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Intrusion Protection and Firewalls

A firewall protects your computer from intrusions by hackers, and helps prevents data from being sent out from your computer without your knowledge. However, it also performs a very important anti-virus function. A number of recent worms have propagated themselves directly via the internet rather than via email attachments. The speed with which such attacks can occur is so rapid, that updates to the anti-virus software cannot keep up. A firewall helps to protects your computer against such problems.

Windows XP has a built in firewall (ICF) which you can activate, but if you have not kept your version of Windows XP up to date with the critical security patches, I think there may be a few holes in the firewall. Therefore I prefer to use a third-party firewall. Before installing a third -party firewall make sure ICF is turned off, but don't do this while you are still connected to the internet (e.g. if you are downloading the firewall prior to installing it)!

Anti-virus software is not the same as firewall software. However, you may have an integrated internet security package, which already contains a firewall. Check to see if you already have one. If you don't have such an integrated security package, then you might consider a standalone third-party firewall such as Zone Alarm, Sygate, Tiny, or Kerio.

Here is an analogy of how a firewall, such as Zone Alarm, works.

Bear in mind that some firewalls may conflict with some anti-virus software, although I exepct such cases will be rare. Anyway, you must configure your firewall to allow your anti-virus software to access the internet, otherwise you will have difficulty obtaining on-line updates.

Most firewalls will offer to block any programmes of yours which attempt to access the internet. In some cases, using the firewall to block a programme can cause the computer to crash. If you are unsure of the programme which the firewall is offering to block, I would suggest that you allow it access, disconnect from the internet, and then try to find out what the programme is. By looking inside your firewall's control panel you can usually see more details about the programme in question. For example, you may see that the obscurely named "wxyz1234.exe" is simply some component of your media player. In most cases the programmes will be perfectly legitimate, especially if you have kept your pc virus-free and spyware-free.

You can test if your firewall is working properly using Steve Gibson's Shields Up scanner.

There are other forms of intrusion we shall look at (when I have time to publish the information here). In the meantime a spyware scanner such as Ad-Aware or Spybot will help, and critical security updates can be installed to protect from other holes e.g. browser hacking.

With regard to anti-spyware software, do not remove any of the spyware components found without first taking expert advice. Some components may be essential for the functioning of certain programmes.

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