Individual submission M. Kucherawy Internet-Draft Cloudmark, Inc. Intended status: Standards Track November 29, 2010 Expires: June 2, 2011 Authentication-Results Registration For Vouch By Reference Results draft-kucherawy-authres-vbr-01 Abstract This memo updates the registry of properties in Authentication- Results: message header fields to allow relaying of the results of a Vouch By Reference query. 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 June 2, 2011. Copyright Notice Copyright (c) 2010 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. Kucherawy Expires June 2, 2011 [Page 1]
Internet-Draft Auth-Results VBR Registration November 2010 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Definition . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . . 5 Appendix A. Authentication-Results Examples . . . . . . . . . . . 6 A.1. VBR Results . . . . . . . . . . . . . . . . . . . . . . . . 6 Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . . 7 Kucherawy Expires June 2, 2011 [Page 2]
Internet-Draft Auth-Results VBR Registration November 2010 1. Introduction [AUTHRES] defined a new header field for electronic mail messages that presents the results of a message authentication effort in a machine-readable format. In the interim, a proposal for rudimentary domain-level reputation called Vouch By Reference [VBR] was published and is now beginning to see popular use. Fortunately, [AUTHRES] created IANA registries of reporting properties, enabling an easy remedy for this problem. This memo thus registers an additional reporting property allowing a VBR result to be relayed as an annotation in a message header. 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. Discussion Vouch By Reference [VBR] introduced a mechanism by which a message receiver can query a "vouching" service to determine whether or not a trusted third party is willing to state that mail from a particular source can be considered legitimate. When this assessment is done at an inbound border mail gateway, it would be useful to relay the result of that assessment to internal mail entities such as filters or user agents. 4. Definition This memo adds to the "Email Authentication Method Name Registry", created by IANA upon publication of [AUTHRES], the "header.md" and "header.mv" reporting items. The value associated with "header.md" in the header field MUST be the DNS domain name about which a VBR query was made. This is typically taken from the "md" tag of the "VBR-Info" header filed. ([VBR] describes the methods for selecting the construction and execution of that query.) The value associated with "header.mv" in the header field MUST be the DNS domain that was queried as the potential voucher for the "header.md" domain. This is typically one of the values of the "mv" tag in the "VBR-Info" header field on the message being evaluated, although a local list of vouchers may be used in place of that value as described in [VBR]. Kucherawy Expires June 2, 2011 [Page 3]
Internet-Draft Auth-Results VBR Registration November 2010 Where the VBR-Info header field was not present on a message but a mail server decides to conduct a VBR query anyway, the server MAY still generate an Authentication-Results field to relay the results of the VBR query. In this instance, the "header.md" value MUST be the domain name that was evaluated as the sending domain using VBR, and the "header.mv" value MUST be the domain name that was used as the voucher. This memo also adds to the "Email Authentication Results Name Registry" the following result codes and definitions: none: No valid VBR-Info header was found in the message, or a domain name to be queried could not be determined. pass: A VBR query was completed and the vouching service queried gave a positive response. fail: A VBR query was completed and the vouching service queried did not give a positive response, or the message contained multiple VBR-Info header fields with different "mc" values. temperror: A VBR query was attempted but could not be completed due to some error that is likely transient in nature such as a temporary DNS error. A later attempt may produce a final result. permerror: A VBR query was attempted but could not be completed due to some error that is likely not transient in nature such as a permanent DNS error. A later attempt is unlikely to produce a final result. 5. IANA Considerations Per [IANA-CONSIDERATIONS], the following item is added to the "Email Authentication Method Name Registry": +------------+----------+--------+----------------+-----------------+ | Method | Defined | ptype | property | value | +------------+----------+--------+----------------+-----------------+ | vbr | RFC5518 | header | md | DNS domain name | | | | | | used as the | | | | | | subject of a | | | | | | VBR query | +------------+----------+--------+----------------+-----------------+ | vbr | RFC5518 | header | mv | DNS domain name | | | | | | of the entity | | | | | | acting as | | | | | | the voucher | +------------+----------+--------+----------------+-----------------+ Kucherawy Expires June 2, 2011 [Page 4]
