I can presum that nobody likes the idea of someone getting access to your computer over the internet.
But there is a possibility that it happens, in most operating systems there are many errors and faults which
leave a door open to people who know how to use these 'backdoors'. Don't be alarmed because there are not
many people who know how to do it. But non the less it is better to be secure than to hope that it won't happen.
And what do you think about computer programs which communicate to other computers across the internet
without you knowing it? A lot of privat information could go across. These programs could accumulate 'innocent'
data like on which page you have been on the internet, to make a profile of the average surfer. There could be such a
program on your computer because it mostly comes 'free' with other free but usefull programs.
But there are also malicious programs which give other people access to your computer, after which the can almost
fully control it. For all theses cases there is a fairly good protection, know as a firewall.
What is a Firewall?
A firewall is a computer or a computer program which checks all internet traffic and can block it or let it pass. The user
of the firewall can make up a set of rules which state if traffic me pass or is blocked. In this manner you can
have full control on your internet access.
In a large network a computer with a very secure operating system is mostly used as a firewall. In smaller networks
or at home this would be to costly and to circumstantial. In these casses a software firewall is used.
Test your computer
To test your own computer for vunerability you can use the link below and go to Steve Gibsons testpage at GRC.com
At that page you can test your firewall and have your ports scanned for leaks. The site itself is great!!
During these test an attempt is made to make contact with your computer. During the specific port scans frequently used
doorways to the internet are tested to see if the are open to the outside world. If there is a leak a warning
and some advice is given.
One of the best firewalls is made by zone labs and is called Zone-alarm. Steve Gibson (GRC.COM) calls it the
best firewall at this moment. A second advantage is that it is free for home-users. In a home situation it therefor can be used without any cost.
After downloading and installing zone-alarm you will be prompted for permission if an attempt is made to connect to
the internet from your computer and if an atempt is made to connect to your computer from the internet.
This could be annoying therefor you can order zone-alarm to make a rule out of the answer you have given. In
the future no question will be asked if the same program atempts to make contact to the internet. After a couple
of days you won't even notice zone-alarm anymore. Unless you have installed an other program which atempts to contact
the internet.
Disadvantages of a firewall
The mean disadvantage of a firewall is that it uses a small portion of processor power en memory. In addition, some programs which are used
to make a direct contact between two computers won't work perfect anymore. This can be solved by giving the program server rights, this will
be asked when such a program starts up for the first time. If there is already a rule for that program then try to remove that rule from the
list and start the program anew and give it server rights.
