Your nginx will get even faster! SYN packets (packets with the SYN flag set) are the first packet sent to initiate a TCP connection. A browser connecting to a web server is a TCP connection. So this will enable the linux kernel to handle incoming connection requests way faster. The effect is that high traffic web servers running with already-optimized applications like nginx will become faster under high load, particularly a flood of incoming new connection requests.

If you are trying to weather a TCP based DDoS attack, you have a better chance at your server staying up, provided your connection isn't saturated.

If you're running a load balancer, reverse proxy, port forwarding, or anything else that will receive significant traffic and requires a TCP connection to your server, your server will be faster.

This also affects anything that listens on a TCP socket, like postfix (email), SSH, FTP, memcached, redis, mysql etc..etc..

This patch makes it easier to scale inbound TCP requests across multiple cores on your CPU. This helps with both denial-of-service protection, as well as scaling up if you're doing a lot of raw packet processing (e.g. a Layer 4 load balancer).