Firewalls

To really understand what a firewall is and does, you need to think about your home and the steps you would take to keep it safe and secure. How safe would you feel without locks on your doors and windows? Would you really let a stranger through your door without some form of official ID? Now imagine your home has hundreds of doors and windows just like an office block. For something that big you would probably employ security guards to patrol and monitor and guard against unwarranted intrusion. Well your firewall does all of this.

How do they work?

The Internet is simply a network of computers that talk to each other. A firewall allows you to decide which connections between your computer and other computers are allowed and which are denied. So how does it do this?

• when the firewall identifies someone or something, not previously authorised by you, attempting to access your computer it will alert you to the fact
• the alert will ask you if you wish to allow access or block access. If you select allow it will become a trusted source and unhindered access will be allowed in the future. If you select block it will prevent access both now and in the future

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Things to remember

At the point you decide whether to allow access or not it is important to remember that there are lots of wolves in sheep's clothing out there. Clever people with criminal intentions or simply just too much time on their hands can disguise their computer to look like a legitimate source.

• if you allow access to your computer from a new source you could leave it wide open to attack
• unless you are 100% sure that the requesting computer is legitimate it would be wise to deny
• if you deny access you can always reverse this decision if you subsequently find it to be ok
• reinstating access will be a lot easier than sorting out the mess after your PC has been compromised

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Getting a firewall

You can get hold of firewalls direct from the Internet or from your local high street PC supplier.

• there are a number of free firewall products available on the Internet that will allow you to protect your home computer
• it is also worth looking at commercial versions which usually come with loads more features and facilities in order to determine which best suits your needs
• whatever your choice, once you have a firewall, you must keep it up to date
• manufacturers of firewalls will issue periodic updates to maintain and improve the performance of their products so it would be wise to check the manufacturer's site at least once a month for any downloads they may have

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