TCP/IP Filtering (Advanced)

When Microsoft created Windows XP, they gave it a built-in software firewall to protect your computer against different types of network attacks. Although the versions of Windows before XP had a featured called 'TCP/IP filtering'. This feature allowed you to filter out different parts of the TCP/IP protocol from entering the computer, such as TCP/UDP ports and IP protocols.

Note: The following is an advanced tip that should only be used by those who have a good understanding of the TCP/IP protocol. This feature has very limited applications since the inclusion of the built-in firewall, but for those who might have a use for it below is the information you will need to get started.

To access the TCP/IP filtering option:

• Open the Control Panel
• Double-click the Network Connections folder
• Right-click your active network connection, and select Properties.
  
• In the General tab, in the list box scroll down until you find 'Internet Protocol (TCP/IP)' and select it.
• Press the Properties button.
• Press the Advanced... button.
• Select the Options tab.
• Select 'TCP/IP filtering' then press the Properties button

From here you can configure TCP/IP filtering, by limiting the incoming TCP/UDP ports, and incoming IP protocols (you must specify the IP protocol number, for example the IP protocol 'General Routing Encapsulation' [GRE] is number 47).

References:

• Internet Protocol Numbers
• TCP and UDP port numbers
  

Notes:

• This feature applies to all network interfaces on your computer.
• This feature does not allow you to block ICMP traffic.
• This feature does not affect outbound traffic or response ports that are created to accept responses from outbound requests.