Nagios

Nagios is an application that monitors systems, networks and infrastructure with alerting capabilities. There is different Nagios agents for collection data are available.

Features

Some features of Nagios Core include:

• Monitoring of network services (SMTP, POP3, HTTP, NNTP, PING, etc.)
• Monitoring of host resources (processor load, disk usage, etc.)
• Simple plugin design that allows users to easily develop their own service checks
• 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
• Alerts or contact notifications when service or host problems occur and get resolved (via email, pager, or user-defined method)
• 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, notification and problem history, log file, etc.

Configuration file

• /etc/nagios3/nagios.cfg

Related terms

• Nagios Remote Plugin Executor (NRPE)

Activities

• Review check_http plugin options
• Review more than 60 plugins installed by Nagios: /usr/lib/nagios/plugins/check_*
• Read StackExchange questions about Nagios: https://serverfault.com/questions/tagged/nagios?tab=Votes
• Read Nagios core changelog: https://github.com/NagiosEnterprises/nagioscore/blob/master/Changelog
• Install Nagios Core using docker: docker pull jasonrivers/nagios && docker run --name nagios4 -p 0.0.0.0:8080:80 jasonrivers/nagios:latest and connect to http://localhost:8080 using nagiosadmin / nagios or apt install nagios3
• Run a manual test: /usr/lib/nagios/plugins/check_tcp -H 127.0.0.1 -p 80

TCP OK - 0.000 second response time on 127.0.0.1 port 80|time=0.000274s;;;0.000000;10.000000

See also

• Nagios, NRPE, Nagios Cross-Platform Agent (NCPA), nagios.cfg, nrpe, nagios4, nagios3, nagios3stats, check_http, Monitoring-plugins, /usr/lib/nagios/plugins/, Nagios logs, nagios.cfg
• Monitoring: Prometheus, Cacti, monit, munin, RRDtool, Zabbix, Netdata, Nagios, Check MK, Icinga, Pingdom, OpsGenie and Datadog, Opsgenie, PRTG, Checkmk
• Nagios Remote Plugin Executor
• Nagios Cross-Platform Agent (NCPA)
• Rpcbind

https://en.wikipedia.org/wiki/Nagios#Nagios_agents

https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/3/en/about.html#whatis