC1995] [RFC5936] it says only:
discussed in [RFC5936] and [RFC5155].
In what way is exposing the full content of a zone a privacy risk? "Privacy risks for the holder of a zone (the risk that someone gets
the data) are discussed in [RFC5936] and [RFC5155]."
In what way is exposing the full contents of a zone a privacy risk?
The contents of the zone could include information such as names of The contents of the zone could include information such as names of
persons used in names of hosts. Best practice is not to use personal persons used in names of hosts. Best practice is not to use personal
information for domain names, but many such domain names exist. information for domain names, but many such domain names exist.
There may also be regulatory or other reasons why the zone content in There may also be regulatory, policy or other reasons why the zone
full must be treated as private. contents in full must be treated as private.
Neither of the RFCs mentioned by RFC7626 contemplates the risk that Neither of the RFCs mentioned in [I-D.bortzmeyer-dprive-rfc7626-bis]
someone gets the data through link eavesdropping. contemplates the risk that someone gets the data through
eavesdropping on network connections, only via enumeration or
unauthorised transfer as described in the following paragraphs.
[RFC5155] specifies NSEC3 to prevent zone enumeration, which is when [RFC5155] specifies NSEC3 to prevent zone enumeration, which is when
queries for the authenticated denial of existences records of DNSSEC queries for the authenticated denial of existences records of DNSSEC
allow a client to walk through the entire zone. Note that the need allow a client to walk through the entire zone. Note that the need
for this protection also motivates NSEC5; zone walking is now for this protection also motivates NSEC5 [I-D.vcelak-nsec5]; zone
possible with NSEC3 due to crypto-breaking advances, and NSEC5 is a walking is now possible with NSEC3 due to crypto-breaking advances,
response to this problem. and NSEC5 is a response to this problem.
[RFC5155] does not address data obtained outside zone enumeration [RFC5155] does not address data obtained outside zone enumeration
(nor does NSEC5). Preventing eavesdropping of zone transfers (this (nor does [I-D.vcelak-nsec5]). Preventing eavesdropping of zone
draft) is orthogonal to preventing zone enumeration, though they aim transfers (this draft) is orthogonal to preventing zone enumeration,
to protect the same information. though they aim to protect the same information.
[RFC5936] specifies using TSIG [RFC2845] for authorization of the [RFC5936] specifies using TSIG [RFC2845] for authorization of the
clients of a zone transfer and for data integrity, but does not clients of a zone transfer and for data integrity, but does not
express any need for confidentiality, and TSIG does not offer express any need for confidentiality, and TSIG does not offer
encryption. Some operators use SSH tunneling or IPSEC to encrypt the encryption. Some operators use SSH tunnelling or IPSec to encrypt
transfer data. Because the AXFR zone transfer is carried out over the transfer data.
TCP from DNS protocol implementations, encrypting AXFR using DNS over
TLS [RFC7858], aka DOT, seems like a simple step forward. This Because the AXFR zone transfer is typically carried out over TCP from
document specifies how to use DOT to prevent zone collection from authoritative DNS protocol implementations, encrypting AXFR using
DNS-over-TLS [RFC7858] seems like a simple step forward. This
document specifies how to use DoT to prevent zone collection from
zone transfers, including discussion of approaches for IXFR, which zone transfers, including discussion of approaches for IXFR, which
uses UDP or TCP. uses UDP or TCP.
Next steps: work on questions at DNS table during Hackathon, expand Next steps: Work on open questions at DNS table during IETF 104
this draft, then solicit discussion on the DPRIVE mailing list. Hackathon, expand this draft, then solicit discussion on the DPRIVE
mailing list.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] and [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
Privacy terminology is as described in Section 3 of [RFC6973]. Privacy terminology is as described in Section 3 of [RFC6973].
DNS terminology is as described in [RFC8499]: DNS terminology is as described in [RFC8499].
