How to Use a Firewall on Your Computer

Turn on and configure the built-in software firewall on your computer to block unauthorized access.

Steps

1
Open your computer security settings.
On Windows, open the Start menu and search for "Windows Security." On Mac, open System Settings and click "Network."
2
Click "Firewall and network protection" on Windows.
On Mac, scroll down and click "Firewall" in the Network settings.
3
Turn the firewall on if it is not already active.
Windows shows your active network profiles. Mac has a single toggle to enable the firewall.
4
Review which apps are allowed through the firewall.
On Windows, click "Allow an app through firewall" to see the list. Remove apps you do not recognize.
5
Turn on firewall notifications for blocked apps.
This lets you know when the firewall stops a program from connecting to the internet.

Is the Windows firewall good enough?Show

Yes, the built-in Windows firewall is effective for most home users. You do not need to buy a third-party firewall.

Will a firewall slow down my internet?Show

No, a firewall does not slow down your internet speed. It checks network traffic but does this so fast you will not notice it.

Do I need a firewall if I have antivirus software?Show

Yes, firewalls and antivirus do different jobs. A firewall blocks network attacks while antivirus finds and removes malicious files.

Written by the HowToDoStuff.online editorial team. Last updated May 18, 2026.