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What
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SUMMARY:
This tip defines a firewall and why it is important for your computer
security.
(This definition of a firewall is NOT complete but meant to provide a
basic explanation of the term, mainly to beginning and intermediate
computer users.)
A basic definition of a firewall is either a software program
or
hardware device you can use when connected to a network (such as
Internet), mainly to help prevent your machine from getting attacked by
a computer virus.
"Attacks" usually occur when an application you are running,
or the
operating system itself, is vulnerable to problems.
Two examples of the types of vulnerabilities that can occur:
* Your multimedia player cannot handle a specially-crafted
audio or
video file. When it tries to play the file, the multimedia player may
crash, or worse, malicious instructions can be embedded in the file
that when read, cause all sorts of problems, including opening a 'back
door' on your computer.
* Your operating system, when sent enough requests from a
malicious
computer on the Internet, could either slow down to a crawl or crash.
This is called a denial-of-service
attack.
Although operating systems and applications are updated to
protect
against known spyware or malware vulnerabilities, software designers
are not perfect and
it is only a matter of time before malicious people find and exploit
problems. Firewalls can literally 'close up' known and potential holes
on your computer. This helps prevent vulnerabilities, even as-of-yet
unknown ones, from being exploited.
Firewalls mainly perform this task in two ways:
* An 'inbound firewall' filters data from an outside network,
hopefully
preventing all but legitimate information from being sent to your
computer.
* An 'outbound firewall' performs the opposite type of
filtering. It
helps prevent a computer that has been attacked from sending certain
types of information to the outside world, announcing that the computer
is vulnerable.
The best firewalls do both to help protect your machine.
Firewalls are not perfect and they alone cannot stop your
computer from
falling victim to malicious activity, but they can greatly lower the
chances.
By the way, the term "firewall" comes from the term "fire
wall", a wall
built inside houses, apartments, or other structures that helps prevent
fires from spreading from one room to another. Likewise, a computer
"firewall" helps prevent problems on the Internet from spilling onto
your computer.