Firewalls - shutting the front door

Last month we looked at computer viruses and how to prevent your computer being infected.
The term "virus" is really a misnomer as the term is used generically to cover viruses, worms and Trojans.

There is a popular misconception that you can only "catch" a virus via e-mail, specifically by clicking on or opening an attachment. But in today's broadband connected world life is no longer that simple.

Your computer can be infected without ever even starting your e-mail program. I didn't believe it either at first - until my PC was infected with a worm while it was sitting idle. Computer hackers spend a lot of time trying to find flaws in the major operating systems in use - notably Microsoft Windows.

And the minute you connect to the internet your computer is easy prey to hackers. A broadband connection is even worse as it means that your PC is virtually permanently connected to the net. With hacking software, your PC can appear like a beacon on the net, ripe for an attack. To protect yourself you need a firewall.

A poll by anti-virus providers Sophos revealed that only 46% of SMEs have implemented firewalls, compared with 70% of larger companies that have taken appropriate steps to monitor their gateways for virus threats.

Think of a firewall as a telephone switchboard. All incoming calls (or data packets in this instance) are screened and only the calls that you want are put through. All traffic to and from the internet goes through the firewall and is "inspected" and checked against a set of rules that define what traffic flows are allowed or disallowed.
This sounds complex, but most firewall software offers a "learn" procedure.

Every time you connect to the net, surf the web and send or receive e-mail, the firewall asks you if it is OK to proceed. The software considers your answer and builds a complex list of rules that define what can and cannot get through the firewall.

After a couple of days you can then switch the firewall to automatic mode and it won't bother you.
The idea is to get the Firewall to automatically let you access the net and send and receive e-mail, but prevent any other malicious attack.

Once a firewall is installed it is important that it is set up properly, otherwise the protection it offers will be as good as useless.

Do they work?

But do Firewalls work? Well, while using VOIP (Voice Over Internet Protocol) software to talk via my computer to someone in California I disabled the firewall as I was having problems. Within two minutes my anti-virus software reported that it had been infected with a worm. A friend's PC contracted a nasty virus after using Microsoft's MSN Messenger software. This resulted in the machine needing a complete reinstall of the Windows operating system. Oh, and he wasn't using a firewall either.

Firewalls can be tricky to set-up and are best left to professionals if you have a network. But even if you have just one PC you should install a personal firewall.

It needn't cost the earth either - Tiny Personal Firewall (www.tinysoftware.com) costs $49 [dollars] while Symantec's Norton Personal Firewall costs £49 for both the PC and Macintosh.

If you are using Microsoft Windows XP there is even a free built-in firewall, but you must ensure it is switched on - go to Control Panel, Network Connections and right-click on the connection you wish to protect. Select "Properties" and under the "advanced" tab make sure the firewall is enabled.

What is Instant Messaging?
Instant messaging is a way to communicate on the internet with text messages you exchange in real-time. It's like e-mail only you send and receive your messages instantly.

You simply maintain a contact list of friends you want to stay in touch with via instant messaging and as long as you and your contacts are both online, you can chat one-on-one in real-time. Most instant messaging services offer the option of chat rooms, where you can set up an instant messaging session with a group of family or friends.
Instant messaging sits between a phone call and e-mail and can be a very productive tool if used correctly.

If used incorrectly it can waste hours of useful employee time!
The most popular instant messaging systems around include MSN Messenger (http://messenger.msn.com), ICQ (http://web.icq.com/), AOL Instant Messenger (http://www.aol.com/) and Yahoo Messenger (http://uk.messenger.yahoo.com/).
There are also some companies that let you access all your instant messaging accounts from a single interface - see Trillian at http://www.ceruleanstudios.com/ or Odigo (http://www.odigo.org/).