One document matched: draft-ietf-marf-spf-reporting-02.txt
Differences from draft-ietf-marf-spf-reporting-01.txt
MARF Working Group S. Kitterman
Internet-Draft Authentication Metrics
Intended status: Standards Track October 24, 2011
Expires: April 26, 2012
SPF Authentication Failure Reporting using the Abuse Report Format
draft-ietf-marf-spf-reporting-02
Abstract
This memo presents extensions to the Abuse Reporting Format (ARF),
and Sender Policy Framework (SPF) specifications to allow for
detailed reporting of message authentication failures in an on-demand
fashion.
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 http://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 26, 2012.
Copyright Notice
Copyright (c) 2011 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
(http://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.
Kitterman Expires April 26, 2012 [Page 1]
Internet-Draft SPF Auth Failure Reporting October 2011
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Keywords . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Imported Definitions . . . . . . . . . . . . . . . . . . . 4
3. Optional Reporting Address for SPF . . . . . . . . . . . . . . 5
4. Requested Reports . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Requested Reports for SPF Failures . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
5.1. SPF Modifier Registration . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6.1. Inherited Considerations . . . . . . . . . . . . . . . . . 9
6.2. Reports From Unrelated Domains . . . . . . . . . . . . . . 9
6.3. Envelope Sender Selection . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . . 10
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 12
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 13
B.1. Minimal SPF DNS record change to add a reporting
address . . . . . . . . . . . . . . . . . . . . . . . . . 13
B.2. SPF DNS record with reporting address, report
interval, and requested report type . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14
Kitterman Expires April 26, 2012 [Page 2]
Internet-Draft SPF Auth Failure Reporting October 2011
1. Introduction
[ARF] defines a message format for sending reports of abuse in the
messaging infrastructure, with an eye toward automating both the
generating and consumption of those reports.
[SPF] is one mechanism for message sender authentication; it is
"path-based" meaning it authenticates the route that a message took
from origin to destination. As with other email authentication
methods, like [DKIM], the output is a verified domain name that can
then be subjected to some sort of evaluation process (e.g.,
comparison to a known-good list, submission to a reputation service,
etc.).
Deployers of message sender authentication technologies are
increasingly seeking visibility into DKIM verification failures,
unauthorized path traversals (SPF failures), and conformance failures
involving the published signing practices (e.g., [ADSP]) of an
Administrative Mail Domain (ADMD; see [EMAIL-ARCH]).
This document extends [SPF] to add an optional reporting address and
an optional means of specifying a desired report format and other
parameters. Extension of [ARF] to add features required for the
reporting of these incidents is covered in
[I-D.MARF-AUTHFAILURE-REPORT].
This document additionally creates a an IANA registry of [SPF] record
modifiers to avoid modifier namespace collisions.
Kitterman Expires April 26, 2012 [Page 3]
Internet-Draft SPF Auth Failure Reporting October 2011
2. Definitions
2.1. Keywords
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [KEYWORDS].
2.2. Imported Definitions
The ABNF token "qp-section" is defined in [MIME].
"local-part" is defined in [MAIL].
"addr-spec" is defined in [MAIL].
Kitterman Expires April 26, 2012 [Page 4]
Internet-Draft SPF Auth Failure Reporting October 2011
3. Optional Reporting Address for SPF
There exist cases in which a domain name owner employing [SPF] for
announcing sending practises may want to know when messages are
received via unauthorized routing. Currently there is no such method
defined in conjunction with standardized approaches such as [ARF].
Similar information can be gathered using a specially crafted [SPF]
record and a special DNS server to track [SPF] record lookups.
This document defines the following optional "modifier" (as defined
in Section 4.6.1 of [SPF]) to SPF records, using the form defined in
that specification:
r= Reporting Address (plain-text; OPTIONAL; no default). MUST be a
local-part or addr-spec (see Section 3.4.1 of [MAIL]) specifying
an e-mail address to which a report SHOULD be sent when mail
claiming to be from this domain (see Section 2.4 of [SPF] for a
description of how domains are identified for SPF checks) has
failed the evaluation algorithm described in [SPF], in particular
because a message arrived via an unauthorized route. The format
of this reply MUST be in the format specified by the "rf=" tag
defined below. If only a local-part is provided, then to generate
a complete address to which the report is sent, the verifier
simply appends to this value an "@" followed by the SPF domain per
paragraph 4.1 of [SPF]. r= modifiers in a record that was reached
by following an include: mechanism MUST be ignored.
