Allowing one vote per computer (not IP, not logged in user)

Question

I have a site where i want to allow a 5 star rating on various things. However, like many other people asking questions on SO, i only want to allow one vote per person.

At first i was planning on logging the IP address when a vote happens and just scan to see if the current IP had voted before or not which would work great.

But then i realized a problem, the site is designed for college students at one particular school. A couple issues with this if i understand IP correctly:

1. People using school computers/connected to the school wifi will have the same IP(maybe a handful, but not unique to each computer)
2. Many people live in houses of 4-8 people, where they would all share the same IP(assuming they are on the same network)

How could i detect unique votes without using IP addresses or having a user login? Is there any other way to do something like this?

Or maybe i am misunderstanding how IP addresses work and i can still use that - hopefully this is the case.

Thanks

Answer 1

You can do this any way you want. There is no "one right way".

On the extreme end, you can have users submit a blood sample when they request an account. You can then check new blood samples against your database. This could result in people submitting family member's blood samples. If that's a concern, you may wish to have them sign a contract, notarized most likely, stating that they have submitted their own blood sample.

You could also have them personally register at your office. You could, for example, collect fingerprints and compare them to your database.

IP addresses are not very useful for this purpose. Some people have access to dozens of IP addresses and in some cases many people share a single IP address.

You could only give a vote to users who have made a large number of intelligent posts to a forum. That would at least cut down on the ease with which people can create voting accounts.