Internet Firewalls

Basically, a 'firewall' provides an extra line of defense between your computer and the Internet. It can block out unwanted intrusions, whether they are hackers or malicious files, and even make you 'invisible' on the Net so no-one knows you're even there.

Symantec recently conducted a survey "To quantify and raise awareness concerning the vulnerability from automated and random hacking attacks for internet users at home and at work." Symantec took a group of 300 computer users, ranging from home users, small businesses and IT directors with remote or laptop users. Each user installed a copy of Norton Personal Firewall onto their machine. After a one month period Symantec collected Intrusion log reports from Norton Personal Firewall showing all intrusion attempts that threatened the system during this month period. The results were staggering.

  • 95% of ALL participants were visited by a hacker during the one month survey period.
  • In a 14 day period within the one month survey, one user suffered 84 separate attacks.
  • There was an average of 50 hacking attempts made each day.
  • Research participants spent an average of 2.5 hours online a day.

You can test the security of your computer whilst connected to the Internet by using either the 'Shields Up' facility on the following site ( This will tell you how vulnerable your computer is whilst connected and how easy it is for someone else to access your files whilst you're online. Some ISPs provide some firewall services (see 'Internet Privacy' below). Later versions of Windows have a built in firewall (make sure it's switched on if it's all you have). There are also stand-alone firewall software products. Here is a selection:

McAfee Personal Firewall
Intego £31.99 (Mac only)
Norton Personal Firewall
ZoneAlarm 'FREE'

Some firewalls also have a design flaw and do not block all that they should, particularly when it comes to 'spyware' (see 'Internet Privacy' below). To test for this flaw, go to and download & run the small 'LeakTest' programme. It will check to see if your firewall is vulnerable.
Firewalls are also available in hardware form. These have traditionally been very expensive, but recently small network products have started to incorporate hardware firewalls for under £100. These would be a good option for anyone with a home network (LAN) and broadband connection.
For more information on 'Firewall' software, see or