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Internet Engineering Task Force (IETF) R. Clayton
Request for Comments: 6692 University of Cambridge
Updates: 6591 M. Kucherawy
Category: Standards Track Cloudmark, Inc.
ISSN: 2070-1721 July 2012


Source Ports in Abuse Reporting Format (ARF) Reports

Abstract

This document defines an additional header field for use in Abuse
Reporting Format (ARF) reports to permit the identification of the
source port of the connection involved in an abuse incident.

This document updates RFC 6591.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6692.

Copyright Notice

Copyright (c) 2012 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.






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Table of Contents

1. Introduction ....................................................2
2. Keywords ........................................................2
3. Source-Port Field Definition ....................................2
4. Time Accuracy ...................................................3
5. IANA Considerations .............................................3
6. Security Considerations .........................................3
7. References ......................................................4
7.1. Normative References .......................................4
7.2. Informative References .....................................4
Appendix A. Acknowledgements .......................................5

1. Introduction

[ARF] defined the Abuse Reporting Format, an extensible message
format for Email Feedback Reports. These reports are used to report
incidents of email abuse. ARF was extended by [AUTHFAILURE-REPORT]
to enable the reporting of email authentication failures. These
specifications provided for the source IP address to be included in a
report. As explained in [LOG], the deployment of IP address sharing
techniques requires the source port values to be included in reports
if unambiguous identification of the origin of abuse is to be
achieved.

This document defines an ARF reporting field to contain this
information and provides guidance for its use.

2. 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].

3. Source-Port Field Definition

A new ARF header field called "Source-Port" is defined. When present
in a report, it MUST contain the client port of the TCP connection
from which the reported message originated, corresponding to the
"Source-IP" field that contains the client address of that same
connection, thereby describing completely the origin of the abuse
incident.

Per, [ABNF], the formal syntax is:

source-port = "Source-Port:" [CFWS] 1*5DIGIT [CFWS] CRLF





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"CFWS", which represents email-style comments or folding white space,
is imported from [MAIL].

When any report is generated that includes the "Source-IP" field (see
Section 3.2 of [ARF]), this field SHOULD also be present, unless the
port number is unavailable.

Use of this field is RECOMMENDED for reports generated per
[AUTHFAILURE-REPORT] (see Section 3.1 of that document).

4. Time Accuracy

[LOG] underscores the importance of accurate clocks when generating
reports that include source port information because of the fact that
source ports can be recycled very quickly in Internet Service
Provider environments. The same considerations described there apply
here.

Report generators that include an Arrival-Date report field MAY
choose to express the value of that date in Universal Coordinated
Time (UTC) to enable simpler correlation with local records at sites
that are following the provisions of [LOG].

5. IANA Considerations

IANA has added the following entry to the "Feedback Report Header
Fields" registry:

Field Name: Source-Port

Description: TCP source port from which the original message was
received

Multiple Appearances: No

Related "Feedback-Type": any

Reference: [RFC6692]

Status: current

6. Security Considerations

This extension introduces no new security considerations not already
covered in [ARF].

Some security considerations related to the general topic of source
port logging can be found in [LOG].



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7. References

7.1. Normative References

[ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.

[ARF] Shafranovich, Y., Levine, J., and M. Kucherawy, "An
Extensible Format for Email Feedback Reports", RFC 5965,
August 2010.

[AUTHFAILURE-REPORT]
Fontana, H., "Authentication Failure Reporting Using the
Abuse Reporting Format", RFC 6591, April 2012.

[KEYWORDS]
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[MAIL] Resnick, P., Ed., "Internet Message Format", RFC 5322,
October 2008.

7.2. Informative References

[LOG] Durand, A., Gashinsky, I., Lee, D., and S. Sheppard,
"Logging Recommendations for Internet-Facing Servers",
BCP 162, RFC 6302, June 2011.
























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Appendix A. Acknowledgements

The authors wish to acknowledge the following for their review and
constructive criticism of this proposal: Steve Atkins, Scott
Kitterman, John Levine, and Doug Otis.

The idea for this work originated within the Messaging Anti-Abuse
Working Group (MAAWG).

Authors' Addresses

Richard Clayton
University of Cambridge
Computer Laboratory
JJ Thomson Avenue
Cambridge CB3 0FD
United Kingdom

Phone: +44 1223 763570
EMail: richard.clayton@cl.cam.ac.uk


Murray S. Kucherawy
Cloudmark, Inc.
128 King St., 2nd Floor
San Francisco, CA 94107
US

Phone: +1 415 946 3800
EMail: superuser@gmail.com





















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