OpenNMS

OpenNMS is a network management platform aimed at large, distributed estates rather than a single rack. It pulls fault, performance, and traffic monitoring into one place, generating alarms, tracking inventory, and measuring service latency and availability across networks that span sites.

Data collection is deliberately broad, spanning SNMP, JSON, WinRM, XML, SQL, JMX, SFTP, FTP, JDBC, HTTP, HTTPS, VMware, WS-Management, and Prometheus. Flow monitoring handles NetFlow v5/v9, IPFIX, and sFlow at 300,000+ flows per second, with BGP monitoring on the OpenBMP standard. Most of it is configured through the web UI or XML.

Scale comes from its architecture: Minions handle distributed monitoring and ingest, Sentinels persist flows, and embedded ActiveMQ-to-Kafka brokers move messages. Dashboards, resource graphs, charts, and layered topology maps can be exported as PDF.