check_mk
Check_MK is an extension to the Nagios monitoring system that allows creating rule-based configuration using Python and offloading work from the Nagios core to make it scale better, allowing more systems to be monitored from a single Nagios server. It comes with a set of system checks, a mod_python and JavaScript based web user interface, and a module that allows fast access to the Nagios core. On top of Nagios it also adds additional features
linux solaris bsd open-source monitoring python
Nagios Core
Nagios Core network monitoring software is a powerful, enterprise-class host, server, application, monitoring and alerting tool
linux solaris bsd open-source monitoring c
NXLog Enterprise and Community Editions
A multi-platform log collection suite to collect, parse, convert and send logs. Integrate with a wide range of products including SIEMs, log analytics dashboards, cloud services, databases, and more.
linux windows bsd solaris osx open-source free commercial logging