A software firewall is a program that runs on a computer to allow or deny traffic between the computer and other computers to which it is connected. The software firewall applies a set of rules to data transmissions through inspection and filtering of data packets. Windows Firewall is an example of a software firewall. It is installed by default when the OS is installed.
Every communication using TCP/IP is associated with a port number. HTTP, for instance, uses port 80 by default. A software firewall, as shown in Figure 1, is capable of protecting a computer from intrusion through data ports. You can control the type of data sent to another computer by selecting which ports will be open and which will be blocked. You must create exceptions to allow certain traffic or applications to connect to the computer. Firewalls block incoming and outgoing network connections, unless exceptions are defined to open and close the ports required by a program.
To disable ports with the Windows Firewall in Windows 7, as shown in Figure 2, follow these steps:
Step 1. Select Start > Control Panel > Windows Firewall > Advanced settings.
Step 2. In the left pane, choose to configure either Inbound Rules or Outbound Rules in the left pane and click New Rule… in the right pane.
Step 3. Select the Port radio button and click Next.
Step 4. Choose TCP or UDP.
Step 5. Choose All local ports or Specific local ports to define individual ports or a port range and click Next.
Step 6. Choose Block the connection and click Next.
Step 7. Choose when the rule applies and click Next.
Step 8. Provide a name and optional description for the rule and click Finish.
To disable ports with the Windows Firewall in Windows Vista, follow these steps:
Step 1. Select Start > Control Panel > Windows Firewall > Change Settings > Continue > Exceptions > Add port….
Step 2. Provide a name and port number or port range.
Step 3. Choose either TCP or UDP and click OK.
To disable ports with the Windows Firewall in Windows XP, follow these steps:
Step 1. Select Start > Control Panel > Windows Firewall > Exceptions > Add Port….
Step 2. Provide a name and port number or port range.
Step 3. Choose either TCP or UDP and click OK.
NOTE: On a secure network, enable the internal OS firewall for additional security. Some applications might not operate properly if the firewall is not configured correctly.