draft-ietf-uta-smtp-tlsrpt-03.txt   draft-ietf-uta-smtp-tlsrpt-04.txt 
Using TLS in Applications D. Margolis Using TLS in Applications D. Margolis
Internet-Draft Google, Inc Internet-Draft Google, Inc
Intended status: Standards Track A. Brotman Intended status: Standards Track A. Brotman
Expires: August 19, 2017 Comcast, Inc Expires: October 5, 2017 Comcast, Inc
B. Ramakrishnan B. Ramakrishnan
Yahoo!, Inc Yahoo!, Inc
J. Jones J. Jones
Microsoft, Inc Microsoft, Inc
M. Risher M. Risher
Google, Inc Google, Inc
February 15, 2017 April 3, 2017
SMTP TLS Reporting SMTP TLS Reporting
draft-ietf-uta-smtp-tlsrpt-03 draft-ietf-uta-smtp-tlsrpt-04
Abstract Abstract
A number of protocols exist for establishing encrypted channels A number of protocols exist for establishing encrypted channels
between SMTP Mail Transfer Agents, including STARTTLS [RFC3207], DANE between SMTP Mail Transfer Agents, including STARTTLS [RFC3207], DANE
[RFC6698], and SMTP MTA STS (TODO: Add ref). These protocols can [RFC6698], and MTA-STS (TODO: Add ref). These protocols can fail due
fail due to misconfiguration or active attack, leading to undelivered to misconfiguration or active attack, leading to undelivered messages
messages or delivery over unencrypted or unauthenticated channels. or delivery over unencrypted or unauthenticated channels. This
This document describes a reporting mechanism and format by which document describes a reporting mechanism and format by which sending
sending systems can share statistics and specific information about systems can share statistics and specific information about potential
potential failures with recipient domains. Recipient domains can failures with recipient domains. Recipient domains can then use this
then use this information to both detect potential attackers and information to both detect potential attackers and diagnose
diagnose unintentional misconfigurations. unintentional misconfigurations.
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 August 19, 2017. This Internet-Draft will expire on October 5, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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
skipping to change at page 2, line 29 skipping to change at page 2, line 29
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Related Technologies . . . . . . . . . . . . . . . . . . . . 4 2. Related Technologies . . . . . . . . . . . . . . . . . . . . 4
3. Reporting Policy . . . . . . . . . . . . . . . . . . . . . . 4 3. Reporting Policy . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Example Reporting Policy . . . . . . . . . . . . . . . . 5 3.1. Example Reporting Policy . . . . . . . . . . . . . . . . 5
3.1.1. Report using MAILTO . . . . . . . . . . . . . . . . . 5 3.1.1. Report using MAILTO . . . . . . . . . . . . . . . . . 5
3.1.2. Report using HTTPS . . . . . . . . . . . . . . . . . 5 3.1.2. Report using HTTPS . . . . . . . . . . . . . . . . . 5
4. Reporting Schema . . . . . . . . . . . . . . . . . . . . . . 6 4. Reporting Schema . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Report Time-frame . . . . . . . . . . . . . . . . . . . . 6 4.1. Report Time-frame . . . . . . . . . . . . . . . . . . . . 6
4.2. Delivery Summary . . . . . . . . . . . . . . . . . . . . 7 4.2. Delivery Summary . . . . . . . . . . . . . . . . . . . . 6
4.2.1. Success Count . . . . . . . . . . . . . . . . . . . . 7 4.2.1. Success Count . . . . . . . . . . . . . . . . . . . . 6
4.2.2. Failure Count . . . . . . . . . . . . . . . . . . . . 7 4.2.2. Failure Count . . . . . . . . . . . . . . . . . . . . 7
4.3. Result Types . . . . . . . . . . . . . . . . . . . . . . 7 4.3. Result Types . . . . . . . . . . . . . . . . . . . . . . 7
