How to Protect Your Computer with a Firewall

Windows computers can be attacked in many ways — and not just with viruses, worms, or Trojan horses. Another popular way to attack a Windows computer is to attempt to communicate to it over any of the network “ports” found on Windows computers. These ports are kind of like TV channels or radio frequencies. Computers are set up to listen for messages that may arrive from other computers — this is how they communicate with one another.

How firewalls work

Firewalls monitor all the communication between your computer and the Internet. Firewalls know what kinds of communication are allowed to flow in and out. They know this because they have something called an “access control list” — a list of rules that specify precisely what kinds of communications are allowed and what kinds

are blocked. The firewalls made for the consumer market (that’s us) are usually preconfigured to offer maximum protection right out of the box.

The configuration required to facilitate communication between two computers in a home network makes them highly vulnerable to attack from any computer on the Internet.

To turn your computer into a tattletale zombie, all anyone on the Internet needs to do is send a specially tailored message from their computer to one of yours — over one of the open ports.

Whether the firewall is a hardware device connected to your network, or a software program in your computer, a firewall will automatically block all unwanted network communication from the Internet, while at the same time permitting any legitimate communication that you need to use your computer.

There are two principal types of firewalls: hardware and software. A hardware firewall is a device connected to the network in such a way that all communications between any computer and the Internet must pass through the firewall and be examined to see whether they should be discarded or allowed to pass through.

A software firewall is a program that runs on a computer and performs the same type of examination of network communications that a hardware firewall does.