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IETF RFC 2825

A Tangled Web: Issues of I18N, Domain Names, and the Other Internet protocols

Last modified on Wednesday, May 10th, 2000

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Network Working Group                  Internet Architecture Board (IAB)
Request for Comments: 2825                             L. Daigle, Editor
Category: Informational                                       May 2000


         A Tangled Web: Issues of I18N, Domain Names, and the
                        Other Internet protocols

 Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

 Copyright Notice

   Copyright © The Internet Society (2000).  All Rights Reserved.

 Abstract

   The goals of the work to "internationalize" Internet protocols
   include providing all users of the Internet with the capability of
   using their own language and its standard character set to express
   themselves, write names, and to navigate the network. This impacts
   the domain names visible in e-mail addresses and so many of today's
   URLs used to locate information on the World Wide Web, etc.  However,
   domain names are used by Internet protocols that are used across
   national boundaries. These services must interoperate worldwide, or
   we risk isolating components of the network from each other along
   locale boundaries.  This type of isolation could impede not only
   communications among people, but opportunities of the areas involved
   to participate effectively in e-commerce, distance learning, and
   other activities at an international scale, thereby retarding
   economic development.

   There are several proposals for internationalizing domain names,
   however it it is still to be determined whether any of them will
   ensure this interoperability and global reach while addressing
   visible-name representation.  Some of them obviously do not. This
   document does not attempt to review any specific proposals, as that
   is the work of the Internationalized Domain Name (IDN) Working Group
   of the IETF, which is tasked with evaluating them in consideration of
   the continued global network interoperation that is the deserved
   expectation of all Internet users.







IAB                          Informational                   PAGE 1 top


RFC 2825 Issues: I18N, Domain Names, and Internet Protocols May 2000 This document is a statement by the Internet Architecture Board. It is not a protocol specification, but an attempt to clarify the range of architectural issues that the internationalization of domain names faces. 1. A Definition of Success The Internationalized Domain Names (IDN) Working Group is one component of the IETF's continuing comprehensive effort to internationalize language representation facilities in the protocols that support the global functioning of the Internet. In keeping with the principles of rough consensus, running code, architectural integrity, and in the interest of ensuring the global stability of the Internet, the IAB emphasizes that all solutions proposed to the (IDN) Working Group will have to be evaluated not only on their individual technical features, but also in terms of impact on existing standards and operations of the Internet and the total effect for end-users: solutions must not cause users to become more isolated from their global neighbors even if they appear to solve a local problem. In some cases, existing protocols have limitations on allowable characters, and in other cases implementations of protocols used in the core of the Internet (beyond individual organizations) have in practice not implemented all the requisite options of the standards. 2. Technical Challenges within the Domain Name System (DNS) In many technical respects, the IDN work is not different from any other effort to enable multiple character set representations in textual elements that were traditionally restricted to English language characters. One aspect of the challenge is to decide how to represent the names users want in the DNS in a way that is clear, technically feasible, and ensures that a name always means the same thing. Several proposals have been suggested to address these issues. These issues are being outlined in more detail in the IDN WG's evolving draft requirements document; further discussion is deferred to the WG and its documents. 3. Integrating with Current Realities Nevertheless, issues faced by the IDN working group are complex and intricately intertwined with other operational components of the Internet. A key challenge in evaluating any proposed solution is the analysis of the impact on existing critical operational standards IAB Informational PAGE 2 top

RFC 2825 Issues: I18N, Domain Names, and Internet Protocols May 2000 which use fully-qualified domain names [RFC 1034], or simply host names [RFC 1123]. Standards-changes can be effected, but the best path forward is one that takes into account current realities and (re)deployment latencies. In the Internet's global context, it is not enough to update a few isolated systems, or even most of the systems in a country or region. Deployment must be nearly universal in order to avoid the creation of "islands" of interoperation that provide users with less access to and connection from the rest of the world. These are not esoteric or ephemeral concerns. Some specific issues have already been identified as part of the IDN WG's efforts. These include (but are not limited to) the following examples. 3.1 Domain Names and E-mail As indicated in the IDN WG's draft requirements document, the issue goes beyond standardization of DNS usage. Electronic mail has long been one of the most-used and most important applications of the Internet. Internet e-mail is also used as the bridge that permits the users of a variety of local and proprietary mail systems to communicate. The standard protocols that define its use (e.g., SMTP [RFC 821, RFC 822] and MIME [RFC 2045]) do not permit the full range of characters allowed in the DNS specification. Certain characters are not allowed in e-mail address domain portions of these specifications. Some mailers, built to adhere to these specifications, are known to fail when on mail having non-ASCII domain names in its address -- by discarding, misrouting or damaging the mail. Thus, it's not possible to simply switch to internationalized domain names and expect global e-mail to continue to work until most of the servers in the world are upgraded. 3.2 Domain Names and Routing At a lower level, the Routing Policy Specification Language (RPLS) [RFC 2622] makes use of "named objects" -- and inherits object naming restrictions from older standards ([RFC 822] for the same e-mail address restrictions, [RFC 1034] for hostnames). This means that until routing registries and their protocols are updated, it is not possible to enter or retrieve network descriptions utilizing internationalized domain names. 3.3 Domain Names and Network Management Also, the Simple Network Management Protocol (SNMP) uses the textual representation defined in [RFC 2579]. While that specification does allow for UTF-8-based domain names, an informal survey of deployed implementations of software libraries being used to build SNMP- compliant software uncovered the fact that few (if any) implement it. IAB Informational PAGE 3 top

