iptables -A INPUT -p tcp -m tcp --dport 111 --tcp-flags FIN,SYN,RST,ACK SYN -m connlimit --connlimit-above 1024 --connlimit-mask 32 -j REJECT --reject-with tcp-reset Posted at Nginx Forum: http://forum.nginx.org/read.php?2,79962,83446#msg-83446