Centos iptables rule config

Hello, This's my diagram web server (port80) <--------> Centos IPTABLES Firewall <---------> Client Currently incoming traffic (port80) from Client will forward to our web server by using this rule echo 1 > /proc/sys/net/ipv4/ip_forward iptables -t nat -A PREROUTING -p tcp -d [login to view URL] --dport 80 -j DNAT --to-destination [login to view URL] iptables -t nat -A POSTROUTING -j MASQUERADE But now I want protect user that using download accelerator program like IDM , Flashget because it make my server load . So I want rule that look like allow only 1 connection from client ip address. Or limit connection per second