At its simplest a firewall is a way to keep unwanted intruders out of your computer. That's it! Any computer which is connected to the internet will need firewall protection. The internet is something of a two way street - when you are connected to it, it is connected to you. Your computer is just another connection at another network address and anyone can access it if they know that address. A good firewall will also stop rogue programs (if you have any) from getting OUT of your computer - more on this later.
How bad is your risk?
It is very easy to test. There is a wonderful website by Gibson Research that has on on-line testing facility called "Shields Up". This will test your computer's connection and tell you if you are exposed.
Click here to try Shields Up and scroll all the way to the bottom of the page and click the
Proceed button. When the testing screen appears, click on
File sharing and
Common Ports.
Do I have a firewall?
The answer is probably YES - but some firewalls are better than others. Windows XP has a firewall built in but it only does half the job. It stops incoming attempts it does not stop outgoing traffic. If you have an infected program then the XP firewall will not stop the program from communicating with the internet or downloading more software on to your PC. If you have some of the internet protection suites such as those from Norton or McAffee then these packages also provide firewall protection. A good place in Windows XP is the Windows security centre. Press the START button, select
Control Panel and click
Security Center. Any firewalls in use should be listed. If you are using an older version of XP or an earlier version of Windows then check the icons in your system tray (the area in the bottom right corner of your screen) and hover over each icon looking for the label "Firewall" or "Security" or "Internet options".
I do not have a firewall - where can I get one?
A good, well known firewall is ZoneAlarm which is free for personal use and only costs a small amount for commercial or business use. It can be downloaded from
ZoneLabs. In many tests it has performed well and is known to give a good level of protection. It stops unauthorised programs from accessing the internet too - a very useful feature. After it is installed it will ask you about any program that tries to access the internet and after a week or so it will know all the programs that should be allowed and all those that should not.
