I have a bit of a problem on my website: a problematic visitor, who basically I want to ban, but I can't ban his IP since it is dynamic. If I ban the whole IP pool then this also blocks all other users on his ISP, which I don't want to do. I could require email subscription to view the website and write on the messageboard, but this would put a lot of users off and there is nothing stopping this guy from getting as many free email addresses as he wants and signing up again and again each time I ban him.

Can anyone suggest any way to get enough information to ban him permanently? Like a combination of the first two bytes of the IP address (which are static) and information such as the browser he uses and OS (unforunately he uses the most common options, windows XP and IE 6.0 so can't really ban everyone with his ISP and that OS and browser either). Any suggestions on how to ban him? The site is in ASP so I can do anything server side scripting allows...

thanks in advance

You could block his subnet, often only the last byte is used for the subnet and the majority of isp's that do dynamic addressing tend to leave people on the same subnet even when their address changes. That would just cost you 256 potential visitors (and you could always include the 'email me' message in the block notificantion)

Well the problem is that I've been monitoring and the last two bytes of his IP address vary so that's 65000 (approx) possible combinations - it blocks a lot of people - I know cos I've tried it. I've tried the email me thing, get too many emails, and there's nothing to stop him emailin me under a different name to get access.

Password only access, and don't give him a password.

Which would work if I knew when it was him emailing for a password. I suppose if you assume that anyone can email under any fake name with any address, then there really is no way to properly ban someone.
*sigh*

If he is problematic then report him to his ISP.

Yeah I thought about doing that. I wonder if they'd actually do anything about it (freedom of speech and all that). Problematic means swearing at most other users if their opinion differs.

Well you can report them to their ISP and maybe they can offer a suggestion to assist you in Banning him from your webpage.

The only other option is to keep banning his usernames until he gets sick of it.

even though i'm not high on these stuffl,
maybe you can put a regulation, to when people can sign up?, like 2 times a month, that way he wouldn't be able to bug you for that long,..i think,

Is there a way to make his posts "invisible" to other members? We've had to do that on one of the sites I moderate to get rid of a pesky person who wasn't *quite* doing something bad enough to be banned, but was walking that line of trolling.

We made the posts "invisible" so this person could post, but no one but the Admins/Mods could see what was being said.

LOL! After about a week of getting NO reaction, the would-be troll buggered off. ;)