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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. Clayton & Kucherawy Standards Track [Page 1]
RFC 6692 ARF Source Ports July 2012 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 Clayton & Kucherawy Standards Track [Page 2]
RFC 6692 ARF Source Ports July 2012 "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]. Clayton & Kucherawy Standards Track [Page 3]
RFC 6692 ARF Source Ports July 2012 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. Clayton & Kucherawy Standards Track [Page 4]
RFC 6692 ARF Source Ports July 2012 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 Clayton & Kucherawy Standards Track [Page 5]