Zenoss Core is an open-source network monitoring and server monitoring product. Currently the most popular IT Management project on SourceForge.Net, Zenoss Core source code is available for free downloads. The active Zenoss community forums have over 50,000 registered members that help each other with Zenoss Core installation, configuration, and trouble shooting. The community also shares ideas with each other on IT management best practices and enhance the overall solution with community-contributed management extensions. - Peter Meyer