Source Ports in Abuse Reporting Format (ARF) Reports
RFC 6692

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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