[ubuntu] Handle Light DDoS Attacks Programatically

Hello,

I am hosting game servers on my Linux Ubuntu servers, and these have been subject to DoS attack, the box itself isn't targetted, but the service is;
it basically floods the UDP protocol and prevent players from having a correct ping.

To this, I have been able to create a script ruing in background which basically gets a portion lf the traffic on a given port,
in this portion takes all the IP, and if an IP appears more than X% of the total portion, then is blocked.

Now, the problem is it is no more a DoS attack, but a DDoS one,
in other words, many IPs are attacking this service making it lag just as it used to with DoS attacks.

These attacks are not powerful enough to fall in the host DDoS mitigation,
and the server traffic load is far from the maximum it can handle, as I said, the service network itself is flooded.

My question would then be: how would I be able to solve this issue ? (Programatically I guess).

Thanks !