防止SYN攻击 轻量级预防
iptables -N syn-flood
iptables -A INPUT -p tcp --syn -j syn-flood
iptables -I syn-flood -p tcp -m limit --limit iptables -N syn-flood
iptiptables -N syn-flood
iptables -A INPUT -p tcp --syn -j syn-flood
iptables -I syn-flood -p tcp -m limit --limit iptables -N syn-flood
ipt