Hide NBU listening ports to external network

Hi,

Recently gotten security advisory, CVE-2015-6550/51/52.

One of the recommendation is to hide NBU listening ports to external network.

Question is do we apply on clients or both server and client?

Please advise.

Master/Media server:  Ver 7.6.0.4

Some clients:  Ver 7.6.0.4

Some clients:   Ver 6.x   (this is why we want to hide the listening ports..)

Thanks in advance.