Install Nagios on CentOS 5

This page summarizes how to perform a basic installation of Nagios on CentOS 5. This tutorial assumes you have root/sudo access and have SELinux set to permissive or disabled.

If you notice a problem with this How-To or would like to provide feedback, please email Matt.

Install

Add RPMForge Yum Repository

• For x86 (32-bit) systems
  • rpm -Uhv http://apt.sw.be/redhat/el5/en/i386/rpmforge/RPMS/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
    • From Dag Wieers

• For x64 (64-bit) systems
  • rpm -Uhv http://apt.sw.be/redhat/el5/en/x86_64/rpmforge/RPMS//rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
    • From Dag Wieers

Install & Configure Prerequisites

• Install Apache
  • yum install httpd php gcc glibc glibc-common gd gd-devel

• Configure Apache to start on boot
  • /sbin/chkconfig --levels 345 httpd on

• Configure iptables to allow Apache traffic
  • /sbin/iptables -I INPUT -p tcp --dport 80 -j ACCEPT
  • /etc/init.d/iptables save
  • /etc/init.d/iptables restart

Install & Configure Nagios

• Install Nagios & Plugins
  • yum install nagios nagios-plugins nagios-plugins-setuid

• Create the default Nagios web access user & set a password
  • htpasswd -c /etc/nagios/htpasswd.users nagiosadmin

• Verify default config files
  • nagios -v /etc/nagios/nagios.cfg

• Start Nagios
  • /etc/init.d/nagios start

• Start Apache
  • /etc/init.d/httpd start

Verify Install

• Try logging into your new Nagios installation by going to http://servername/nagios/ and logging in with nagiosadmin and the password you set.

Notes

• Resources on configuring Nagios can be found in the official documentation. In addition, the CentOS wiki has a nice page here.

• Not all plugins will run without additional packages being installed (Ex. check_mysql won't run without installing mysql).