RFC 2825 Issues: I18N, Domain Names, and Internet Protocols May 2000 This may cause inability to enter or display correct data in network management tools, if such names are internationalized domain names. 3.4 Domain Names and Security Critical components of Internet public key technologies (PKIX, [RFC 2459], IKE [RFC 2409]) rely heavily on identification of servers (hostnames, or fully qualified domain names) and users (e-mail addresses). Failure to respect the character restrictions in these protocols will impact security tools built to use them -- Transport Layer Security protocol (TLS, [RFC 2246]), and IPsec [RFC 2401] to name two. Failure may not be obvious. For example, in TLS, it is common usage for a server to display a certificate containing a domain name purporting to be the domain name of the server, which the client can then match with the server name he thought he used to reach the service. Unless comparison of domain names is properly defined, the client may either fail to match the domain name of a legitimate server, or match incorrectly the domain name of a server performing a man-in-the- middle attack. Either failure could enable attacks on systems that are now impossible or at least far more difficult. 4. Conclusion It is therefore clear that, although there are many possible ways to assign internationalized names that are compatible with today's DNS (or a version that is easily-deployable in the near future), not all of them are compatible with the full range of necessary networking tools. When designing a solution for internationalization of domain names, the effects on the current Internet must be carefully evaluated. Some types of solutions proposed would, if put into effect immediately, cause Internet communications to fail in ways that would be hard to detect by and pose problems for those who deploy the new services, but also for those who do not; this would have the effect of cutting those who deploy them off from effective use of the Internet. The IDN WG has been identified as the appropriate forum for identifying and discussing solutions for such potential interoperability issues. Experience with deployment of other protocols has indicated that it will take years before a new protocol or enhancement is used all over the Internet. So far, the IDN WG has benefited from proposed solutions from all quarters, including organizations hoping to IAB Informational PAGE 4 top

RFC 2825 Issues: I18N, Domain Names, and Internet Protocols May 2000 provide services that address visible-name representation and registration -- continuing this process with the aim of getting a single, scalable and deployable solution to this problem is the only way to ensure the continued global interoperation that is the deserved expectation of all Internet users. 5. Security Considerations In general, assignment and use of names does not raise any special security problems. However, as noted above, some existing security mechanisms are reliant on the current specification of domain names and may not be expected to work, as is, with Internationalized domain names. Additionally, deployment of non-standard systems (e.g., in response to current pressures to address national or regional characterset representation) might result in name strings that are not globally unique, thereby opening up the possibility of "spoofing" hosts from one domain in another, as described in [RFC 2826]. 6. Acknowledgements This document is the outcome of the joint effort of the members of the IAB. Additionally, valuable remarks were provided by Randy Bush, Patrik Faltstrom, Ted Hardie, Paul Hoffman, and Mark Kosters. 7. References [RFC 821] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821, August 1982. [RFC 822] Crocker, D., "Standard for the Format of ARPA Internet Text Messages", STD 11, RFC 822, August 1982. [RFC 1034] Mockapetris, P., "Domain Names - Concepts and Facilities", STD 13, RFC 1034, November 1987. [RFC 1123] Braden, R., "Requirements for Internet Hosts -- Application and Support", STD 3, RFC 1123, November 1989. [RFC 2401] Kent, S. and R. Atkinson, "Security Architecture for the Internet Protocol", RFC 2401, November 1998. [RFC 2409] Harkins, D and D. Carrel, "The Internet Key Exchange (IKE)", RFC 2409, November 1998. [RFC 2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996. IAB Informational PAGE 5 top

RFC 2825 Issues: I18N, Domain Names, and Internet Protocols May 2000 [RFC 2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. [RFC 2459] Housley, R., Ford, W., Polk, W. and D. Solo, "Internet X.509 Public Key Infrastructure Certificate and CRL Profile", RFC 2459, January 1999. [RFC 2579] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J. and M. Rose, "Textual Conventions for SMIv2", RFC 2579, April 1999. [RFC 2622] Alaettinoglu, C., Villamizar, C., Gerich, E., Kessens, D., Meyer, D., Bates, T., Karrenberg, D. and M. Terpstra, "Routing Policy Specification Language (RPSL)", RFC 2622, June 1999. [RFC 2826] IAB, "IAB Technical Comment on the Unique DNS Root", RFC 2826, May 2000. 8. Author's Address Internet Architecture Board EMail: iab@iab.org Membership at time this document was completed: Harald Alvestrand Ran Atkinson Rob Austein Brian Carpenter Steve Bellovin Jon Crowcroft Leslie Daigle Steve Deering Tony Hain Geoff Huston John Klensin Henning Schulzrinne IAB Informational PAGE 6 top

RFC 2825 Issues: I18N, Domain Names, and Internet Protocols May 2000 9. Full Copyright Statement Copyright © The Internet Society (2000). 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 implementation 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. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. IAB Informational PAGE 7 top

A Tangled Web: Issues of I18N, Domain Names, and the Other Internet protocols RFC TOTAL SIZE: 15612 bytes PUBLICATION DATE: Wednesday, May 10th, 2000 LEGAL RIGHTS: The IETF Trust (see BCP 78)


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