4.3.1. Routing Failures . . . . . . . . . . . . . . . . . . 7 4.3.1. Negotiation Failures . . . . . . . . . . . . . . . . 7
4.3.2. Negotiation Failures . . . . . . . . . . . . . . . . 7 4.3.2. Policy Failures . . . . . . . . . . . . . . . . . . . 7
4.3.3. Policy Failures . . . . . . . . . . . . . . . . . . . 8 4.3.3. General Failures . . . . . . . . . . . . . . . . . . 8
4.3.4. General Failures . . . . . . . . . . . . . . . . . . 8 4.3.4. Transient Failures . . . . . . . . . . . . . . . . . 8
4.3.5. Transient Failures . . . . . . . . . . . . . . . . . 8
5. Report Delivery . . . . . . . . . . . . . . . . . . . . . . . 8 5. Report Delivery . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Report Filename . . . . . . . . . . . . . . . . . . . . . 9 5.1. Report Filename . . . . . . . . . . . . . . . . . . . . . 8
5.2. Compression . . . . . . . . . . . . . . . . . . . . . . . 9 5.2. Compression . . . . . . . . . . . . . . . . . . . . . . . 9
5.3. Email Transport . . . . . . . . . . . . . . . . . . . . . 10 5.3. Email Transport . . . . . . . . . . . . . . . . . . . . . 9
5.4. HTTPS Transport . . . . . . . . . . . . . . . . . . . . . 10 5.4. HTTPS Transport . . . . . . . . . . . . . . . . . . . . . 10
5.5. Delivery Retry . . . . . . . . . . . . . . . . . . . . . 11 5.5. Delivery Retry . . . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. Appendix 1: Example Reporting Policy . . . . . . . . . . . . 12 8. Appendix 1: Example Reporting Policy . . . . . . . . . . . . 11
8.1. Report using MAILTO . . . . . . . . . . . . . . . . . . . 12 8.1. Report using MAILTO . . . . . . . . . . . . . . . . . . . 11
8.2. Report using HTTPS . . . . . . . . . . . . . . . . . . . 12 8.2. Report using HTTPS . . . . . . . . . . . . . . . . . . . 12
9. Appendix 2: JSON Report Schema . . . . . . . . . . . . . . . 12 9. Appendix 2: JSON Report Schema . . . . . . . . . . . . . . . 12
10. Appendix 3: Example JSON Report . . . . . . . . . . . . . . . 15 10. Appendix 3: Example JSON Report . . . . . . . . . . . . . . . 14
11. Normative References . . . . . . . . . . . . . . . . . . . . 16 11. Normative References . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
The STARTTLS extension to SMTP [RFC3207] allows SMTP clients and The STARTTLS extension to SMTP [RFC3207] allows SMTP clients and
hosts to establish secure SMTP sessions over TLS. The protocol hosts to establish secure SMTP sessions over TLS. The protocol
design is based on "Opportunistic Security" (OS) [RFC7435], which design is based on "Opportunistic Security" (OS) [RFC7435], which
provides interoperability for clients that do not support STARTTLS maintains interoperability with clients that do not support STARTTLS
but means that any attacker who can delete parts of the SMTP session but means that any attacker who can delete parts of the SMTP session
(such as the "250 STARTTLS" response) or redirect the entire SMTP (such as the "250 STARTTLS" response) or redirect the entire SMTP
session (perhaps by overwriting the resolved MX record of the session (perhaps by overwriting the resolved MX record of the
delivery domain) can perform a downgrade or interception attack. delivery domain) can perform a downgrade or interception attack.
Because such "downgrade attacks" are not necessarily apparent to the Because such "downgrade attacks" are not necessarily apparent to the
receiving MTA, this document defines a mechanism for sending domains receiving MTA, this document defines a mechanism for sending domains
to report on failures at multiple parts of the MTA-to-MTA to report on failures at multiple stages of the MTA-to-MTA
conversation. conversation.
