Network Working Group                                       S. Josefsson
Internet-Draft                                              RSA Security
Expires: May 25, 2001                                  November 24, 2000


                             DNS URL scheme
                      draft-josefsson-dns-url-00.txt

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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   This Internet-Draft will expire on May 25, 2001.

Copyright Notice

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

Abstract

   This draft describe a URL scheme for DNS resources.














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Table of Contents

   1. Introduction and background  . . . . . . . . . . . . . . . . . . 3
   2. DNS URL Scheme . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3. Character encoding considerations  . . . . . . . . . . . . . . . 3
   4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   5. DNS URL scheme BNF definition  . . . . . . . . . . . . . . . . . 4
   6. Security Considerations  . . . . . . . . . . . . . . . . . . . . 4
      References . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
      Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
      Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 6








































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1. Introduction and background

   DNS [1][2] is a widely deployed protocol used to, among other
   things, translate domain names into IP addresses.  More recent work
   has added support for storing certificates in DNS [5].  To be able
   to locate certificates available via network resources, URLs are
   often used.  To be able to reference certificates stored in DNS by a
   URL, a DNS URL scheme is required. The DNS URL scheme described here
   can be used to reference any DNS resource record, not only
   certificates.

   This memo is known to be incomplete and perhaps lack some of the
   background research required to properly define a new URL scheme.
   Especially the BNF should not be regarded as cast in stone.

2. DNS URL Scheme

   A DNS URL designate a DNS resource record; by domain name, type and
   class and optionally server.  The DNS URL follow the generic syntax
   from RFC 2396 [4], and is described using ABNF [3] in section 5.

   A DNS URL is of the following general form.  This is intended to
   illustrate, not define, the scheme.

   dns:[//server/]domain;type=TYPE[;class=CLASS]

   Unless specified, the "server" is assumed to be locally configured,
   and "class" to be the Internet class ("IN").

3. Character encoding considerations

   Since 8-bit characters are not permitted in URLs, they must be
   encoded as per the "URI Generic Syntax" RFC.  The character set
   issue should be dealt with in this section, but awaits the outcome
   of the IDN work group.

4. Examples

   This illustrate a DNS query for "www.example.org" for the Internet
   class and the Address type:

   dns:www.example.org;class=IN;type=A

   This illustrate a DNS query for "simon.example.org" for the CERT
   type in the Internet class:

   dns:simon.example.org;type=CERT

   This illustrate a DNS query for "ftp.example.org" from the DNS


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   server "internal-dns.example.org" server, and the address type:

   dns://internal-dns.example.org/ftp.example.org;type=A

5. DNS URL scheme BNF definition

   Strings are not case sensitive and free insertion of
   linear-white-space is not permitted.

   dnsurl       = "dns:" [ "//" hostport "/" ] hostname
                  ";TYPE=" type [";TYPE=" class]
                                ; See RFC 2396 for "hostport" and
                                ; "hostname" definition

   type         = "A" / "NS" / "MD" / ...
                                ; Any standard DNS type

   class        = "IN" / "CH" / ...
                                ; Any standard DNS class

6. Security Considerations

   A DNS URL does not embed confidential information.  If used to
   encode domain names in the Internet DNS environment, even the
   information retrieved is public.  If a DNS URL is used within a
   "internal" DNS environment, the same security considerations of the
   DNS environment apply to the use and handling of DNS URLs themselves
   and the data returned by looking up these URLs.

   This draft does not affect the security considerations related to
   DNS itself.

References

   [1]  Mockapetris, P., "Domain Names - Concepts and Facilities", RFC
        1034, November 1987.

   [2]  Mockapetris, P., "Domain Names - Implementation and
        Specification", RFC 1035, November 1987.

   [3]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
        Specifications: ABNF", RFC 2234, November 1997.

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

   [5]  Eastlake, D. and O. Gudmundsson, "Storing Certificates in the
        Domain Name System (DNS)", RFC 2538, March 1999.


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Author's Address

   Simon Josefsson
   RSA Security
   Arenav¬Ągen 29
   Stockholm  121 29
   Sweden

   Phone: +46 8 7250914
   EMail: sjosefsson@rsasecurity.com









































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Full Copyright Statement

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

   This document and translations of it may be copied and furnished to
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Acknowledgement

   Funding for the RFC editor function is currently provided by the
   Internet Society.



















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