Zabbix - Track, record, alert and visualize performance and availability of IT resources
Fluentd - Fluentd is a cross platform open source data collection solution originally developed at Treasure Data.
Observium - Observium
logstash - logstash is a tool for managing events and logs.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
Fortinet FortiAnalyzer - Fortinet FortiAnalyzer is a powerful product for Security Fabric Analytics and Automation.