Nagios Core Installation - wAlber47/Tech-Journal GitHub Wiki

This page describes how to install Nagios Core and Nagios Plugins on CentOS 7.

Disable SELinux

Security-Enhanced Linux is a Linux kernel security module that provides a mechanism for supporting access control security policies, including mandatory access controls. We need to disable this so that Nagios can work fully.

  • setenforce 0 then modify /etc/selinux/config and change enforcing to disabled

Installing Prerequisites

There are some basic programs that Nagios will need to use.

  • yum install httpd php php-cli gcc glibc glibc-common gd gd-devel net-snmp openssl-devel wget unzip -y

You will also need a user/group for Nagios to use.

  • useradd nagios
  • useradd nagcmd
  • usermod -aG nagcmd nagios
  • usermod -Ag nagcmd apache

Downloading and Installing Nagios

Run these commands to download and extract the files needed.

  • cd /tmp
  • wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.1.1.tar.gz
  • wget http://www.nagios-plugins.org/download/nagios-plugins-2.1.1.tar.gz
  • tar zxf nagios-4.1.1.tar.gz
  • tar zxf nagios-plugins-2.1.1.tar.gz

Now navigate to nagios-4.1.1 from temp and compile the files with these commands. Each command may take some time.

  • ./configure --with-command-group=nagcmd
  • make all
  • make install
  • make install-init
  • make install-config
  • make install-commandmode
  • make install-webconf

Create Password

In order to use the Nagios Core web GUI we need to create a password for the "nagiosadmin" account we created earlier. Store this password somewhere and do not forget it. The command below will prompt you for a password.

  • htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

Install Plugins

We downloaded the plugins earlier, but now they need to be install and compiled. Navigate to /tmp/nagios-plugins-2.1.1.

  • ./configure --with-nagios-user=nagios --with-nagios-group=nagios --with-openssl
  • make all
  • make install

Firewall Configuration

Nagios' web page will be hidden behind a firewall, you have to run these commands so that you can access the GUI.

  • firewall-cmd --zone=public --add-port=80/tcp --permanent
  • firewall-cmd --reload

Starting HTTPD Service

  • systemctl enable httpd
  • systemctl start httpd

Starting Nagios Service

Now that everything is configured properly we can start the service and access the page.

  • Try systemctl enable nagios and systemctl start nagios.

If neither of those work, then follow these next steps to create your own service for Nagios.

  • sudo vi /etc/systemd/system/nagios.service
  • Add the following from this page.
  • sudo systemctl enable /etc/systemd/system/nagios.service
  • sudo systemctl start nagios
  • sudo systemctl restart nagios
  • sudo systemctl enable nagios

Accessing Nagios Web GUI

As long as you followed everything in this guide, you should be able to go to http://`nagios-ip`/nagios/ and see your dashboard.