OpenNMS (http://www.opennms.org/) - is a free and open-source enterprise grade network monitoring and network management platform (Open Source).

It is developed and supported by a community of user and developers as well as by the The OpenNMS Group, offering commercial services, training and support..

OpenNMS is written in Java, and thus can run on any platform with support for a Java SDK version 1.6 or higher.[6] Precompiled binaries are available for most Linux distributions, Windows, Solaris and OS X. In addition to Java, it requires the PostgreSQL database

Features:

• Network services monitoring (Web, DNS, DHCP, сервисы СУБД (Oracle, MSSQL, PostgreSQL etc.);

• Automatic detection (discovery) of network devices and their condition control;

• Event management (Syslog, SNMP trap etc.)

• System objects status change notification;

• Accumulation and view monitoring data;

• Distributed architecture;

• Integration with higher-level systems;