The port forwarding firewall app allows an administrator to direct incoming service requests via port (or port ranges) to other devices on the Local Area Network (LAN). The destination device is usually a server providing an Internet service like hosting an on-premise website (HTTP port 80) or mail server (SMTP port 25), but can also be a desktop or other device (remote desktop using RDP, Bit Torrent client etc.).
To learn more about this app, click here
Documentation for ClearOS 6 can be found here.
Documentation for ClearOS 7 can be found here.