try allowing all guests, but use your log tables 2 track them 4 a few dias,,, go over your ip logs and look 4 any ips that are trying 2 access areas that concern U. After U have a list of ips that U believe 2 be problem childs, next use software that redirects them or slows down there connections... Or Ban groups at one time...
Remember if somebody wants in they will find a way...> proxies < , but U still can make life hard on those pesky runts...
Use .htaccess it works best...
Good Luck