Nagios

Nagios
Name	Nagios
Developer	Ethan Galstad, Nagios Enterprises
Released	1999
Programming language	C, Perl, Shell
Operating system	Unix-like
License	GNU General Public License (original), proprietary variants
Website	www.nagios.org

Nagios is a computer system and network monitoring application suite originally authored to monitor hosts, services, and infrastructure components. It provides alerting and reporting for system administrators regarding outages, performance degradation, and capacity issues. The software ecosystem has influenced a range of monitoring projects, forks, commercial products, and operational practices across enterprises, service providers, cloud platforms, and high‑availability environments.

History

The project began in 1999 by Ethan Galstad, inspired by earlier monitoring tools used at universities and research labs, drawing conceptual lineage from Big Brother (software), MRTG, Cacti, and RRDtool ecosystems. Early adoption occurred among academic institutions and internet service providers such as MIT, Stanford University, and regional networks, while contributions from volunteers and companies shaped extensions resembling patterns in OpenNMS and Icinga forks. Over time, forks and commercializations produced projects like Icinga, Centreon, and vendor offerings from SolarWinds and Zenoss, reflecting broader trends exemplified by Red Hat acquisitions and the rise of Amazon Web Services monitoring services. The governance and trademarking led to the establishment of Nagios Enterprises and parallel community efforts, in a manner comparable to disputes seen between MySQL AB and corporate maintainers in other open source histories.

Architecture

Nagios employs a modular, plugin-based architecture with a central monitoring daemon that executes checks and processes results similar in principle to agentless paradigms used by SaltStack and agent/collector designs found in Prometheus and Datadog. Core components include the scheduler, event handlers, notification modules, and a web interface, analogous to components in Zabbix and Sensu. The system integrates state storage and logging, historically relying on flat files and text-based status storage prior to integrations with SQLite or external databases in forked implementations. Communication to remote systems is typically achieved through SSH, SNMP, NRPE, and custom protocols, interoperating with standards such as Simple Network Management Protocol used by vendors like Cisco Systems and Juniper Networks. High-availability deployments mirror patterns used in Pacemaker and Corosync clusters for failover.

Features

Nagios provides host and service checks, alert escalation, flexible notification schemes, and plugin execution, paralleling capabilities found in SolarWinds Orion and PRTG Network Monitor. It supports scheduling of check intervals and maintenance windows comparable to features in HP OpenView and IBM Tivoli Monitoring. Graphing and performance trending typically integrate with RRDtool, Graphite, or InfluxDB in the same way that Grafana dashboards visualize telemetry from many systems. The web interface offers status overview, historical logs, and configuration browsing, while APIs and event handlers enable automation workflows similar to integrations seen in Ansible and Jenkins for incident remediation. Notification channels include email, SMS gateways, and paging systems used by organizations like PagerDuty and OpsGenie.

Deployment and Configuration

Deployments range from single-server setups to distributed monitoring infrastructures used by telecommunications firms and cloud operators such as AT&T and Rackspace. Configuration traditionally uses plain text files defining hosts, services, contacts, and timeperiods, comparable to declarative patterns in Apache HTTP Server configuration and Nginx virtual host files. Tools and frontends for configuration management include wrappers and GUIs developed by projects like Centreon, MK Livestatus, and NagiosQL, akin to provisioning workflows in Puppet and Chef. Scaling strategies employ distributed pollers, proxies, and federated architectures similar to designs in OpenStack telemetry projects, with orchestration often managed alongside Kubernetes or virtualization stacks from VMware.

Plugins and Integrations

A rich ecosystem of community and vendor plugins exists, offering checks for databases such as MySQL, PostgreSQL, and Oracle Database; middleware like Apache HTTP Server and Nginx; virtualization platforms such as VMware ESXi and Hyper-V; and cloud services including Amazon EC2 and Microsoft Azure. Integrations extend to log aggregators like Splunk and ELK Stack components (Elasticsearch, Logstash, Kibana)), configuration management and orchestration platforms such as SaltStack and Terraform, and incident response tools like ServiceNow. The plugin model encouraged contributions from vendors including Hewlett Packard Enterprise and Dell EMC, and aligns with adapter patterns used by Telegraf and Fluentd.

Reception and Criticism

Nagios received praise for its extensibility and low barrier to entry, earning adoption across academia, startups, and enterprises, similar to the early acclaim of OpenBSD for robustness. Criticisms center on configuration complexity, scalability limits in very large environments, performance overhead of forking check processes, and a dated web UI compared with modern systems like Prometheus combined with Grafana. Forks such as Icinga emerged in part due to governance and usability concerns, echoing community splits seen in other projects like LibreOffice and MariaDB. Commercial forks and proprietary offerings from Nagios Enterprises and competitors addressed some issues by adding GUI-driven configuration, database backends, and support contracts, mirroring industry responses to maturation in open source ecosystems.

Category:Network monitoring software