Number 262 - March 2005

Firewall Basics
by Amy Quarterman, Coastal Computer News Jan/Feb 2005
Firewall. A term often mentioned at corporate meetings by managers and system administrators in a grand, sweeping manner. "Oh, don't worry, our firewall will block that. Don't worry, our firewall will protect us." Home computer users are even now hearing the term as a possible product to help protect their home PCs. But these references beg the question, what exactly is a firewall and how does it work?    According to Jim Kaufmann, Senior Security Analyst at Sallie Mae, "in simple terms, a firewall is a traffic cop." It is used to screen and filter data coming into a network or machine and if necessary, also to filter data going out. In most cases, it is used to keep inappropriate and destructive data out of a network or home PC.    When you have a connection to the Internet, you have created an open door into your personal PC. Whether you dial-up or use DSL or Cable Modem to get to the Internet, you could be putting your machine at risk.    Hackers on the Internet run scanner software to find open ports and machines to target for virus attacks, spam attacks (stealing your e-mail address to send fraudulent material out), denial of service attacks (flooding Internet sites with sign-ons to clog the server), stolen IP addresses, etc. It is imperative to protect your machine from this type of rogue attackers and their tactics.    Depending on how a firewall is configured when first purchased, it can be used to block access to specific sites on the Internet and can block specific external traffic coming in from the Internet. It also can be used to log and lock down source and destination ports, so that tracking can be done on anything inappropriate trying to come in or go out and act accordingly.    So, who should use firewalls? The answer, suggested by David Ehinger, IT Security Manager, Rolls-Royce North America, is "anyone connected to the Internet. Even if you don't care about protecting your system, the rest of	us don't want your system available to be used for attacks on us because you didn't protect yourself."    Most corporations have been on the "firewall bandwagon" for 7 years or more, but the trend is just starting to catch on for small businesses and home users. Kaufmann even recommends firewalls for everyone, mentioning that "home use personal firewalls can run from about $100, while corporate firewalls are usually $3,000 and up." He goes onto say that "security works best with a layered approach: server security, network security, and desktop security." As with all security products, as Kaufmann states, it is important to rely one more than one "catch all" way to keep your computer secure. Many PCs that you buy right off the shelf may only have the basics: an operating system, a word processor system, and possibly an internet browser system. Just this "vanilla" flavor of home computing is inherently unsafe and open to security exposures and loopholes. The layered approach should include:    1. If you use the Internet from home or work, you should automatically use the most current anti-virus software.    2. If you connect to work from home, make sure not to transmit files to and from your personal machine and your corporate network. From either direction, you can be exposing your machine or your company's network to unsafe, infected or corrupted files.    3. Consider purchasing a personal firewall for your home machine. They have many options on the market now and they are easily available and affordable over the Internet.    For more information about Information Security Web or CERIAS research and sponsorship programs, contact: Jennifer Kurtz CERIAS Manager of Strategic Relations and Communications 765 494-7806 ikurtz@cerias.purdue.edu
Number 262 - March 2005