DoS Attacks against my Online Game
DDraceNetwork is an open source online game I’ve been running since 2013 with a community of volunteers. The game is available for free, I’m hosting servers for it in many countries around the world so that we have trusted official ranks. The servers are paid for by donations, which I stop collecting once the cost of the servers for the current year is covered. I wrote about DDNet in a previous post in 2016 and also a bit about the game history in 2013.
Pretty much since the beginning we have been suffering from DoS attacks against the servers. Since the Steam release in 2020 the player number has increased significantly, so that we have about 1300 players playing on average.
Based on the rising player number the urge to deal with the DoS problem is larger than ever. A few months ago for example we organized a Tournament for everyone in the community to participate. Unfortunately the event was the continuous target of DoS attacks for multiple hours, with players fleeing from one server to the next, trying to find a safe refuge. These bandwidth graphs for our servers in Netherlands and Germany respectively illustrate the problem:
Since DDNet only runs online and you feel every small network latency it is predestined as a target for DoS attacks. Outside of attacks our servers don’t need to be particularly powerful for regular gameplay, 1 CPU core can support 150 players concurrently, memory consumption is minimal. So the total we are paying for our ~23 servers around the world is only ~2300 € for the year 2021.
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