Wikipedia
NetXMS
NetXMS is an open source network management system. It can be used for monitoring entire IT infrastructures, starting with SNMP-capable hardware (such as switches and routers) and ending with applications on servers.
Victor Kirhenshtein and Alex Kirhenshtein are the original authors and current maintainers of NetXMS. NetXMS runs natively on Windows, Linux, and other Unix variants. It is licensed under the GNU General Public License version 2 as published by the Free Software Foundation.