A firewall is a program that blocks outside machines from having free access to your computer when it is connected to the Internet. A firewall will also block programs on your computer from accessing the internet without permission, preventing viruses and other unwanted programs from accessing your computer. Changing your firewall options so that nothing can disable the firewall involves removing all "exceptions," which are special rules allowing certain programs to access the web without supervision.
Navigate to the "Security Center" by clicking on the "Start" menu, then going to the "Control Panel. Once there, click on the option for "Windows Firewall."
Choose "Change Settings," which is located next to the line that reads, "Windows Firewall is on (off)."
Check the box that reads "Block All Incoming Connections." This will guard your computer against all programs trying to access your machine from the Internet.
Click the tab marked "Exceptions." This will display a list of programs that you have given specific permission to access the Internet without your constant supervision. Deselect all of these boxes, then press "OK."
Reboot your computer so your setting changes take effect.
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