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Personal Firewalls

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• What is a personal firewall?
• Why is a firewall important for computer security?
• Some operating systems provide free built-in personal firewalls
• What do I need to know after installing a personal firewall?

What is a personal firewall?

In the task of fortifying a computer against assault, a firewall takes the position of the defensive wall and guarded gate protecting a castle. In order for information to cross the firewall, it must be approved by the firewall's set of rules.

If the information is not approved to enter, the firewall blocks it. This helps prevent external attacks from causing damage. Most firewalls are also set to check whether information is approved to leave. This helps control the amount of damage if a firewall-protected machine is infected by a virus or otherwise compromised and tries to send attacks out.

Personal firewalls can be provided as an optional part of your operating system (Windows XP, Macintosh OS X, and Linux/Unix systems) or they can be installed as separate software, just like antivirus software.

Off-campus home networking: If you have more than one computer in your residence, and you have networked your computers with each other and with the Internet using a router, your router might also provide a firewall for you. Read the directions provided with your router to see whether it contains a firewall. More layers of firewalls are not a bad thing, as long as you only run one firewall at a time on your computer itself.

Why is a firewall important for computer security?

Computers connected to the Internet can be subject to electronic tampering, eavesdropping, and vandalism from malicious people seeking to obtain your personal data or create chaos in your life. Some attacks can damage or destroy your homework or research; other attacks can permit someone else to control your computer remotely, read your credit card number, or make your system unusable. You need to protect your operating system, your work, and your personal information from unauthorized access through the Internet.

A personal firewall, along with antivirus software and system patching, are vital parts of computer security and maintenance which every computer owner should understand and use. While the campus firewalls provide some protection from attacks originating from off-campus, there are tens of thousands of people and hundreds of thousands of machines within the campus firewall. Many people take their computers with them to other locations, and nearly everyone accesses off-campus locations through the Internet and email. Anyone who gets a virus can set it free inside the firewalls without even realizing it. Having both a personal firewall and antivirus software on your computer, along with regular system patching, helps protect you from consequences like these.

Some operating systems provide free built-in personal firewalls

The following list provides more information about the availability of built-in firewall software for several operating systems.

Windows XP: Built-in firewall - ICF Windows 2000, NT, ME, 98, or 95: Not built in; third-party firewall software is available.

Macintosh OS X: Built-in firewall - IPFW Macintosh 9.x or earlier: Not built in; third-party firewall software is available.

Unix and Linux: Most *x systems provide firewalls, usually ipchains for Linux variants and.ipfilter for Unix variants. See your system's man pages for more information.

What do I need to know after installing a personal firewall?

First, if something that used to work stops working, don't panic. Any software-based personal firewall can be temporarily or permanently disabled if you can't figure out how to get a program to work with or through your firewall. Most firewalls can also be reconfigured to permit specific network connections in and out. However, be aware that if you do loosen the restrictions on your firewall or disable it, you will lower your system's security.

In order to be able to customize your firewall's settings to suit your networking needs, read the firewall vendor's instructions thoroughly.

You may be surprised if apparently non-network-related functions stop working. For example, on some multi-button mice, clicking a fourth or fifth button launches a window to their manufacturer's website. Most personal firewalls are not preconfigured to expect a four or five button mouse to launch a window that requests network access, and therefore the firewall will block the mouse -- which typically stops the mouse from working at all, until you either log out and log in or reboot.

If something like this happens to you, take note of the pop-up window your firewall software gives when it halts the action. It will indicate what program was stopped and why. If you know that the program is safe to use (for example, your mouse driver), then go into the firewall's controls and add the program to your list of permitted actions.