Nagios is a powerful monitoring system that monitors your servers and/or services and alerts staff if a problem should arise. The system is plugable which gives administrators the ability to write their own or use hundreds of pre written plugins to monitor their infrastructure.
yum -y install http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm yum -y install nagios nagios-plugins-all
If you do not do this you will get a warning from nagios when it checks itself to make sure apache is running.
touch /var/www/html/index.html
chkconfig httpd on chkconfig nagios on
By default the web interface is password protected, the default user is nagiosadmin so we'll change this users password. You can change this username too but it requires you to modify the nagios configuration files to match.
htpasswd -c /etc/nagios/passwd nagiosadmin
By default alerts will be sent to nagios@localhost. You can change this by editing /etc/nagios/objects/contacts.cfg and changing this address
service httpd start service nagios start
You can now open your browser and goto your server's hostname or ip address prefixed with /nagios. You will be prompted for a username and password. The username is nagiosadmin unless you changed it, and the password is what you set above.
Example: http://192.168.1.1/nagios
We will now create a configuration file to monitor an additional host. We will monitor ICMP and SSH
Create and edit a file in /etc/nagios/conf.d/server1.domain.cfg
define host {
use linux-server
host_name server1.domain.com
alias server1.domain.com
address 10.0.0.1
}
define service {
use generic-service
host_name server1.domain.com
service_description PING
check_command check_ping!100.0,20%!500.0,60%
}
define service {
use generic-service
host_name server1.domain.com
service_description SSH
check_command check_ssh
}
Next you need to reload nagios
service nagios reload