A firewall is a system designed to prevent unauthorized access to or from a private network. It is a hardware device, software program or combination of both configured to control communications between other computer programs in a network. Software programs communicate with each other by opening communication channels called ports. When you open a Web browser and enter your favorite Web site address, the browser connects to the Web server (somewhere on the Internet) by using port 80, which is reserved for the transfer of Web pages to Web browser programs. Not only does good software (like your Web browser) use ports, but so do computer viruses and hacker programs.Firewalls are configured to block some ports and allow others; thereby, controlling which programs have access (like Web browsers) and which do not (like viruses). Right now on the Internet, virus and hacker programs are scanning ports looking for computers to connect to and spread their payload (the virus). One currently active virus called W32.Korgo.X uses port 445 to connect to victim computers and infect them. The virus attempts to stop the antivirus programs and other services that automatically download critical updates on the infected computer. It adds itself to the list of automatically started programs so the virus will run each time the computer starts. Finally, it begins looking for other computers to infect.Normally port 445 is used by Windows-based computers for looking up information in Microsoft Directory Services. It allows computers to access shared files on a Windows network. This feature (port 445) is very useful when running a network (even in a home network), but it should never be opened to the Internet. If the virus encounters your computer without a firewall blocking port 445, you can expect to get the virus.The W32.Korgo.X virus is just one of the estimated 68,000 viruses known to exist on the Internet. While not all of them can connect to your system directly through unprotected ports, dozens of new, even more dangerous viruses are discovered every day. Due to this enormous and ever growing threat, it is essential every computer be protected behind a firewall.Firewalls can be confusing systems. They range in complexity, from full-fledged systems that require their own computer (and a three-week training course) to operate down to a free program you download from the Internet; you can have it up and running in 10 minutes. To keep things simple, I suggest using a software-based firewall for home computer users who connect to the Internet. The good news is some companies offer free basic firewall service.The personal firewall programs offered by Zone Labs (www.zonelabs.com) and Sygate (www.sygate.com) work well and are simple to install and configure. Even the firewall included in Windows XP (Home and Professional) is better than no firewall at all. To enable it, type “Internet Connection Firewall (ICF)” in Windows Help (push start and then help and support in Windows XP). Soon Microsoft will release Service Pack 2 for Windows XP, which will significantly improve the quality of this free firewall. Once installed, the new Service Pack 2 version of ICF (called Windows Firewall) will have all the features of the free firewalls listed.However, if you need to protect a business network, it is important to build a security solution that is “layered”. By layering, I mean using more than one system to keep your network safe. That way your network remains protected in the likely event something goes wrong with one system. For example, the router used to connect your network to the Internet should have a built in firewall. This firewall will hide your network from the Internet and provide a single, configurable system to control inbound and outbound ports for the entire network. Then use a combined antivirus/intrusion detection system like Symantec Corporation’s Norton Internet Security that runs on each computer in the network. It not only protects each machine from viruses, but will block hacker attacks from other computers on the network should something bad get through the router/firewall device.Firewalls are a necessity when connecting to the Internet. They help protect your investment in technology, your privacy while surfing and the security of all users on the global network we call the Internet. Please use firewalls, and Happy Surfing!
