Question: How to configure CentOS/RHEL system as Nagios NRPE Client so it can be monitored from Nagios-Server for system health/performance?
Enable EPEL REPO (Fedora Repository) and Install Required Packages
1. Download the epel repository packages for CentOS/RHEL 5 and 6.
FOR CentOS/RHEL 6:
# wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
For CentOS/RHEL 5:
# wget http://dl.fedoraproject.org/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm
2. Install Epel repostiory
# yum install /path/to/downloaded/rpm/with/wget/epel-release-X-X.noarch.rpm
where X-X is your version eg. CentOS 6 or CentOS 5 rpm file.
3. Enable epel repo and install nrpe and nagios-plugins from it.
# yum --enablerepo=epel install nrpe nagios-plugins
4. After the installation, disable EPEL repo ( just in case ):
# yum-config-manager --disable epel
5. Install below packages which are required later on by NRPE or any 3rd party Nagios Plugin:
# yum install xinetd gcc openssl-devel make lm_sensors net-snmp-utils postresql-libs
Install and configure Xinetd
1. Install xinetd which is necessary for NRPE:
# yum install xinetd
2. Configure xinetd for NRPE by creating xinetd file for NRPE
# vi /etc/xinetd.d/nrpe
### & (Paste below rows)
service nrpe
{
flags = REUSE
type = UNLISTED
port = 5666
socket_type = stream
wait = no
user = nagios
group = nagios
server = /usr/sbin/nrpe
server_args = -c /etc/nagios/nrpe.cfg --inetd
log_on_failure += USERID
disable = no # change
only_from = 127.0.0.1 XXX.XXX.XXX.XXX ### Replace XXX.XXX.XXX.XXX with actual Nagios Server IP
}
Above entry will allow xinetd access from XXX.XXX.XXX.XXX Nagios Server and localhost 127.0.0.1.
Configuration
1. Add nrpe port to /etc/services – Add NRPE service to /etc/services and make sure port 5666 (default) is open on Firewall:
# echo "nrpe 5666/tcp # NRPE" >> /etc/services
2. Make necessary changes to nrpe.conf – Edit nrpe.cfg and add allowed hosts which can talk to NRPE daemon eg. Nagios Server or any Other NRPE Client (edit allowed_hosts= stanza).
# vi /etc/nagios/nrpe.cfg allowed_hosts=127.0.0.1, XXX.XXX.XXX.XXX ### Replace XXX.XXX.XXX.XXX with desired IP addresses
3. Start xinetd/nrpe and enable them at system boot:
# service xinetd start # service nrpe start # chkconfig xinetd on # chkconfig nrpe on
Misc
Nagios NRPE commands can be added in file /etc/nagios/nrpe.cfg.
Example confing:
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
To install additional plugins from EPEL:
# yum install nagios-plugins-all
Above yum command will install all additional Nagios Plugins which can be used for system checks. All plugins will be located in /usr/lib64/nagios/plugins – please remember to set proper permissions/user for any 3rd party plugin ( User/group should be: nagios:nagios and permissions: 755 )
Additional plugins can be found here.
Test NRPE Client from Nagios Server
From Nagios Server test new NRPE Client configuration by using check_nrpe plugin:
./check_nrpe -H NEWLY_CONFIGURED_NRPE_CLIENT_IP nrpe-2.15-2.el6.x86_64
Now proceed with the further configuration on Nagios Server (add client-node-config/commands to check).