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I filled a survey today which states that it can only be done once a month. If I try to do it again, I am not allowed as expected.
I am trying to find out how they know that it is from the same computer.
So far, here is what I tried :
I used another computer on the same LAN, and I am allowed to fill the survey. So it is not my IP address.
I used the first computer, but with another "private" IP address (192.168.X.X), and I am not allowed to fill the survey again. So it is not the combination of IP address + private IP address.
In Chrome, I cleared everything from the past hour and I still can not fill the survey again. So it is not something they put on my computer.
The only option I can think of is my MAC address, but I am not sure it is an information they have access to and I don't really know how to change it (on Ubuntu).
So I am curious as to how can they uniquely identify my computer as a computer which answered the survey.
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I'll be that if you use a different browser, it will work. This is quite often done with fingerprinting like this: http://panopticlick.eff.org/. Related: http://programmers.stackexchange.com/questions/122372/is-browser-fingerprinting-a-viable-technique-for-identifying-anonymous-users
– beatgammit – 2013-07-13T18:39:14.883I doubt it's the MAC address, since they can be changed trivially. Also, browser having access to the MAC address would be a huge security hole. – AnonymousLurker – 2013-07-13T18:49:31.337