Minimal PSTN address format in Internet Mail
draft-ietf-fax-minaddrgen-01
The information below is for an old version of the document that is already published as an RFC.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 2303.
|
|
---|---|---|---|
Author | Claudio Allocchio | ||
Last updated | 2013-03-02 (Latest revision 1998-01-06) | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Intended RFC status | Proposed Standard | ||
Formats | |||
Additional resources | Mailing list discussion | ||
Stream | WG state | (None) | |
Document shepherd | (None) | ||
IESG | IESG state | Became RFC 2303 (Proposed Standard) | |
Consensus boilerplate | Unknown | ||
Telechat date | (None) | ||
Responsible AD | (None) | ||
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draft-ietf-fax-minaddrgen-01
Network Working Group C. Allocchio
INTERNET-DRAFT GARR-Italy
Expires: June 1998 December 1997
Minimal PSTN address format in Internet Mail
(draft-ietf-fax-minaddrgen-01.txt)
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts. Internet Drafts are draft
documents valid for a maximum of six months. Internet Drafts may be
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not appropriate to use Internet Drafts as reference material or to
cite them other than as a ``working draft'' or ``work in progress.''
Please check the I-D abstract listing contained in each Internet Draft
directory to learn the current status of this or any other Internet
Draft.
1. Introduction
Since the very first e-mail to PSTN services gateway appeared, a
number of different methods to specify a PSTN address as an e-mail
address have been used by implementors. Two major objectives for
this were
- enable an e-mail user to access these services from his/her
e-mail interface;
- enable some kind of ''PSTN over e-mail service'' transport, to
reduce the costs of PSTN long distance transmissions, and use
the existing e-mail infrastructure.
This memo describes the MINIMAL addressing method to encode PSTN
addresses into e-mail addresses and the standard extension mechanism
to allow definition of further standard elements. The opposite problem,
i.e. to allow a traditional numeric-only PSTN device user to access
the e-mail transport service, is not discussed here.
All implementations supporting this PSTN over e-mail service MUST
support as a minimum the specification described in this document.
The generic complex case of converting the whole PSTN addressing
into e-mail is out of scope in this minimal specification: there
is some work in progress in the field, where also a number of
standard optional extensions are being defined.
In this document the formal definitions are described using ABNF
syntax, as defined into [7]. We will also use some of the ''CORE
DEFINITIONS'' defined in ''APPENDIX A - CORE'' of that document. The
exact meaning of the capitalised words
"MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "MAY", "OPTIONAL"
is defined in reference [6].
2. Minimal PSTN address
The minimal specification of a PSTN address in e-mail address is
as follows:
pstn-address = pstn-mbox [ qualif-type1 ]
pstn-mbox = service-selector "=" global-phone
service-selector = 1*( DIGIT / ALPHA / "-" )
; note that SP (space) is not allowed in
; service-selector.
; service-selector MUST be handled as a case
; INSENSITIVE string by implementations.
Specifications adopting the "pstn-address" definition MUST define a
unique case insensitive "service-selector" element to identify the
specific messaging service involved.
These specifications MUST also define which minimal "qualif-type1"
extensions, if any, MUST be supported for the specified service.
Implementations confirming to these minimal requirements specification
are allowed to ingnore any other non-minimal extensions address
element which can be present in the "pstn-address". However, conforming
implementations MUST preserve all "qualif-type1" address elements they
receive.
The generic "qualif-type1" element is defined as:
qualif-type1 = "/" keyword "=" string
keyword = 1*( DIGIT / ALPHA / "-" )
; note that SP (space) is not allowed in keyword
string = PCHAR
; note that printable characters are %x20-7E
As such, all "pstn-address" extensions elements MUST be defined in the
"qualif-type1" form.
2.1 Minimal "global-phone" definition
We now define the minimal supported syntax for global-phone:
global-phone = "+" 1*( DIGIT , written-sep )
written-sep = ( "-" / "." )
The use of other dialling schemas for PSTN numbers (like private
numbering plans or local dialling conventions) is also allowed.
However, this does not preclude nor remove the minimal compulsory
requirement to support the "global-phone" syntax as defined above.
Any non "global-phone" dialling schema MUST NOT use the leading
"+" between the "=" sign and the dialling string. The "+" sign is
strictly reserved for the standard "global-phone" syntax.
Note:
The specification of these different dialling schemas is out of scope
for this minimal specification.
User specification of PSTN e-mail addresses will be facilitated if
they can insert these separators between dial elements like digits etc.
For this reason we allow them in the syntax the written-sep element.
Implementors' note:
Use of the written-sep elements is allowed, but not recommended. Any
occurences of written-sep elements in a pstn-mbox MUST be ignored by
all conformant implementations. User Agents SHOULD remove written-sep
elements before submitting messages to the Message Transport System.
2.2 Some examples of a minimal "pstn-address"
VOICE=+3940226338
FAX=+12027653000/T33S=6377
SMS=+33-1-88335215
3. The e-mail address of the I-pstn device: mta-I-pstn
An "I-pstn device" has an e-mail address, or to be more exact, a
name which enables a mail system to identify it on the e-mail
global system.
