A firewall protects your computer from hackers by closing any ports you are not using. There are many good firewalls available at no cost for private use.
Updating a firewall
Firewalls need to be updated once in a while. After you’ve downloaded the update, shut down the program and restart your computer. During this time your computer may be unprotected. Therefore you should close your connection during any firewall upgrades.
Maximising the effect of your firewall
Most firewalls can be easily set to block all communication over the Internet. In fact, your computer may appear to be turned off. Keep your firewall active when you don’t intend to go on the Internet to reduce the window of opportunity for a potential attack.
What can happen if you don’t use a firewall?
Most computers are set up with all their ports open to the Internet. This set-up allows hackers to attack your computer almost at will. A firewall closes the ports you are not using and effectively limits the number of programmes exposed to malware (malicious software).