php/javascript user info collecting

Question

I believe some users on my site are using IP masks to create more than one account. Due to the nature of my site/game it's against the rules and I need to remove players like this.

I currently track their IP, host, browser type and such with PHP, I also use javascript/jquery to get their screen size. I also have a little script set up that tells me if their coming through a forwarding service. It says this certain player is although his IP doesn't match any proxy lists I've come across.

Basically I'm looking for any other info I can collect that I can compare and determine if a suspect player is actually another players second account. Any suggestions?

Answer 1

The only thing i can think of is using telephone number as part of subscription process. And sending some sort of verification code via SMS.

Also you can start setting cookies.

And is it possible to imagine some sort of detection as part of your game/application. Like you add some game elements that would expose suspects to some secret knowledge. Setup honeypots. Like you show some secret 'cheat' codes or specific link/location to one suspected double and not to the other. Then if the other tries to use that info - you got him... Basically build some sneaky intelligence into your app

Combining these with all the other detection techniques, could make it very close to 100% bulletproof and can be a lot of fun.