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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 5598 (ref. 'EMAIL-ARCH') ** Obsolete normative reference: RFC 4408 (ref. 'SPF') (Obsoleted by RFC 7208) Summary: 2 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 REPUTE Working Group N. Borenstein 3 Internet-Draft Mimecast 4 Intended status: Standards Track M. Kucherawy 5 Expires: March 2, 2014 August 29, 2013 7 A Reputation Response Set for Email Identifiers 8 draft-ietf-repute-email-identifiers-09 10 Abstract 12 This document defines a response set for describing assertions a 13 reputation service provider can make about email identifers, for use 14 in generating reputons. 16 Status of this Memo 18 This Internet-Draft is submitted in full conformance with the 19 provisions of BCP 78 and BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF). Note that other groups may also distribute 23 working documents as Internet-Drafts. The list of current Internet- 24 Drafts is at http://datatracker.ietf.org/drafts/current/. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 This Internet-Draft will expire on March 2, 2014. 33 Copyright Notice 35 Copyright (c) 2013 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents 40 (http://trustee.ietf.org/license-info) in effect on the date of 41 publication of this document. Please review these documents 42 carefully, as they describe your rights and restrictions with respect 43 to this document. Code Components extracted from this document must 44 include Simplified BSD License text as described in Section 4.e of 45 the Trust Legal Provisions and are provided without warranty as 46 described in the Simplified BSD License. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 51 2. Terminology and Definitions . . . . . . . . . . . . . . . . . . 3 52 2.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 2.2. Email Definitions . . . . . . . . . . . . . . . . . . . . . 3 54 2.3. Other Definitions . . . . . . . . . . . . . . . . . . . . . 3 55 3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 3.1. Assertions . . . . . . . . . . . . . . . . . . . . . . . . 3 57 3.2. Response Set Extensions . . . . . . . . . . . . . . . . . . 4 58 3.3. Query Extensions . . . . . . . . . . . . . . . . . . . . . 5 59 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 60 4.1. Registration of 'email-id' Reputation Application . . . . . 5 61 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 62 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 63 6.1. Normative References . . . . . . . . . . . . . . . . . . . 6 64 6.2. Informative References . . . . . . . . . . . . . . . . . . 7 65 Appendix A. Positive vs. Negative Assertions . . . . . . . . . . . 7 66 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 8 67 Appendix C. Public Discussion . . . . . . . . . . . . . . . . . . 8 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 70 1. Introduction 72 This document specifies a response set for describing reputation of 73 an email identifier. A "response set" in this context is defined in 74 [I-D.REPUTE-MODEL] and is used to describe assertions a reputation 75 service provider can make about email identifiers as well as meta- 76 data that can be included in such a reply beyond the base set 77 specified there. 79 An atomic reputation response is called a "reputon", defined in 80 [I-D.REPUTE-MEDIA-TYPE]. That document also defines a media type to 81 contain a reputon for transport, and also creates a registry for 82 reputation applications and the interesting parameters of each. 84 2. Terminology and Definitions 86 This section defines terms used in the rest of the document. 88 2.1. Key Words 90 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 91 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 92 document are to be interpreted as described in [KEYWORDS]. 94 2.2. Email Definitions 96 Commonly used definitions describing entities in the email 97 architecture are defined and discussed in [EMAIL-ARCH]. 99 2.3. Other Definitions 101 Other terms of importance in this document are defined in 102 [I-D.REPUTE-MODEL], the base document for the reputation services 103 work. 105 3. Discussion 107 The expression of reputation about an email identifier requires 108 extensions of the base set defined in [I-D.REPUTE-MODEL]. This 109 document defines and registers some common assertions about an entity 110 found in a piece of [MAIL]. 112 3.1. Assertions 114 The "email-id" reputation application recognizes the following 115 assertions: 117 abusive: The subject identifier is associated with sending or 118 handling > email of a personally abusive, threatening, or 119 otherwise harassing nature. 121 fraud: The subject identifier is associated with sending or handling 122 of fraudulent email, such as "phishing" (some good discussion on 123 this topic can be found in [IODEF-PHISHING]) 125 invalid-recipients: The subject identifier is associated with 126 delivery attempts to nonexistent recipients 128 malware: The subject identifier is associated with the sending or 129 handling of malware via email 131 spam: The subject identifier is associated with sending or handling 132 of unwanted bulk email 134 For all assertions, the "rating" scale is linear: A value of 0.0 135 means there is no data to support the assertion, a value of 1.0 means 136 all accumulated data support the assertion, and the intervening 137 values have a linear relationship (i.e., a score of "x" is twice as 138 strong of an assertion as a value of "x/2"). 