anti DDoS

[asilvapino]

hey! great work, can u help me with instructions to add an anti DDoS to the server? right now steam oficial servers are being ddos everywhere

[hazmeister]

I've been looking at some options, once I've reviewed them properly I'll add them to the top of the README.

• If using Linux and you have root access on your server, you can block some traffic using iptables. SirPlease have an easy to use script which can set this up for you. I've previously been using a subset of these rules which were partially effective, game lagged but didn't return to lobby and was playable for the rest of the session. Trying the full set now. I attempted to roll them into the image, but there are some pain points between how docker works with iptables, and it appeared less effective, so I think application will be required separately.
• if you can't try that, there are some plugins for sourcemod you could try in this thread.
• Some cloud providers claim to offer free protection from DDoS. Linode offer a free $100 credit to try running a server on their infra.
• You could try running your server on a non standard port (much higher than 27015), not sure if the this might impact who can join you, and I suspect the attackers are using the master server list to find targets.
• There's a command line argument called -nomaster which won't list your server. This might be fine for games with friends, but not helpful if you're hoping matchmaking will add extra players.

I suspect iptables will be the most effective, but are not an option for everyone.

[asilvapino]

Well i think changing the port to a higher number works. no new attacks. Thanks for the info, i implemented some recomendations directly on my mikrotik router, just in case.

[antimomentum]

Iv been playing on Official Dedicated servers recently for coop campaign and we (randos and myself) keep getting returned to the lobby in most games. I saw some updates for l4d2 that included some DoS fixes. Is this recent stuff still DoS or is it DDoS?