ABNF:
spf-report-tag = %x72 "=" qp-section
rf= Reporting Format (plain-text; OPTIONAL; default is "arf"). The
value MUST be a colon-separated list of tokens representing
desired reporting formats in decreasing order of preference. Each
element of the list MUST be a token that is taken from the
registered list of report formats. See
[I-D.MARF-AUTHFAILURE-REPORT] for a description of recognized
formats. The verifier generating reports SHOULD generate a report
using the first token in the list that represents a report format
it is capable of generating. If no supported formats are
requested, then a report MUST not be sent.
ABNF:
spf-rf-tag = %x72 %x66 "=" rep-format 0*( ":" rep-format )
Kitterman Expires April 26, 2012 [Page 5]
Internet-Draft SPF Auth Failure Reporting October 2011
ri= Requested Report Interval (plain-text; OPTIONAL; default is
"0"). The value is an unsigned 32-bit integer that specifies the
number of incidents for which to skip reports, i.e. for a value of
"1", every other report about a given type of incident (e.g. SPF
related) should be skipped. A value of "0" requests a report for
every incident. Where the requested interval is not zero, the
agent generating a report SHOULD include an "Incidents:" field in
the generated report so the receiving agent has some indication of
how many reports were suppressed.
ABNF:
spf-ri-tag = %x72 %x69 "=" 1*DIGIT
ro= Requested Reports (plain-text; OPTIONAL; default is "all"). The
value MUST be a colon-separated list of tokens representing those
conditions under which a report is desired. See Section 4.1 for a
list of valid tags.
ABNF:
spf-ro-type = ( "all" / "e" / "f" / "s" )
spf-ro-tag = %x72 %x6f "=" spf-ro-type 0* ( ":" spf-ro-type )
In the absence of an 'r=' tag in the SPF record, all other fields
defined above MUST be ignored.
Kitterman Expires April 26, 2012 [Page 6]
Internet-Draft SPF Auth Failure Reporting October 2011
4. Requested Reports
This memo also includes, as the "ro" tokens defined above, the means
by which the sender can request reports for specific circumstances of
interest. Verifiers MUST NOT generate reports for incidents that do
not match a requested report, and MUST ignore requests for reports
not included in this these lists.
4.1. Requested Reports for SPF Failures
The following report requests are defined for SPF results:
all All reports are requested.
e Reports are requested for messages that produced an SPF result of
"TempError" or "PermError".
f Reports are requested for messages that produced an SPF result of
"Fail".
s Reports are requested for messages that produced an SPF result of
"SoftFail".
Kitterman Expires April 26, 2012 [Page 7]
Internet-Draft SPF Auth Failure Reporting October 2011
5. IANA Considerations
As required by [IANA-CONSIDERATIONS], this section contains registry
information for the new [SPF] modifiers.
5.1. SPF Modifier Registration
IANA is requested to create the Sender Policy Framework Modifier
Registry, to include a list of all registered SPF modifier names and
their defining documents.
New registrations or updates MUST be published in accordance with the
"Specification Required" guidelines as described in
[IANA-CONSIDERATIONS]. New registrations and updates MUST contain
the following information:
1. Name of the modifier being registered or updated
2. The document in which the specification of the modifier is
published
3. New or updated status, which MUST be one of:
current: The field is in current use
deprecated: The field is in current use but its use is
discouraged
historic: The field is no longer in current use
An update may make a notation on an existing registration indicating
that a registered field is historic or deprecated if appropriate.
+------------+-----------------+---------+
| MODIFIER | REFERENCE | STATUS |
+------------+-----------------+---------+
| exp | RFC4408 | current |
| redirect | RFC4408 | current |
| r | (this document) | current |
| rf | (this document) | current |
| ri | (this document) | current |
| ro | (this document) | current |
+------------+-----------------+---------+
Kitterman Expires April 26, 2012 [Page 8]
Internet-Draft SPF Auth Failure Reporting October 2011
6. Security Considerations
Security issues with respect to these reports are similar to those
found in [DSN].
