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Sunday, September 11, 2016

Install NRPE Nagios Core Agent on CentOS 7

Install NRPE Nagios Core Agent on CentOS 7

We have already configured our Nagios Monitoring Server in our previous post Install & Configure Nagios Core 4.4 on CentOS 7. Now, its time to add some hosts to our Nagios Monitoring Server. For this purpose, we need to install a Monitoring Agent software on our Host. There are so many Monitoring Agents are available, that works well with not only Nagios, but other forks of Nagios (such as Icinga). But after having some research we have selected NRPE (Nagios Remote Process Executor) for the purpose.

In this post, we will install NRPE Nagios Core Agent on CentOS 7 host to add it to Nagios Monitoring Server.

Before moving forward, it is required to have basic concepts of Nagios Core 4. Therefore, it is highly recommended that you should have Learning Nagios - Third Edition. It will be really helpful for you during your Nagios journey.

Install NRPE Nagios Core Agent on CentOS 7

System Specification:

1) Nagios Monitoring Server – A working Nagios Core Server.

  • Hostname - nagios01.example.com
  • IP Address -

2) Linux Host – A CentOS 7 machine, in which we are going to install NRPE.

  • Hostname - dbserver01.example.com
  • IP Address -


Install and Configure NRPE Nagios Core Agent on CentOS 7:

Connect to the Linux host using ssh and install prerequisite packages.

# yum install -y gcc glibc glibc-common gd gd-devel make net-snmp openssl-devel

Create user that own Nagios plugins and NRPE files & processes.

# useradd nagios
# passwd nagios

Create directories to download Nagios plugins & NRPE.

# mkdir -p /soft/nagios

Download Nagios Plugins 2.1.2 from https://www.nagios.org/downloads/nagios-plugins/

# cd /soft/nagios
# wget https://nagios-plugins.org/download/nagios-plugins-2.1.2.tar.gz

Extract and install Nagios plugins.

# tar -xvf nagios-plugins-2.1.2.tar.gz
# cd nagios-plugins-2.1.2
# ./configure
# make
# make install

Download NRPE Agent from Nagios Exchange.

# cd /soft/nagios
# wget https://github.com/NagiosEnterprises/nrpe/archive/3.0.1.tar.gz

Extract and install NRPE.

# tar -xvzf 3.0.1.tar.gz
# cd nrpe-3.0.1/
# ./configure
# make all
# make install-daemon

Open the server port, used by NRPE Daemon.

# firewall-cmd –-permanent –-add-port=5666/tcp
# firewall-cmd –reload

Configure NRPE.

# mkdir /usr/local/nagios/etc/
# cp sample-config/nrpe.cfg /usr/local/nagios/etc/nrpe.cfg
# vi /usr/local/nagios/etc/nrpe.cfg

Add the localhost (IPv4 & IPv6 both) & Nagios Monitoring Server IP addresses separated by Comma ','.


Start the NRPE Daemon.

# /usr/local/nagios/bin/nrpe -c /usr/local/nagios/etc/nrpe.cfg -d

At Nagios Monitoring Server add this Linux host and define some services.

# vi /usr/local/nagios/etc/objects/linux.cfg
## Default Linux Host Template ##
define host{
name                            linux-box               ; Name of this template
use                             generic-host            ; Inherit default values
check_period                    24x7        
check_interval                  5       
retry_interval                  1       
max_check_attempts              10      
check_command                   check-host-alive
notification_period             24x7    
notification_interval           30      
notification_options            d,r     
contact_groups                  admins  
register                        0                       ; DONT REGISTER THIS - ITS A TEMPLATE
## Default
define host{
use                             linux-box               ; Inherit default values from a template
host_name                       dbserver01  ; The name we're giving to this server
alias                           dbserver01              ; A longer name for the server
address                        ; IP address of Remote Linux host

define service{
use                     generic-service
host_name               dbserver01
service_description     CPU Load
check_command           check_nrpe!check_load
define service{
use                     generic-service
host_name               dbserver01
service_description     Total Processes
check_command           check_nrpe!check_total_procs
define service{
use                     generic-service
host_name               dbserver01
service_description     Current Users
check_command           check_nrpe!check_users
define service{
use                     generic-service
host_name               dbserver01
service_description     SSH Monitoring
check_command           check_nrpe!check_ssh
define service{
use                     generic-service
host_name               dbserver01
service_description     FTP Monitoring
check_command           check_nrpe!check_ftp

Now, add this config file to nagios.cfg.

# vi /usr/local/nagios/etc/nagios.cfg

Define the check_nrpe command.

# vi /usr/local/nagios/etc/objects/commands.cfg
define command{
 command_name check_nrpe
 command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$

Restart Nagios service to reload changes

# systemctl restart nagios.service

Browse the Nagios Web UI, and check the services of dbserver01.

Nagios Core Web UI

NRPE Nagios Core Agent has been successfully installed on our CentOS 7 host.

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  1. would you mind i want to know what we need to install nrpe on nagios server.thanks sir

    1. You are welcome Htet. Installation of NRPE is not required on Nagios Server, because Local System metrics directly collected by Nagios itself.

  2. Thanks a lot MR ahmer,
    I think i need two system :
    The first : Nagios core 4, plugins 2
    The second : plugins 2, nrpe
    That is true ??

    1. Yes, you are right.

      Infact, we need NRPE on every client system, that we want to monitor with Nagios Core Server.

    2. thank you so much ,
      i'm sorry i have other question about this line :
      vi /usr/local/nagios/etc/objects/linux.cfg
      is not working for me .
      what can i do ?

    3. Contact me on Facebook please.


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