how to open/close port numbers

If you want to do this directly from the NIC then open network/properties, select your NIC/Properties/tcpip properties. Select the advanced button then hit the options tab. You will see two entries, one for IP Security and TCP/IP Filtering. Select TCP/IP Filtering and open/close desired ports.

The second way of doing this is with RRAS. Setting the server up as a router with at least two NIC's. You can then use RRAS to direct traffic through the chosen nic and control port usage.

Have Fun.

jab.