Hacked clients can take on whatever name they want. They could simply use a name they already know is on the server, and then the whitelist is useless.
Yeah, but it prevents the basic griefers - Which is one step above what we currently have.
Plus, I doubt anyone cares that much about your server to hack into it.
You forgot to say how he hacked our server, had no visible name in-game, created multiple copies of himself and blew a gigantic hole behind the Orre spawn point.
Yeah... I think I'm going to be taking some time off from minecraft until this every-day hacker/griefer business settles down. Getting tired of making things to have them destroyed the next day.