Protecting your host from SYN floods
From Alexey's iproute documentation, adapted to netfilter and with more plausible paths. If you use this, take care to adjust the numbers to reasonable values for your system.
If you want to protect an entire network, skip this script, which is best suited for a single host.
It appears that you need the very latest version of the iproute2 tools to get this to work with 2.4.0.
#! /bin/sh ...