Recently i'v been having attacks on my server that I can only describe as DDOS/Flood.
What would happen is randomly i'll get around 50 new players join under 30 seonds, all with random names (i.e h74Jk439 or G7b8UizX) and all have separate IP's. I'm assuming it is a player-launched via a hack-client - it generates a random name, proxy's the account, and makes it join. These attacks don't really do anything but spam chat but did manage to cause a overflow crash one time.
Any ideas on what this is or how to prevent it?
(Besides white-listing or changing to Online Mode)