If you spend a lot of time on the internet and you are not behind a
firewall, then you are living on borrowed time. Putting some protection
between you and the internet is probably the third most important thing
that you can do (after getting virus
checking software and performing regular backups).
The diagram above shows an unprotected system using a DSL modem. As you
can see, someone on the internet can attach the computer system easily
as the DSL modem provides no protection (some DSL modems have built-in
firewalls). An attacker can get through any type of modem - DSL, cable,
56K, 28.8 or whatever. If the device gets you on the internet, you are
vulnerable.
For those with a DSL, cable modem or other "always-on" connection, you
MUST get a firewall. This is critical, as your machine is always
live and it most likely has a fixed IP address. This makes it easier for
your system to be "found" and attacked.
What a personal firewall does is isolate your computer from the rest
of the internet. It does this by inspecting each packet of data to determine
if it it should be allowed to get to (and in some cases from your machine.)
The best protection completely hides your computer - this is called stealth
mode.
You have the option of installing a software firewall or a hardware
firewall.
Software Firewall - A software firewall runs on your computer
system in the background. It intercepts each network request and determines
if the request is valid or not. Software firewalls offer the following
advantages:
-
They are generally very inexpensive
-
They are very easy to configure
They have the following disadvantages:
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Since they run on your computer they require resources (CPU, memory and
disk space) from your system.
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They can introduce incompatibilities into your operating system.
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You must install exactly the correct version for your operating system.
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You must purchase one copy for each system on your home network.
Hardware Firewall - A hardware firewall is generally a small
box which sits between your computer and your modem. In general, hardware
firewalls have the following advantages:
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They tend to provide more complete protection than software firewalls
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A hardware firewall can protect more than one system at a time
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They do not effect system performance since they do not run on your system.
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They are independent of your operating system and applications.
They have the following disadvantages:
-
They tend to be expensive, although if you have a number of machines to
protect it can cost less to purchase one hardware firewall than a number
of copies of a software product.
-
Since they do not run on your computer, they can be challenging to configure.
Firewall mixture - The best protection is a combination of
both hardware and software firewalls. This is the ideal, since both have
different advantages and disadvantages. Personally, I use a SonicWall
hardware firewall combined with ZoneAlarm Pro, which is installed
on my Windows 2000 Professional system. The SonicWall protects
my home network since it sits between the hub and the DSL modem, and ZoneAlarm
Pro offers some additional protection for each system.
Testing Your Firewall - To test your firewall,
surf to http://www.internet-tips.net/cgi-bin/lnkinlte.cgi?l=.grc
and request a probe. You will be given a very good report of exactly
what issues were found and what to do about them. Once the probe is finished
several excellent personal firewall products are recommended. My personal
favorite is ZoneAlarm Pro, primarily because it's protection is excellent
and it is trivial to use.
Some Firewalls - A selection of personal
firewalls is listed below.
ZoneAlarm Pro
- By far the best software firewall available. ZoneAlarm offers protection
from both incoming connections and outgoing connections. It is also extremely
easy to configure, has low system impact and is very inexpensive (a free
version is also available).
Norton Internet Security
2001 (which was the AtGuard product from WRQ until a few months
ago). Norton is a reasonable firewall, although it does have some vulnerabilities.
It offers weak protection from outgoing connections and is somewhat difficult
to configure if you want it to operate differently from the default.
BlackIce -
A good choice in firewalls. Much easier than Norton to configure, but with
the same vulnerabilities.
What I've done on my system is:
-
Used a SonicWall hardware firewall to protect my entire home
network.
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Installed ZoneAlarm Pro on each system to provide additional
safety
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And installed Norton Internet Security for it's privacy protection.
Due to the rapidly changing nature of the internet, it's very important
to be continually monitoring security issues. You may purchase the perfect
personal firewall today, only to find out in six months that it's been
hacked to pieces. So be sure to be looking around, and be ready to get
a newer and better product quickly. This is not one of those issues where
you can scrimp and save. Your system is at risk. |
