Step 1: Disable SELinux

sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config
setenforce 0
sestatus

Step 2: Install required Packages

yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
yum install wget php gcc glibc-common gd gd-devel make net-snmp perl perl-devel openssl

Step 3: Download package

wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.4.tar.gz

Step 4: Extract the package

tar -xvf nagios-4.4.4.tar.gz

Step 5: Create and user and Group

groupadd nagcmd
useradd -g nagcmd nagios 
usermod -aG nagcmd apache  
groupadd nagios
usermod -aG nagios nagios
id nagios 

Step 6: Compile the package

cd nagios-4.4.4
./configure --with-command-group=nagcmd 
make all
make install
make install-init
make install-commandmode
make install-config
make install-exfoliation

Step 7: Create nagiosadmin user and password for web console access. Enable and Start Services.

htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
systemctl status httpd
systemctl start httpd
systemctl enable httpd
systemctl start nagios
systemctl enable nagios
systemctl status httpd
systemctl status nagios

Step 8: Download and install Nagios plugins

cd /tmp
wget https://nagios-plugins.org/download/nagios-plugins-2.3.3.tar.gz
tar -xvf nagios-plugins-2.3.3.tar.gz
cd nagios-plugins-2.3.3
./configure –with-nagios-user=nagios –with-nagios-group=nagios
make
make install
cd /usr/local/nagios/libexec/
ls
cd /root/nagios-4.4.4
ls
make install-webconf
systemctl restart httpd

Step 9: Login to Web Console

Step 10: After successful installation of plugins, you can see all services checks completes normally