DoT: DNS-over-TLS as specified in [RFC7858]
DoH: DNS-over-HTTPS as specified in [RFC8484]
3. Zone Transfer Confidentiality Overview 3. Zone Transfer Confidentiality Overview
4. Zone Transfer with DOT - Authentication 4. Zone Transfer with DoT - Authentication
Subsection - TSIG 4.1. TSIG
Subsection - Mutual TLS 4.2. Mutual TLS
5. Session Establishment and Closing 5. Session Establishment and Closing
Subsection - AXFR Sessions 5.1. AXFR Sessions
The connection flow in AXFR is a NOTIFY from the primary server to The connection flow in AXFR is a NOTIFY from the primary server to
the secondary server, and then an AXFR request from the secondary to the secondary server, and then an AXFR request from the secondary to
the primay after which the data flows. the primary after which the data flows.
The connection for AXFR SHOULD be established using port 853, as The connection for AXFR via DoT SHOULD be established using port 853,
specified in [RFC7858]. If there is no response on port 853, the as specified in [RFC7858]. If there is no response on port 853, the
connection MAY be attempted using port 443. connection MAY be attempted using port 443 in case the server offers
DoT service on this port.
TODO: diagram of connection flow for AXFR, without and with DOT TODO: diagram of connection flow for AXFR, without and with DoT
Subsection - IXFR Sessions (?) 5.2. IXFR Sessions
[RFC1995] specifies that Incremental Transfer may use UDP if the [RFC1995] specifies that Incremental Transfer may use UDP if the
entire IXFR response can be contained in a single DNS packet, entire IXFR response can be contained in a single DNS packet,
otherwise, TCP is used. otherwise, TCP is used.
Given this, how should confidentiality of IXFR be provided? To QUESTION: Given this, how should confidentiality of IXFR be provided?
discuss: should IXFR have a mode in which TCP is mandatory? or
should there be an approach of starting with DNS over DTLS, and
switching to DNS over TLS with a TCP switch? In workloads where
there are frequent IXFRs, is the persistent mode that TCP-Mode would
enable (as well as the retries, a benefit?
Subsection - Policies for Both AXFR and IXFR To discuss:
In order to assure the confidentiality of the zone information, all o should IXFR have a mode in which TCP is mandatory?
the servers (primary and secondary) MUST have a consistent
confidentiality use. If any do not, this is a weak link for
attackers to exploit. How to do this is TBD.
The entire group (the primary and all secondaries) MUST have a o should IXFR have a mode in which TLS is mandatory?
consistent policy on Strict or Non-Strict mode of operation. How to
do this is TBD.
Subsection - Next Steps o In workloads where there are frequent IXFRs, is the persistent
connection mode that TCP-Mode would enable (as well as the
retries) a benefit?
Upcoming open hackathon experiments will feed into this Session 5.3. Policies for Both AXFR and IXFR
In order to assure the confidentiality of the zone information,
entire group of servers involved in XFR (the primary and all
secondaries) MUST have a consistent policy of requiring
confidentiality. If any do not, this is a weak link for attackers to
exploit. How to do this is TBD.
Additionally, the entire group of servers involved in XFR (the
primary and all secondaries) MUST have a consistent policy of
requiring Strict or Opportunistic DoT [RFC8310]. How to do this is
TBD.
5.4. Next Steps
Upcoming IETF Hackathon experiments will feed into this Session
Establishment and Closing section, as much about this needs Establishment and Closing section, as much about this needs
exploration as well as dicussion on the mailing list. exploration as well as discussion on the mailing list.
6. Performance Considerations 6. Performance Considerations
The details in [RFC7858] about using persistent connections and TLS The details in [RFC7858] and [RFC8310] about e.g. using persistent
Session Resume are fully applicable to DNS Transfer over DOT as well. connections and TLS Session Resumption [RFC5077] are fully applicable
to DNS Zone Transfer over DoT as well.
7. Implementation Considerations 7. Implementation Considerations
TBA TBA
8. IANA Considerations 8. IANA Considerations
TBD TBD
9. Security Considerations 9. Security Considerations
This document specifies a security measure against a DNS risk, the This document specifies a security measure against a DNS risk: the
risk that an attacker collects entire DNS zones through eavesdropping risk that an attacker collects entire DNS zones through eavesdropping
on plaintext DNS zone transfers. It presents a new Security on clear text DNS zone transfers. It presents a new Security
Consideration for DNS. Some questions to discuss are: should DOT in Consideration for DNS. Some questions to discuss are: should DoT in
this new case be required to use only TLS1.3 and higher to avoid this new case be required to use only TLS 1.3 and higher to avoid
residual exposure? How should padding be used (if it should)? residual exposure? How should padding be used (if it should)?
