Nagios is a popular open source computer system and network monitoring software application. It watches hosts and services, alerting users when things go wrong and again when they get better.
Nagios was originally designed to run under GNU/Linux, but also runs well on other Unix variants. It is free software, licensed under the terms of the GNU General Public License version 2 as published by the Free Software Foundation.
- Monitoring of network services (SMTP, POP3, HTTP, NNTP, ICMP, SNMP, FTP, SSH).
- Monitoring of host resources (processor load, disk usage, system logs) on a majority of network operating systems, including Microsoft Windows with the NSClient++ plugin or Check_MK.
- Monitoring of anything else like probes (temperature, alarms...) which have the ability to send collected data via a network to specifically written plugins.
- Monitoring via remotely-run scripts via Nagios Remote Plugin Executor.
- 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 (shell scripts, C++, Perl, Ruby, Python, PHP, C#, etc.)
- Plugins available for graphing of data (Nagiosgraph, Nagiosgrapher, PNP4Nagios, and others available)
- Parallelized service checks available.
- 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 e-mail, 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.
Click image to enlarge.