Ports to be opened for Site Server for Cloud-enabled Management

Hi,

We have implemented CEM for a customer with ITMS 7.5. Now, even though all pre-requisites have been met the communication with the NS is not happening through the internet for CEM clients. I am aware that port 443 is used for communication between internet based clients, IG server and NS. Are there any addiotional ports to be opened on the Site Server(Internet Package Server) for it to work?

Thanks