Best Firewalls for Small Business, A firewall is a computer security device that is situated between a small business’s internal network and the Internet. It can work at either the software or the hardware level to prevent unwanted outside access to the company’s computer system. Matthew Sarrel, writing for PC Magazine, provided the following definition: “A firewall must contain a stateful packet inspection (SPI) engine, which examines the content of packets and grants access to your network only if the traffic appears legitimate. Firewalls can also block inappropriate inbound and outbound traffic based on rules or filters. Internet Protocol (IP) filtering, for example, can block employees behind the firewall from accessing or receiving mail from specific IP addresses. Also, traffic can be blocked based on your network card’s unique identifier, called a MAC (media access control) address. Many firewalls can control traffic using keyword and domain filters, letting you block traffic to specific sites. More sophisticated firewalls let you create complex rules.” The firewall thus basically acts as a guard, identifying each packet of information before it is allowed to pass through. It is one of the most effective forms of protection yet developed against hackers operating on the Internet. A “stateful” engine, by the way, is electronics parlance for software able to remember its earlier states, usually by saving values in memory.

Ideally, a firewall will detect intruders, block them from entering the company’s computer network, notify the system administrator, record information about the source of the attempted break-in, and produce reports to help authorities track down the culprits. Since firewalls can be set to monitor both incoming and outgoing Internet traffic, they can also be used to prevent employees from accessing games, newsgroups, or adult sites on the Internet.

Despite the potential advantages of firewalls, however, some small businesses remain unprotected. Owners sometimes believe that firewalls are too expensive or demand too much technical expertise. Others believe that no hacker would be interested in the information contained on their computers. Wrong! Intruders often seek unprotected computers to serve as unknowing transmitters for spam mail. Later the company may discover this when many sites that have protected themselves refuse the company’s own mail. Many hackers also seek to disrupt companies’ operations just for the hell of it. A small business may lose valuable information or cause itself no end of hassle by failing to erect a firewall.