Home Firewalls: Your Computer's Locked Front Door

Firewalls originated in the construction industry. Their purpose was to isolate one part of a building from another during a fire, thus limiting the damage. Automobiles also had firewalls installed between the engine and the occupants to reduce the potential impact of fires and heat, and added the advantage of reducing noise.

In the same manner, firewalls for computers were developed to isolate one group of computers from another. Originally, all computers were simply interconnected and each computer could talk to all of the others connected on a common network. This was fine until a computer virus was formed and spread from one computer to all of the computers on the network.

The result was that most of the computers shut down or became so clogged with virus generated traffic that they could not function. It was quickly decided that a device needed to be developed to isolate computers from each other. This led to the development of the computer firewall. While some argued that firewalls were not necessary, others knew that as the network grew, the lack of firewalls could have a strong negative impact on the network.

Today's computer firewalls have not changed much since they were first developed. They have a few more bells and whistles, but they still perform the same basic function: to keep computers apart.

They do this by limiting what connections can be made from the external side of the firewall (usually the bad guys) to the inside of the firewall (the protected side). They operate in a manner similar to the receptionist who directs telephone calls to the designated party if the call is expected or to voicemail if the party is busy. Just as a boss gives a receptionist directions on which calls to allow and which ones to drop, computer firewalls have rule sets that define which connections are allowed and which ones are not.

While most businesses have had firewalls for some time, they have only recently started becoming popular with home users. With the advent of broadband connections and home operating systems such as Windows XP, manufacturers now include computer firewalls as standard equipment. If they are not turned on however, they are essentially useless.

Start at the network connection

Most home computers fall into one of two connection categories, broadband or dial-up. If you have a dial-up connection, then you still need a firewall, but this section will not apply to you. For broadband users, regardless of whether the connection is DSL or cable modem, you most likely have a broadband router. This device connects to either the phone line or the cable and provides a place to plug in your computer or your network.

Search for the model of your broadband router on a search engine in your browser to see if it contains a firewall. If it does, then check with your service provider or router hardware manufacturer for instructions to ensure the firewall is enabled. If it does not, then make sure you follow the steps as discussed in the next section.

Moving to the home computer

Most of this tutorial is directed at home users with Windows XP. If you are running an older version of Windows such as Windows 95, Windows 98, Windows NT, or Windows 2000, you should upgrade your operating system. The newer operating systems offer better security support. If you are using MacOS, then consult the information that came with your system or the Apple website. If you are running Linux, then you are most likely advanced enough to already know how to enable your firewall. However if enabling a firewall is new to you, then consult the Internet for information regarding IPTables configuration.

For Windows XP, select the "Start" button, open the control panel, and double click on the Windows Firewall icon. If the firewall is designated as off, click the "on" button. If you determined in the previous step that your broadband router had a firewall and it is enabled, you can leave the "Don't allow exceptions" box unchecked. This will allow, for instance, other computers on your home network to share files or printers and not be blocked by the firewall on your computer.

If you do allow exceptions, click on that tab to see what exceptions are being allowed. Remember, for each exception on the firewall, you are allowing that service to be accessed from an outside computer. Should there be a weakness in that service, it could lead to a compromise.

If you are connecting to an unsecured, high speed wired or wireless network, such as one in Starbucks or a hotel room, then make sure the "Don't allow exceptions" box is checked. This will provide the highest level of protection available but may impact certain network functions such as sharing files and printers.

If you still have questions, try using Microsoft's help at www.microsoft.com. It can quite often answer many questions. Additionally, your internet service provider can also help you to address many concerns.

These helpful tips are provided by Digital Defense, Inc., a computer security company working with your bank as a responsible member of the community to help insure the privacy and security of our nation's financial information.