Tuesday, 9 April 2013

Monitor Remote Linux Host using Nagios:

Configuration steps on the Nagios monitoring server to monitor remote host:

Download NRPE Add-on:

Download nrpe-2.12.tar.gz from Nagios.org and move to /home/downloads:

Install check_nrpe on the nagios monitoring server:

# tar xvfz nrpe-2.12.tar.gz
# cd nrpe-2.1.2
# ./configure
# make all
# make install-plugin
./configure will give a configuration summary as shown below:

*** Configuration summary for nrpe date ***:

General Options:
NRPE port: 5666
NRPE user: nagios
NRPE group: nagios
Nagios user: nagios
Nagios group: nagios

Note: I got the “checking for SSL headers… configure: error: Cannot find ssl headers” error message while performing ./configure. Install openssl-devel as shown below and run the ./configure again to fix the problem.

# rpm -ivh openssl-devel-0.9.7a-43.16.i386.rpm krb5-devel-1.3.4-47.i386.rpm zlib-devel- e2fsprogs-devel-1.35-12.5.

Verify whether nagios monitoring server can talk to the remotehost.
#/usr/local/nagios/libexec/check_nrpe -H
NRPE v2.12

Note: in the ip-address of the remotehost where the NRPE and nagios plugin was installed as explained above.

Create host and service definition for remotehost:

Create a new configuration file /usr/local/nagios/etc/objects/remotehost.cfg to define the host and service definition for this particular remotehost. It is good to take the localhost.cfg and copy it as remotehost.cfg and start modifying it according to your needs.

host definition sample:

define host{
use linux-server
host_name remotehost
alias Remote Host
contact_groups admins

Service definition sample:

define service{
use generic-service
service_description Root Partition
contact_groups admins
check_command check_nrpe!check_disk

Note: In all the above examples, replace remotehost with the corresponding hostname of your

Dont forget to include
 in /usr/local/nagios/etc/nagios.cfg

Restart the nagios service:

Restart the nagios as shown below and login to the nagios web (http://nagios-server/nagios/) to verify the status of the remotehost linux sever that was added to nagios for monitoring.

# service nagios reload


On Red Hat, For me the ./configure command was hanging with the the message: “checking for redhat spopen problem…”. Add --enable-redhat-pthread-workaround to the ./configure command as a work-around for the above problem.

You may also modify commands.cfg to add check_nrpe that was not by default in that file.

# ‘check_nrpe’ command definition
define command{
command_name check_nrpe
command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -t 30 -c $ARG1$

add the following in /objects/commands.cfg of the Nagios server.

define command{
command_name check_nrpe
command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$

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