How Firewalls Work

By: Jeff Tyson

Proxy Servers and DMZ

A function that is often combined with a firewall is a proxy server. The proxy server is used to access Web pages by the other computers. When another computer requests a Web page, it is retrieved by the proxy server and then sent to the requesting computer. The net effect of this action is that the remote computer hosting the Web page never comes into direct contact with anything on your home network, other than the proxy server.

Proxy servers can also make your Internet access work more efficiently. If you access a page on a Web site, it is cached (stored) on the proxy server. This means that the next time you go back to that page, it normally doesn't have to load again from the Web site. Instead it loads instantaneously from the proxy server.


There are times that you may want remote users to have access to items on your network. Some examples are:

  • Web site
  • Online business
  • FTP download and upload area

­ In cases like this, you may want to create a DMZ (Demilitarized Zone). Although this sounds pretty serious, it really is just an area that is outside the firewall. Think of DMZ as the front yard of your house. It belongs to you and you may put some things there, but you would put anything valuable inside the house where it can be properly secured.

Setting up a DMZ is very easy. If you have multiple computers, you can choose to simply place one of the computers between the Internet connection and the firewall. Most of the software firewalls available will allow you to designate a directory on the gateway computer as a DMZ.

Once you have a firewall in place, you should test it. A great way to do this is to go to and try their free Shields Up! security test. You will get immediate feedback on just how secure your system is!

For more information on firewalls and related topics, check out the links below.

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