What is a firewall?
What is a firewall?
A firewall is a software program or piece of hardware that helps screen out hackers, viruses, and worms that try to reach your computer over the Internet. If you can’t start Windows Firewall or you are getting an error, use Microsoft free tool to diagnose and fix problems.
- If you use a computer at home, the most effective and important first step you can take to help protect your computer is to turn on a firewall.
- Windows 8, Windows 7, Windows Vista, and Windows XP SP2 or higher have a firewall built-in and turned on by default. (Note: Support for Windows XP ended in April 2014.)
- If you have more than one computer connected in the home, or if you have a small-office network, it is important to protect every computer. You should have a hardware firewall (such as a router) to protect your network, but you should also use a software firewall on each computer to help prevent the spread of a virus in your network if one of the computers becomes infected.
- If your computer is part of a business, school, or other organizational network, you should follow the policy established by the network administrator.
Automatically diagnose and fix problems with Windows Firewall
- Select the Download button on this page.
- In the File Download dialog box, click Run or Open, and then follow the steps in the Windows Firewall Troubleshooter.
- This troubleshooter might be in English only. However, the automatic fix also works for versions of Windows in other languages.
- If you’re not on the computer that has the problem, save the troubleshooter to a flash drive or a CD, and then run it on the computer that has the problem.
- Windows Firewall isn’t the default firewall
- Windows Firewall doesn’t start
- Windows couldn’t start Windows Firewall (Service-specific error 5 (0x5))
- Remote Assistance isn’t working because it’s blocked by Windows Firewall
- You’re unable to access shared files and printers because sharing is blocked by Windows Firewall
- BFE service is missing
- Firewall won’t start (Error Code 80070424)
- Windows 7
- Windows 8
- Windows 8.1
- Windows 10