Request for Comments: 4143
Category: Standards Track
Facsimile Using Internet Mail (IFAX) Service of ENUM
Status of This Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright © The Internet Society (2005).
This document describes the functional specification and definition of the ENUM Naming Authority Pointer (NAPTR) record for IFax service. IFax is "facsimile using Internet mail". For this use, the Domain Name System (DNS) returns the email address of the referenced IFax system. This mechanism allows email-based fax communication to use telephone numbers instead of requiring the sender to already know the recipient email address.
1. Functional Specification
An IFax client makes a [ENUMbis] DNS query, using the target system's telephone number. The returned NAPTR record specifies an email address to be used for reaching the target system. The email address is then used in accordance with Simple Mode of Facsimile using Internet Mail [RFC3965], Extended Facsimile using Internet Mail [RFC2532], or Full Mode Fax Profile for Internet Mail [FFPIM] is applied.
The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as defined in "Key words for use in RFCs to Indicate Requirement Levels" [KEYWORDS].
2. IFax Service Registration
Service Name : "E2U+ifax"
URI Scheme: "mailto"
The URI Scheme is "mailto" because facsimile is a profile of standard Internet mail and uses standard Internet mail addressing.
Functional Specification: See section 1
Security Considerations: See section 3
Intended usage: COMMON Author: Kiyoshi Toyoda (email@example.com) Dave Crocker (firstname.lastname@example.org)
3. Security Considerations
DNS, as used by ENUM, is a globally distributed database. Thus, any information stored in it is visible to anyone anonymously. Although this is not qualitatively different from publication in a telephone directory, it does expose the data subject to automatic data collection without any indication that this has been done or by whom.
Data harvesting by third parties is often used to generate lists of targets for unrequested information; in short, the lists are used to address "spam". The publication of a telephone number in ENUM, especially when it is an associated Internet fax service, may be used to send "junk faxes", for example.
In the case of electronic mail, users subscribed to mailing lists can have "sacrificial" email accounts. These special-purpose addresses help the user filter out unrequested email. This is not so easy with published telephone numbers. The PSTN E.164 number assignment process is much more involved and less flexible; usually a single E.164 number (or a fixed range of numbers) is associated with each PSTN access. Thus, it is not possible to use a "sacrificial" phone number.
Due to the implications of publishing data in a globally accessible database, as a principle, the data subject MUST give explicit informed consent to data being published in ENUM.
In addition to the specific security considerations given above, the Security Considerations section of [ENUMbis] applies to this document.
The following is an example of the use of IFax service in a NAPTR record.
$ORIGIN 188.8.131.52.184.108.40.206.6.4.e164.arpa IN NAPTR 10 10 "u" "E2U+ifax:mailto" "!^.*$!mailto:email@example.com!"
5. IANA Considerations
This specification creates a DNS NAPTR registration, according to the terms specified in [ENUMbis].
The registration details are contained in section 2, Fax Service Registration.
6.1. Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [ENUMbis] Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation Discovery System (DDDS) Application (ENUM)", RFC 3761, April 2004. [RFC3965] Toyoda, K., Ohno, H., Murai, J., and D. Wing, "A Simple Mode of Facsimile Using Internet Mail", RFC 3965, December 2004. [RFC2532] Masinter, L. and D. Wing, " Extended Facsimile Using Internet Mail", RFC 2532, March 1999. [FFPIM] Crocker, D. and G. Klyne, "Full-mode Fax Profile for Internet Mail (FFPIM)", RFC 4142, November 2005.
Kiyoshi Toyoda Research and Development Laboratory Panasonic Communications Co., Ltd. 4-1-62 Minoshima Hakata-ku, Fukuoka 812-8531 Japan Phone: +81-50-3380-5181 EMail: firstname.lastname@example.org Dave Crocker Brandenburg InternetWorking 675 Spruce Drive Sunnyvale, CA 94086 USA Phone: +1.408.246.8253 EMail: email@example.com
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