Network / NMS
Nagios Core
Nagios Enterprises
The granddaddy of open-source monitoring — host/service up-down checks via a vast plugin ecosystem; the ancestor of Icinga, Checkmk, Naemon and others.
- Category
- Network / NMS
- License
- Open source
- Deployment
- Self-hosted
- Cost
- Free
- Free tier
- Yes
- Self-host effort
- Heavy
- Maturity
- Legacy
- Popularity
- Foundational legacy incumbent
The catch
Showing its age — flat-file config, no native autodiscovery, weak built-in graphing/UI; you bolt on plugins for everything, which is why so many forks exist to replace it.
Monitors
NetworkServersMetrics
Protocols
SNMPICMP / ping
Capabilities
AlertingAPI
Built for
SMBSRE / DevOpsHomelab
The honest take
The bedrock everything else forked from. Still runs the world’s check_ scripts, but starting fresh on raw Nagios Core in 2026 means signing up for flat-file config and manual everything. Pick a descendant.