Wednesday, July 27, 2005

I.T. Tips #1 : Firewalls

Here's the first of what I hope is another series on this blog, I.T. Tips. As many people in the blogsphere have at least a passing understanding of technology, I thought it might be nice to dispense some of the wisdom I have gleaned from years of computer work.

Today's subject is Firewalls.

What does it do?
A firewall is a piece of hardware and/or software that helps defend your computer from intrusion from the outside world.

How does it do it?
A firewall works by selectively opening and closing channels to and from your computer, called ports, that may be exploited by hackers trying to plant viruses into your computer. For example, in Windows XP, there are several ports that, if left unprotected, allow remote parties (hackers) to take control of the system without anyone knowing it. While these security holes are continuously being identified and patched, it's still important to have a means in place to protect from the unknown, and that's where a firewall comes in.

Firewalls also provide an important service by masking you from being seen. There is a method, called a Ping (like sonar in The Hunt For Red October, I love that movie...) that, by default, your computer will answer to. Kind of like Marco Polo. The remote computer says "Marco" and your computer says "Polo." The thing about this is, if your computer responds, people know that it's there. And, if they know it's there, they know they can try to hack it. So a firewall protects your computer by not even letting it hear the first "Marco."

Ping masking isn't the only service firewalls provide. They also provide something called IP Masking, which means that it hides the computer's true address from the Internet. For example, let's say you live in a house with 6 apartments (apartments are computers in this analogy, keep up). Junk mail will probably get sent directly to the street address, 101 Sunnyside Dr. A firewall acts like a sorter, dropping anything that isn't destined for a specific apartment within the building straight into the trash. Even if there's only one apartment in the building, the firewall will only pass along messages that are adressed to "Apartment #1", thereby cutting out a significant portion (40%+) of the crap that's tying to come in.

Let me pause for just a moment and mention that this mail analogy has nothing to do with email.

The IP masking function goes a step furthur in protecting you by only allowing data that's in response to something you sent. Kind of like blocking phone solicitations.

What's the difference between hardware firewalls and software firewalls?
Well, first off, think of a hardware firewall as a mini computer that only has firewall software on it. Hardware firewalls have the advantage of being separate from your computer and specifically built for the task, so they help protect your computer in a static, unchanging environment (like your home). Software firewalls travel with your computer, allowing you to be protected even when you're away from home. They also have the ability to be more easily configured by the end user, which is a nice feature. My personal suggestion is to have both a hardware AND a software firewall.

Pffft, firewalls are for sissies, I don't need one, right?
Sure, as long as you don't mind having your computer ass-raped on a regular basis. I like to use the following comparison to illustrate why EVERY computer connected to the Internet should have a firewall:

Surfing the net with a firewall is like swimming in your backyard pool.

Surfing the net without a firewall is like swimming in a urine trough at a local sporting event. You're bound to catch something you don't want.

A recent study found that the average infection time for a brand new computer running Windows XP Service Pack 1 was 45 SECONDS after connecting to the Internet.

Anyhow, I'm out of things to say about firewalls. I'll update this with some useful firewall links a little later in the week, stay tuned.
posted by S.C. @ 3:27 PM |

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