Per-IP rate limiting with iptables

Every second, Pusher’s main pub-sub system handles 9,000 new WebSocket connections. No sweat. But earlier this year, when the system started receiving spikes of 20,000 new connections every second per server, the sweat began to bead on our foreheads. What, or who, were these new connections? Were they malicious or mistaken? Most importantly, how could we keep the system going for everyone else while we dealt with this mysterious new force? This is the story of how we quelled the biggest threat t...

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