Recipient domains may also use the mechanisms defined by MTA-STS Recipient domains may also use the mechanisms defined by MTA-STS
(TODO: Add ref) or DANE [RFC6698] to publish additional encryption (TODO: Add ref) or DANE [RFC6698] to publish additional encryption
and authentication requirements; this document defines a mechanism and authentication requirements; this document defines a mechanism
for sending domains that are compatible with MTA-STS or DANE to share for sending domains that are compatible with MTA-STS or DANE to share
success and failure statistics with recipient domains. success and failure statistics with recipient domains.
Specifically, this document defines a reporting schema that covers Specifically, this document defines a reporting schema that covers
failures in routing, STARTTLS negotiation, and both DANE [RFC6698] failures in routing, STARTTLS negotiation, and both DANE [RFC6698]
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SMTP MTA Strict Transport Security (MTA-STS, TODO: Add ref). SMTP MTA Strict Transport Security (MTA-STS, TODO: Add ref).
1.1. Terminology 1.1. Terminology
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in [RFC2119]. document, are to be interpreted as described in [RFC2119].
We also define the following terms for further use in this document: We also define the following terms for further use in this document:
o STS Policy: A definition of the expected TLS availability, o MTA-STS Policy: A definition of the expected TLS availability,
behavior, and desired actions for a given domain when a sending behavior, and desired actions for a given domain when a sending
MTA encounters problems in negotiating a secure channel. STS is MTA encounters problems in negotiating a secure channel. MTA-STS
defined in [TODO] is defined in [TODO]
o DANE Policy: A mechanism for enabling the administrators of domain o DANE Policy: A mechanism by which administrators can supply a
names to specify the keys used in that domain's TLS servers. DANE record that can be used to validate the certificate presented by
is defined in [RFC6698] an MTA. DANE is defined in [RFC6698].
o TLSRPT Policy: A policy specifying the endpoint to which sending o TLSRPT Policy: A policy specifying the endpoint to which sending
MTAs should deliver reports. MTAs should deliver reports.
o Policy Domain: The domain against which an STS or DANE Policy is o Policy Domain: The domain against which an MTA-STS or DANE Policy
defined. is defined.
o Sending MTA: The MTA initiating the delivery of an email message. o Sending MTA: The MTA initiating the delivery of an email message.
2. Related Technologies 2. Related Technologies
o This document is intended as a companion to the specification for o This document is intended as a companion to the specification for
SMTP MTA Strict Transport Security (MTA-STS, TODO: Add ref). SMTP MTA Strict Transport Security (MTA-STS, TODO: Add ref).
o The Public Key Pinning Extension for HTTP [RFC7469] contains a o The Public Key Pinning Extension for HTTP [RFC7469] contains a
JSON-based definition for reporting individual pin validation JSON-based definition for reporting individual pin validation
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o The Domain-based Message Authentication, Reporting, and o The Domain-based Message Authentication, Reporting, and
Conformance (DMARC) [RFC7489] contains an XML-based reporting Conformance (DMARC) [RFC7489] contains an XML-based reporting
format for aggregate and detailed email delivery errors. format for aggregate and detailed email delivery errors.
3. Reporting Policy 3. Reporting Policy
A domain publishes a record to its DNS indicating that it wishes to A domain publishes a record to its DNS indicating that it wishes to
receive reports. These SMTP TLSRPT policies are distributed via DNS receive reports. These SMTP TLSRPT policies are distributed via DNS
from the Policy Domain's zone, as TXT records (similar to DMARC from the Policy Domain's zone, as TXT records (similar to DMARC
policies) under the name "smtp-tlsrpt". For example, for the Policy policies) under the name "_smtp-tlsrpt". For example, for the Policy
Domain "example.com", the recipient's TLSRPT policy can be retrieved Domain "example.com", the recipient's TLSRPT policy can be retrieved
from "smtp-tlsrpt.example.com". from "_smtp-tlsrpt.example.com".
