Install Nagios Core from RPM on CentOS 7 / RHEL 7

Nagios is a free software, which offers monitoring and alerting services for servers, switches, applications and services.

This tutorial describes simple Nagios Core and Nagios Plugins installation from rpm packages on CentOS 7 / RedHat 7. There is no need to configure and compile Nagios Core tar.gz based source files unless you really need the newest version.

Steps:

1. Install Apache HTTP server

Install httpd rpm from the default repo:

[root@tuxfixer ~]# yum install httpd

2. Prepare Rpmfind repository

We will use Rpmfind repository (www.rpmfind.net) to download Nagios Core and Nagios Plugins.

Create rpmfind repository file:

[root@tuxfixer ~]# touch /etc/yum.repos.d/rpmfind.repo

Edit repository file to look like below:

# Rpmfind repository file

[rpmfind]
name=Rpmfind repository
baseurl=ftp://195.220.108.108/linux/epel/7/x86_64/
enabled=1
gpgcheck=0

Verify repository list:

[root@tuxfixer ~]# yum repolist

3. Install Nagios rpms

[root@tuxfixer ~]# yum install nagios nagios-common nagios-plugins-all

4. Setup Nagios admin password

Create new password for nagiosadmin:

[root@tuxfixer ~]# htpasswd -c /etc/nagios/passwd nagiosadmin

5. Enable services

Start and enable httpd service:

[root@tuxfixer ~]# systemctl start httpd
[root@tuxfixer ~]# systemctl enable httpd

Start and enable nagios service:

[root@tuxfixer ~]# systemctl start nagios
[root@tuxfixer ~]# systemctl enable nagios

6. Configure firewalld for Apache and Nagios

Open port 80/tcp to allow http traffic:

[root@tuxfixer ~]# firewall-cmd --zone=public --add-port=80/tcp --permanent

Reload firewalld service:

[root@tuxfixer ~]# firewall-cmd --reload

7. Connect to Nagios Dashboard

Navigate to Nagios WebGUI in your Web Browser:

http://host_ip/nagios

Log in using credentials: nagiosadmin / password_you_set_in_step_4