A troll is someone who posts controversial, inflammatory, irrelevant, or off-topic messages on a forum. That means that they are human users who just want to post messed up messages. having said that, the only way you can do is ban them one by one. But it does get frustrating. So make sure that they are "trolling" and are not bots just spamming up your board. If they are bots, you can use one of several MODS on the Mods data base.
People sleep peacefully at night only because rough men stand ready to fight for them!