Install Nagios

	Install Nagios in order to watch server's status. httpd is also needed.
[1]	Install Nagios

[root@s ~]#  yum --enablerepo=dag -y install nagios nagios-plugins     # install from  DAG [root@ns ~]#  vi /etc/nagios/nagios.cfg # line 52: uncomment cfg_dir=/etc/nagios/servers [root@ns ~]#  vi /etc/httpd/conf.d/nagios.conf # line 16: add IPs you allow Allow from  127.0.0.1 192.168.0. # line 33: add IPs you allow Allow from  127.0.0.1 192.168.0. [root@ns ~]#  mkdir /etc/nagios/servers [root@ns ~]#  chown nagios. /etc/nagios/servers [root@ns ~]#  vi /etc/nagios/objects/contacts.cfg # line 35: change to admin's email address       email webmaster@localhost [root@ns ~]#  htpasswd -c /etc/nagios/htpasswd.users nagiosadmin New password: # set password Re-type new password: Adding password for user nagios [root@ns ~]#  /etc/rc.d/init.d/httpd restart Stopping httpd: [  OK  ] Starting httpd: [  OK  ] [root@ns ~]#  /etc/rc.d/init.d/nagios start Starting nagios: done. [root@ns ~]#  chkconfig nagios on

[2]	Access with web browser to 'http://(your hostname or IP address)/nagios/', then following screen is shown. Input nagiosadmin for user and password set with htpasswd in [1].

[3]	Just logined.

[4]	Click "Services" on the left menu. The notification option for 'HTTP' and 'SSH' is disabled  by default, so chnage them to enable. Click bell-icon.

[5]	Click "Enable notifications for this service".

[6]	Click "Commit" button.

[7]	Click "Done".

[8]	The notification option for 'HTTP' is just enabled. Turn enable for SSH too by the same procedure.

[9]	Try to stop SSH by hand, then turn status for SSH like follows after few minutes.

[10]	Make sure emailbox, then following email comes.