Individual submission R. Clayton
Internet-Draft University of Cambridge
Updates: 5965, 6591 (if approved) M. S. Kucherawy
Intended status: Standards Track Cloudmark, Inc.
Expires: November 06, 2012 May 07, 2012

Source Ports in ARF Reports
draft-kucherawy-marf-source-ports-03

Abstract

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

This document updates RFC5965 and RFC6591.

Status of this Memo

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This Internet-Draft will expire on November 06, 2012.

Copyright Notice

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Table of Contents

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 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 TCP source port matching the "Source-IP" field in the same report, thereby describing completely the origin of the abuse incident.

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

Per, [ABNF], the formal syntax is:

"CFWS" is imported from [MAIL].

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

Use of this field is RECOMMENED 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 is requested to add the following entry to the Feedback Report Header Fields registry:

Field Name:
Source-Port
Description:
TCP source port from which the reported connection originated
Multiple Appearances:
No
Related Feedback-Type:
any
Reference:
[this document]
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].

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 Report 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., "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", RFC 6302, June 2011.

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: msk@cloudmark.com