Nagios since it’s inception in 1999 has become one of the most popular and open source monitoring system (under the free license GNU General Public License) to monitor IT infrastructure problems. It alerts you about any critical problem that might occur in your infrastructure through e-mail, SMS and pager. Installation and configuration of Nagios is comparatively simpler than other infrastructure monitoring tools.

Although numerous plugins are available in the internet to monitor different services and for graphing of the data, plugin can also be customized as per your requirement by using tools like shell scripts, C++, Perl, Ruby, Python, PHP, C#, etc. DuringNagios configuration you have to keep the following in mind.

  • Lines starting with ‘#’ character are considered as comments and are ignored while processing.
  • Inconfiguration lines the characters that appear after a semicolon (;) arealso treated as comments hence are not processed.
  • Directive names are case-sensitive.

To get data from the monitoring host’s you will need aNagios agent. Below are some popular Nagios Agents:

  • NRPE
  • NRDP
  • NSClient++

Below are some protocols used for monitoring:

  • SMTP
  • POP3
  • HTTP
  • NNTP
  • ICMP
  • SNMP
  • FTP
  • SSH

Below are some Host resources which can be monitored:

  • Processor load
  • Disk usage
  • System logs