Managing Linux® Systems with Webmin™ System Administration and Module Development

19.9. Setting Up Port Forwarding

On a network that uses NAT to hide internal systems from the Internet, outside hosts cannot connect directly to those on the internal network. This is great for security, but can be annoying if there is some internal service that you do want to make available to the outside world. For example, your mail server system may not be the firewall host, which would normally make it inaccessible from the Internet. Fortunately, there is a solution to this problem—port forwarding.

This lets you redirect all connections to some port on the firewall system to a different host and port on your internal network. For a mail server, all data received on port 25 might be sent to the same port on the host that is actually being ...