DNS Resolver Information Key for DNS64
draft-fobser-resinfo-dns64-00
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| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
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|---|---|---|---|
| Author | Florian Obser | ||
| Last updated | 2024-10-21 | ||
| Replaced by | draft-bortzmeyer-add-resinfo-dnssecval-dns64, draft-bortzmeyer-resinfo-dnssecval | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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draft-fobser-resinfo-dns64-00
Network Working Group F. Obser
Internet-Draft OpenBSD
Intended status: Informational 21 October 2024
Expires: 24 April 2025
DNS Resolver Information Key for DNS64
draft-fobser-resinfo-dns64-00
Abstract
This document specifies a DNS Resolver Information Key/Value pair to
inform DNS clients of the presence of DNS64.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 24 April 2025.
Copyright Notice
Copyright (c) 2024 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
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 2
2. Relation to RFC 7050 . . . . . . . . . . . . . . . . . . . . 2
3. dns64 Resolver Information Key/Value . . . . . . . . . . . . 3
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3.1. Examples . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
DNS64 [RFC6147] performed by a DNS resolver together with NAT64
[RFC6146] allows an IPv6-only client to initiate communications by
name to an IPv4-only server. To achieve this, the DNS resolver
synthesizes AAAA records from A records. However, this breaks DNSSEC
[RFC4033] [RFC4034] [RFC4035] validation for DNS clients of the
resolver if they perform their own validation. [RFC6147] Section 3
discusses this in detail. In general, a validating DNS client has to
be aware that a resolver is performing DNS64.
[RFC9606] specifies a DNS resource record (RR) type RESINFO to allow
resolvers to publish information about their capabilities and
policies. This can be used to inform DNS clients that DNS64 is
performed by the DNS resolver.
1.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Relation to RFC 7050
[RFC7050] describes a heuristic to learn the IPv6 prefix used by a
NAT64 gateway. Nodes can use this information to perform local
address synthesis, for example using 464XLAT [RFC6877].
This has security implications, making [RFC7050] difficult to deploy.
A modern mechanism, like PREF64 [RFC8781] is easier to deploy,
leading to a desire to deprecate [RFC7050] entirely.
A validating DNS client on the other hand still needs to know about
the presence of DNS64 on the DNS resolver it uses, as noted in the
introduction. Using the [RFC9606] RESINFO mechanism and not using
the learned information for address synthesis avoids the security
problems of [RFC7050].
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3. dns64 Resolver Information Key/Value
dns64: The presence of this key indicates that the DNS resolver
performs address synthesis.
Note that, per the rules for the keys defined in Section 6.4 of
[RFC6763], if there is no '=' in a key, then it is a boolean
attribute, simply identified as being present, with no value.
The DNS resolver MAY return an IPv6 prefix or a comma separated
list of prefixes to indicate not just that DNS64 is being
performed but also to let the client know which prefix or prefixes
are in use. The prefixes MUST be represented using the canonical
representation format of [RFC5952].
3.1. Examples
DNS64 address synthesis is performed by the DNS resolver. No
information about the used prefix is given.
resolver.example.net. 7200 IN RESINFO dns64
DNS64 address synthesis is performed. The [RFC6052] Well-Known
Prefix 64:ff9b::/96 is used.
resolver.example.net. 7200 IN RESINFO dns64=64:ff9b::/96
DNS64 address synthesis is performed. The [RFC6052] Well-Known
Prefix 64:ff9b::/96 and the Network-Specific Prefix 2001:db8:64::/56
are used.
resolver.example.net. 7200 IN RESINFO
dns64=64:ff9b::/96,2001:db8:64::/56
4. Security Considerations
The security considerations of [RFC9606] apply.
5. IANA Considerations
The IANA is requested to add the key "dns64", with the description of
"The presence of the key indicates that DNS64 address synthesis is
performed", and a reference to this document.
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+=======+========================================+===============+
| Name | Description | Reference |
+=======+========================================+===============+
| dns64 | The presence of the key indicates that | RFC EDITOR: |
| | DNS64 address synthesis is performed. | THIS DOCUMENT |
+-------+----------------------------------------+---------------+
Table 1
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952,
DOI 10.17487/RFC5952, August 2010,
<https://www.rfc-editor.org/rfc/rfc5952>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<https://www.rfc-editor.org/rfc/rfc6763>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC9606] Reddy.K, T. and M. Boucadair, "DNS Resolver Information",
RFC 9606, DOI 10.17487/RFC9606, June 2024,
<https://www.rfc-editor.org/rfc/rfc9606>.
6.2. Informative References
[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/rfc/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/rfc/rfc4034>.
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[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/rfc/rfc4035>.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010,
<https://www.rfc-editor.org/rfc/rfc6052>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <https://www.rfc-editor.org/rfc/rfc6146>.
[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van
Beijnum, "DNS64: DNS Extensions for Network Address
Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
DOI 10.17487/RFC6147, April 2011,
<https://www.rfc-editor.org/rfc/rfc6147>.
[RFC6877] Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
Combination of Stateful and Stateless Translation",
RFC 6877, DOI 10.17487/RFC6877, April 2013,
<https://www.rfc-editor.org/rfc/rfc6877>.
[RFC7050] Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
the IPv6 Prefix Used for IPv6 Address Synthesis",
RFC 7050, DOI 10.17487/RFC7050, November 2013,
<https://www.rfc-editor.org/rfc/rfc7050>.
[RFC8781] Colitti, L. and J. Linkova, "Discovering PREF64 in Router
Advertisements", RFC 8781, DOI 10.17487/RFC8781, April
2020, <https://www.rfc-editor.org/rfc/rfc8781>.
Author's Address
Florian Obser
OpenBSD
Email: florian+ietf@narrans.de
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