Policies consist of the following directives: Policies consist of the following directives:
o "v": This value MUST be equal to "TLSRPTv1". o "v": This value MUST be equal to "TLSRPTv1".
o "rua": A URI specifying the endpoint to which aggregate o "rua": A URI specifying the endpoint to which aggregate
information about policy failures should be sent (see the section information about policy failures should be sent (see the section
_Reporting_ _Schema_ for more information). Two URI schemes are _Reporting_ _Schema_ for more information). Two URI schemes are
supported: "mailto" and "https". supported: "mailto" and "https".
* In the case of "https", reports should be submitted via POST * In the case of "https", reports should be submitted via POST
([RFC2818]) to the specified URI. ([RFC2818]) to the specified URI.
* In the case of "mailto", reports should be submitted to the * In the case of "mailto", reports should be submitted to the
specified email address. When sending failure reports via specified email address. When sending failure reports via
SMTP, sending MTAs MUST NOT honor SMTP STS or DANE TLSA SMTP, sending MTAs MUST deliver reports despite any TLS-related
failures. failures. This may mean that the reports are delivered in the
clear.
o "ruf": Future use. (There may also be a need for enabling more
detailed "forensic" reporting during initial stages of a
deployment. To address this, the authors consider the possibility
of an optional additional "forensic reporting mode" in which more
details--such as certificate chains and MTA banners--may be
reported.)
The formal definition of the "smtp-tlsrpt" TXT record, defined using The formal definition of the "_smtp-tlsrpt" TXT record, defined using
[RFC5234], is as follows: [RFC5234], is as follows:
tlsrpt-record = tlsrpt-version *WSP %x3B tlsrpt-rua tlsrpt-record = tlsrpt-version *WSP %x3B tlsrpt-rua
tlsrpt-version = "v" *WSP "=" *WSP %x54 %x4C %x53 tlsrpt-version = "v" *WSP "=" *WSP %x54 %x4C %x53
%x52 %x50 %x54 %x76 %x31 %x52 %x50 %x54 %x76 %x31
tlsrpt-rua = "rua" *WSP "=" *WSP tlsrpt-uri tlsrpt-rua = "rua" *WSP "=" *WSP tlsrpt-uri
tlsrpt-uri = URI tlsrpt-uri = URI
; "URI" is imported from [@!RFC3986]; commas (ASCII ; "URI" is imported from [@!RFC3986]; commas (ASCII
; 0x2C) and exclamation points (ASCII 0x21) ; 0x2C) and exclamation points (ASCII 0x21)
; MUST be encoded; the numeric portion MUST fit ; MUST be encoded; the numeric portion MUST fit
; within an unsigned 64-bit integer ; within an unsigned 64-bit integer
If multiple TXT records for "smtp-tlsrpt" are returned by the If multiple TXT records for "_smtp-tlsrpt" are returned by the
resolver, records which do not begin with "v=TLSRPTv1;" are resolver, records which do not begin with "v=TLSRPTv1;" are
discarded. If the number of resulting records is not one, senders discarded. If the number of resulting records is not one, senders
MUST assume the recipient domain does not implement TLSRPT. MUST assume the recipient domain does not implement TLSRPT.
3.1. Example Reporting Policy 3.1. Example Reporting Policy
3.1.1. Report using MAILTO 3.1.1. Report using MAILTO
smtp-tlsrpt.example.com. IN TXT \ _smtp-tlsrpt.example.com. IN TXT \
"v=TLSRPTv1;rua=mailto:reports@example.com" "v=TLSRPTv1;rua=mailto:reports@example.com"
3.1.2. Report using HTTPS 3.1.2. Report using HTTPS
smtp-tlsrpt.example.com. IN TXT \ _smtp-tlsrpt.example.com. IN TXT \
"v=TLSRPTv1; \ "v=TLSRPTv1; \
rua=https://reporting.example.com/v1/tlsrpt" rua=https://reporting.example.com/v1/tlsrpt"
4. Reporting Schema 4. Reporting Schema
The report is composed as a plain text file encoded in the JSON The report is composed as a plain text file encoded in the JSON
format ([RFC7159]). format ([RFC7159]).
