Learn how to install NRPE in CentOS 7 with this comprehensive step-by-step guide. Ensure smooth monitoring of your network services and hosts. #centlinux #linux #nagios
Table of Contents
Problem Definition
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.
what is NRPE?
NRPE (Nagios Remote Plugin Executor) is a Nagios plugin that allows you to execute plugins on remote hosts. It enables you to monitor local resources (like disk usage, CPU load, memory usage, etc.) on remote machines. The NRPE addon consists of two pieces:
- NRPE Daemon: Runs on the remote hosts and listens for requests.
- NRPE Plugin: Runs on the Nagios server and is used to execute commands on the remote hosts.
By using NRPE, you can monitor the performance and health of remote systems, ensuring that they meet the desired operational standards. This setup is particularly useful for managing and monitoring multiple servers in a network from a central Nagios 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 (PAID LINK). It will be really helpful for you during your Nagios journey.
Environment Specification
In this post, we will install NRPE Nagios Core Agent on CentOS 7 host to add it to Nagios Monitoring Server. Here, we use following two Linux servers for this installation guide.
1) Nagios Monitoring Server – A working Nagios Core Server.
- Hostname – nagios01.example.com
- IP Address – 192.168.229.129/24
2) Linux Host – A CentOS 7 machine, in which we are going to install NRPE.
- Hostname – dbserver01.example.com
- IP Address – 192.168.229.133/24
Read Also: How to install NSClient on Windows
Install NRPE in 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 success # firewall-cmd –reload success
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 ‘,’.
allowed_hosts=127.0.0.1,::1,192.168.229.129
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 192.168.229.133 ; 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
cfg_file=/usr/local/nagios/etc/objects/linux.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.
NRPE Nagios Core Agent has been successfully installed on our CentOS 7 host.
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Final Thoughts
Installing NRPE on CentOS 7 can greatly enhance your ability to monitor network services and hosts efficiently. By following the steps outlined in this guide, you should be able to set up NRPE with ease and ensure your systems are running smoothly.
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