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Firewalls, using and choosing

March 16th, 2007 · No Comments

Hello to all and a great big welcome back to The Weekly Geek!

This week we are going to discuss firewalls. Computer firewalls are meant to be just like the firewalls between buildings. They are barriers designed to prevent fire, or in computer terms to prevent unwanted intruders from entering.

Think of a firewall as a containment field. As a rule of thumb hardware firewalls keep hackers and rouge programs from coming in to your computer and software firewalls prevent unauthorized information or programs from coming in or going out of your computer, so it is my humble yet amazingly accurate opinion that you should have both.

A hardware firewall is normally built into your internet router. Routers are devices that bring two networks together, in this case the internet and your home computer system(s). As a rule of thumb they connect between your modem and your computer however, some routers are built into cable/DSL (high speed) modems.

The settings of a hardware firewall are usually set, at the factory, for ease of installation so security is set at a minimum. I strongly urge you to look for your owners’ manual and check out what is able to be altered, some brands offer more control than others.
Hardware firewalls block ports on your computer or home network, there are over 65,000 ports that connect your computer to the outside world. These ports are how you connect to things like the internet, e-mail, printers and digital cameras.

Unfortunately hackers also use these ports to go into your computer and steal information, setup an illegal web site or plant Spyware. If you had a hardware firewall with ports 69, 135 and 4444 blocked then you would have been immune to the Blaster worm that went about causing havoc. If you use UPS for shipping and tracking on the internet you must have ports 8080, 443 and 880 open. In other words, do not get a hardware firewall and block all ports, you need to learn which ones to leave open and which ones to close. The best way is by doing what you are doing right now, take a little time each week and learn something new about your computer and the internet.

If you have a dial-up connection you will not have one of these hardware firewalls. If you have a high speed connection and connect straight from the modem to your computer you probably do not have one either. High speed internet connections really need one and having a hardware firewall on a dial-up modem connection will not slow things down.
I used to use a Netgear FR114P which allows four computers to connect to the internet and share a printer as well as protect my network with a firewall. It has many nice base features, another favorite of mine is the Linksys BEFW11S4 which allows wired and wireless networking with a firewall.

Currently I use the Linksys WRT55AG and a Netgear 12 port gigabit switch, simply because I can.

If you go to buy a firewall for home, be sure that it has NAT (Network Address Translation) and SPI (Stateful Packet Inspection). To the best of my knowledge, currently all new routers support NAT and SPI. These will allow you internet access while protecting against DoS (Denial of Service) attacks from hackers.

Software firewalls range from free to about $50. These programs will need to be “trained”. This occurs during the first couple of weeks after you install the software.

Think of a Software Firewall as a butler at your door. He requests an invitation for any program attempting to enter your home, or computer in this case. When a program tries to leave your home (connect to the internet) they have to have a “pass” allowing them out.

Software firewalls take a restrictive approach to the internet and all communication from your machine (just the opposite of hardware firewalls which are fairly liberal). The firewall program will pop up with an alert the first time you try to connect to the internet. Look for a setting that makes your internet connection permanent, usually by placing a check mark next to a box that states “make this setting permanent”. The first time you print the same thing will happen. Spyware, Windows Media Player and other programs will try to automatically connect to the internet, you can block these attempts with a software firewall.

Be sure to allow your antivirus to be able to update automatically every time.

Software firewalls will not allow computers on a home network to communicate unless you configure them to specifically talk so if you have a home network adjust the settings as necessary.

I have tried many different versions and my favorites are Outpost Personal Firewall by Agnitum (It is not for the faint of heart), Kerio Personal Firewall from Kerio Technologies (www.kerio.com) and Zone Alarm created by Zone Labs. Each of these manufacturers has basic and advanced more full featured versions that are available.

Here is a real world example of why you should have both firewalls, last month a friend of mine was called out to check out some troubles a small business was having with their main computer (server). In the past he had encouraged the owner to purchase and install firewalls, the owner felt that anti-virus programs “were enough of a cost” and could not justify the “extra expense”. On this occasion, it turned out that a hacker had broken into the business computer and hijacked it for illegal purposes. There was no firewall and no virus so no-one had been the wiser until the computer began to slow down at random times. After digging my friend found most of the tools the hacker had used, the new “locks” the hacker had put into place to prevent tracking or stopping him. The hacker has set up a file sharing service on this computer and was distributing illegal copies of movies using the business’s computer, internet and resources. Since the movies were big, every time one or more was being taken by users of a certain file sharing service (my friend would not tell me which one) the business’s computer would slow down. Now, if the hacker had placed something worse, say porn, then the business would be liable to the FBI and other sources, their computer could have been taken away and unless the owner could “prove” the he or she knew nothing about the site they might have been prosecuted. The moral of the story is that it will happen to your so take the time to protect yourself now.

Now a word of warning, just because you have a firewall does not mean that a virus cannot get through so please remember my previous advice over the last several weeks, Multiple layers of security are necessary.

  1. You need to run critical updates for your operating system (Windows) weekly.
  2. You need to buy an anti-virus program and renew it yearly, and update it at least once a day.
  3. You should purchase and anti-trojan program (update it daily too) and have it and the anti-virus program running in the background at all times.
  4. You should download a good anti-spyware program like AVG’s Anti-Spyware and run it at least once a week.
  5. Next you should purchase a hardware firewall, read the manual, search newsgroups and configure it to block incoming attacks.
  6. Then purchase or download a free software firewall, train it in what should and should not be allowed to go out from your computer(s).
  7. Finally, use common sense, if you receive an unexpected email or spam (junk email) do not respond to it, just delete it (we will cover spam filters in a future edition). If you let your mind get the better of you and you want to see pictures of Anna Kournikova, go to her official web site, do not open unexpected email with pictures of her (it’s a worm and virus).

Stay tuned for next weeks fun filled edition of The Weekly Geek when we will get back to optimizing your computer by automating boring tasks.

Tags: Internet · Security · Software