Fire! Fire! Firewall!

This blog article is about firewalls. In the real world, a firewall is a barrier used to prevent the spread of fire or some other destructive force. In computers, a firewall is software or hardware that’s designed to keep the bag guys out of your computer.

Andrew Clarke

A computer firewall monitors traffic (communications) to and from your computer, and it determines whether or not to allow that traffic to continue. For example, when you check your email, your computer downloads information from your email provider using an IP address and a port. An IP address is like your home address or a business address. A port is like a window or a door. When it comes to email, your email provider determines which port (window) you will use. Everyone uses the same port for that particular email provider, but not all email providers use the same port. There are standards that all email providers adhere to, but that’s a topic for another blog article. When you send mail, a different port is used. This setup keeps everything running smoothly because your email provider knows that mail will be picked up from one port and sent out through another port, much like the setup at some fast food restaurants.

The computer network used at your place of business is normally protected by a hardware firewall. A hardware firewall is a piece of physical equipment with only one purpose in life. It monitors all incoming and outgoing internet traffic and makes a determination about whether it continues on or not based on the rules in the firewall. These rules can be set to allow traffic from an IP address for a specific port only. The rules can also allow all traffic to an IP address, but no traffic from that IP address. There are many configuration options to meet everyone’s communication needs.

The bad guys are constantly probing IP addresses and ports to find “open windows” that they can use to gain access. Luckily for you, Windows comes with it’s own firewall preinstalled on your computer. You are also lucky because your router provides another layer of protection because it acts as your own personal hardware firewall.

This is the place where I remind you not to click on links from sources you don’t know. The reason is because some of those links are designed to open ports (unlock windows) from the inside. Clicking on bad links is the equivalent of letting a burglar into your house. Once he’s in, he can let the rest of his buddies in.

In my next blog article, I will explore an alternative firewall choice known as Zone Alarm. The firewall built into your router works well, but configuring it is normally difficult. The Windows firewall is fine, but you may want more control over your traffic than it allows. Zone Alarm is meant as a free alternative to the Windows firewall.

I’ll see you next month. In the meantime, feel free to post suggestions about articles you would like to see in the future.

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