draft-ietf-add-ddr-05.txt   draft-ietf-add-ddr-06.txt 
ADD T. Pauly ADD T. Pauly
Internet-Draft E. Kinnear Internet-Draft E. Kinnear
Intended status: Standards Track Apple Inc. Intended status: Standards Track Apple Inc.
Expires: 4 August 2022 C.A. Wood Expires: 6 October 2022 C. A. Wood
Cloudflare Cloudflare
P. McManus P. McManus
Fastly Fastly
T. Jensen T. Jensen
Microsoft Microsoft
31 January 2022 4 April 2022
Discovery of Designated Resolvers Discovery of Designated Resolvers
draft-ietf-add-ddr-05 draft-ietf-add-ddr-06
Abstract Abstract
This document defines Discovery of Designated Resolvers (DDR), a This document defines Discovery of Designated Resolvers (DDR), a
mechanism for DNS clients to use DNS records to discover a resolver's mechanism for DNS clients to use DNS records to discover a resolver's
encrypted DNS configuration. This mechanism can be used to move from encrypted DNS configuration. This mechanism can be used to move from
unencrypted DNS to encrypted DNS when only the IP address of a unencrypted DNS to encrypted DNS when only the IP address of a
resolver is known. This mechanism is designed to be limited to cases resolver is known. This mechanism is designed to be limited to cases
where unencrypted resolvers and their designated resolvers are where unencrypted resolvers and their designated resolvers are
operated by the same entity or cooperating entities. It can also be operated by the same entity or cooperating entities. It can also be
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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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 4 August 2022. This Internet-Draft will expire on 6 October 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 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 (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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3. DNS Service Binding Records . . . . . . . . . . . . . . . . . 4 3. DNS Service Binding Records . . . . . . . . . . . . . . . . . 4
4. Discovery Using Resolver IP Addresses . . . . . . . . . . . . 5 4. Discovery Using Resolver IP Addresses . . . . . . . . . . . . 5
4.1. Use of Designated Resolvers . . . . . . . . . . . . . . . 6 4.1. Use of Designated Resolvers . . . . . . . . . . . . . . . 6
4.2. Verified Discovery . . . . . . . . . . . . . . . . . . . 7 4.2. Verified Discovery . . . . . . . . . . . . . . . . . . . 7
4.3. Opportunistic Discovery . . . . . . . . . . . . . . . . . 8 4.3. Opportunistic Discovery . . . . . . . . . . . . . . . . . 8
5. Discovery Using Resolver Names . . . . . . . . . . . . . . . 8 5. Discovery Using Resolver Names . . . . . . . . . . . . . . . 8
6. Deployment Considerations . . . . . . . . . . . . . . . . . . 9 6. Deployment Considerations . . . . . . . . . . . . . . . . . . 9
6.1. Caching Forwarders . . . . . . . . . . . . . . . . . . . 9 6.1. Caching Forwarders . . . . . . . . . . . . . . . . . . . 9
6.2. Certificate Management . . . . . . . . . . . . . . . . . 10 6.2. Certificate Management . . . . . . . . . . . . . . . . . 10
6.3. Server Name Handling . . . . . . . . . . . . . . . . . . 10 6.3. Server Name Handling . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 6.4. Handling non-DDR queries for resolver.arpa . . . . . . . 10
6.5. Interaction with Network-Designated Resolvers . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8.1. Special Use Domain Name "resolver.arpa" . . . . . . . . . 11 8.1. Special Use Domain Name "resolver.arpa" . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 11 9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix A. Rationale for using SVCB records . . . . . . . . . . 13 Appendix A. Rationale for using SVCB records . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
When DNS clients wish to use encrypted DNS protocols such as DNS- When DNS clients wish to use encrypted DNS protocols such as DNS-
over-TLS (DoT) [RFC7858] or DNS-over-HTTPS (DoH) [RFC8484], they over-TLS (DoT) [RFC7858] or DNS-over-HTTPS (DoH) [RFC8484], they
require additional information beyond the IP address of the DNS require additional information beyond the IP address of the DNS
server, such as the resolver's hostname, non-standard ports, or URL server, such as the resolver's hostname, non-standard ports, or URL
paths. However, common configuration mechanisms only provide the paths. However, common configuration mechanisms only provide the
resolver's IP address during configuration. Such mechanisms include resolver's IP address during configuration. Such mechanisms include
network provisioning protocols like DHCP [RFC2132] and IPv6 Router network provisioning protocols like DHCP [RFC2132] and IPv6 Router
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connections, or in the URI host for DoH requests. connections, or in the URI host for DoH requests.
When performing discovery using resolver IP addresses, clients MUST When performing discovery using resolver IP addresses, clients MUST
use the IP address as the URI host for DoH requests. use the IP address as the URI host for DoH requests.
