Introduction
There are many variations of firewalls. Each has a slightly different application. When looking to install a firewall, it is not a simple answer to give when asked which one to select. Does your needs assessment determine why you need a firewall? Take a look below to determine the type of firewall that will meet your need. After you determine the type of firewall you need, the hardest step will be selecting a vendor.
Free Firewall
Many software and desktop firewalls are free. Many of these firewalls are
Linux or BSD based and can be quickly set up to protect a small to medium size company quickly. Also free firewalls often come in the form of a desktop firewall (sometimes called a personal firewall)
Desktop Firewall
Any software installed on an operating system to protect a single computer, like the
one included with Windows XP, is called a desktop or personal firewall. This type of firewall is designed to protect a single desktop computer. This is a great protection mechanism if the network firewall is compromised.
Software Firewall
This type of firewall is a software package installed on a server operating system which turns the server into a full fledged firewall. Many people do not consider this the most secure type of firewall as you have the inherit security issues of the underlying operating system. This type of firewall is often used as an application firewall. This means the firewall is optimized to protect applications such as web application and email servers. Software firewalls have complex filters to inspect the content of the network traffic to insure that type of traffic is properly formatted. This type of firewall is usually (but not always) behind hardware firewalls (explanation to follow).
Hardware Firewall
A hardware firewall is a dedicated hardware device with a proprietary operating system or a stripped down operating system core. These firewalls include network routers with additional firewall capabilities. These firewalls are designed to handle large amounts of network traffic. Hardware firewalls are often placed on the perimeter of the network to filter the internet noise and only allow pre-determined traffic into the network. Sometimes hardware firewalls are used in conjunction with software firewalls so the hardware firewall filters out the traffic and the software firewall inspects the network traffic. When hardware firewalls are bombarded with bogus network traffic they drop the unwanted traffic only letting in the right traffic. This not only protects the software firewall but allows the software firewall only has to inspect proper network traffic thus the combination optimizes the network throughput.
Conclusion
So when determining the firewall, remember there are many different types and even more vendors. One thing to make sure is that you deploy a firewall that your IT team can manage it effectively.
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