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Nagios main screen.png
Screenshot of the Nagios Core web interface
Original author(s) Ethan Galstad and others
Initial release March 14, 1999[1]
Stable release 4.1.1 / August 19, 2015; 5 months ago (2015-08-19)[2]
Written in C
Operating system Cross-platform
Type Network monitoring
License GPLv2
Operating principle of Nagios

Nagios /ˈnɑːɡs/, an open-source computer-software application, monitors systems, networks and infrastructure. Nagios offers monitoring and alerting services for servers, switches, applications and services. It alerts users when things go wrong and alerts them a second time when the problem has been resolved.

Ethan Galstad and a group of developers originally wrote Nagios as NetSaint. As of 2015 they actively maintain both the official and unofficial plugins. Nagios is a recursive acronym: "Nagios Ain't Gonna Insist On Sainthood"[3] - "sainthood" makes reference to the original name NetSaint, which changed in response to a legal challenge by owners of a similar trademark.[4] "Agios" (or "hagios") also transliterates the Greek word άγιος, which means "saint".

Nagios was originally designed to run under Linux, but it 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.

In 2006 a survey[citation needed] asked members of the nmap-hackers mailing-list to identify their favorite network-security tools. In the survey 3243 people voted; Nagios came in 67th overall and 5th among traffic-monitoring tools. (Nmap itself was excluded from the list.) Another survey, in 2011, placed Nagios at 69th place.[5]


Status reporting in Nagios

Nagios is open source software licensed under the GNU GPL V2. It provides:

  • 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,etc.) 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.
  • A simple plugin design that allows users to easily develop their own service checks depending on needs, by using their tools of choice (shell scripts, C++, Perl, Ruby, Python, PHP, C#, etc.)
  • Available data graphing plugins
  • Parallelized service checks
  • The ability to define network host using 'parent' hosts, allowing the detection of and distinction between hosts that are down or 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)
  • The 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
  • An optional web-interface for viewing current network status, notifications, problem history, log files, etc.
  • Data storage via text files rather than database

Nagios Agents[edit]


Nagios Remote Plugin Executor (NRPE) is a Nagios agent that allows remote system monitoring using scripts that are hosted on the remote systems. It allows for monitoring of resources such as disk usage, system load or the number of users currently logged in. Nagios periodically polls the agent on remote system using the check_nrpe plugin.

NRPE allows you to remotely execute Nagios plugins on other Linux/Unix machines. This allows you to monitor remote machine metrics (disk usage, CPU load, etc.). NRPE can also communicate with some of the Windows agent addons, so you can execute scripts and check metrics on remote Windows machines as well.


Nagios Remote Data Processor (NRDP) is a Nagios agent with a flexible data transport mechanism and processor. It is designed with an architecture that allows it to be easily extended and customized. NRDP uses standard ports and protocols (HTTP(S) and XML) and can be implemented as a replacement for NSCA.


This program is mainly used to monitor Windows machines. Being installed on a remote system NSClient++ listens to port TCP 12489. The Nagios plugin that is used to collect information from this addon is called check_nt. As NRPE, NSClient++ allows to monitor the so-called 'private services' (memory usage, CPU load, disk usage, running processes, etc.) Nagios is a host and service monitor which is designed to inform your network problems

Controversial takeover of nagios-plugins site[edit]

On 16 January 2014, Nagios Enterprises redirected the domain to a web server controlled by Nagios Enterprises without notifying the Nagios Plugins community team. In response, the original community plugin team has renamed the project to Monitoring Plugins and created a new project website at [6][7]

See also[edit]

Further reading[edit]


  1. ^ "NetSaint Change Log". 2002-03-01. Archived from the original on 2006-05-01. 
  2. ^ "Nagios Core 4.x Version History". 2014-06-03. Retrieved 2014-06-15. 
  3. ^ Galstad, Ethan (2009-08-24). "FAQ Database: Miscellaneous: What does Nagios mean?". Nagios: Frequently Asked Questions. Nagios Enterprises, LLC. Retrieved 2014-06-02. The official meaning is that N.A.G.I.O.S. is a recursive acronym which stands for "Nagios Ain't Gonna Insist On Sainthood". 
  4. ^ "2005-02-22 - Ethan Galstad". FOSDEM 2005. 2005-02-22. Retrieved 2014-06-02. Although we were able to eventually reach an amicable agreement on my future use of the name "NetSaint", I felt it was prudent to change the name in order to prevent any future mishaps. 
  5. ^ "SecTools.Org: Top 125 Network Security Tools". Retrieved 2014-06-02. 
  6. ^ Holger Weiß (2014-01-16). "HEADS UP New project name: Monitoring Plugins". Retrieved 2014-06-02. 
  7. ^ "Bug 1054340: Update upstream URL to". Red Hat. 2014-01-16. Retrieved 2014-06-02.  External link in |title= (help)

External links[edit]