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tld_dmarc_r5.txt
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Network Working Group S. Kitterman
Internet-Draft Kitterman Technical Services
Updates: 7489 (if approved) October 6, 2018
Intended status: Informational
Expires: April 9, 2019
DMARC (Domain-based Message Authentication, Reporting, and Conformance)
Extension For TLDs (Top Level Domains)
draft-kitterman-dmarc-tld-00
Abstract
DMARC (Domain-based Message Authentication, Reporting, and
Conformance) is a scalable mechanism by which a mail-originating
organization can express domain-level policies and preferences for
message validation, disposition, and reporting, that a mail-receiving
organization can use to improve mail handling. DMARC itself does not
apply to domains above the organizational level, such as TLDs (Top
Level Domains). For the subset of TLDs (or other non-organizational
domains) that require DMARC usage, it is appropriate to provide TLD
level DMARC capability. This memo describes an extension to DMARC to
enable a subset of DMARC functionality for such domains.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 9, 2019.
Copyright Notice
Copyright (c) 2018 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
Kitterman Expires April 9, 2019 [Page 1]
Internet-Draft TLD DMARC October 2018
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology and Definitions . . . . . . . . . . . . . . . . . 3
2.1. Conventions Used in This Document . . . . . . . . . . . . 3
2.2. Top Level Domain (TLD) . . . . . . . . . . . . . . . . . 3
2.3. TLD Operator (TLDO) . . . . . . . . . . . . . . . . . . . 3
2.4. TLDO Controlled Domain Names . . . . . . . . . . . . . . 3
2.5. Non-existent Domains . . . . . . . . . . . . . . . . . . 3
3. TLD DMARC Updates to DMARC Requirements . . . . . . . . . . . 3
3.1. General Updates . . . . . . . . . . . . . . . . . . . . . 4
3.2. Section 6.1 DMARC Policy Record . . . . . . . . . . . . . 4
3.3. Section 6.5. Domain Owner Actions . . . . . . . . . . . 4
3.4. Section 6.6.3. Policy Discovery . . . . . . . . . . . . 4
3.5. Section 7. DMARC Feedback . . . . . . . . . . . . . . . 4
4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 4
4.1. Feedback leakage . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6.1. DMARC Top Level Domain (TLD) Registry . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
DMARC [RFC7489] provides email sending organizational policy
information to email receivers. Due to the design of DMARC [RFC7489]
and the nature of the Internet email architecture [RFC5598], there
are interoperability issues associated with DMARC [RFC7489]
deployment. These are discussed in Interoperability Issues between
DMARC and Indirect Email Flows [RFC7960]. These issues are not
applicable to TLDs, since they do not send mail.
DMARC [RFC7489], by design, does not support requirements of TLD
operators. For TLDs that require use of DMARC [RFC7489], a subset of
DMARC reporting and enforcement capability is needed for TLD
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operators to effectively manage and monitor implementation of TLD
requirements.
2. Terminology and Definitions
This section defines terms used in the rest of the document.
2.1. Conventions Used in This Document
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.
2.2. Top Level Domain (TLD)
The global Internet Domain Name System (DNS) is documented in
numerous Requests for Comment (RFC). It defines a tree of names
starting with root, ".", immediately below which are Top Level Domain
names such as ".com" and ".us". The usage for TLD DMARC is broader
and includes all domains above the organizational level in the tree,
e.g., ".gov.uk".
2.3. TLD Operator (TLDO)
A TLD Operator manages operations within their TLD.
2.4. TLDO Controlled Domain Names
TLDO Controlled Domain Names are names in the DNS that are managed by
a TLDO and are not available for use as Organizational Domains (the
term organizational domains is defined in DMARC [RFC7489]).
Depending on TLD policy, these will have one (e.g., ".com") or more
(e.g., ".co.uk") name components.
2.5. Non-existent Domains
For DMARC [RFC7489] purposes, a non-existent domain is a domain name
that publishes none of A, AAAA, or MX records. This is a broader
definition than that in NXDOMAIN [RFC8020].
3. TLD DMARC Updates to DMARC Requirements
This document updates DMARC [RFC7489] as follows:
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3.1. General Updates
References to "Domain Owners" also apply to TLDOs.
3.2. Section 6.1 DMARC Policy Record
TLD DMARC records are published as a subdomain of the TLD. For the
TLD ".example", the TLDO would post DMARC preferences in a TXT record
at "_dmarc.example".
3.3. Section 6.5. Domain Owner Actions
In addition to the DMARC [RFC7489] domain owner actions, TLDOs will
need to update the "DMARC Top Level Domain (TLD) Registry". This
registry is defined in Section 6.1.
3.4. Section 6.6.3. Policy Discovery
A new step between step 3 and 4 is added:
3A. If the set is now empty and the TLD of the Organizational Domain
is listed in the DMARC TLD Registry, the Mail Receiver MUST query
the DNS for a DMARC TXT record at the DNS domain matching the
Organizational Domain with one label removed in place of the
RFC5322.From domain in the message (if different). A possibly
empty set of records is returned.
