What exactly is a firewall? The very term “firewall” originally meant a wall to contain a fire or at least stop a fire from spreading. The term emerged in the late 1980s when computer networks were in place. But instead of stopping a fire the purpose was to stop outsiders from accessing the network.
Now if movies and TV are to be believed a “firewall” is now some form of ultra high-tech obstacle that protects sensitive information. How exactly it works in this fiction is never really made clear. And just as unclear is how a guy with a laptop that seems otherwise unconnected to anything can suddenly break through. In this world of cyberpunk and techno thrill fiction savvy hackers are also able to type away – also seemingly at random – to gain access to a computer.
The truth is very different. In reality a firewall is just a basic program or simple piece of hardware that any computer user, especially those with a broadband connection should have running at all times. And more importantly, if your computer is connected to the Internet via a broadband connection then it has an Internet Protocol signature, or IP address. And just like a street address it means that the site can be found.
If you wouldn’t leave the front door wide open, you probably shouldn’t leave your PC unprotected, because other online users can access that IP address, and this is why a firewall becomes so important. A firewall can therefore provide secure access to the Internet, allowing safe traffic into and out of your computer or private network, while at the same time automatically blocking intruders and hackers. Moreover, the firewall gives you the power to decide which programs should be able to connect to the Internet, while also shielding you from being attacked through security holes in un-patched software.
So while a network or computer firewall can be compared to the firewalls meant to stop the spread of fire, the purpose is quite different. A firewall in a building is a worst-case scenario part of the construction, whereas a firewall for a computer is something you probably use regularly without even knowing. And for a small business with a network it is absolutely essential.
This post is part of the series: Firewall basics
This short series of articles provides an introduction to firewalls: what they are and how they work.