How to Secure Your Small Network

Maintaining network security can be a major challenge for small to medium businesses (SMBs), but this how-to guide can help.

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 $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 $1000 (see "Sub-$1000 UTM Appliances"). 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.

CONTENT AND KEYWORD FILTERING

With content and keyword filtering, you can block access to specific IP addresses, domains, and URLs by invoking the vendor's database of inappropriate Web sites and keywords in various categories, as well as by adding or subtracting your own. Content filtering isn't just for porn. You could block Web mail sites, for example, or video-streaming services. You can use filtering on outgoing data as well as incoming data, so you could prevent people within your network from sending explicit e-mail or instant messages. Check to confirm that the UTM appliances you're considering have the content-filtering capabilities you need.

SPAM FILTERING

A few UTM appliances have antispam filters, but most offer it only as an extra-cost option (if at all). Because spam filtering can have a major effect on firewall throughput, many IT experts prefer to use a separate spam filter at the mail server. Your ISP probably can perform this task at little or no extra charge if you use its e-mail services. If you run your own e-mail server behind your firewall, UTM appliance-based spam filtering may be appropriate.

INTRUSION DETECTION AND PREVENTION

Intrusion detection goes beyond the simple packet header inspection that all firewalls perform, actually examining the packets' contents as well. Together with deep-packet inspection, intrusion detection and prevention systems use ever-evolving rules and behavioral algorithms to block suspected attacks, much as antivirus software does.

DATA-LEAKAGE PREVENTION

Less commonly available--but important to some small businesses--is data-leakage prevention. "Data leakage" refers to the loss of proprietary information and documents from the network via e-mail, e-mail attachments, instant messaging, Web site uploads, and so on. Law and medical offices especially need to prevent transmittal of client or patient data; they can be sued if such information leaks out.

DLP software uses content filtering or simply blocks e-mail attachments and file transfers. You may be able to simulate DLP by using regular content and port filtering tools, but you'll need to anticipate some of the ways data can leak, and some expertise in security configuration is extremely valuable. A security consultant can be a big help here.

GATEWAY THROUGHPUT

One of the first specs you'll see on any UTM appliance datasheet is firewall performance or throughput, expressed in mbps (megabits per second). These numbers can provide a rough guide to performance, but they may not factor in the impact of the UTM tools you use--from intrusion detection to antivirus to content filtering--which can reduce throughput by up to 50 percent, though some gateways handle the hit better than others due to speedier processors or more efficient software. Antispam filters usually have the heaviest impact on throughput.

Most vendors have try-before-you-buy programs, so take advantage of these arrangements to ensure that the UTM appliance you ultimately select has the features you need and doesn't bog down under your network's loads. When you count the number of users on your network, remember to include peripheral network devices such as NASs, printers, and PDAs, since they may count toward the "recommended" user load.

ACCESS CONTROL AND AUTHENTICATION

To prevent unauthorized users from accessing your LAN, most UTM appliances support one or more authentication schemes, such as Windows Active Directory, LDAP, RADIUS, or an internal user database. They also provide MAC address filtering to prevent unregistered devices from accessing your LAN; unfortunately, MAC addresses are easy to spoof.

WAN FAILOVER/REDUNDANCY

One very important difference between standard firewall routers and many UTM appliances is the presence on the latter of a second (and sometimes even a third) WAN port. In case of an outage, you could balance the network load between two regular connections--say, one DSL and one cable. You can set one up as the primary, with the second kicking in only during an outage, or you can divide loads on a round-robin or percentage basis. This is a great way to establish outage protection without investing in an expensive T1 line (and the accompanying service-level guarantees).

VPN GATEWAY

For secure connections between offices, during business travel, or in support of telecommuting, virtual private network support is a must-have feature. Most UTM appliances can serve as VPN gateways for incoming connections. Remote users can connect to the gateway and can access LAN resources securely over an encrypted tunnel.

WIRELESS SECURITY

Most small businesses want Wi-Fi network access, so wireless security features in a UTM appliance are very important. Some appliances have a built-in wireless router, enabling them to run Wi-Fi traffic through the same strong filters that they use for Internet traffic. Others let you use third-party Wi-Fi access points to create special security zones for wireless networks.

ANNUAL SUBSCRIPTION FEES

Normally to get the various UTM filtering capabilities above and beyond those of a basic firewall (including antivirus, antispyware, content filtering, intrusion detection, and spam checking) you must pay for an annual subscription. Though you can use the hardware without a subscription, you'll lose most of the appliance's security value if you adopt that approach. So before choosing a UTM appliance, investigate the annual subscription price for virus definitions and software/firmware updates, and find out whether costs go up as the number of users does. Some vendoes use a sliding scale of this type, while others don't.

Also, check to see whether the initial purchase price includes the cost of the first year's subscription. Since subscriptions may run to $500 or more, having to pay separately for the first year is a significant factor. You'll want to compare the total cost of ownership--for both equipment and annual maintenance--over the number of years you expect to own the appliance. Another variable is installation fees, if you'll be hiring a consultant.

That's a quick review of the key features of UTM appliances, but you may want to consider other features as well, such as support for VoIP services (which may be adversely affected by filtering tools), the ability to set up zones governed by different security levels (say, a public zone and a private zone), dynamic DNS support, printer sharing, and monitoring and reporting tools that proactively provide crucial information (such as WAN outages or peak load times) in a form that even a part-time IT person can understand and act on.

SUB-$1000 UTM APPLIANCES

All of the UTM appliances listed below provide the basics--a business-class VPN firewall router with antivirus and antispyware protection, intrusion detection, content filtering, and monitoring tools--and many have additional areas of special strength or extra features. Most bundle an initial one-year subscription for antivirus and antispyware updates. Recommended network capacities range from 8 to 25 users, but all of these vendors offer higher-end models for larger businesses as well.

The entry level SonicWall TZ 180, Fortinet FortiGate-50B, and D-Link NetDefend DFL-CPG310 cost less than $500 and can be set up by a non-IT professional. Even so, it's a good idea to hire a security expert, if possible, to set things up properly. A network is only as secure as its weakest point, which usually isn't the router.

Moving up the UTM scale, the Check Point UTM-1 Edge Appliance, the Secure Computing SnapGear SG580, and the ZyXel ZyWall 5 UTM cost around $500 to $700; and the Calyptix AccessEnforcer AE500, the eSoft InstaGate 404e, and the Juniper Networks Secure Services Gateway 5 run all the way up to $1000. The extra money pays for enterprise-class features, more software options (for which you'll need to buy annual renewals), and the ability to scale up to more users without buying new hardware. The InstaGate 404e, for example, offers modular e-mail and Web "ThreatPaks" that cover far more than basic antivirus tools do, while the Juniper SSG5 amounts to a branch-office version of the company's enterprise security system.

Calyptix AccessEnforcer AE500

Check Point UTM-1 Edge Appliance

D-Link NetDefend DFL-CPG310

eSoft InstaGate 404e

Fortinet FortiGate-50B & FortiWifi-50B

Juniper Networks Secure Services Gateway 5

Secure Computing SnapGear SG580

SonicWall TZ 180 TotalSecure 10 or 25

ZyXel ZyWall 5 UTM

Becky Waring is a Berkeley, California-based technology writer who specializes in networking, mobility, and multimedia topics.

This story, "How to Secure Your Small Network" was originally published by PCWorld.

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