A hacker is someone who tries to 'break into' (electronically-speaking) a computer or network with a view to stealing information (eg passwords and sensitive documents), changing information (eg replacing Tony Blair's message with a smutty one) or destroying files and documents. Hackers seek to exert some sort of control, hopefully from their perspective, without you knowing it's happening. Very often a hacker is someone who takes on the challenge and wants to prove they've succeeded in exposing a 'security' weakness in your system or in Microsoft's software, for example.

Hackers can only penetrate a system whilst it is connected to an external network (eg the internet). So a computer is only at risk from hacking whilst it is actually online. To stop a hacker getting into a computer a Firewall (usually just some software installed on the computer being protected) needs to be set up between it and the outside world. A Firewall, as the name suggests, is there to stop the 'Fire' (the hacker) getting any further.

There are many Firewall software packages on the market which can be installed to prevent a hacker gaining unauthorised access. If a computer is on a network (eg in a company) then the software needs to allow computers within the network to communicate with each other whilst denying an external computer any access.

Good 'Personal Firewall' software packages for PCs are available to purchase from companies like Symantec and McAfee. Zone Labs have an excellent package, ZoneAlarm, which can be downloaded over the internet.

ZoneAlarm is available free (as a download) for personal use. Downloading should take less than 10 minutes with a 56k modem (the file is about 3Mb in size) - a small price to pay for denying hackers their satisfaction and protecting you at the very least from the embarrassing loss of your privacy.

Personal Firewalls  McAfee   Symantec   Zone Labs  To download ZoneAlarm free click here and select 'FREE Download'