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5. Firewall a must for home computer

By Mark Alberstat and
Chris Watt

THERE ARE ONLY a few universal truths. One is that if you are on the Internet, someone at some time will try to hack into your computer. Another is that you have software loaded that will want to get out onto the Net without your knowledge. To prevent, or at least diminish the chance of either of these from happening, you need a firewall.

A firewall is a piece of hardware, software, or both, designed to prevent unauthorized access to or from your computer. If you are on a network at your office but can't reach the Net from your own computer, a firewall is blocking you. If you know your network is connected to another part of the company but you can't access it, again, a firewall is at work.

Personal hardware firewalls, ranging from $80 and up, help to protect you from other people trying to break in to your machine. These firewalls filter incoming network traffic and reject packets that do not appear to be replies to your own outgoing traffic. Thus, a personal firewall will happily admit the data for that Web page you just requested, but probes from worms or hackers looking for vulnerable network software will be stopped cold.

More sophisticated personal firewalls, often called broadband routers, typically feature ports allowing you to connect multiple computers and onboard servers to manage your internal network. Normally, broadband routers also feature network address translation (nat) capabilities, making any number of computers behind your firewall appear as just one system on the Net. Besides providing some measure of security, broadband routers allow you to easily share your Net connection among multiple computers in your home or office, making them an increasingly popular item.

On a large network, hardware firewalls can also control traffic by filtering on keywords or domains. If you have similar concerns at home, programs like NetNanny are available for monitoring your children's surfing habits.

Although hardware firewalls work well when configured correctly, they are a bit beyond the knowledge and ability of the average computer user. As with most software and hardware, they come with default settings that will be adequate for most users.

Software firewalls, such as Zone Alarm, Norton Internet Security and BlackIce Defender, can be effective in preventing software on your system from accessing the Net (whether you want them to or not). Unfortunately, they are not as effective against people who are bound and determined to get into your PC.

The most popular of the lot is ZoneAlarm. This highly configurable software package can be downloaded at several shareware sites or at

Most software firewalls will ask you if a certain program is allowed to access the Net when it first tries to do so. You can then allow or deny it access and the software keeps track of this for future attempts. One of the biggest problems with software firewalls is that many users will not recognize the name of the executable in this pop-up window. Not many users would recognize the file wuauclt.exe as being the Windows automatic update client and could easily tell the firewall not to allow it to access the Net, thus missing valuable updates and security patches. Another file that may pop up is ndisuio.sys, which is an internal Windows driver that should be allowed to access the Net.

Another problem with these firewalls is that during the first few days after installation, the user is constantly being asked to approve or deny various programs. Frustration often wins out and the "allow" button will be hit more often than is wanted or needed, diminishing the firewall's effectiveness.

Anyone with a spare PC and a willingness to learn can set up a Linux-based firewall for free that will outperform any firewall you can buy off the shelf. The simplest Linux firewall distribution is "floppyfw, " which can be downloaded from This tiny piece of software runs comfortably off a single 3.25-inch disk and can be configured from any DOS, Windows or Linux machine (you can actually do it from MacOS as well, but this takes work).

No matter what software or hardware solution you implement for a firewall, hackers will continue to try to get into your computer and certain programs will want to get out. Keeping your solution up to date with the latest releases and patches, however, will go a long way from actually inviting inappropriate access to or from your computer.

The Mousepad runs every two weeks. It's a service of Chebucto Community Net, a community-owned Internet provider. If you have a question about computing, e-mail If we use your question in a column, we'll send you a free mousepad.


The Mousepad Index


Originally published 23 March 2003


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