A firewall is the gateway that restricts access between networks in agreement with local security policy.

Computer virus attacks are in the news all the time. Everyone knows about them and puts antivirus software on their computers. It’s pretty standard stuff. A little lesser known, but just as important is software that scans your computer for spyware and removes it too.

Most people think that’s all they need to surf the web safely. What they don’t realize is that they’re missing a very important third piece of the internet security equation, a firewall. Without a firewall, your computer is wide open to an array of attacks, break-ins and probes. It’s a “must have” if you plan on doing any kind of online banking or purchasing with credit cards.

Just like a wall built to keep fires from spreading in buildings, a computer firewall keeps all the nasty stuff roaming around in the internet from getting into your computer. While cable and DSL are easier to probe, don’t think that by being on dial-up you’re any safer.

So, how does a firewall work?

Firewalls use one of three methods:

Packet Filtering – Filters are created and used to analyze small pieces of data called packets. Packets that make it through the filter then go on to the requesting system, while those that don’t are discarded.

Proxy Service – The firewall retrieves information from the internet and sends it to the requesting system and vice versa.

Stateful Inspection – This method compares specific parts of a packet against a database of trusted information. By monitoring all the states of network connections, the firewall will only allow packets that contain information from known connection states. All other packets will be discarded by the firewall.

Packet filtering was the first generation of firewalls, followed by stateful inspection and the most commonly used today, proxy service. Windows XP, Vista and a few other operating systems come with their own firewall built in. If you don’t have an operating system with its own firewall, you can download one for free very easily.

Here are a few links to the most popular according to our search using Google:

Along with software, there are hardware firewalls as well. They typically reside in a cable or DSL router and are considered to be the most secure of the two types of firewalls. Additionally, hardware firewalls are relatively inexpensive at $100 or less in a broadband router/ hub/ modem bundle. Using both a hardware and software firewall will give any network a very high degree of security.

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