PC Security: Firewalls - Part One
You probably know that you need a firewall. But the
chances are good that you don't actually understand the purpose of the firewall
or exactly what it does. Most average users do not - they just (hopefully)
know that they need one to protect their PC.
When you think of a firewall, think of an actual firewall that is used to
prevent the spread of fire from one area to another. A firewall may be inside
of a building, but it may also be outside of a building. For example, when
you see a farmer plow up numerous rows of earth around a field that he plans
to burn - or a field that accidentally caught fire, he is in essence creating
But interior firewalls are what we are discussing here. Those are ultra thick
steel walls that will not burn. They are much like the material and structure
of a vault. The firewall prevents the fire from gaining access to the area
that it was designed to protect. A computer firewall, or network firewall,
acts the same way. It prevents access to your computer. It puts limitations
that you specify on the programs and data that go in or out of your computer
Firewalls come in two flavors: Hardware and Software. In a network, hardware
firewalls are often used, but software must also be used to control that
hardware. Likewise, without the appropriate hardware, the software has no
function. Corporations take advantage of firewalls by allowing all of the
computers in the corporation to communicate with each other, and the Internet,
but by restricting communication with those computers from the Internet.
Internal firewalls may also be used in corporations to prevent some computers
from accessing or communicating with others. This prevents information leaks
in some cases, and of course viruses in many others.
A software firewall is often referred to as a personal firewall. It is called
such because it is used on personal computers more than anywhere else. These
types of firewalls use resources on the PC that it is protecting, but they
run slower than hardware firewalls.
Firewalls serve to keep both viruses and hackers out of your system. They
serve to control the traffic that comes into and goes out of your system.
You might think of them as 'gatekeepers.' You control the gatekeeper, and
tell it what may and may not come in and out of your system. Obviously, you
would allow inbound and outbound traffic for email, inbound traffic for
auto-updating software, and outbound traffic to access the Internet.
Firewalls must be educated, but they learn fast. For example, the first time
a program - either from the outside or the inside, tries to move past the
firewall, the firewall will ask you (the teacher) if this should be allowed.
The next time the program tries to move, it will remember your answer.
An open port on your computer is a hackers best friend - and their access
to your computers. An open port can be used to gain access to your computer,
or to let a worm or some other nasty virus in. Firewalls serve to close any
port that is not being used for legitimate reasons, and will restrict traffic
through that port while it is open, only allowing movement that you have
specified. Furthermore, a good firewall will make the open port invisible,
so that a hackers scanning software doesn't see it.
This does not guarantee that firewalls cannot be breached. The firewall is
part of the computer system. It is a program just like any other program
on your computer. If a virus sneaks in with traffic that you allow, such
as email, the firewall can be attacked by the virus.
Now that you understand the importance of a firewall, you may not be so irritated
when the firewall alert box pops up. Now, you know that it is just doing
the job that you need it to do for you - it is protecting your computer!
PC Security: Index
Stopping Spam Part 1
Stopping Spam Part 2
PC Security: Spam
Email Security and Spam
Protecting Computers From Viruses
Trojan Horse Viruses
Removing a Virus
Cell Phone Viruses
Firewalls Part 1
Firewalls Part 2
Security: Parental Control Software
Malware - Spyware and Adware
Pop Up Windows
Security: Safe Public Computer
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