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WHOIS Protocol Specification

The information below is for an old version of the document that is already published as an RFC.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 3912.
Author Leslie Daigle
Last updated 2013-03-02 (Latest revision 2004-04-01)
RFC stream Internet Engineering Task Force (IETF)
Stream WG state (None)
Document shepherd (None)
IESG IESG state RFC 3912 (Draft Standard)
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD Ted Hardie
Send notices to (None)
Network Working Group                                          L. Daigle
Internet-Draft                                            VeriSign, Inc.
Obsoletes: RFC812, RFC954 (if                             March 31, 2004
Expires: September 29, 2004

                      WHOIS Protocol Specification

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://

   The list of Internet-Draft Shadow Directories can be accessed at

   This Internet-Draft will expire on September 29, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2004). All Rights Reserved.


   This document updates the specification of the WHOIS protocol,
   thereby obsoleting RFC954. The update is intended to remove the
   material from RFC954 that does not have to do with the on-the-wire
   protocol, and is no longer applicable in today's Internet.  This
   document does not attempt to change or update the protocol per se, or
   document other uses of the protocol that have come into existence
   since the publication of RFC954.

1. Introduction

   WHOIS is a TCP-based transaction-oriented query/response protocol

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   that is widely used to provide information services to Internet
   users.  While originally used to provide "white pages" services and
   information about registered domain names, current deployments cover
   a much broader range of information services. The protocol delivers
   its content in a human-readable format. This document updates the
   specification of the WHOIS protocol, thereby obsoleting RFC954 [1].

   For historic reasons, WHOIS lacks many of the protocol design
   attributes, for example internationalisation and strong security,
   that would be expected from any recently-designed IETF protocol.
   This document does not attempt to rectify any of those short comings.
   Instead, this memo documents the WHOIS protocol as it is. In some
   areas, this document does document particular well known shortcomings
   of the WHOIS protocol.  The discussion of possible protocols to carry
   out these functions, with updated capabilities to address the short
   comings, is being addressed in a separate IETF activitiy (CRISP
   Working Group).

2. Protocol Specification

   A WHOIS server listens on TCP port 43 for requests from WHOIS
   clients.  The WHOIS client makes a text request to the WHOIS server,
   then the WHOIS server replies with text content.  All requests are
   terminated with ASCII CR and then ASCII LF. The response might
   contain more than one line of text, so the presence of ASCII CR or
   ASCII LF characters does not indicate the end of the response.  The
   WHOIS server closes its connection as soon as the output is finished.
   The closed TCP connection is the indication to the client that the
   response has been received.

3. Protocol Example

   If one places a request of the WHOIS server located at
   for information about "Smith", the packets on the wire will look

      client                           server at

      open TCP   ---- (SYN) ------------------------------>
                 <---- (SYN+ACK) -------------------------
      send query ---- "Smith<CR><LF>" -------------------->
      get answer <---- "Info about Smith<CR><LF>" ---------
                 <---- "More info about Smith<CR><LF>" ----
      close      <---- (FIN) ------------------------------
                 ----- (FIN) ----------------------------->

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4. Internationalisation

   The WHOIS protocol has not been internationalised.  The WHOIS
   protocol has no mechanism for indicating the character set in use.
   Originally, the predominant text encoding in use was US-ASCII. In
   practice, some WHOIS servers, particularly those outside the USA,
   might be using some other character set either for requests, replies,
   or both. This inability to predict or express text encoding has
   adversely impacted the interperability (and, therefore, usefulness)
   of the WHOIS protocol.

5. Security Considerations

   The WHOIS protocol has no provisions for strong security. WHOIS lacks
   mechanisms for access control, integrity, and confidentiality.
   Accordingly, WHOIS-based services should only be used for information
   which is non-sensitive and intended to be accessible to everyone. The
   absence of such security mechanisms means this protocol would not
   normally be acceptable to the IETF at the time of this writing.

6. Acknowledgements

   Ran Atkinson created an earlier version of this document.

Normative References

   [1]  Harrenstien, K., Stahl, M. and E. Feinler, "NICNAME/WHOIS", RFC
        954, October 1985.

Author's Address

   Leslie Daigle
   VeriSign, Inc.
   21355 Ridgetop Circle
   Dulles, VA  20166


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   This document and the information contained herein is provided on an

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   Funding for the RFC Editor function is currently provided by the
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