Ok, i used to write the longer version when i was still using Centos 5, recently i went back to the article and found out that there is actually a shorter way to setup EVERYTHING. So here i am writing a shorter version to setup nagios on centos 6.
Setup Nagios Server
This is the server that will have vshell and nagios web interface. All you have to do is to install epel-release for your centos
yum install -y epel-release
and starts install nagios via yum
yum install -y nagios nagios-devel nagios-plugins* gd gd-devel httpd php gcc glibc glibc-common openssl
Now we need to make sure nagiosadmin is our username and password is set
htpasswd -c /etc/nagios/passwd nagiosadmin
which you can setup all the configuration at /etc/nagios/cgi.cfg and if you would like to change the configuration on apache, it is located at /etc/httpd/conf.d/nagios.conf
Once you have installed nagios, remember to startup nagios and apache whenever you restart!
service httpd restart chkconfig httpd on service nagios restart chkconfig nagios on
and you can access it via http://localhost/nagios with username and password you have just setup above!!! Pretty easy ya!
Now you might want to install nrpe on each server you wish to monitor next,
Installing nrpe with nagios-plugins on each server
Now, you really want to just have all these in yum when you have like 20 servers? It will be a nightmare if you just build all these by source (which i did last time instead of writing a scripts, yeah i'm dumb, i know). All you need to do via yum is
yum install nrpe nagios-plugins-all
And configure nrpe via
adding your nagios ip into it so that your nagios server is allowed to penetrate each 'slave' you have lol.
Now all you need to do is to setup all the services you wish to let your man to do on your 'slaves'.
command[check_users]=/usr/lib64/nagios/plugins/check_users -w 5 -c 10 command[check_load]=/usr/lib64/nagios/plugins/check_load -w 15,10,5 -c 30,25,20 command[check_hda1]=/usr/lib64/nagios/plugins/check_disk -w 20% -c 10% -p /dev/hda1 command[check_zombie_procs]=/usr/lib64/nagios/plugins/check_procs -w 5 -c 10 -s Z command[check_total_procs]=/usr/lib64/nagios/plugins/check_procs -w 150 -c 200
and these can be setup at the same path as /etc/nagios/nrpe.cfg and you should be able to add more 'action' to it if you want.
and remember to setup nrpe to run on startup
service nrpe start chkconfig nrpe on