As an example, for a message with the Organizational Domain of
"example.compute.amazonaws.com.cn", the query for TLD DMARC would use
"_dmarc.compute.amazonaws.com.cn".
3.5. Section 7. DMARC Feedback
Operational note for TLD DMARC: For TLDOs, feedback for non-existent
domains is desired and useful. Because of the constraints on TLD
DMARC scope, there are not significant privacy considerations
associated with this reporting (See Section 4).
4. Privacy Considerations
This document does not significantly change the Privacy
Considerations of [RFC7489].
4.1. Feedback leakage
Providing feedback reporting to TLDOs can, in some cases, create
leakage of information outside of an organization to the TLDO. There
are roughly three cases to consider:
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o Branded TLDs (e.g., ".google"), RUA and RUF reports based on TLD
DMARC have the potential to contain information about emails
related to entities managed by the organization. Since both the
TLDO and the Organizational Domain owners are common, there is no
privacy risk for either normal or Non-existent Domain reporting.
o Multi-organization TLDs that require DMARC usage (e.g., ".bank"):
TLD DMARC based reports will only be generated for domains that do
not publish a DMARC policy at the organizational level. For
domains that do publish the required DMARC policy records, the
feedback reporting addresses (RUA and RUF) of the organization
will be used. Since TLD DMARC is limited to TLDs that mandate
organizational domains publish DMARC policy for existing domains,
the risk of this issue is limited to organizational domains that
are out of compliance with TLD policy.
o Multi-organization TLDs (e.g., ".com") that do not mandate DMARC
usage. Privacy risks for organizational domains within such TLDs
would be significant. This is mitigated by the limitation to only
include TLDs listed in the public IANA DMARC TLD Registry
described in Section 6.1.
TLDOs will receive feedback on non-existant domains, which may be
similar to existing organizational domains. Feedback related to such
cousin domains have a small risk of carrying information related to
an actual organizational domain. To minimize this potential concern,
TLD DMARC feedback is best limited to Aggregate Reports. Feedback
Reports carry more detailed information and present a greater risk.
5. Security Considerations
This document does not change the Security Considerations of
[RFC7489].
6. IANA Considerations
This section describes actions requested to be completed by IANA.
6.1. DMARC Top Level Domain (TLD) Registry
IANA is requested to create a new DMARC Top Level Domain (TLD)
Registry within the Domain-based Message Authentication, Reporting,
and Conformance (DMARC) Parameters Registry.
Names of TLDs participating in TLD DMARC must be registered with IANA
in this new sub-registry. New entries are assigned only for TLDs
that require use of DMARC. The requirement has to be documented in a
manner that satisfies the terms of Expert Review, per [RFC5226]. The
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Internet-Draft TLD DMARC October 2018
Designated Expert needs to confirm that provided documentation
adequately describes TLD policy to require domain owners to use DMARC
or that all domain owners are part of a single organization with the
TLDO.
The initial set of entries in this registry is as follows:
+-------------+----------------+---------------+
| TLD | Reference | Status |
+-------------+----------------+---------------+
| .bank | this document | current |
+-------------+----------------+---------------+
| .insurance | this document | current |
+-------------+----------------+---------------+
7. References
7.1. 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/info/rfc2119>.
[RFC7489] Kucherawy, M., Ed. and E. Zwicky, Ed., "Domain-based
Message Authentication, Reporting, and Conformance
(DMARC)", RFC 7489, DOI 10.17487/RFC7489, March 2015,
<https://www.rfc-editor.org/info/rfc7489>.
[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/info/rfc8174>.
7.2. Informative References
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
[RFC5598] Crocker, D., "Internet Mail Architecture", RFC 5598,
DOI 10.17487/RFC5598, July 2009,
<https://www.rfc-editor.org/info/rfc5598>.
Kitterman Expires April 9, 2019 [Page 6]
Internet-Draft TLD DMARC October 2018
[RFC7960] Martin, F., Ed., Lear, E., Ed., Draegen. Ed., T., Zwicky,
E., Ed., and K. Andersen, Ed., "Interoperability Issues
between Domain-based Message Authentication, Reporting,
and Conformance (DMARC) and Indirect Email Flows",
RFC 7960, DOI 10.17487/RFC7960, September 2016,
<https://www.rfc-editor.org/info/rfc7960>.
[RFC8020] Bortzmeyer, S. and S. Huque, "NXDOMAIN: There Really Is
Nothing Underneath", RFC 8020, DOI 10.17487/RFC8020,
November 2016, <https://www.rfc-editor.org/info/rfc8020>.
Acknowledgements
TBS
Author's Address
Scott Kitterman
Kitterman Technical Services
3611 Scheel Dr
Ellicott City, MD 21042
United States of America
Phone: +1 301 325-5475
Email: [email protected]
Kitterman Expires April 9, 2019 [Page 7]