Aggregate reports contain the following fields: Aggregate reports contain the following fields:
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4. Reporting Schema 4. Reporting Schema
The report is composed as a plain text file encoded in the JSON The report is composed as a plain text file encoded in the JSON
format ([RFC7159]). format ([RFC7159]).
Aggregate reports contain the following fields: Aggregate reports contain the following fields:
o Report metadata: o Report metadata:
* The organization responsible for the report * The organization responsible for the report
* Contact information for one or more responsible parties for the * Contact information for one or more responsible parties for the
contents of the report contents of the report
* A unique identifier for the report * A unique identifier for the report
* The reporting date range for the report * The reporting date range for the report
o Policy, consisting of: o Policy, consisting of:
* One of the following policy types: (1) The SMTP MTA STS policy * One of the following policy types: (1) The MTA-STS policy
applied (as a string) (2) The DANE TLSA record applied (as a applied (as a string) (2) The DANE TLSA record applied (as a
string) (3) The literal string "no-policy-found", if neither a string, with each RR entry of the RRset listed and separated by
TLSA nor MTA-STS policy could be found. a semicolon) (3) The literal string "no-policy-found", if
neither a TLSA nor MTA-STS policy could be found.
* The domain for which the policy is applied * The domain for which the policy is applied
* The MX host * The MX host
* An identifier for the policy (where applicable) * An identifier for the policy (where applicable)
o Aggregate counts, comprising result type, sending MTA IP, o Aggregate counts, comprising result type, sending MTA IP,
receiving MTA hostname, session count, and an optional additional receiving MTA hostname, session count, and an optional additional
information field containing a URI for recipients to review information field containing a URI for recipients to review
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The "Result Types" section will elaborate on the failed The "Result Types" section will elaborate on the failed
negotiation attempts. This field contains an aggregate count of negotiation attempts. This field contains an aggregate count of
failed connections. failed connections.
4.3. Result Types 4.3. Result Types
The list of result types will start with the minimal set below, and The list of result types will start with the minimal set below, and
is expected to grow over time based on real-world experience. The is expected to grow over time based on real-world experience. The
initial set is: initial set is:
4.3.1. Routing Failures 4.3.1. Negotiation Failures
o "mx-mismatch": This indicates that the MX resolved for the
recipient domain did not match the MX constraint specified in the
policy.
4.3.2. Negotiation Failures
o "starttls-not-supported": This indicates that the recipient MX did o "starttls-not-supported": This indicates that the recipient MX did
not support STARTTLS. not support STARTTLS.
o "certificate-host-mismatch": This indicates that the certificate o "certificate-host-mismatch": This indicates that the certificate
presented did not adhere to the constraints specified in the STS presented did not adhere to the constraints specified in the MTA-
or DANE policy, e.g. if the CN field did not match the hostname STS or DANE policy, e.g. if the MX does not match any identities
of the MX. listed in the Subject Alternate Name (SAN) [RFC5280].
o "certificate-expired": This indicates that the certificate has o "certificate-expired": This indicates that the certificate has
expired. expired.
o "certificate-not-trusted": This a label that covers multiple o "certificate-not-trusted": This a label that covers multiple
certificate related failures that include, but not limited to certificate related failures that include, but not limited to
errors such as untrusted/unknown CAs, certificate name contraints, errors such as untrusted/unknown CAs, certificate name
certificate chain errors etc. When using this declaration, the constraints, certificate chain errors etc. When using this
reporting MTA SHOULD utilize the "failure-reason" to provide more declaration, the reporting MTA SHOULD utilize the "failure-reason"
information to the receiving entity. to provide more information to the receiving entity.
o "validation-failure": This indicates a general failure for a o "validation-failure": This indicates a general failure for a
reason not matching a category above. When using this reason not matching a category above. When using this
declaration, the reporting MTA SHOULD utilize the "failure-reason" declaration, the reporting MTA SHOULD utilize the "failure-reason"
to provide more information to the receiving entity. to provide more information to the receiving entity.
