ip forwarding for web server

iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to 123.49.42.202:80
iptables -A FORWARD -d 123.49.42.202 -p tcp --dport 80 -j ACCEPT
/sbin/iptables -A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE


here eth0 is connected to internet