Install Dev Tools, PHP, Nginx

  sudo yum install nginx php php-fpm php-common gcc glibc glibc-common gd gd-devel make net-snmp unzip -y
  sudo yum groupinstall 'Development Tools' -y

Nginx – Nagios Configuration

  cd /etc/nginx/conf.d
  sudo vi nagios.conf

Nginx - Nagios Configuration with PHP-FCGI

server {
    listen 80;
    server_name nagios.yebbare.com;
    access_log /var/log/nginx/nagios-access.log;
    error_log /var/log/nginx/nagios-error.log info;
    root /usr/local/nagios/share;
    index index.php;
    auth_basic "Nagios Restricted Access";
    auth_basic_user_file /usr/local/nagios/passwd;

    location /stylesheets {
        alias /usr/local/nagios/share/stylesheets;
    }
    location ~ .cgi$ {
        root /usr/local/nagios/sbin/;
        include fastcgi_params;
        rewrite ^/nagios/cgi-bin/(.*).cgi /$1.cgi break;
        fastcgi_param AUTH_USER $remote_user;
        fastcgi_param REMOTE_USER $remote_user;
        fastcgi_pass unix:/var/run/fcgiwrap.socket;
        fastcgi_param SCRIPT_FILENAME /usr/local/nagios/sbin/$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_script_name;
    }
    location ~ .php$ {
        include fastcgi_params;
        fastcgi_pass unix:/var/run/php-fpm/nagios.socket;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME /usr/local/nagios/share$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_script_name;
    }
    location ~ (.*.(ogg|ogv|svg|svgz|eot|otf|woff|mp4|ttf|rss|atom|jpg|jpeg|gif|png|ico|zip|tgz|gz|rar|bz2|doc|xls|exe|ppt|tar|mid|midi|wav|bmp|rtf))$ {
        root /usr/local/nagios/share/;
        rewrite ^/nagios/(.*) /$1 break;
        access_log off; expires max;
    }
}

Firewall Configuration

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

Creating User

  useradd nagios
  usermod -aG nagios nginx

Create nagios.conf for PHP-FPM

  sudo vi /etc/php-fpm.d/nagios.conf

Conf file for nagios-php-fpm

[nagios]

listen = /var/run/php-fpm/nagios.socket
listen.owner = nginx
listen.group = nginx
listen.mode=0660
listen.allowed_clients = 127.0.0.1

user = nagios
group = nagios
pm = dynamic
pm.max_children = 50
pm.start_servers = 5
pm.min_spare_servers = 5
pm.max_spare_servers = 35

slowlog = /var/log/php-fpm/www-slow.log

php_flag[display_errors] = on
php_admin_value[error_log] = /var/log/php-fpm/nagios-error.log
php_admin_flag[log_errors] = on
php_value[session.save_handler] = files
php_value[session.save_path] = /var/lib/php/session

Restarting PHP-FPM and Enabling at start-up

  sudo systemctl restart php-fpm
  sudo systemctl enable php-fpm

Download Nagios Core

  wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.3.tar.gz

Untar

  tar zxf nagios-4.4.3.tar.gz
  cd nagios-4.4.3

Compiling the binaries and installing Nagios

  sudo su
  cd nagios-4.4.3
  ./configure && make all && make install && make install-init && make install-config && make install-commandmode && make install-webconf

Verifying Nagios Configuration

  /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

- Installing Extra Plugins

  yum install nagios-plugins-all -y

Creating soft link for new plugins and also remove the default plugins

  rm -rf /usr/local/nagios/libexec
  ln -s /usr/lib64/nagios/plugins /usr/local/nagios/libexec
  chown -R nagios:nagios /usr/local/nagios/libexec

Start Nagios and Enable nagios for startup at boot

  systemctl start nagios
  systemctl enable nagios

Creating password for nagiosadmin user

  htpasswd -c /usr/local/nagios/passwd nagiosadmin

Creating directory for user and creating links

  mkdir /usr/local/nagios/share/nagios
  cd /usr/local/nagios/share/nagios/
  ln -s /usr/local/nagios/share/stylesheets/ stylesheets
  ln -s /usr/local/nagios/share/js js

Installing spawn-fcgi

  yum install fcgi-devel spawn-fcgi -y

Installing fcgiwrap and installing by compiling binaries

  cd /usr/local/src/ && git clone https://github.com/gnosek/fcgiwrap.git && cd fcgiwrap && autoreconf -i && ./configure && make && make install

Adding the spawn-fcgi configuration

Create Config file for SPAWN-FCGI

  vim /etc/sysconfig/spawn-fcgi

Configuration for SPAWN-FCGI

FCGI_SOCKET=/var/run/fcgiwrap.socket
FCGI_PROGRAM=/usr/local/sbin/fcgiwrap
FCGI_USER=nginx
FCGI_GROUP=nginx
FCGI_EXTRA_OPTIONS="-M 0700"
OPTIONS="-u $FCGI_USER -g $FCGI_GROUP -s $FCGI_SOCKET -S $FCGI_EXTRA_OPTIONS -F 1 -P /var/run/spawn-fcgi.pid -- $FCGI_PROGRAM"

Starting and Enabling Spawn-fcgi

  systemctl start spawn-cgi
  systemctl enable spawn-cgi

you can now access https://your_website.tld/nagios