Linux Administrator: Nagios 4 : Install

Saturday, November 29, 2025

Nagios 4 : Install

	Install Nagios 4 which is an enterprise open source monitoring system.
[1]	Install and start Apache httpd, refer to here.
[2]	Configure SSL/TLS setting for Apache httpd, refer to here. (not required but recommended)
[3]	Install PHP, refer to here.
[4]	Install Nagios Server. Also Install basic plugins to monitor Nagios Server itself.

# install from EPEL

[root@dlp ~]# dnf --enablerepo=epel -y install nagios nagios-plugins-{ping,disk,users,procs,load,swap,ssh,http}

[5]	Configure Nagios.

[root@dlp ~]# vi /etc/httpd/conf.d/nagios.conf
# line 16-17 : change access permission if you need ( also change line 47-48 )

#
Require all granted
#Require host 127.0.0.1
Require ip 127.0.0.1 10.0.0.0/24
# add nagios admin user

[root@dlp ~]# htpasswd /etc/nagios/passwd nagiosadmin

New password:     # set any password

Re-type new password:
Adding password for user nagiosadmin
[root@dlp ~]# systemctl enable --now nagios

[root@dlp ~]# systemctl restart httpd

[6]	If SELinux is enabled, change policy.

# install from EPEL

[root@dlp ~]# dnf --enablerepo=epel -y install nagios-selinux
[root@dlp ~]# vi nagios-php.te
# create new

module nagios-php 1.0;

require {
        type httpd_t;
        type nagios_spool_t;
        type ping_exec_t;
        type nagios_unconfined_plugin_t;
        class file { execute execute_no_trans map getattr open read };
        class process setcap;
        class icmp_socket { create getopt setopt };
        class udp_socket { connect create getattr };
}

#============= nagios_unconfined_plugin_t ==============
allow nagios_unconfined_plugin_t ping_exec_t:file { execute execute_no_trans open read };
allow nagios_unconfined_plugin_t ping_exec_t:file map;
allow nagios_unconfined_plugin_t self:icmp_socket { create getopt setopt };
allow nagios_unconfined_plugin_t self:process setcap;
allow nagios_unconfined_plugin_t self:udp_socket { connect create getattr };

#============= httpd_t ==============
allow httpd_t nagios_spool_t:file { getattr open read };

[root@dlp ~]# checkmodule -m -M -o nagios-php.mod nagios-php.te

[root@dlp ~]# semodule_package --outfile nagios-php.pp --module nagios-php.mod

[root@dlp ~]# semodule -i nagios-php.pp

[7]	If Firewalld is running, allow HTTP service.

[root@dlp ~]# firewall-cmd --add-service={http,https}

success
[root@dlp ~]# firewall-cmd --runtime-to-permanent

success

[8]	Access to [http://(Nagios server's hostname or IP address)/nagios/] from a client which is in the network allowed by Nagios server and authenticate to login with the Nagios administration user [nagiosadmin] you added.