Question

I’m developing a site where you are not allowed to login on multiple accounts on one computer, but I do not know how to do this. The method has to be:

• Cross-platform (can be used on Windows/Mac/Linux clients).
• Browser independent.

This is to avoid some users exploiting multiple users to gain unfair advantages, while still allowing two persons on a local network to connect as long as they are on different computers.

Any tips?

Answer 1

Edit: I consider my answer a hack and would love to see a best practice alternative.

As much as I hate them, checking against Flash Cookies would work here. Most users don’t know they are even on the computer so you don’t have to worry much about them getting deleted. Go to this link and see how many have been sitting on your computer for ages without your knowledge: Flash Cookie Manager.

I don’t think Flash works with iPhone though, but you didn’t mention it.

Here is adobe’s take on the flash install base. Wikipedia also has a take on flash penetration.