10. Acknowledgements 10. Acknowledgements
Benno, Shumon, Tim The authors thank Benno Overeinder, Shumon Huque and Tim Wicinski for
review and discussions.
11. Contributors 11. Contributors
The following contributed significantly to the document: The following contributed significantly to the document:
12. Changelog 12. Changelog
draft-hzpa-dprive-xfr-over-tls-01
o Editorial changes, updates to references.
draft-hzpa-dprive-xfr-over-tls-00 draft-hzpa-dprive-xfr-over-tls-00
o Initial commit o Initial commit
13. References 13. Normative References
13.1. Normative References
[I-D.bortzmeyer-dprive-rfc7626-bis] [I-D.bortzmeyer-dprive-rfc7626-bis]
Bortzmeyer, S. and S. Dickinson, "DNS Privacy Bortzmeyer, S. and S. Dickinson, "DNS Privacy
Considerations", draft-bortzmeyer-dprive-rfc7626-bis-02 Considerations", draft-bortzmeyer-dprive-rfc7626-bis-02
(work in progress), January 2019. (work in progress), January 2019.
[I-D.dickinson-dprive-bcp-op] [I-D.vcelak-nsec5]
Dickinson, S., Overeinder, B., Rijswijk-Deij, R., and A. Vcelak, J., Goldberg, S., Papadopoulos, D., Huque, S., and
Mankin, "Recommendations for DNS Privacy Service D. Lawrence, "NSEC5, DNSSEC Authenticated Denial of
Operators", draft-dickinson-dprive-bcp-op-01 (work in Existence", draft-vcelak-nsec5-08 (work in progress),
progress), July 2018. December 2018.
[RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995,
DOI 10.17487/RFC1995, August 1996, DOI 10.17487/RFC1995, August 1996, <https://www.rfc-
<https://www.rfc-editor.org/info/rfc1995>. editor.org/info/rfc1995>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
<https://www.rfc-editor.org/info/rfc2119>. editor.org/info/rfc2119>.
[RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
Wellington, "Secret Key Transaction Authentication for DNS Wellington, "Secret Key Transaction Authentication for DNS
(TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,
<https://www.rfc-editor.org/info/rfc2845>. <https://www.rfc-editor.org/info/rfc2845>.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig, [RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
"Transport Layer Security (TLS) Session Resumption without "Transport Layer Security (TLS) Session Resumption without
Server-Side State", RFC 5077, DOI 10.17487/RFC5077, Server-Side State", RFC 5077, DOI 10.17487/RFC5077,
January 2008, <https://www.rfc-editor.org/info/rfc5077>. January 2008, <https://www.rfc-editor.org/info/rfc5077>.
skipping to change at page 6, line 42 skipping to change at page 7, line 22
Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008, Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,
<https://www.rfc-editor.org/info/rfc5155>. <https://www.rfc-editor.org/info/rfc5155>.
[RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol
(AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010,
<https://www.rfc-editor.org/info/rfc5936>. <https://www.rfc-editor.org/info/rfc5936>.
[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, Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013, DOI 10.17487/RFC6973, July 2013, <https://www.rfc-
<https://www.rfc-editor.org/info/rfc6973>. editor.org/info/rfc6973>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC7626] Bortzmeyer, S., "DNS Privacy Considerations", RFC 7626,
DOI 10.17487/RFC7626, August 2015,
<https://www.rfc-editor.org/info/rfc7626>.
[RFC7766] Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and
D. Wessels, "DNS Transport over TCP - Implementation
Requirements", RFC 7766, DOI 10.17487/RFC7766, March 2016,
<https://www.rfc-editor.org/info/rfc7766>.
[RFC7830] Mayrhofer, A., "The EDNS(0) Padding Option", RFC 7830,
DOI 10.17487/RFC7830, May 2016,
<https://www.rfc-editor.org/info/rfc7830>.
