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. 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 and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 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. Josefsson Expires May 25, 2001 [Page 1] Internet-Draft DNS URL scheme November 2000 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 Josefsson Expires May 25, 2001 [Page 2] Internet-Draft DNS URL scheme November 2000 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 Josefsson Expires May 25, 2001 [Page 3] Internet-Draft DNS URL scheme November 2000 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. Josefsson Expires May 25, 2001 [Page 4] Internet-Draft DNS URL scheme November 2000 Author's Address Simon Josefsson RSA Security Arenav„gen 29 Stockholm 121 29 Sweden Phone: +46 8 7250914 EMail: sjosefsson@rsasecurity.com Josefsson Expires May 25, 2001 [Page 5] Internet-Draft DNS URL scheme November 2000 Full Copyright Statement Copyright (C) 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. Josefsson Expires May 25, 2001 [Page 6]