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How can I block my competitor's IP address range from my website?

Are you looking for free network tools to find an IP address range? This advice from our security expert shows you whois tools available to you and then explains how to block these ranges from viewing your Web resources, in this expert response.

I'm having a problem with a local competitor and need to get his IP address or possibly the range he is using so that I can exclude his IP/IPs from seeing my web site. I'm sure he is on a wireless network and should be able to take a laptop within range. How do I get this info? I've looked all over to see if there is software that will easily do this but have come up blank. Packet sniffing programs don't seem to do it either.
There are several ways to get this information. Let's explore one method here: You could start by pinging the domain name, i.e., ping DomainName.com. You can also use any number of who is tools, such as Robtex.com's Domain Name Server records, or SamSpade.org's tool. This should provide domain information and the IP address of the server.

The next step would be to take a look at one of the regional RIR's (Regional Internet Registry). The RIR's are...

the organizations overseeing the allocation and registration of Internet number resources within a particular region of the world. For the US, the site to review is www.ARIN.net -- the American Registry for Internet Numbers (ARIN). You will need to enter the IP address of the organization's Web server. Look over the results as there should be a sub net mask provided and a range.

While this will provide you the information needed to block your competitors IP address range they could always use a proxy, such as TOR, to get around this restriction.

This was last published in November 2008

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