What is a firewall?
The task of a firewall is to look at traffic coming into your computer via the Internet and block anything that hasn't been invited by you. When you type in an Internet address or click on a link on a webpage, you are asking that the page concerned be sent to your computer. The firewall recognises this traffic and allows it in, but blocks any incoming connections which you have not asked for, as these would most probably be an attempt by a criminal to take control of your computer. Think of the firewall as the immigration officer at the airport, who wants to know where you've come from, and if you have an invitation to be in the country.
NB: you should only have ONE firewall program on your computer; two or more will conflict, and can actually make the computer less secure as a result.
How do I check whether I have a firewall program running?
Go to Control Panel and open Windows Security Center (see the link on the left for more details). If all is well, you will see "Firewall On".
If the Firewall section is green and says "On", is everything OK?
No, not necessarily. You need to investigate a little further. You need to check that you only have ONE firewall program running. To check the firewall, click on the down arrow at the right-hand end of the firewall bar to see the details. If you see something like this, there's a problem:
Although Windows has not raised an alarm, it has noted that there are TWO firewall programs running. If you see that both Windows Firewall and another firewall program are switched on, switch Windows Firewall off. Just go to Control Panel, double-click Windows Firewall, click Off, and then OK (in Windows Vista you will need to click Change Settings first). The Firewall window will warn you against this, but in this case, it's the right thing to do. Windows can be stupid sometimes, and contradict itself! Close and re-open Security Center, and you should now see just one firewall program running.
What should I do if Windows Security Center reports a firewall problem?
If there is no firewall switched on, it should be fairly easy to correct using a button right next to the warning (see below). Click on Turn on (Vista) or Recommendations, Enable now (XP). If you are unable to switch a firewall program on, we advise you to ask an expert for help, as your computer is at risk.
Can I test my firewall to see if it's working?
Yes, you can. Gibson Research Corporation* have a quick and simple online test which will tell you whether you are really protected from hackers. Go to www.grc.com and follow the links to the ShieldsUP! test, then click on the "All Service Ports" option. This tests whether there is any possible route into your computer over the Internet. It takes about 5 minutes, and will clearly tell you if your computer has passed or failed. If your computer fails this test, we recommend that you ask a computer expert to investigate and put things right.
Are firewalls as simple as this page makes out?
No, not at all. The subject of firewalls is a very complicated one, even for computer experts. We have very much simplified and abbreviated the essentials here, to avoid confusing non-experts. We will be providing more detailed information about firewalls in Level 3 of this website.