How to prevent ban evasion

[Turnip]

Hi,

I have a website where users can create an account. Currently, if they are banned, it will just mean that they cannot view the site logged into the banned account. They can perfectly easily delete the cookie, register for another account, and wreak more havok. I (think) that I can get their IP address (using ASP) Server.RequestVariables("HTTP_REMOTE_ADDR"), or something like that at least. Thing is, more than one person can have the same IP address (AOL users especially), and I dont want to stop someone who hasnt done anything wrong from accessing my site. So what I want to know is if there is any way that I can uniquely identify a site visitor which will enable me to stop them from viewing the site if I so wish. Short of that, how can I find out their ISP so I can speak to their ISP in the event of very serious offences.

Thanks a lot
Turnip

[Dangermouse]

Well if you dont want to ban IP's/IP Ranges there is not a lot you can do, IP is what uniquely identifies you.

You can find out the isp by using (not sure how to do it in ASP) gethostbyaddr, there should be something in ASP for it. It looks up the ip, and returns the host name, and should have the ISP domain at the end. Eg mine is m159-mp1.cvx1-b.gfd.dial.ntli.net (my ISP is teconet, but ran by NTL(i))

[Turnip]

I was under the understanding that often more than one person might have the same IP address, and so that if I banned IPs, I might be stopping people accessing the site. Is this not the case?

[stymiee]

For dial up users it's possible but keep in mind that not every AOL user is visiting your site. So if you ban a small group of them by banning an IP class you're not hurting yourself much if at all. Plus you can always remove it after a few months after the loser has finally stopped trying to troll your site.

[The New Guy]

Mabye you could create a que, where you manually add users, people so if they have similiar IP or a stupid/rude username or whatever, you can just not sign them up, also the extra time needed will discourage them.