Depends on the size of the attack, that will determine the amount of protection you need. If it is comming from a few IP's thats pretty easy to take care of with a few scripts. Litespeed is what you need to also be on as well with reverse DNS. You need the right host, and I have plenty in my mind if you ever run into a big one you can't take care of. There small hosting companies that specialize in that, liquidweb, theplanet etc will not protect you.