The following from W2K Help:
"To configure Internet connection sharing for applications and services
Open Network and Dial-up Connections.
Right-click the shared connection, and then click Properties.
On the Sharing tab, verify the Enable Internet connection sharing for this connection check box is selected, and then click Settings.
If you want to configure a network application for the computers sharing the connection, on the Applications tab, click Add, and then do the following:
In Name of application, type an easily recognized name for the application.
In Remote server port number, type the port number of the remote server where the application resides, and then click either TCP or UDP.
In TCP or UDP or both, type the port number for the port on your home network that the application will connect to. Some applications require TCP and UDP port numbers.
If you want to configure a service to provide to users on remote networks, on the Services tab, click Add, and then do the following:
In Name of Service, type an easily recognized name for the service.
In Service port number, type the port number of the computer where the service resides, and then click either TCP or UDP.
In Name or address of server computer on private network, type the name or TCP/IP address of the computer on your home network where the service resides.
Important
If you do not know the values for the remote server port number, incoming response port numbers, or the service port number, see your system administrator.
Notes
To open Network and Dial-up Connections, click Start, point to Settings, and then click Network and Dial-up Connections.
To configure Internet connection sharing, you must be logged on as an Administrator or a member of the Administrators group.
You must enable Internet connection sharing to configure applications and services."
Port mapping is also available if you configure NAT through RRAS though using a bit different procedure.
-MW
