okay so there are a couple of things you can do if you are hosting the forums yourself,
the first thing is i would buy myself some sort of internet security appliance from like Cisco like a router made for small businesses that had a vpn / hardware based firewall, deep data packet inspection etc the second thing is i would honestly get myself some professional help too try and protect myself like a web application firewall from godaddy or someshit here is a link of theyre website security packages if you need security for hosting a website and dont have cash for hardware based protection
Website Security From Godaddy