[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "Specification for DNS over Transport and P. Hoffman, "Specification for DNS over Transport
Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
2016, <https://www.rfc-editor.org/info/rfc7858>. 2016, <https://www.rfc-editor.org/info/rfc7858>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8310] Dickinson, S., Gillmor, D., and T. Reddy, "Usage Profiles [RFC8310] Dickinson, S., Gillmor, D., and T. Reddy, "Usage Profiles
for DNS over TLS and DNS over DTLS", RFC 8310, for DNS over TLS and DNS over DTLS", RFC 8310,
DOI 10.17487/RFC8310, March 2018, DOI 10.17487/RFC8310, March 2018, <https://www.rfc-
<https://www.rfc-editor.org/info/rfc8310>. editor.org/info/rfc8310>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC8467] Mayrhofer, A., "Padding Policies for Extension Mechanisms
for DNS (EDNS(0))", RFC 8467, DOI 10.17487/RFC8467,
October 2018, <https://www.rfc-editor.org/info/rfc8467>.
[RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS
(DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018,
<https://www.rfc-editor.org/info/rfc8484>. <https://www.rfc-editor.org/info/rfc8484>.
[RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
January 2019, <https://www.rfc-editor.org/info/rfc8499>. January 2019, <https://www.rfc-editor.org/info/rfc8499>.
13.2. Informative References
[NSEC5Research]
Goldberg, S., Naor, M., Papadopoulos, D., and L. Reyzin,
"NSEC5: Provably Preventing DNSSEC Zone Enumeration",
2015, <https://www.ndss-symposium.org/ndss2015/ndss-2015-
programme/
nsec5-provably-preventing-dnssec-zone-enumeration/>.
[RFC7129] Gieben, R. and W. Mekking, "Authenticated Denial of
Existence in the DNS", RFC 7129, DOI 10.17487/RFC7129,
February 2014, <https://www.rfc-editor.org/info/rfc7129>.
[RFC7816] Bortzmeyer, S., "DNS Query Name Minimisation to Improve
Privacy", RFC 7816, DOI 10.17487/RFC7816, March 2016,
<https://www.rfc-editor.org/info/rfc7816>.
[RFC7871] Contavalli, C., van der Gaast, W., Lawrence, D., and W.
Kumari, "Client Subnet in DNS Queries", RFC 7871,
DOI 10.17487/RFC7871, May 2016,
<https://www.rfc-editor.org/info/rfc7871>.
[RFC7873] Eastlake 3rd, D. and M. Andrews, "Domain Name System (DNS)
Cookies", RFC 7873, DOI 10.17487/RFC7873, May 2016,
<https://www.rfc-editor.org/info/rfc7873>.
[RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram
Transport Layer Security (DTLS)", RFC 8094,
DOI 10.17487/RFC8094, February 2017,
<https://www.rfc-editor.org/info/rfc8094>.
Authors' Addresses Authors' Addresses
Han Zhang Han Zhang
Salesforce Salesforce
San Francisco, CA San Francisco, CA
United States United States
Email: hzhang@salesforce.com Email: hzhang@salesforce.com
Pallavi Aras Pallavi Aras
Salesforce Salesforce
Herndon, VA Herndon, VA
skipping to change at page 9, line 4 skipping to change at page 8, line 17
United States United States
Email: hzhang@salesforce.com Email: hzhang@salesforce.com
Pallavi Aras Pallavi Aras
Salesforce Salesforce
Herndon, VA Herndon, VA
United States United States
Email: paras@salesforce.com Email: paras@salesforce.com
Willem Toorop Willem Toorop
NLnet Labs NLnet Labs
Science Park 400 Science Park 400
Amsterdam Amsterdam 1098 XH Amsterdam 1098 XH
The Netherlands The Netherlands
Email: willem@nlnetlabs.nl Email: willem@nlnetlabs.nl
Sara Dickinson Sara Dickinson
Sinodun IT Sinodun IT
Magdalen Centre Magdalen Centre
Oxford Science Park Oxford Science Park
Oxford OX4 4GA Oxford OX4 4GA
United Kingdom United Kingdom
Email: sara@sinodun.com Email: sara@sinodun.com
Allison Mankin Allison Mankin
Salesforce Salesforce
Herndon, VA Herndon, VA
United States
Email: allison.mankin@gmail.com Email: allison.mankin@gmail.com
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