When you are running a web application, or a voice service or a server , and there are normally large traffic, and for some reason you get attacked DoS attack, what do you do to help keep your server and services running while the attak is ongoing, and how to block it if its attacking Protocol servers?
You can't, that's why (D)Dos attacks are so succesful
The only way to protect your servers is to move to a Hi-Cap datacentre where the staff are friendly enough to take action.
Most botnets thesedays are between 10,000 and 200,000 nodes big, that's more than a few gigabits of bandwidth, sometimes even a whole terabit.
Therefore it helps to be Co-Lo'd in a datacentre with at least Dual-OC92 connections.
And hope that you don't have to pay Per-Gigabyte bandwidth bills either
Call your ISP and have them deal with it at the router level... they may even have to call their upstream provider.
but basically, if someone wants to keep bother you with DDOS attacks, you are screwed
Not true, you can protect yourself from DDoS attacks. You just can't do it in house
Obviously it is a paid service, and I'm sure there are others, but this is the only one that came to mind.