Photos: Inside the Free Software Foundation

A stuffed Tux (the mascot of the Linux kernel) takes pride of place on a filing cabinet in the FSF office. Despite the different motivations of the free software and open source movements and a long-running disagreement over whether the operating system should be named GNU/Linux or Linux, Brown says the FSF has no issues with Linus Torvalds or the kernel project.

"There is a huge difference [between the free software and open source movements], but it is the difference between like-minded people," said Brown. "The key difference is that, if tomorrow Microsoft made its software work for a change, offered it for free and gave you access to the source code, would these people stop supporting free software?"

"The problem with the message of open source is that it doesn't ensure the type of protection we need. We've got a world in which we are being challenged by things like software patents and DRM. Unless you care about freedom, you will probably not care about these issues. We care about freedom so we really care about DRM," Brown added.