I've been hosting game-servers since a long time and I keep updating my iptables firewall time and again to block most attacks. One of my game-server port is being flooded with "SSDP" requests and my game-server replies to that with a "disconnect" packet.
Here is how the stream is established coming from Source Port 1900 while the destination is my game-server port,
I have the following iptables configuration that should have been blocking the outgoing "disconnect" packets but it's not working anymore and I have no idea why.
I have temporarily blocked input from UDP source-port 1900 but that is not a good enough solution as my game-server is vulnerable to many other packets so the outgoing "disconnect" packet is something that has to be blocked.
I'm not sure if -m multiport match might be required to block this?