By default, most programs are blocked by Windows Firewall to help make your computer more secure. To work properly, some programs might require you to allow them to communicate through the firewall.
Open Windows Firewall by clicking the Start button , and then clicking Control Panel. In the search box, type firewall, and then click Windows Firewall.
In the left pane, click Allow a program or feature through Windows Firewall.
Click Change settings.
If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
Select the check box next to the program you want to allow, select the network locations you want to allow communication on, and then click OK.
Before allowing a program through the firewall, make sure you understand the risks involved. For more information, see What are the risks of allowing programs through a firewall?
For information about opening ports in Windows Firewall, see Open a port in Windows Firewall.
If you’re having trouble allowing other computers to communicate with your computer through Windows Firewall, you can try using the Incoming Connections troubleshooter to automatically find and fix some common problems.
Open the Incoming Connections troubleshooter by clicking the Start button , and then clicking Control Panel. In the search box, type troubleshooter, and then click Troubleshooting. Click View all, and then click Incoming Connections.
For information about advanced firewall troubleshooting, see Windows Firewall with Advanced Security Troubleshooting Guide: Diagnostics and Tools and Troubleshooting Windows Firewall settings in Windows XP Service Pack 2 for advanced users.