How to secure the UDP port of a game server?

Question

Debian

Good evening sirs. There is a game server, DDoS protection is good, but the game server is attacked at the application level, UDP port. They flood in packets and you can’t connect to it, but the players are not knocked out. How to be?

Answer 1

set a rate limit in iptables, something like:
iptables -I INPUT -p udp -i eth0 --dport $portnumber -m state --state NEW -m recent --update --seconds 60 --hitcount 10 -j
DROP calculate the rate of an ordinary player in order to set the threshold twice as high, you can select by making a chain with -j ACCEPT for some known ip of an ordinary player and using iptables -vnL to look at the packet counter in this rule.