I am using a Debian 6 - 64bit OS and my server is ddosed/flooded through udp protocol from time to time. I basically host game-servers and my firewall is set to rate-limit the packets on allowed ports but sometimes the rate per IP is low but the number of IPs are more so my server sends outgoing icmp unreachable replies to the attacking IP which does no benefit but chokes/saturates the port even more.
I'm looking on how to disable this feature. Actually the ports that get attacked are allowed through firewall and I can't disable them although it would solve the issue. I run a number of servers over some port ranges so I can't continually keep accepting these ports one by one and decided to allow the total port range I might require.
I'm looking at some kernel ability to stop this?