Note that since IP addresses are not supported by default in the TLS Note that since IP addresses are not supported by default in the TLS
SNI, resolvers that support discovery using IP addresses will need to SNI, resolvers that support discovery using IP addresses will need to
be configured to present the appropriate TLS certificate when no SNI be configured to present the appropriate TLS certificate when no SNI
is present for both DoT and DoH. is present for both DoT and DoH.
6.4. Handling non-DDR queries for resolver.arpa
DNS resolvers that support DDR by responding to queries for
_dns.resolver.arpa SHOULD treat resolver.arpa as a locally served
zone per [RFC6303]. In practice, this means that resolvers SHOULD
respond to queries of any type other than SVCB for _dns.resolver.arpa
with NODATA and queries of any type for any domain name under
resolver.arpa with NODATA.
6.5. Interaction with Network-Designated Resolvers
Discovery of network-designated resolvers (DNR, [I-D.ietf-add-dnr])
allows a network to provide designation of resolvers directly through
DHCP [RFC2132] [RFC8415] and IPv6 Router Advertisement (RA) [RFC4861]
options. When such indications are present, clients can suppress
queries for "resolver.arpa" to the unencrypted DNS server indicated
by the network over DHCP or RAs, and the DNR indications SHOULD take
precedence over those discovered using "resolver.arpa" for the same
resolver if there is a conflict.
The designated resolver information in DNR might not contain a full
set of SvcParams needed to connect to an encrypted resolver. In such
a case, the client can use an SVCB query using a resolver name, as
described in Section 5, to the authentication-domain-name (ADN).
7. Security Considerations 7. Security Considerations
Since clients can receive DNS SVCB answers over unencrypted DNS, on- Since clients can receive DNS SVCB answers over unencrypted DNS, on-
path attackers can prevent successful discovery by dropping SVCB path attackers can prevent successful discovery by dropping SVCB
packets. Clients should be aware that it might not be possible to packets. Clients should be aware that it might not be possible to
distinguish between resolvers that do not have any Designated distinguish between resolvers that do not have any Designated
Resolver and such an active attack. To limit the impact of discovery Resolver and such an active attack. To limit the impact of discovery
queries being dropped either maliciously or unintentionally, clients queries being dropped either maliciously or unintentionally, clients
can re-send their SVCB queries periodically. can re-send their SVCB queries periodically.
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reuse for other purposes where the resolver wishes to provide reuse for other purposes where the resolver wishes to provide
information about itself to the client. information about itself to the client.
The "resolver.arpa" SUDN is similar to "ipv4only.arpa" in that the The "resolver.arpa" SUDN is similar to "ipv4only.arpa" in that the
querying client is not interested in an answer from the authoritative querying client is not interested in an answer from the authoritative
"arpa" name servers. The intent of the SUDN is to allow clients to "arpa" name servers. The intent of the SUDN is to allow clients to
communicate with the Unencrypted Resolver much like "ipv4only.arpa" communicate with the Unencrypted Resolver much like "ipv4only.arpa"
allows for client-to-middlebox communication. For more context, see allows for client-to-middlebox communication. For more context, see
the rationale behind "ipv4only.arpa" in [RFC8880]. the rationale behind "ipv4only.arpa" in [RFC8880].
IANA is requested to add an entry in "Transport-Independent Locally-
Served DNS Zones" registry for 'resolver.arpa.' with the description
"DNS Resolver Special-Use Domain", listing this document as the
reference.
9. References 9. References
9.1. Normative References 9.1. Normative References
[I-D.ietf-add-svcb-dns] [I-D.ietf-add-svcb-dns]
Schwartz, B., "Service Binding Mapping for DNS Servers", Schwartz, B., "Service Binding Mapping for DNS Servers",
Work in Progress, Internet-Draft, draft-ietf-add-svcb-dns- Work in Progress, Internet-Draft, draft-ietf-add-svcb-dns-
01, 21 October 2021, 02, 1 February 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-add- <https://datatracker.ietf.org/doc/html/draft-ietf-add-
svcb-dns-01>. svcb-dns-02>.
[I-D.ietf-dnsop-svcb-https] [I-D.ietf-dnsop-svcb-https]
Schwartz, B., Bishop, M., and E. Nygren, "Service binding Schwartz, B., Bishop, M., and E. Nygren, "Service binding
and parameter specification via the DNS (DNS SVCB and and parameter specification via the DNS (DNS SVCB and
HTTPS RRs)", Work in Progress, Internet-Draft, draft-ietf- HTTPS RRs)", Work in Progress, Internet-Draft, draft-ietf-
dnsop-svcb-https-08, 12 October 2021, dnsop-svcb-https-08, 12 October 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-dnsop- <https://datatracker.ietf.org/doc/html/draft-ietf-dnsop-
svcb-https-08>. svcb-https-08>.
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.
J., and E. Lear, "Address Allocation for Private J., and E. Lear, "Address Allocation for Private
Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918, Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918,
February 1996, <https://www.rfc-editor.org/rfc/rfc1918>. February 1996, <https://www.rfc-editor.org/rfc/rfc1918>.
