sudo iptables -t nat -A PREROUTING -s 192.168.2.1 -p tcp --dport 80 -j ACCEPT
sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 192.168.2.1:3128
sudo iptables -t nat -A POSTROUTING -j MASQUERADE
sudo iptables -t mangle -A PREROUTING -p tcp --dport 3128 -j DROP