Bulk C-Class IP Checker

I need a system that can check many websites at once, to see if they have duplicate C-class IPs. An example of what I am looking for is here: [login to view URL] I do not need any other information like that website has, I only want the returned results of which websites have the same C-class IP. If no duplicate C-class IPs are found, then it should say "all unique IPs etc.." The system must use a "captcha" image to prevent spam bots and unauthorized use. ## Deliverables It must NOT be in .asp format. Anything else is fine.