How would I got about this...

[lutics]

I am getting a lot of multi users on my forum (as in 1 person making accounts) with the same IP. I want to make a check on the reg page. So basically it does this.

Checks If the IP already has a Username, If it does then error message, and post forgot password link and display username of current user.

If not. It will display registration.

Is this possible and what would be the most efficient way to make this.

If you don't get what I'm trying to do, just ask and I'll try explain it more.