Marcos Sanz Internet Draft DENIC eG Document: draft-sanz-whois-srv-01.txt Gerhard Winkler NIC.AT Expires: January 2005 July 2004 Using DNS SRV records to locate whois servers Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. 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 in January, 2005 Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract Whois servers are used to locate administrative, technical and security contacts for given IP addresses, domain names or other network objects associated with an organisation, e.g. AS numbers. While usually Top Level Domain (TLD) registries run a whois server, there is no generic name for it and it may not even be obvious that the TLD registry's whois server is the right one to ask, since there are TLDs where registration takes place under specialised second level domains (e.g. UK, AT). The Regional Internet Registries (RIR) also provide whois service as part of their coordination task. Sanz & Winkler Expires - January 2005 [Page 1] SRV records to locate whois servers July 2004 All this can be solved by central "master" or "meta" whois servers, which keep track of all new and changing servers and refer to the DNS registries' or RIRs' whois servers. This document proposes a DNS-based approach which eliminates the need for a central master repository and works down to lower levels in the hierarchy. It is the intent to locate a whois server as close to the target (in terms of hierarchy) as possible, while preserving the opportunity to locate higher level servers for escalation purposes. Document Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [2]. Other terms used in this document are defined in the DNS specification RFC-1034 [3]. Table of Contents 1. Format.........................................................2 2. Usage..........................................................3 3. Clarifications.................................................3 4. Registries and Usability.......................................4 5. Authority......................................................4 6. Security Considerations........................................4 7. References.....................................................5 8. Author's Addresses.............................................5 A. Acknowledgments................................................5 B. Intellectual Property and Copyright Statements.................6 1. Format The general format of DNS SRV records is documented in RFC 2782: _Service._Proto.Name TTL Class SRV Priority Weight Port Target Therefore the simplest format of an SRV record to locate a whois server is: _nicname._tcp IN SRV 0 0 43 whois.nic.example. The symbolic name of the service is defined as "nicname" (case insensitive) and the protocol is TCP based, as per RFC 954 [4]. Sanz & Winkler Expires - January 2005 [Page 2] SRV records to locate whois servers July 2004 Priority and Weight have a value of 0 in the example above just for readability purposes. Target and Port (in the example "whois.nic.example." and "43") have to be substituted with the values the administrator has chosen for the whois server. 2. Usage The service record functionality is meant as an extension to the existing whois service and not as a new service. If there is a whois server running for a specific domain, such an SRV record can be defined. When used for looking up information about a domain, whois clients can do DNS lookups for SRV records, and can use the retrieved target information to point their whois queries accordingly. This kind of client is called "SRV-cognizant" or "SRV-aware" whois client. It is imaginable that this functionality could be extended for other purposes (like IP address space allocation), but this remains open for a future discussion. 3. Clarifications The SRV-cognizant whois client MUST NOT modify the domain name to be looked up in the whois server, independently of the domain source of the SRV record. In the absence of a whois protocol whose specification calls for the use of other weighting information, the field Weight in the SRV record keeps the standard meaning specified in [5]. As defined in [5] the client SHOULD abort if it finds a record like: _nicname._tcp IN SRV 0 0 0 . This means the SRV processing SHOULD be aborted at that level, since that record is an explicit statement that the service is not supported there. But nothing avoids the client to search for other SRV records above or below that level. There is no definition of which target should be used by an SRV- cognizant whois client if no whois server could be discovered by means of SRV records. The client MAY try addressing the whois query to "whois". (cf. RFC 2219 [6]). The use of a default whois server is local dependent. Sanz & Winkler Expires - January 2005 [Page 3] SRV records to locate whois servers July 2004 4. Registries and Usablility This concept of using SRV records can be applied for different kinds of registries. These can be Domain Registries and Address Registries as well. There is no distinction between theses two or any limitation for any other kinds as the whois protocol is content independant. One important topic to this are search strategies. They may vary in dependancy of the kind of the registry. This is due to different delegation structures between different kinds of registries. General search concepts can be used and the two main principles are discussed in [7]. 5. Authority There is no authority which defines who should run a whois server. At present it is common use for most domain registries and all address registries to offer such a service to the public. The mechanism of SRV records offers an easy way for finding an whois server to the public. This means, a SRV-cognizant whois client, searching from the top, would find a SRV record within a few steps. However, and independant of any search strategy, if the client decides to search for more SRV records, more than one whois server could be discovered. There is no authority, and obviously no algorithm, that defines which whois server or whois answer is the right one. 6. Security Considerations The same security considerations as defined in [5] should apply. There is no discussion on security, data protection and privacy relating to the contents of the whois server in this paper. This is a responsibility of the whois server operator and has nothing to do with a mechanism that describes how whois servers can be discovered. The strategies described in this document could allow an organisation, by means of DNS query logging, to find out who is issuing whois queries about them even without operating a whois server themselves. An SRV-cognizant whois client should always display, together with the whois data, the whois server it is getting its data from. Sanz & Winkler Expires - January 2005 [Page 4] SRV records to locate whois servers July 2004 7. References 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. 2 Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 3 Mockapetris, P., "Domain names - concepts and facilities", RFC 1034, November 1987 4 Harrenstien, K., "NICNAME/WHOIS", RFC 954, October 1985 5 Gulbrandsen, A., "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, February 2000 6 Hamilton, M., "Use of DNS Aliases for Network Services", BCP 17, RFC 2219, October 1997 7 [crips-whois-cohabitation] Newton, Sanz, Winkler , "..." draft-ietf-crips-whois-cohabitation-02, work in progress 8. Author's Addresses Marcos Sanz DENIC eG Wiesenhuettenplatz 26 D-60329 Frankfurt/Main, Germany Email: sanz@denic.de Gerhard Winkler Vienna University Computer Center / NIC.AT Universitaetsstrasse 7 A-1100 Vienna, Austria Email: gerhard.winkler@univie.ac.at A. Acknowledgments We would like to thank Kim Davies, Peter Koch and Andrew Newton among others for their useful input. Sanz & Winkler Expires - January 2005 [Page 5] SRV records to locate whois servers July 2004 B. Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. 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