Running a network without monitoring it is like playing with fire: Sooner or later you're bound to get burned.

But a number of IT departments feel they're either too small or don't want to pay for the best-known commercial products such as IBM's Tivoli, HP OpenView, CA eHealth or Microsoft Operations Manager.

There is another option: Open source monitoring applications.

That's what Xander Toushek turned to earlier this year after he was hired as a team leader in the systems department of Marketlink Solutions, a Canadian business consulting, Web design and IT hosting company.

The firm has 40 servers in two data centres with a storage area network, one in Canada and another in New York City, 20 switches and 10 routers. It also manages two data centres for customers. But Toushek discovered it was using an "antiquated" monitoring application whose way of finding if a device was working was by pinging it. "We were always on the reactive end of failures and maintenance," he said.

Toushek had been evaluating Zenoss Core, the free version of an open source IT monitoring system from Zenoss before joining Marketlink. Once there, he convinced the president to spend US$5,000 on the Zenos Appliance, a fully-configured Linux rack server running Zenoss Enterprise.

"It's worked out extremely well," he said. "Zenoss does full SNMP logging, sys logging, all your Windows-based events. With the executive view of the network you can actually see which devices are up, are down, which need attention for a system-level error. You know what the operation metrics are, what the thresholds are."

While there are many open source network monitoring applications, IDC senior analyst Tracy Corbo says only a handful are truly open - that is distributed under a licence approved by the Open Source Initiative. They include offerings from Zenoss, Nagois, OpenNMS, Zabbix, Hyperic and GroundWork Open Source.

Some are entirely free, while others have versions with extra features than can only be purchased and include support. Depending on the features you need, they can be a legitimate alternative to packaged monitoring software, Corbo wrote in a recent report, and not just on price.

Open software has the ability to be customized, which can be appealing to those with special needs. Web sites of these vendors boast an impressive list of North American customers, ranging from state governments and a division of IBM to universities. Among them are some Canadian banks and cable companies. However, none were willing to be interviewed for this article so we can't say exactly how the apps are being used. Still, for monitoring systems, open source tools can fill in gaps left by other solutions.