Internet Tips: Find the Name Behind a Malicious IP Address

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I learn a lot from PC World readers, and I don't acknowledge often enough how the column is steered by your questions and gentle corrections. This month, your fellow readers share tips on identifying who is trying to connect to your computer, creating a shortcut to a Web site, and speeding searches on

Who's Calling, Please?

In many cases when your firewall blocks access to a remote system, or your spam or phishing filter traps a potential e-mail attack, the only information it reports about the source is an IP address. To learn more about the individual or outfit behind the address, reader Rick Tschernjawski of Syracuse, New York, recommends using the command-line program nslookup in the TCP/IP networking protocol in Windows 2000 and XP.

To find the more-descriptive domain name associated with a cryptic IP address such as '', click Start, Run, type command in the Open field (cmd in Windows 2000), and press <Enter>. At the command prompt, enter nslookup followed by a space and the IP address. Press <Enter>, and after a short delay, nslookup will report first the name of the domain name system (DNS) server used for the lookup, followed by the IP address and domain name that you want to know about (see Figure 1

Figure 1: Convert an IP address into a domain name and server address using nslookup in Windows XP.
). Type exit to close the command-prompt window. The program will also do forward lookups, providing the IP address linked to a domain name.

If you use a router or wireless hub, nslookup may complain that "default servers are not available," but nevertheless it will still provide the lookup information. For a more in-depth explanation of the nslookup command in Windows, browse to Microsoft's documentation page.

Sometimes, just knowing the domain name can help you identify the frauds. For example, you can report spam to the sending ISP by firing off a message to 'abuse@domain, where 'domain' is the domain name that you looked up. Other times, you need more than a name. For finding the phone numbers, e-mail addresses, and other contact information related to a domain name or an IP address, Tschernjawski recommends the Whois lookup tools at The site also offers a handy geolocation tool that tells you where in the world a particular IP address is located.

Shortcuts to Web Sites

When you launch your browser, it automatically loads whatever site you've selected as your home page. But there are probably many times when you want to open your browser to a site other than your home page. For those occasions, Pensacola, Florida, reader Donald Darden offers a time-saver: Right-click the desktop (or inside any folder) and choose New, Shortcut. Enter the site's URL (for example,, click Next, give the shortcut a name (maybe the name of the site), and click Finish. Then double-click the shortcut to go directly to your local movie guide or sports scores, without having to pass through your home page.

Faster Finds

Ben Hyman of Champaign, Illinois, who uses's service religiously, has a Firefox shortcut. Begin by choosing Bookmarks, Manage Bookmarks, clicking New Bookmark, and entering a name in the Name field and in the Location field. Type pcw (or whatever you want) in the Keyword field, and click OK. Close the bookmark manager. To browse to a link printed in PC World, just type pcw (or the text you entered) followed by a space and then the link number in Firefox's address field, and press <Enter>.

Zap Your Google Cookie

If you're like me, you worry that Google is compiling a complex psychological profile based on your accumulated search requests. ("Mr. Spanbauer, you display inordinate interest in Chuck Norris, potato guns, and self-hypnosis. We have alerted the authorities.") Luckily for all of us, Ksoft's free G-Zapper utility cleans the information that identifies you uniquely out of the Google cookie, thereby protecting your privacy. So take off that tinfoil hat and download G-Zapper.

Send your questions and tips to We pay $50 for published items. Scott Spanbauer is a contributing editor for PC World.
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