In Internet mail, this is the Right Hand Side (RHS) part of the
address, i.e. the part on the right of the "@" sign. We will call
this "mta-I-pstn"
mta-I-pstn = domain
For "domain" strings used in SMTP transmissions, the string MUST conform
to the requirements of that standard's <domain> specifications [1], [3]
and their updates. For "domain" strings used in message content headers,
the string MUST conform to the requirements of the relevant standards [2],
[3] and their updates.
Note: in both cases, the standards permit use of "domain names" or "domain
literals" in addresses.
4. The pstn-email
The complete structure used to transfer a minimal PSTN address over the
Internet e-mail transport system is called "pstn-email". This object
is a an e-mail address which conforms to RFC822 [2] (and its updates)
"addr-spec" syntax, with some extra structure which allows the PSTN
number to be identified.
pstn-email = ["/"] pstn-address ["/"] "@" mta-I-pstn
Implementors' note:
The optional "/" characters can result from other mail transport
services gateways, where it is also an optional element.
Implementations MUST accept the optional slashes but SHOULD NOT
generate them. Gateways are allowed to strip them off when
converting to Internet mail addressing.
4.1 Multiple subaddresses
In case a particular service requires multiple subaddresses (in any form
defined by the specific standard specification for that service), and
these subaddresses need to be given on the same "pstn-mbox", multiple
"pstn-email" elements will be used.
Implementors' note:
The UA could accept multiple subaddress elements for the same
global-phone, but it must generate multiple "pstn-mbox" elements
when passing the message to the MTA.
4.2 Some examples of "pstn-email"
VOICE=+3940226338@worldvoice.com
FAX=+1.202.7653000/T33S=6377@faxserv.org
/SMS=+33-1-88335215/@telecom.com
5. Conclusions
This proposal creates a minimal standard encoding for PSTN addresses
within the global e-mail transport system and defines the standard
extension mechanism to be used to introduce specific new elements.
The proposal requires no changes to existing e-mail software. Each
specific PSTN service using this proposal MUST define its own
"service-selector" specification and MUST define the eventual other
"qualif-type1" elements to be supported for its minimal addressing
specification. An example is in reference [13].
6. Security Considerations
This document specifies a means by which PSTN addresses can be
encoded into e-mail addresses. As routing of e-mail messages is
determined by Domain Name System (DNS) information, a successful
attack on this service could force the mail path via some particular
gateway or message transfer agent where mail security can be
affected by compromised software.
There are several means by which an attacker might be able to
deliver incorrect mail routing information to a client. These
include: (a) compromise of a DNS server, (b) generating a
counterfeit response to a client's DNS query, (c) returning
incorrect "additional information" in response to an unrelated
query. Clients SHOULD ensure that mail routing is based only
on authoritative answers. Once DNS Security mechanisms [5]
become more widely deployed, clients SHOULD employ those mechanisms
to verify the authenticity and integrity of mail routing records.
7. Copyright
"Copyright (C) The Internet Society (date). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implmentation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be followed,
or as required to translate it into languages other than English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE."
8. Author's Address
Claudio Allocchio
Sincrotrone Trieste
SS 14 Km 163.5 Basovizza
I 34012 Trieste
Italy
RFC822: Claudio.Allocchio@elettra.trieste.it
X.400: C=it;A=garr;P=Trieste;O=Elettra;
S=Allocchio;G=Claudio;
Phone: +39 40 3758523
Fax: +39 40 3758565
9. References
[1] RFC821 Simple Mail Transfer Protocol. J. Postel. (August 1982)
[2] RFC822 Standard for the format of ARPA Internet text messages. D.
Crocker. (August 1982)
[3] RFC1123 Requirements for Internet hosts - application and support. R.T.
Braden. (October 1989)
[4] RFC1528 Principles of Operation for the TPC.INT Subdomain: Remote
Printing -- Technical Procedures. C. Malamud & M. Rose. (October 1993)
[5] RFC2065 Domain Name System Security Extensions. D. Eastlake, 3rd, C.
Kaufman. (January 1997)
[6] RFC2119 Key words for use in RFCs to Indicate Requirement Levels.
S. Bradner (March 1997)
[7] RFC2234 Augmented BNF for Syntax Specifications. D. Crocker,
P. Overell (November 1997).
[8] ITU F.401 - Message Handling Services: Naming and Addressing for Public
Message Handling Service; recommendation F.401 (August 1992)
[9] ITU F.423 - Message Handling Services: Intercommunication Between the
Interpersonal Messaging Service and the Telefax Service; recommendation
F.423 (August 1992)
[10] ITU E.164 - Numbering plan for the ISDN era; recommendation E.164/I.331
(August 1991)
[11] ITU T.33 - Facsimile routing utilizing the subaddress; recommendation
T.33 (July, 1996)
[12] ETSI I-ETS 300,380 - Universal Personal Telecommunication (UPT): Access
Devices Dual Tone Multi Frequency (DTMF) sender for acoustical coupling
to the microphone of a handset telephone (March 1995)
[13] RFCxxxx (DRAFT-IETF-FAX-ADDRMINFAX-xx.TXT) Minimal FAX address format
in Internet Mail. C. Allocchio (xxxx 199x)
[14] RFCxxxx (DRAFT-KILLE-MIXER-RFC1327BIS-xx.TXT) MIXER (Mime Internet
X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIME.
S.E. Kille. (xxxx 199x)