140 3.2. Response Set Extensions 142 The "email-id" reputation application recognizes the following 143 OPTIONAL extensions to the basic response set defined in 144 [I-D.REPUTE-MEDIA-TYPE]: 146 identity: A token indicating the source of the identifier; that is, 147 where the subject identifier was found in the message. This MUST 148 be one of: 150 dkim: The signing domain, i.e. the value of the "d=" tag, found 151 on a valid [DKIM] signature in the message 153 ipv4: The IPv4 address of the client 155 ipv6: The IPv6 address of the client 157 rfc5321.helo: The RFC5321.Helo value used by the (see [SMTP]) 158 client 160 rfc5321.mailfrom: The RFC5321.MailFrom value of the envelope of 161 the message (see [SMTP]) 163 rfc5322.from: The RFC5322.From field of the message (see [MAIL]) 165 spf: The domain name portion of the identifier (RFC5321.MailFrom 166 or RFC5321.Helo) verified by [SPF]) 168 sources: A token relating a count of the number of sources of data 169 that contributed to the reported reputation. This is in contrast 170 to the "sample-size" parameter, which indicates the total number 171 of reports across all reporting sources. 173 A reply that does not contain the "identity" or "sources" extensions 174 is making a non-specific statement about how the reputation returned 175 was developed. A client can use or ignore such a reply at its 176 discretion. 178 3.3. Query Extensions 180 A query within this application can include the OPTIONAL query 181 parameter "identity" to indicate which specific identity is of 182 interest to the query. Legal values are the same as those listed in 183 Section 3.2. 185 4. IANA Considerations 187 This memo presents one action for IANA, namely the registration of 188 the reputation application "email-id". 190 4.1. Registration of 'email-id' Reputation Application 192 This section registers the "email-id" reputation application, as per 193 the IANA Considerations section of [I-D.REPUTE-MEDIA-TYPE]. The 194 registration parameters are as folows: 196 o Application name: email-id 198 o Short description: Evaluates DNS domain names or IP addresses 199 found in email identifiers 201 o Defining document: [this document] 203 o Status: current 205 o Subject: A string appropriate to the identifier of interest (see 206 Section 3.2 of this document) 208 o Application-specific query parameters: 210 identity: (current) as defined in Section 3.3 of this document 212 o Application-specific assertions: 214 abusive: (current) as defined in Section 3.1 of this document 216 fraud: (current) as defined in Section 3.1 of this document 218 invalid-recipients: (current) as defined in Section 3.1 of this 219 document 221 malware: (current) as defined in Section 3.1 of this document 223 spam: (current) as defined in Section 3.1 of this document 225 o Application-specific response set extensions: 227 identity: (current) as defined in Section 3.2 of this document 229 5. Security Considerations 231 This document is primarily an IANA action and doesn't describe any 232 protocols or protocol elements that might introduce new security 233 concerns. 235 Security considerations relevant to email and email authentication 236 can be found in most of the documents listed in the References 237 sections below. Information specific to use of reputation services 238 can be found in [I-D.REPUTE-CONSIDERATIONS]. 240 6. References 242 6.1. Normative References 244 [DKIM] Crocker, D., Ed., Hansen, T., Ed., and M. Kucherawy, Ed., 245 "DomainKeys Identified Mail (DKIM) Signatures", RFC 6376, 246 September 2011. 248 [EMAIL-ARCH] 249 Crocker, D., "Internet Mail Architecture", RFC 5598, 250 July 2009. 252 [I-D.REPUTE-MEDIA-TYPE] 253 Borenstein, N. and M. Kucherawy, "A Media Type for 254 Reputation Interchange", draft-ietf-repute-media-type 255 (work in progress), November 2012. 257 [I-D.REPUTE-MODEL] 258 Borenstein, N. and M. Kucherawy, "A Model for Reputation 259 Reporting", draft-ietf-repute-model (work in progress), 260 November 2012. 262 [KEYWORDS] 263 Bradner, S., "Key words for use in RFCs to Indicate 264 Requirement Levels", BCP 14, RFC 2119, March 1997. 266 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 267 October 2008. 269 [SPF] Wong, M. and W. Schlitt, "Sender Policy Framework (SPF) 270 for Authorizing Use of Domains in E-Mail, Version 1", 271 RFC 4408, April 2006. 273 6.2. Informative References 275 [I-D.REPUTE-CONSIDERATIONS] 276 Kucherawy, M., "Operational Considerations Regarding 277 Reputation Services", draft-ietf-repute-considerations 278 (work in progress), November 2012. 280 [IODEF-PHISHING] 281 Cain, P. and D. Jevans, "Extensions to the IODEF-Document 282 Class for Reporting Phishing", RFC 5901, July 2010. 284 [MAIL] Resnick, P., Ed., "Internet Message Format", RFC 5322, 285 October 2008. 287 Appendix A. Positive vs. Negative Assertions 289 [I-D.REPUTE-CONSIDERATIONS] some current theories about reputation, 290 namely that it is possibly more impactful to develop positive 291 reputations and focus on giving preferential treatment to content or 292 sources that earn those. However, the assertions defined in this 293 document are all clearly negative in nature. 295 In effect, this document is recording current use of reputation and 296 of this framework in particular. It is expected that, in the future, 297 the application being registered here will be augmented, and other 298 applications registered, that focus more on positive assertions 299 rather than negative ones. 301 Appendix B. Acknowledgments 303 The authors wish to acknowledge the contributions of the following to 304 this specification: Scott Hollenbeck, Scott Kitterman, Peter Koch, 305 John Levine, Danny McPherson, S. Moonesamy, Doug Otis, and David F. 306 Skoll. 308 Appendix C. Public Discussion 310 Public discussion of this suite of memos takes place on the 311 domainrep@ietf.org mailing list. See 312 https://www.ietf.org/mailman/listinfo/domainrep. 314 Authors' Addresses 316 Nathaniel Borenstein 317 Mimecast 318 203 Crescent St., Suite 303 319 Waltham, MA 02453 320 USA 322 Phone: +1 781 996 5340 323 Email: nsb@guppylake.com 325 Murray S. Kucherawy 326 270 Upland Drive 327 San Francisco, CA 94127 328 USA 330 Email: superuser@gmail.com