A firewall is one of the most important pieces of security software that a computer user can have. A firewall, in most cases, in the only defense of your network from the malicious aspects of the Internet However, this may be one of the most overlooked pieces of software on a home computer. Knowing what to look for in a firewall can greatly help you decide if your firewall is effective, or if one of these free alternatives can help.
A firewall works my monitoring Internet traffic that goes into your network. Your network may include the four computers in your house, or it could include just your laptop. Regardless of the size of the network, the fundamental aspects as of your network work the same as just about any network setup in a home today. Traffic going in and our of your network follows certain routes, and will always occur on certain ports. For example, all traffic from your web browser will travel through ports 80 and 443. If you use an email client, you will be using ports 110 and 25. If you use an IMAP connection, port 143 will be used. There are also other services, depending on your operating system, that will open other ports. All of these ports, if left unchecked, could be a back door into your network.
A proper and effective firewall can cut the changes of one of these ports becoming compromised, and in some cases erase any chance of an intrusion. A good firewall will always alert of a new connection anywhere on your network. While this can seem like a burden, and a little bit annoying at first, this green light / red light type of control will always help improve your security. When you know what is trying to access your network, you can better figure out what your weak areas are. If your firewall is reporting applications trying to access port 25 over and over, you know you may have a virus or spyware on your computer that is trying to send out email.