ENUM WG                                                          R. Mahy
Internet-Draft                                               Plantronics
Expires: September 23, 2006                               March 22, 2006


   A Telephone Number Mapping (ENUM) Service Registration for Instant
                        Messaging (IM) Services
                   draft-ietf-enum-im-service-00.txt

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Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document registers a Telephone Number Mapping (ENUM) service for
   Instant Messaging (IM).  Specifically, this document focuses on
   provisioning im: URIs in ENUM.

1.  Discussion

   ENUM (E.164 Number Mapping, RFC 3761 [1]) is a system that uses DNS
   (Domain Name Service, RFC 1034 [2]) to translate telephone numbers,



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   such as +12025332600, into URIs (Uniform Resource Identifiers, RFC
   2396 [3]), such as im:user@example.com.  ENUM exists primarily to
   facilitate the interconnection of systems that rely on telephone
   numbers with those that use URIs to identify resources.

   Instant Messaging (IM) is a service defined in RFC 2778 [5] that
   allows users to send and receive typically short, often textual
   messages in near real-time.  The IETF has defined a generic URI used
   to identify an IM service for a particular resource: the 'im' URI
   scheme (defined in RFC 3861 [4]).  RFC 3861 [4] also defines rules
   for discovering service running specific protocols, such as SIP (the
   Session Initiation Protocol, RFC 3261 [7]) and XMPP (the eXtensible
   Messaging and Presence Protocol, RFC 3921 [8]) from a specific im:
   URI.

   RFC 3953 [9] already defines an enumservice for presence services
   which returns pres: URIs (also defined in RFC 3861 [4]).  This
   document registers an enumservice for advertising IM information
   associated with an E.164 number.

2.  ENUM Service Registration

   As defined in RFC 3761 [1], the following is a template covering
   information needed for the registration of the enumservice specified
   in this document:
   Service name: "E2U+im"
   URI scheme(s): "im:"
   Functional Specification: This Enumservice indicates that the
      resource identified is an 'im' URI.  The 'im' URI scheme does not
      identify any particular protocol that will be used to handle
      instant messaging receipt or delivery, rather the mechanism in RFC
      3861 [4] is used to discover whether an IM protocol supported by
      the party querying ENUM is also supported by the target resource.
   Security considerations: See section 3.
   Intended usage: COMMON
   Author: Rohan Mahy (rohan@ekabal.com)

3.  Security Considerations

   The Domain Name System (DNS) does not make policy decisions about
   which records it provides to a DNS resolver.  All DNS records must be
   assumed to be available to all inquirers at all times.  The
   information provided within an ENUM record set must therefore be
   considered open to the public -- which is a cause for some privacy
   considerations.

   Revealing an IM URI by itself is unlikely to introduce many privacy
   concerns, although, depending on the structure of the URI, it might



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   reveal the full name or employer of the target.  The use of anonymous
   URIs mitigates this risk.

   More serious security concerns are associated with potential attacks
   against an underlying Instant Messaging system (for example, message
   forgery and tampering).  For this reason, IM protocols have a number
   of security requirements (detailed in RFC 2779 [6]) that call for
   authentication, integrity and confidentiality properties, and similar
   measures to prevent such attacks.  Any instant messaging protocol
   used in conjunction with the 'im' URI scheme is required to meet
   these requirements.

   Unlike a traditional telephone number, the resource identified by an
   im URI may require that callers provide cryptographic credentials for
   authentication and authorization before instant messages are
   exchanged.  In concert with instant messaging protocols, ENUM can
   actually provide far greater protection from unwanted callers than
   does the existing PSTN, despite the public availability of ENUM
   records.

4.  IANA Considerations

   This document requests registration of the "IM" Enumservice according
   to the definitions in this document and RFC 3761 [1].

5.  References

5.1  Normative References

   [1]  Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource
        Identifiers (URI) Dynamic Delegation Discovery System (DDDS)
        Application (ENUM)", RFC 3761, April 2004.

   [2]  Mockapetris, P., "Domain names - concepts and facilities",
        STD 13, RFC 1034, November 1987.

   [3]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
        Resource Identifiers (URI): Generic Syntax", RFC 2396,
        August 1998.

   [4]  Peterson, J., "Address Resolution for Instant Messaging and
        Presence", RFC 3861, August 2004.

5.2  Informational References

   [5]  Day, M., Rosenberg, J., and H. Sugano, "A Model for Presence and
        Instant Messaging", RFC 2778, February 2000.




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   [6]  Day, M., Aggarwal, S., Mohr, G., and J. Vincent, "Instant
        Messaging / Presence Protocol Requirements", RFC 2779,
        February 2000.

   [7]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
        Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
        Session Initiation Protocol", RFC 3261, June 2002.

   [8]  Saint-Andre, P., Ed., "Extensible Messaging and Presence
        Protocol (XMPP): Instant Messaging and Presence", RFC 3921,
        October 2004.

   [9]  Peterson, J., "Telephone Number Mapping (ENUM) Service
        Registration for Presence Services", RFC 3953, January 2005.


Author's Address

   Rohan Mahy
   Plantronics

   Email: rohan@ekabal.com





























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