The Egress Firewall app enforces policy on traffic leaving your network. Two modes are available - allow all and blanket block. Allow all allows all outgoing traffic through, with the exception of rules you create based on destination port or hostname. Blanket block prevents all outgoing traffic from passing through the firewall unless specifically allowed.
To learn more about this app, click here
Documentation for ClearOS 6 can be found here.
Documentation for ClearOS 7 can be found here.