Safe and secure

Acting as a gateway between your PC and the internet, a firewall is an essential security tool that no computer should be without. If no firewall is used, your PC will be left highly vulnerable to attack from a variety of sources – ­ it could even end up being used for malicious purposes, such as sending out spam email.

In this Back to Basics feature, we explain why firewalls are so important, how they work and what you can do with them. And, if you don’t already have one, we’ll point you in the direction of some free firewalls.

Firewall basics
There are countless services and applications that make legitimate use of your internet connection; for example, an instant messaging request from a friend or your anti-virus software checking for updates online.

However, simply letting all data flow freely between your PC and the internet leaves you open to attack. This is where a firewall comes in. In simple terms, a firewall sits between your PC and the internet, checking all inbound and outbound communication.

So, for example, when data is sent to your PC from the internet, the firewall will first inspect it to determine whether it should be allowed through. If permission is granted, the data will continue on its way as normal, but if the firewall considers it a risk the data will be stopped in its tracks.

Types of firewall
If you have a router, it quite likely has what’s called a hardware firewall built in. Hardware firewalls offer a good level of protection but they are often tricky to set up and you won’t be able to easily configure them to allow or deny internet access for specific applications installed on your PC.

It therefore makes sense to install a software firewall on each PC in your home network.

You may have noticed the Windows Firewall application that’s included as standard with all versions of Windows since XP. This does a good job of monitoring incoming data for suspicious activity and, in its basic form, is very easy to use.

However, if you want more control over which programs can access the internet automatically, you will need to open the Vista utility called Windows Firewall with Advanced Settings. Although this offers a good degree of control, it’s aimed at IT professionals, so home users may find it fiddly and tiresome to use.

We recommend that consumers opt for a third-party firewall, and there are plenty of alternatives that are easier to use. The majority of security suites, such as those from Symantec and McAfee, come with a comprehensive firewall built in, but there is also a selection of firewalls that are free to download and use (see the Firewalls for Free box for more information).