How to prevent some local application on the client from connecting to a localhost service using the loopback (localhost / 127.0.0.1) address.
While the Symantec Endpoint Protection Firewall is technically capable of monitoring the loopback traffic, this traffic is allowed automatically and it is not currently possible to override this behavior. This is by design, to avoid unforeseen side effects when creating firewall rules.
This applies all versions of Symantec Endpoint Protection 14.x.
Workaround: