Business owners who have an Internet connection normally have their computers behind a firewall -- even if they don't know it. A firewall acts as a "one-way" mirror, hiding your local data network from the outside world while letting you access the Internet easily. Microsoft Windows has its own firewall, and routers, DSL and cable modems typically include this capability as a security feature. However, firewalls do not solve all security problems, and they require significant technical knowledge to use effectively.
Hackers on the Internet constantly seek out new targets using software that looks for weaknesses. According to the Internet Storm Center, tests conducted with Windows XP with the firewall turned off resulted in compromised computers an average of four minutes after being connected to the Internet. A firewall passes legitimate data to your computer or network but does not respond to unrequested probes from the outside. The ability for firewalls to isolate your network from outside attacks makes them essential for basic Internet security.
Every router on the Internet has a unique code called an IP address, where IP stands for "Internet Protocol." For each address, data can pass through thousands of different "ports," which are numbered sub-addresses each assigned to different kinds of functions, such as Web browsing, email and other applications. A firewall lets you block traffic to some ports and pass data to others, providing flexibility to safely accommodate different network needs.
No Malware Protection
Though a firewall blocks random probing of your network by outsiders, it does not block malware. Viruses and other forms of malicious software enter your network through "trusted" data such as websites and email. Even if you have a firewall, you still need anti-malware software to protect your PCs from infections.
Though you can set up a firewall for a small business easily and never need to change it, firewall maintenance for larger organizations becomes a full-time job. Changes in business needs, technical demands and computer hardware require daily revisions to the firewall to keep the network safe and efficient. The complex nature of firewall maintenance means hiring a specialist to ensure only the right kind of data flows through your network.
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