6.1. Inherited Considerations
Implementors are advised to consider the Security Considerations
sections of [SPF], [ARF], and [I-D.MARF-AUTHFAILURE-REPORT].
6.2. Reports From Unrelated Domains
SPF records can be used by other domains via include mechanisms and
redirect modifiers. If reporting addresses included in these records
are specified with a full addr-spec then reports for other,
potentially unrelated, domains may be reported to this address. In
theory, malicious senders might use this as a path for generating
large numbers of feedback reports. To mitigate this issue, specify
reporting addresses with a local-part so that reports will be
directed to the original domain from which the message causing the
feedback report was sent.
6.3. Envelope Sender Selection
In the case of transmitted reports in the form of a new message, it
is necessary to construct the message so as to avoid amplification
attacks, deliberate or otherwise. Thus, per Section 2 of [DSN], the
envelope sender address of the report SHOULD be chosen to ensure that
no delivery status reports will be issued in response to the report
itself, and MUST be chosen so that these reports will not generate
mail loops. Whenever an [SMTP] transaction is used to send a report,
the MAIL FROM command MUST use a NULL return address, i.e. "MAIL
FROM:<>". The HELO/EHLO command SHOULD pass [SPF] HELO checks.
Kitterman Expires April 26, 2012 [Page 9]
Internet-Draft SPF Auth Failure Reporting October 2011
7. References
7.1. Normative References
[ARF] Shafranovich, Y., Levine, J., and M. Kucherawy, "An
Extensible Format for Email Feedback Reports", RFC 5965,
August 2010.
[EMAIL-ARCH]
Crocker, D., "Internet Mail Architecture", RFC 5598,
October 2008.
[I-D.MARF-AUTHFAILURE-REPORT]
Fontana, H., "Authentication Failure Reporting using the
Abuse Report Format", June 2011.
[IANA-CONSIDERATIONS]
Alvestrand, H. and T. Narten, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226, May 2008.
[KEYWORDS]
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[MAIL] Resnick, P., "Internet Message Format", RFC 5322,
October 2008.
[MIME] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
[SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008.
[SPF] Wong, M. and W. Schlitt, "Sender Policy Framework (SPF)
for Authorizing Use of Domains in E-Mail, Version 1",
RFC 4408, April 2006.
7.2. Informative References
[ADSP] Allman, E., Delany, M., Fenton, J., and J. Levine, "DKIM
Sender Signing Practises", RFC 5617, August 2009.
[DKIM] Allman, E., Callas, J., Delany, M., Libbey, M., Fenton,
J., and M. Thomas, "DomainKeys Identified Mail (DKIM)
Signatures", RFC 4871, May 2007.
[DSN] Moore, K. and G. Vaudreuil, "An Extensible Message Format
Kitterman Expires April 26, 2012 [Page 10]
Internet-Draft SPF Auth Failure Reporting October 2011
for Delivery Status Notifications", RFC 3464,
January 2003.
Kitterman Expires April 26, 2012 [Page 11]
Internet-Draft SPF Auth Failure Reporting October 2011
Appendix A. Acknowledgements
The author wishes to acknowledge the following for their review and
constructive criticism of this proposal: Murray Kucherawy, Tim
Draegen, and Julian Mehnle.
Kitterman Expires April 26, 2012 [Page 12]
Internet-Draft SPF Auth Failure Reporting October 2011
Appendix B. Examples
B.1. Minimal SPF DNS record change to add a reporting address
v=spf1 mx:example.org r=postmaster -all
B.2. SPF DNS record with reporting address, report interval, and
requested report type
v=spf1 mx:example.org -all r=postmaster@example.net rf=arf ri=10 ro=e
Kitterman Expires April 26, 2012 [Page 13]
Internet-Draft SPF Auth Failure Reporting October 2011
Author's Address
Scott Kitterman
Authentication Metrics
3611 Scheel Dr
Ellicott City, MD 21042
US
Phone: +1 301 325 5475
Email: skitterman@authmetrics.com
Kitterman Expires April 26, 2012 [Page 14]
| PAFTECH AB 2003-2026 | 2026-04-24 04:29:25 |