OPEN SOURCE MONITORING ENGINE

Nagios Core Features

Comprehensive network, server, and application monitoring with powerful capabilities.

ENTERPRISE EDITION

Need Enterprise Features? Try Nagios XI

Get all the monitoring power of Core plus enterprise-grade UI and management tools.

✓ Modern Web Dashboards

✓ Configuration Wizards

✓ Advanced Reporting

✓ Capacity Planning

✓ Professional Support

✓ Enterprise Integrations

NAGIOS CORE FEATURES

Comprehensive Monitoring Capabilities

Experiment, learn, and monitor anything in your environment with an open-source tool built for curious builders and tech enthusiasts.

Network Monitoring

Network Services Monitor SMTP, POP3, HTTP, NNTP, ICMP, SNMP, FTP, SSH and more
Network Protocols Full protocol monitoring including TCP, UDP, ICMP ping
Bandwidth Monitoring Track network bandwidth usage and performance
Device Availability Monitor routers, switches, firewalls, and network devices
Network Host Hierarchy Define parent hosts to detect down vs unreachable hosts
SNMP Monitoring Comprehensive SNMP v1, v2c, and v3 support
Network Discovery Automatically discover network devices

Nagios excels at network monitoring with proven reliability detecting and distinguishing between hosts that are down versus unreachable.

Server & Host Monitoring

Processor Load Monitor CPU usage and load averages
Disk Usage Track disk space, I/O performance, and mount points
Memory Monitoring Monitor RAM usage, swap, and memory leaks
Process Monitoring Ensure critical processes are running
Linux/Unix Servers Native monitoring for all Unix-based systems
Windows Servers Full Windows monitoring via NSClient++ or NRPE
Resource Utilization Complete visibility into system resources

Monitor host resources including processor load, disk usage, system logs, and more on Linux, Unix, and Windows systems.

Application & Service Monitoring

Database Servers Monitor SQL Server, Oracle, MySQL, PostgreSQL, MongoDB
Web Servers Apache, Nginx, IIS, Tomcat monitoring
Mail Servers SMTP, POP3, IMAP service checks
Directory Services LDAP, Active Directory monitoring
Application Servers JBoss, WebLogic, Citrix, and more
Custom Application Simple plugin design for custom service checks
API Monitoring REST API and web service health checks

The simple plugin design allows users to easily develop their own service checks for any custom application.

Alerting & Notifications

Contact Notifications Alert when problems occur and when resolved
Multiple Methods Email, pager, SMS, or user-defined notification methods
Escalation Paths Route alerts to different teams based on severity
Time-Based Alerting Schedule notifications based on time of day
Notification Dependencies Prevent alert storms with smart dependencies
Flap Detection Identify services with intermittent issues
Custom Alert Scripts Run any notification method you can script

Get notified immediately when critical infrastructure fails, with flexible notification methods and intelligent escalation.

Event Handlers & Automation

Event Handlers Define actions to run during service/host events
Proactive Resolution Automatically fix problems before they escalate
Service Recovery Auto-restart failed services
Parallelized Checks Execute service checks in parallel for efficiency
Scheduled Operations Plan maintenance windows and upgrades
Automatic Log Rotation Built-in log file management
Redundant Monitoring Support for implementing backup monitoring hosts

Event handlers enable proactive problem resolution—fix issues automatically before they impact users.

Plugins & Extensibility

Simple Plugin Design Easy-to-use API for custom checks
Standard Plugins 50+ official plugins included
Community Plugins Thousands of plugins from active community
Any Language Write plugins in Bash, Python, Perl, C, PHP, etc.
Check Commands Flexible command definitions
Remote Execution NRPE, SSH, or custom methods

If you can check it with a script, you can monitor it with Nagios. The plugin architecture is powerful and extensible.

Reporting & Web Interface

Web Interface View current network status and performance
Notification History Complete record of all alerts
Problem History Track issues over time
Log File Access Review detailed monitoring logs
Availability Reports Uptime and SLA tracking
Performance Data Export metrics for graphing
Status CGI Functional web interface included

Optional web interface provides current status, notification history, and problem tracking. For advanced dashboards, consider Nagios XI.

Integration & Data Access

Status Files Real-time status data in accessible format
External Commands Programmatic control via command pipe
Performance Data Export to Grafana, InfluxDB, Prometheus
Event Broker Module interface for extensions
NDOUtils Database export for reporting
API Integration Integrate with ticketing, CMDB, automation
Third-Party Tools Works with PagerDuty, Slack, ServiceNow

Nagios integrates with your existing tools through multiple APIs, data exports, and event broker modules.

HOW NAGIOS CORE WORKS

Simple, Proven Server-Agent Architecture

Nagios uses a server-agent architecture where the Nagios server is installed on a host, and plugins are installed on remote hosts/servers to be monitored.

Process scheduler sends signals to run plugins on local/remote hosts. The scheduler manages when checks are executed based on configured intervals and dependencies.

Plugins run checks and collect data (CPU, memory, disk, services). Each plugin is a standalone script that performs specific monitoring tasks and returns status information.

Plugins send collected data back to the scheduler. This includes status codes (OK, WARNING, CRITICAL, UNKNOWN), performance metrics, and descriptive output.

Scheduler processes results, triggers alerts, updates GUI. The engine evaluates state changes, applies notification rules, executes event handlers, and updates the web interface.

Admins receive alerts and GUI displays current status. Notifications are sent via configured methods (email, SMS, custom scripts) and the web interface reflects real-time system state.

20+ YEARS OF UPTIME

Why Choose Nagios Core for Your Monitoring Needs

Continuous monitoring, instant alerts, and broad platform support help you eliminate manual checks, reduce maintenance costs, and stay ahead of critical issues.

Eliminates Periodic Testing

Continuous real-time monitoring replaces manual periodic checks, catching issues instantly.

Detects Split-Second Failures

Catches intermittent problems before they become critical incidents affecting users.

Reduces Maintenance Costs

Lower costs without sacrificing performance through automation and early detection.

Timely Management Notifications

Keep management informed with immediate alerts on control issues and breakdowns.

Cross-Platform Support

Runs on any operating system—Linux, Unix, Windows, and more.

Active Community

Excellent support from an active community with 1M+ users worldwide.

Extensive Database Support

Monitor SQL Server, Oracle, MySQL, PostgreSQL, and other database servers.

Active Development

Continuous improvements and updates from dedicated development team.

Ready to Start Monitoring?

Join thousands of organizations who trust Nagios for their infrastructure monitoring.