Port forwarding is used when you have a virtual machine communicating with the outside world using shared networking and would like other computers to be able to access certain services running in it (e.g. HTTP server, FTP server, or any other service listening for client requests on a particular port). In order to do so, you have to tell the host machine to forward all data that it receives on a certain port to the appropriate port in the virtual machine. This is accomplished by creating a port forwarding entry using the PHT_PORT_FORWARDING handle. A port forwarding entry has the following properties:

• The source port number in the host computer. All data that the host computer receives on this port will be forwarded to the virtual machine.
• The destination virtual machine identified by its IP address. The address can be determined using the standard tools of the guest operating system.
• The destination port number in the virtual machine. All data will be forwarded from the source port on the host machine to this port.

To obtain a list of the handles containing information about existing port forwarding entries, use the PrlVirtNet_GetPortForwardList function. To create a new port forwarding entry, use PrlPortFwd_Create to create a new handle. Use the functions describes in this section to define or modify the port forwarding entry properties and then use the PrlVirtNet_SetPortForwardList function to save it.