A CDN such as www.cloudflare.com would filter abusive users out; it's actually what it's designed to do, and you can set how anal retentive you'd like it to be and it does it on it's own automatically.

Cloudflare has a free version, which I use on all of my UBB sites, that works just fine.

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
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