Sure, open source software is free -- as in beer. It can also get you sued if you're not cautious."You have to be careful" about when, where and how you use open source software in a commercial environment, said Janet Campbell, legal counsel for the Eclipse Foundation, speaking Tuesday at Interop.

You also need to ensure that you, or someone in your organization, understands the license terms. "Active management is the key," said Campbell. "You need to set up a process to review new [open source] additions or changes to the way you use existing code."

Otherwise you could end up like Verizon. The telecom giant was recently sued by the developers of an open source utility called BusyBox. Verizon uses BusyBox in the routers supplied with its FiOS broadband service.

Verizon ran afoul of the General Public License, under which BusyBox is licensed, because it failed to distribute the BusyBox source code to end users, as required by the GPL. Verizon eventually was forced to settle with the developers.

"Even some experts disagree on how the GPL should be interpreted," noted Campbell.

To keep its own house in order, the Eclipse Foundation uses search and code matching tools to do a deep dive on software submitted by contributors to ensure that it doesn't raise any intellectual property issues.

It also rejects contributions licensed under liberal open source licenses, such as MIT or BSD, that have been modified with restrictive riders such as, "Not for use in nuclear facilities" or "Use must be for good, not evil."

"We don't want to be in a position to have to interpret that," said Campbell.

The bottom line for organizations that use open source software in commercial applications: "Know what you have, where you have it, and how it's being used," said Campbell.