Internet-Draft Auth-Results VBR Registration November 2010 Also, the following item is added to the "Email Authentication Method Results Registry": +-----------+--------------+------------+---------+-----------------+ | Code | Existing/New | Defined In | Method | Meaning | +-----------+--------------+------------+---------+-----------------+ | none | existing | RFC5451 | vbr | Section 4 | | | | | (added) | | +-----------+--------------+------------+---------+-----------------+ | pass | existing | RFC5451 | vbr | Section 4 | | | | | (added) | | +-----------+--------------+------------+---------+-----------------+ | fail | existing | RFC5451 | vbr | Section 4 | | | | | (added) | | +-----------+--------------+------------+---------+-----------------+ | temperror | existing | RFC5451 | vbr | Section 4 | | | | | (added) | | +-----------+--------------+------------+---------+-----------------+ | permerror | existing | RFC5451 | vbr | Section 4 | | | | | (added) | | +-----------+--------------+------------+---------+-----------------+ 6. Security Considerations This memo creates a mechanism for relaying [VBR] results using the structure already defined by [AUTHRES]. The Security Considerations sections of those documents should be consulted. 7. References 7.1. Normative References [AUTHRES] Kucherawy, M., "Message Header Field for Indicating Message Authentication Status", RFC 5451, April 2009. [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [VBR] Hoffman, P., Levine, J., and A. Hathcock, "Vouch By Reference", RFC 5518, April 2009. 7.2. Informative References [IANA-CONSIDERATIONS] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. Kucherawy Expires June 2, 2011 [Page 5]
Internet-Draft Auth-Results VBR Registration November 2010 Appendix A. Authentication-Results Examples This section presents an example of the use of this new item header field to indicate VBR results. A.1. VBR Results A message that triggered a VBR query, returning a result: Authentication-Results: mail-router.example.net; dkim=pass (good signature) header.d=newyork.example.com header.b=oINEO8hg; vbr=pass (voucher.example.net) header.md=newyork.example.com header.mv=voucher.example.org Received: from newyork.example.com (newyork.example.com [192.0.2.250]) by mail-router.example.net (8.11.6/8.11.6) for <recipient@example.net> with ESMTP id i7PK0sH7021929; Fri, Feb 15 2002 17:19:22 -0800 DKIM-Signature: v=1; a=rsa-sha256; s=rashani; d=newyork.example.com; t=1188964191; c=relaxed/simple; h=From:Date:To:VBR-Info:Message-Id:Subject; bh=sEu28nfs9fuZGD/pSr7ANysbY3jtdaQ3Xv9xPQtS0m7=; b=oINEO8hgn/gnunsg ... 9n9ODSNFSDij3= From: sender@newyork.example.com Date: Fri, Feb 15 2002 16:54:30 -0800 To: meetings@example.net VBR-Info: md=newyork.example.com; mc=list; mv=voucher.example.org Message-Id: <12345.abc@newyork.example.com> Subject: here's a sample Example 1: Header field reporting results from a VBR query Here we see an example of a message that was signed using DKIM and also included a VBR-Info header field. On receipt it is found that the "md=" field in the latter and the "d=" field in the former matched and also that the DKIM signature verified, so a VBR query was performed. The vouching service, voucher.example.org, indicated the sender can be trusted, so a "pass" result is included in the Authentication-Results field affixed prior to delivery. Kucherawy Expires June 2, 2011 [Page 6]
Internet-Draft Auth-Results VBR Registration November 2010 Appendix B. Acknowledgements The author wishes to acknowledge the following for their review and constructive criticism of this proposal: JD Falk, John Levine, Alessandro Vesely Author's Address Murray S. Kucherawy Cloudmark, Inc. 128 King St., 2nd Floor San Francisco, CA 94107 US Phone: +1 415 946 3800 EMail: msk@cloudmark.com Kucherawy Expires June 2, 2011 [Page 7]
