Nagios — Monitoring That's Been Catching Problems Since 1999

Nagios is the monitoring system that most modern tools are built on top of. It watches servers, services, network devices, and SSL certificates — and alerts before your customers notice something's wrong. We've run Nagios for years alongside newer tools, and it still catches things others miss.

How We Use It

Our Nagios instance monitors every server and service we manage — HTTP endpoints, disk space, CPU load, memory, SSL expiry, database connections, mail queues. Alerts go to Zammad so nothing gets lost.

We write custom check plugins for application-specific monitoring. If a background job queue backs up or a replication lag grows, Nagios catches it and creates a ticket before anyone complains.

Nagios runs our SLA reporting too. Uptime numbers come from actual monitoring data, not promises on a slide deck.

What We've Learned Running It

Alert fatigue kills monitoring. A default Nagios install sends too many notifications for things that don't matter. We tune thresholds, set proper escalation paths, and configure dependencies so you only get alerted when action is actually needed.

NRPE (the remote check agent) needs careful firewall rules and TLS configuration. A misconfigured agent is a security hole. We lock it down properly — allowed hosts, encrypted transport, no unnecessary exposure.

What You Get

A fully configured Nagios instance monitoring your infrastructure. Custom checks for your specific services. Alert routing to email, Slack, or your ticket system. SLA dashboards. Proper thresholds so you get signal, not noise. We handle updates and add new checks as your infrastructure grows.