[RFC6303] Andrews, M., "Locally Served DNS Zones", BCP 163,
RFC 6303, DOI 10.17487/RFC6303, July 2011,
<https://www.rfc-editor.org/rfc/rfc6303>.
[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names", [RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, DOI 10.17487/RFC6761, February 2013, RFC 6761, DOI 10.17487/RFC6761, February 2013,
<https://www.rfc-editor.org/rfc/rfc6761>. <https://www.rfc-editor.org/rfc/rfc6761>.
[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/rfc/rfc7858>. 2016, <https://www.rfc-editor.org/rfc/rfc7858>.
[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/rfc/rfc8484>. <https://www.rfc-editor.org/rfc/rfc8484>.
9.2. Informative References 9.2. Informative References
[I-D.ietf-add-dnr]
Boucadair, M., Reddy, T., Wing, D., Cook, N., and T.
Jensen, "DHCP and Router Advertisement Options for the
Discovery of Network-designated Resolvers (DNR)", Work in
Progress, Internet-Draft, draft-ietf-add-dnr-06, 22 March
2022, <https://datatracker.ietf.org/doc/html/draft-ietf-
add-dnr-06>.
[I-D.ietf-tls-esni] [I-D.ietf-tls-esni]
Rescorla, E., Oku, K., Sullivan, N., and C. A. Wood, "TLS Rescorla, E., Oku, K., Sullivan, N., and C. A. Wood, "TLS
Encrypted Client Hello", Work in Progress, Internet-Draft, Encrypted Client Hello", Work in Progress, Internet-Draft,
draft-ietf-tls-esni-13, 12 August 2021, draft-ietf-tls-esni-14, 13 February 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-tls- <https://datatracker.ietf.org/doc/html/draft-ietf-tls-
esni-13>. esni-14>.
[I-D.schinazi-httpbis-doh-preference-hints] [I-D.schinazi-httpbis-doh-preference-hints]
Schinazi, D., Sullivan, N., and J. Kipp, "DoH Preference Schinazi, D., Sullivan, N., and J. Kipp, "DoH Preference
Hints for HTTP", Work in Progress, Internet-Draft, draft- Hints for HTTP", Work in Progress, Internet-Draft, draft-
schinazi-httpbis-doh-preference-hints-02, 13 July 2020, schinazi-httpbis-doh-preference-hints-02, 13 July 2020,
<https://datatracker.ietf.org/doc/html/draft-schinazi- <https://datatracker.ietf.org/doc/html/draft-schinazi-
httpbis-doh-preference-hints-02>. httpbis-doh-preference-hints-02>.
[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-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997, Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997,
<https://www.rfc-editor.org/rfc/rfc2132>. <https://www.rfc-editor.org/rfc/rfc2132>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/rfc/rfc4861>.
[RFC5507] IAB, Faltstrom, P., Ed., Austein, R., Ed., and P. Koch, [RFC5507] IAB, Faltstrom, P., Ed., Austein, R., Ed., and P. Koch,
Ed., "Design Choices When Expanding the DNS", RFC 5507, Ed., "Design Choices When Expanding the DNS", RFC 5507,
DOI 10.17487/RFC5507, April 2009, DOI 10.17487/RFC5507, April 2009,
<https://www.rfc-editor.org/rfc/rfc5507>. <https://www.rfc-editor.org/rfc/rfc5507>.
[RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J. [RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J.
Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105, Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105,
DOI 10.17487/RFC6105, February 2011, DOI 10.17487/RFC6105, February 2011,
<https://www.rfc-editor.org/rfc/rfc6105>. <https://www.rfc-editor.org/rfc/rfc6105>.
[RFC8106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, [RFC8106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
"IPv6 Router Advertisement Options for DNS Configuration", "IPv6 Router Advertisement Options for DNS Configuration",
RFC 8106, DOI 10.17487/RFC8106, March 2017, RFC 8106, DOI 10.17487/RFC8106, March 2017,
<https://www.rfc-editor.org/rfc/rfc8106>. <https://www.rfc-editor.org/rfc/rfc8106>.
[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/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/rfc/rfc8415>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>. <https://www.rfc-editor.org/rfc/rfc8446>.
[RFC8880] Cheshire, S. and D. Schinazi, "Special Use Domain Name [RFC8880] Cheshire, S. and D. Schinazi, "Special Use Domain Name
'ipv4only.arpa'", RFC 8880, DOI 10.17487/RFC8880, August 'ipv4only.arpa'", RFC 8880, DOI 10.17487/RFC8880, August
2020, <https://www.rfc-editor.org/rfc/rfc8880>. 2020, <https://www.rfc-editor.org/rfc/rfc8880>.
Appendix A. Rationale for using SVCB records Appendix A. Rationale for using SVCB records
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