4.3.3. Policy Failures 4.3.2. Policy Failures
4.3.3.1. DANE-specific Policy Failures 4.3.2.1. DANE-specific Policy Failures
o "tlsa-invalid": This indicates a validation error in the TLSA o "tlsa-invalid": This indicates a validation error in the TLSA
record associated with a DANE policy. record associated with a DANE policy. None of the records in the
RRset were found to be valid.
o "dnssec-invalid": This indicates a failure to authenticate DNS o "dnssec-invalid": This would indicate that no valid records were
records for a Policy Domain with a published TLSA record. returned from the recursive resolver. The request returned with
SERVFAIL for the requested TLSA record.
4.3.3.2. STS-specific Policy Failures 4.3.2.2. MTA-STS-specific Policy Failures
o "sts-invalid": This indicates a validation error for the overall o "sts-invalid": This indicates a validation error for the overall
MTA-STS policy. MTA-STS policy.
o "webpki-invalid": This indicates that the MTA-STS policy could not o "webpki-invalid": This indicates that the MTA-STS policy could not
be authenticated using PKIX validation. be authenticated using PKIX validation.
4.3.4. General Failures 4.3.3. General Failures
When a negotiation failure can not be categorized into one of the When a negotiation failure can not be categorized into one of the
"Negotiation Failures" stated above, the reporter SHOULD use the "Negotiation Failures" stated above, the reporter SHOULD use the
"validation-failure" category. As TLS grows and becomes more "validation-failure" category. As TLS grows and becomes more
complex, new mechanisms may not be easily categorized. This allows complex, new mechanisms may not be easily categorized. This allows
for a generic feedback category. When this category is used, the for a generic feedback category. When this category is used, the
reporter SHOULD also use the "failure-reason-code" to give some reporter SHOULD also use the "failure-reason-code" to give some
feedback to the receiving entity. This is intended to be a short feedback to the receiving entity. This is intended to be a short
text field, and the contents of the field should be an error code or text field, and the contents of the field should be an error code or
error text, such as "X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION". error text, such as "X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION".
4.3.5. Transient Failures 4.3.4. Transient Failures
Transient errors due to too-busy network, TCP timeouts, etc. are not Transient errors due to too-busy network, TCP timeouts, etc. are not
required to be reported. required to be reported.
5. Report Delivery 5. Report Delivery
Reports can be delivered either as an email message via SMTP or via Reports can be delivered either as an email message via SMTP or via
HTTP POST. HTTP POST.
5.1. Report Filename 5.1. Report Filename
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For instance, this is a possible Subject field for a report to the For instance, this is a possible Subject field for a report to the
Policy Domain "example.net" from the Sending MTA Policy Domain "example.net" from the Sending MTA
"mail.sender.example.com". It is line-wrapped as allowed by "mail.sender.example.com". It is line-wrapped as allowed by
[RFC5322]: [RFC5322]:
Subject: Report Domain: example.net Subject: Report Domain: example.net
Submitter: mail.sender.example.com Submitter: mail.sender.example.com
Report-ID: <735ff.e317+bf22029@mailexample.net> Report-ID: <735ff.e317+bf22029@mailexample.net>
Note that, when sending failure reports via SMTP, sending MTAs MUST Note that, when sending failure reports via SMTP, sending MTAs MUST
NOT honor SMTP STS or DANE TLSA failures. NOT honor MTA-STS or DANE TLSA failures.
5.4. HTTPS Transport 5.4. HTTPS Transport
The report MAY be delivered by POST to HTTPS. If compressed, the The report MAY be delivered by POST to HTTPS. If compressed, the
report should use the media type "application/gzip" (see [RFC6713]), report should use the media type "application/gzip" (see [RFC6713]),
and "text/json" otherwise. and "text/json" otherwise.
