Windows 8 comes with a built-in firewall that is similar to the one found in Windows 7. This firewall, usually known as the Windows Firewall, allows you to stay protected even if do not have third-party application firewalls installed.
If you turned off the Windows Firewall during the Windows 8 installation, you can turn it back on via the Control Panel. The process it takes to open the Control Panel in Windows 8 is slightly different from Windows 7 due to the introduction of the Metro UI.
Log in to your Windows 8 user account. You will now see the Metro UI.
Point your mouse to the lower right corner of the screen. A sidebar will show up on the right side of the screen.
Click the “Control Panel” option on the sidebar. Windows 8 will now open the Control Panel.
Click the “System and Security” option. Once you are inside the System and Security window, click on “Windows Firewall.”
Click “Turn Windows Firewall on or off” on the left side of the window.
Click the radio button under both the private and public settings sections. Now click the “OK” button to turn on the firewall in Windows 8.