How to make a safe Voting system ?

[Anon]

Hi,

I have build a little voting system for my web site.

It uses a table where stores the id of the voted item, the date and the IP address of the user who has voted.

With the intention to allow only one vote for user for each day, I am making the following checkings:

1- user ip is logged so I can check the IP and lock multiple votes

2- I also added a session variable to disable the voting system if the user has already voted

3- I have added a cookie that I use to check if the user has already voted today (in case he has changed his IP address).

My problem is that all these precautions seems not to be enoght: I still see that some body votes more then one time in a day... and they do this by changing their IP address (I don't know how) and by (I suppose) deleting or refusing my cookie on their browser.

What I ask all of you is: does any body have any suggestion to get a better vote blicking system ?

I want at last 24 hours before a user can re-vote and also, thinking o proxies, I suppose the check IP address could be a problem...

Thank you for any help about !

Fabio

[leifr]

Hi!

I had the same problem, because my users just didn't accept the cookie set by my voting script.
So now I force them to let the cookie be set. My voting script sets the cookie and then it relocates to itself and checks if the cookie has been accepted. If the cookie was successfully set the script adds a database entry.
It works quite well, because most users don't know how to delete a cookie.
You may try it at http://www.gbg-rs.de/ (German site).

Leif

[sethadam1]

You could also force them to a login prompt and allow each user 1 vote.