Nagios

Nagios is a popular open source and GPL-licensed system and network monitoring application. It watches hosts and services that you specify, alerting you when things go bad and when they get better.

Nagios, originally created under the Netsaint name, was written and is currently maintained by Ethan Galstad, along with an army of developers actively maintaining both official and unofficial plugins.

Nagios was originally designed to run under Linux, but is also reported to run on other Unices as well.

Overview

• Monitoring of network services (SMTP, POP3, HTTP, NNTP, ICMP, SNMP)
• Monitoring of host resources (processor load, disk usage, system logs) on a majority of network operating systems, even Microsoft Windows with the NRPE_NT plugin.
• Remote monitoring supported through SSH or SSL encrypted tunnels.
• Simple plugin design that allows users to easily develop their own service checks depending on needs, by using the tools of choice (Bash, C++, Perl, Python, PHP, C#, etc.)
• Parallelized service checks
• Ability to define network host hierarchy using "parent" hosts, allowing detection of and distinction between hosts that are down and those that are unreachable
• Contact notifications when service or host problems occur and get resolved (via email, pager, SMS, or any user-defined method through plugin system)
• Ability to define event handlers to be run during service or host events for proactive problem resolution
• Automatic log file rotation
• Support for implementing redundant monitoring hosts
• Optional web interface for viewing current network status, notifications, problem history, log files, etc.

External sites

• http://www.nagios.org