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Question: What exactly is a firewall?
- Alex J.
Duluth, GA

Alex,

A firewall is software or a hardware device that filters information coming in to a computer network. They are installed most commonly between different network zones of trust. For example, a home network is a zone and the internet is another zone. In this age of hackers and viruses, there's no way to trust every request that comes across a network (especially from the Internet) to your computer. Firewalls are used to keep these unwanted intrusions at bay. Your Internet connection probably passes through several firewalls on its way to and from websites you visit.

First, your personal firewall (like the one included in Windows XP and Vista), can control traffic to and from your computer, letting you determine which applications can send and receive data, and alert you when something violates the firewall's rules.

Next, if you use a router (for sharing your Internet connection over broadband), there may be a firewall included.

Your ISP most likely has a firewall installed in its servers that direct internet traffic to keep its own network more secure. Similarly, the companies that hosts the websites you visit also have their own firewalls. Email servers also need firewalls to keep spammers from using their resources.

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