Network security can be a thorny issue for small businesses because they generally lack pricey equipment and dedicated IT people who have the expertise to lock down a local area network. But addressing security is nevertheless essential: Just one customer data breach could easily wipe out a small business, and constantly battling viruses, spyware, and spam can sap employee productivity.

Threats may come from wireless deployments, too--Wi-Fi is a great convenience but also a serious weak point in most networks--as well as from Web site breaches and from employee downloads of illegitimate material. (Since you are responsible for employees' use of your network, that last vulnerability can have serious consequences.) And that list doesn't even count bandwidth wasted when employees visit sites like MySpace and Facebook, or watch YouTube videos, on company time. How can you secure your small business against so many disparate threats, constrained as you are by limited resources?

The task is actually not as difficult as it may sound, thanks to enterprise-grade security technology that has been trickling down to the small-business level. So-called UTM (unified threat management) security appliances offer one-stop "security-in-a-box" protection that even part-time network administrators can deploy.

Basically, UTM appliances are firewall routers supplemented with powerful features such as antivirus and antispyware capabilities, intrusion detection and/or prevention, spam filtering, and Web content filtering (for blocking traffic such as porn sites and software downloads). These appliances may have other useful features as well, such as the ability to wall off a guest wireless network from the rest of the LAN, an array of secondary wide-area-network ports for redundancy or failover, and extensive logging and reporting systems.

Formerly the domain of network pros with deep pockets, UTM appliances for networks of 8 to 25 users now sell for as little as US$400, including a year's subscription to product updates and virus and malware definition services. I found many vendors offering full-featured UTM products for less than US$1000. All of them market higher-priced products for larger businesses, too. Some UTM appliances are more user-friendly than others, but all can be installed by a third-party reseller and then maintained fairly easily.

Key UTM features explained

Unlike standard firewall routers, UTM appliances vary widely in their features and capabilities--and for the most part, you get what you pay for. Here are the major features to look for when choosing a network security package for your small business.

Antivirus, antispyware, and antiphishing tools

By stopping viruses and malware at the Internet gateway, you can reduce the burden on individual computers and prevent most threats from reaching your network. Antivirus tools also provide a second layer of protection beyond your individual PCs' virus checkers, which frustrated users may disable and negligent users may update too infrequently. Gateway checkers can't find every piece of malware, however, because they lack the horsepower needed to emulate the programs on each computer. Thus you should retain the virus and spyware tools on each PC.

It's also worth finding out the brand of virus or malware checker that the UTM appliances you are considering use. Some devices work with their own software, but most rely on third-party tools from companies such as McAfee, Kaspersky, or even ClamAV (the open-source option). You should make sure that ongoing support will be available.