Network Working Group L. Daigle
Request for Comments: 3912 VeriSign, Inc.
Obsoletes: 954, 812 September 2004
Category: Standards Track
WHOIS Protocol Specification
1. Introduction
WHOIS is a TCP-based transaction-oriented query/response protocol 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 RFC 954 [1].
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RFC 3912 WHOIS Protocol Specification September 2004 2. Protocol SpecificationA 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 whois.nic.mil for information about "Smith", the packets on the wire will look like:
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) ----------------------------->
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 interoperability (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.
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RFC 3912 WHOIS Protocol Specification September 2004 6. AcknowledgementsRan Atkinson created an earlier version of this document. Ken Harrenstien, Mary Stahl, and Elizabeth Feinler were the authors of the original Draft Standard for WHOIS.
7. References 7.1. Normative References[1] Harrenstien, K., Stahl, M., and E. Feinler, "NICNAME/WHOIS", RFC
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RFC 3912 WHOIS Protocol Specification September 2004
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