5.5. Delivery Retry 5.5. Delivery Retry
In the event of a delivery failure, regardless of the delivery In the event of a delivery failure, regardless of the delivery
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DMARC [RFC7489] defines an elegant solution for verifying DMARC [RFC7489] defines an elegant solution for verifying
delegation; however, since the attacker had less ability to delegation; however, since the attacker had less ability to
generate large reports than with DMARC failures, and since the generate large reports than with DMARC failures, and since the
reports are generated by the sending MTA, such a delegation reports are generated by the sending MTA, such a delegation
mechanism is left for a future version of this specification. mechanism is left for a future version of this specification.
8. Appendix 1: Example Reporting Policy 8. Appendix 1: Example Reporting Policy
8.1. Report using MAILTO 8.1. Report using MAILTO
smtp-tlsrpt.mail.example.com. IN TXT \ _smtp-tlsrpt.mail.example.com. IN TXT \
"v=TLSRPTv1;rua=mailto:reports@example.com" "v=TLSRPTv1;rua=mailto:reports@example.com"
8.2. Report using HTTPS 8.2. Report using HTTPS
smtp-tlsrpt.mail.example.com. IN TXT \ _smtp-tlsrpt.mail.example.com. IN TXT \
"v=TLSRPTv1; \ "v=TLSRPTv1; \
rua=https://reporting.example.com/v1/tlsrpt" rua=https://reporting.example.com/v1/tlsrpt"
9. Appendix 2: JSON Report Schema 9. Appendix 2: JSON Report Schema
The JSON schema is derived from the HPKP JSON schema [RFC7469] (cf. The JSON schema is derived from the HPKP JSON schema [RFC7469] (cf.
Section 3) Section 3)
{ {
"organization-name": organization-name, "organization-name": organization-name,
"date-range": { "date-range": {
"start-datetime": date-time, "start-datetime": date-time,
"end-datetime": date-time "end-datetime": date-time
}, },
"contact-info": email-address, "contact-info": email-address,
"report-id": report-id, "report-id": report-id,
"policy": { "policy": {
"policy-type": policy-type, "policy-type": policy-type,
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o "report-id": A unique identifier for the report. Report authors o "report-id": A unique identifier for the report. Report authors
may use whatever scheme they prefer to generate a unique may use whatever scheme they prefer to generate a unique
identifier. It is provided as a string. identifier. It is provided as a string.
o "policy-type": The type of policy that was applied by the sending o "policy-type": The type of policy that was applied by the sending
domain. Presently, the only three valid choices are "tlsa", domain. Presently, the only three valid choices are "tlsa",
"sts", and the literal string "no-policy-found". It is provided "sts", and the literal string "no-policy-found". It is provided
as a string. as a string.
o "policy-string": The string serialization of the policy, whether o "policy-string": The string serialization of the policy, whether
TLSA record or STS policy. Any linefeeds from the original policy TLSA record or MTA-STS policy. Any linefeeds from the original
MUST be replaced with [SP]. TODO: Help with specifics. policy MUST be replaced with [SP]. TODO: Help with specifics.
o "domain": The Policy Domain upon which the policy was applied. o "domain": The Policy Domain upon which the policy was applied.
For messages sent to "user@example.com" this field would contain For messages sent to "user@example.com" this field would contain
"example.com". It is provided as a string. "example.com". It is provided as a string.
o "mx-host-pattern": The pattern of MX hostnames from the applied o "mx-host-pattern": The pattern of MX hostnames from the applied
policy. It is provided as a string, and is interpreted in the policy. It is provided as a string, and is interpreted in the
same manner as the "Checking of Wildcard Certificates" rules in same manner as the "Checking of Wildcard Certificates" rules in
Section 6.4.3 of [RFC6125]. Section 6.4.3 of [RFC6125].
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