Open-Source Network Monitoring Tools: Cacti, Nagios Core, Icinga 2, Zabbix, and Prometheus

Maintaining a website’s normal operation is a core responsibility for system administrators, making continuous monitoring and optimal network performance essential.

Modern networks employ various monitoring approaches: network‑monitoring tools track traffic and response times, while application performance management solutions collect data from the application stack, and security measures protect sites from attacks.

This article focuses on open‑source network monitoring tools that help you observe nodes and applications, detect performance degradation early, and view overall network health.

1. Cacti

Cacti is a graphical solution that uses rrdtool for charting and stores SNMP‑collected data in a MySQL database, allowing administrators to generate traffic graphs on Windows and Linux.

It provides templates to accelerate monitoring setup and lets you create custom graph or data‑source templates for future use.

Address: https://www.cacti.net/index.php

2. Nagios Core

One of the most renowned open‑source monitoring tools, Nagios Core can automatically discover devices, monitor system health changes, and produce detailed performance graphs.

Its extensibility is a key strength; for example, the Nagios V‑Shell adds an AngularJS‑based PHP web interface with a searchable table and a CodeIgniter‑designed RESTful API.

Additional functionality can be added via plugins from the Nagios Exchange.

Address: https://www.nagios.org/projects/nagios-core/

3. Icinga 2

Icinga 2 builds on Nagios Core, offering a flexible RESTful API for custom configurations and a dashboard for real‑time performance data.

It supports both real‑time and historical monitoring, provides robust alerting, and runs on Windows, Debian, RHEL, SLES, Ubuntu, Fedora, and OpenSUSE.

Address: https://icinga.com/products/icinga-2/

4. Zabbix

Zabbix is a leading open‑source monitoring platform used by companies from Dell to Salesforce, offering scalable monitoring for networks, servers, cloud services, applications, and services.

It can track bandwidth usage, network health, configuration changes, and automatically detect connected devices.

Address: https://www.zabbix.com/

5. Prometheus

Prometheus is designed for monitoring time‑series data, storing metrics locally for quick access and supporting queries by time range or keyword.

Its Alertmanager handles notifications via email, PagerDuty, or OpsGenie, and the UI integrates with Grafana and third‑party data sources such as Docker, StatsD, and JMX.