If you have a cable router, DSL router, or other network router that shares its Internet connection with computers on your intranet, you can manually configure the router to protect your intranet while allowing access to selected services from the Internet. You configure your router to forward requests for individual services to your server. This process is called port mapping or port forwarding, because each service communicates through an abstract, numbered communication port. Unlike the Ethernet port on your computer, these ports aren’t physical.
You can configure port mapping on an AirPort device by using the Server app. For information, see Manage AirPort port mapping and Wi-Fi login.
You can manually configure port mapping on most Internet routers by using their configuration software. Usually, the configuration software consists of several webpages. Using a web browser on any computer connected to your intranet, you go to the webpage with settings for port mapping or port forwarding. In some cases, you can select standard services such as web or VPN and specify that each be mapped to your server’s IP address. In other cases, you must enter port numbers for services and enter your server’s IP address for each one.
For a list of services and the corresponding ports for which you might want to set up port mapping or forwarding, see Services and ports.