What is a firewall?

Answer: A firewall is a piece of hardware, or software, between your computer network and the Internet. Its job is to block unwanted network traffic to your computer while still allowing network traffic out from your computer. Unwanted network traffic means malicious software (viruses) and people (hackers).

Firewalls exist to protect you and your computer from risk. If you do not have a firewall, you definitely need one. It is much too risky to have a computer connected to the Internet without a firewall.

Most firewalls block incoming network traffic and allow outgoing network traffic by default. They can be fine-tuned to allow certain types of network traffic while denying other types. For instance, you might allow Web traffic but deny remote desktop connections.

Most firewalls do not block outgoing network traffic allowing you to send and receive email or surf the Web.

Many people already have a firewall installed and do not know it. Windows XP and Vista have a firewall built in, and after XP Service Pack 2 the firewall is turned on by default. The Windows firewall is not very configurable and most people I know do not trust it. For people that do not have a firewall, or do not trust their existing firewall, there are many three-party solutions available.

There are two kinds of firewalls -- hardware and software. An example of a hardware firewall would be a router. Many, if not all, routers have a firewall built in. For most people this is adequate. Hardware routers stop network traffic before it even gets to your computer. However, most routers do not filter outgoing traffic.

Network traffic leaving your computer matters because many viruses open a network connection from your computer and attempt to spread to other computers. If your firewall does not filter outgoing traffic, it is only doing half the job.

Software firewalls run on your computer. They are close to the network layer meaning the network traffic has to go through your software firewall before reaching your operating system. Software firewalls are harder to setup than hardware firewalls. Typically, you configure software firewalls to filter incoming and outgoing network traffic, which is what you want.

I personally prefer a hardware solution for home use. My router acts as a firewall filtering incoming network traffic. I rely on the firewall, sensible Internet habits, proper configuration, up-to-date patches, and my anti-virus software to keep my computer safe. At work, I use a mixed solution. A hardware firewall built into our DSL router, and a software firewall running on our server.

A firewall cannot keep your computer safe from everything but it is an important part of keeping yourself and your computer protected from Internet threats.

David can be reached by e-mail at dwilliams@paragonforce.com or by telephone at 384-3040.