Iptables and IP forwarding

Hi, I understand that I need to have ip_forwarding=1 to allow my containers access to an external mysql database. That is the only access from the containers to the outside world I need. Can anybody please provide me with the iptables rules to deny any other access from the containers?

So, I want the host server to forward traffic from the containers to only IP 8.8.8.8 port 3306 for example and nothing else.

Thanks!