Summary:
The WhoIs database lists those entities (individuals/companies) that have registered domain names. Most Unix installations come with a command line program (whois) for querying this information. Alternatively, Network Solutions provide a Web interface at http://www.networksolutions.com/cgi-b in/whois/whois.
You can also find the owner of an IP address if you use this database.
Getting information on an IP Address
WhatIs is a search engine that has a similar name to WhoIs.
http://www.whois.sc provides an awesome search engines for looking up current and expired domain names and displaying them in color-coded output. It will also usually give whois info for an IP address (e.g, http://www.whois.sc/81.136.11.58).
Try also: http://samspade.org/t/lookat?a=000000 (replace 000000 with the number queried)
Before you get paranoic about IP addresses, checkout WhoIs. That will typically give you some information about an IP address, for example:
whois 81.136.11.58
% This is the RIPE Whois server.
% The objects are in RPSL format.
%
% Rights restricted by copyright.
% See http://www.ripe.net/ripencc/pub-services/db/copyright.html
inetnum: 81.136.0.0 - 81.136.23.255
remarks: *******************************************************
remarks: * Please send abuse reports to abuse@btopenworld.com *
remarks: *******************************************************
netname: BT-ADSL
descr: IP Pools
country: GB
admin-c: BTOW1-RIPE
tech-c: BTOW1-RIPE
status: ASSIGNED PA
mnt-by: BTNET-MNT
mnt-lower: BTNET-MNT
mnt-routes: BTNET-MNT
changed: preston.dialip@bt.com 20031114
source: RIPE
route: 81.128.0.0/11
descr: BT Public Internet Service
origin: AS2856
mnt-by: BTNET-MNT
changed: support@bt.net 20030615
source: RIPE
role: BT OPENWORLD OPERATIONAL SUPPORT
remarks: ********************************************************
remarks: * Please send abuse reports to abuse@btopenworld.com *
remarks: * *
remarks: ********************************************************
address: BT
address: Openworld
address: UK
e-mail: ims.adastral@btopenworld.com
admin-c: IT337-RIPE
tech-c: RJG3-RIPE
nic-hdl: BTOW1-RIPE
mnt-by: BTNET-MNT
changed: preston.dialip@bt.com 20030520
source: RIPE