What is a firewall, and why should you use one? A firewall is basically a gatekeeper between your computer or network and the wider internet. It prevents communication between your network and the internet that you don't want, while allowing communication that you do. That is why it's a good idea to always have a firewall running to help protect you from many of the dangers of online life.
There are two types of firewalls, software and hardware. If you are running an OS that is even slightly recent (Windows XP and up, OS X, any Linux or Unix) you have a software firewall available on your computer. If it is fairly recent (Windows XP SP 2, OS X 10.4, Linux depends on distro) the firewall is already activated and protecting you. One way to find out is to go ShieldsUP!, and follow the instructions. ShieldsUP! checks the first 1056 ports to see if your firewall is blocking them.
If you have a router between your computer(s) and the internet, it probably also functions as a hardware firewall. Most, if not all, let you open ports for online gaming or other programs. The software firewall that came with your OS probably will, too. But it may be a lot harder to setup.
Most consumer routers use Network Address Translation (NAT). NAT hides the real addresses of the computers connected to the router making it harder for bad guys to access them. Originally that was an additional benefit, but as viruses, trojans and other means of attacking networked computers have proliferated, it's become an essential function.
If you would like to learn more about firewalls, check out these links:
- Wikipedia's Firewall page
- How Firewalls Work at howstuffworks.com
- The Home PC Firewall Guide atfirewallguide.com.
There are other topics you can look up to understand more about firewalls, such as Network Address Translation (NAT) and proxy servers. And don't forget anti-virus and anti-spyware protection. It takes more than just a firewall to protect a modern networked computer.
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