This article describes how to install and configure NRPE from source for use with Nagios Core/XI. The linux-nrpe-agent that ships with Nagios XI is only supported on CentOS, RHEL, OpenSUSE, SLES, Ubuntu, and Debian. Most monitored environments consist of many different distributions, therefore may need to compile NRPE and its associated plugins.

This procedure is intended for Nagios XI administrators who are new to NRPE or Nagios XI and have to use a source-based install method for NRPE, usually due to unsupported Linux distributions or security restrictions in corporate environments.

This guide is broken up into several sections and covers different Linux distributions and non-Linux operating systems.

If you only want to install the check_nrpe plugin, refer to the section at the bottom of this KB article.

NRPE 3.2.1 and Nagios Plugins 2.2.1 is what this guide instructs you to install, however, future versions should also work fine with these steps.

It is assumed that you are logged onto the machine you are installing NRPE as the root user, or a user with sufficient privileges. All of the steps below were tested on the operating systems (OS) listed after a clean install of the OS. Some OS's like Ubuntu and SUSE have stricter user permissions, in those cases the listed commands have sudo in front of them to ensure you are able to complete the steps. A best effort has been made to ensure if you follow all the relevant steps you will end up with a working installation of NRPE.


RHEL | CentOS | Oracle Linux

Prerequisites

Make sure that you have the following packages installed.

yum install -y gcc glibc glibc-common openssl openssl-devel perl wget

 

Downloading the Source 

cd /tmp
wget --no-check-certificate -O nrpe.tar.gz https://github.com/NagiosEnterprises/nrpe/archive/nrpe-3.2.1.tar.gz
tar xzf nrpe.tar.gz

 

Compile

Note that if you want to pass arguments through NRPE you must specify this in the configuration option as indicated below. If you prefer to you can omit the --enable-command-args flag. Removing this flag will require that all arguments be explicitly set in the nrpe.cfg file on each server monitored.

cd /tmp/nrpe-nrpe-3.2.1/
./configure --enable-command-args
make all

 

Create User And Group

This creates the nagios user and group.

make install-groups-users

 

Install Binaries

This step installs the binary files, the NRPE daemon and the check_nrpe plugin.

If you only wanted to install the daemon, run the command make install-daemon instead of the command below. However it is useful having the check_nrpe plugin installed for testing purposes.

If you only wanted to install the check_nrpe plugin, refer to the section at the bottom of this KB article as there a lot of steps that can be skipped. Installing only the plugin is usually done on your Nagios server and workers.

make install

 

Install Configuration Files

This installs the config files.

make install-config

 

Update Services File

The /etc/services file is used by applications to translate human readable service names into port numbers when connecting to a machine across a network.

echo >> /etc/services
echo '# Nagios services' >> /etc/services
echo 'nrpe    5666/tcp' >> /etc/services

 

Install Service / Daemon

This installs the service or daemon files.

===== CentOS 5.x / 6.x | RHEL 5.x / 6.x | Oracle Linux 5.x / 6.x =====

make install-init

 

===== CentOS 7.x | RHEL 7.x | Oracle Linux 7.x =====

make install-init
systemctl enable nrpe.service

 

Information on starting and stopping services will be explained further on.

 

Configure Firewall

Port 5666 is used by NRPE and needs to be opened on the local firewall.

===== CentOS 5.x / 6.x | RHEL 5.x / 6.x | Oracle Linux 5.x / 6.x =====

iptables -I INPUT -p tcp --destination-port 5666 -j ACCEPT
service iptables save
ip6tables -I INPUT -p tcp --destination-port 5666 -j ACCEPT
service ip6tables save

 

===== CentOS 7.x | RHEL 7.x | Oracle Linux 7.x =====

firewall-cmd --zone=public --add-port=5666/tcp
firewall-cmd --zone=public --add-port=5666/tcp --permanent

 

Update Configuration File

The file nrpe.cfg is where the following settings will be defined. It is located:

/usr/local/nagios/etc/nrpe.cfg
 

allowed_hosts=

At this point NRPE will only listen to requests from itself (127.0.0.1). If you wanted your nagios server to be able to connect, add it's IP address after a comma (in this example it's 10.25.5.2):

allowed_hosts=127.0.0.1,10.25.5.2

 

dont_blame_nrpe=

This option determines whether or not the NRPE daemon will allow clients to specify arguments to commands that are executed. We are going to allow this, as it enables more advanced NPRE configurations.

dont_blame_nrpe=1

 

The following commands make the configuration changes described above.

sed -i '/^allowed_hosts=/s/$/,10.25.5.2/' /usr/local/nagios/etc/nrpe.cfg
sed -i 's/^dont_blame_nrpe=.*/dont_blame_nrpe=1/g' /usr/local/nagios/etc/nrpe.cfg

 

Start Service / Daemon

Different Linux distributions have different methods of starting NRPE.

===== CentOS 5.x | RHEL 5.x | Oracle Linux 5.x =====

service nrpe start

 

===== CentOS 6.x | RHEL 6.x | Oracle Linux 6.x =====

start nrpe

 

===== CentOS 7.x | RHEL 7.x | Oracle Linux 7.x =====

systemctl start nrpe.service

 

Test NRPE

Now check that NRPE is listening and responding to requests.

/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1

 You should see the output similar to the following:

NRPE v3.2.1

If you get the NRPE version number (as shown above), NRPE is installed and configured correctly.

You can also test from your Nagios host by executing the same command above, but instead of 127.0.0.1 you will need to replace that with the IP Address / DNS name of the machine with NRPE running.

 

Service / Daemon Commands

Different Linux distributions have different methods of starting / stopping / restarting / status NRPE.

===== CentOS 5.x | RHEL 5.x | Oracle Linux 5.x =====

service nrpe start
service nrpe stop
service nrpe restart
service nrpe status

 

===== CentOS 6.x | RHEL 6.x | Oracle Linux 6.x =====

start nrpe
stop nrpe
restart nrpe
status nrpe

 

===== CentOS 7.x | RHEL 7.x | Oracle Linux 7.x =====

systemctl start nrpe.service
systemctl stop nrpe.service
systemctl restart nrpe.service
systemctl status nrpe.service

 

Installing The Nagios Plugins 

NRPE needs plugins to operate properly. The following steps will walk you through installing Nagios Plugins.

These steps install nagios-plugins 2.2.1. Newer versions will become available in the future and you can use those in the following installation steps. Please see the releases page on GitHub for all available versions.

Please note that the following steps install most of the plugins that come in the Nagios Plugins package. However there are some plugins that require other libraries which are not included in those instructions. Please refer to the following KB article for detailed installation instructions:

Documentation - Installing Nagios Plugins From Source

 

Prerequisites 

Make sure that you have the following packages installed.

===== CentOS 5.x =====

yum install -y gcc glibc glibc-common make gettext automake wget openssl-devel net-snmp net-snmp-utils epel-release
yum install -y perl-Net-SNMP
cd /tmp
wget http://ftp.gnu.org/gnu/autoconf/autoconf-2.60.tar.gz
tar xzf autoconf-2.60.tar.gz
cd /tmp/autoconf-2.60
./configure
make
make install

 

===== CentOS 6.x / 7.x =====

yum install -y gcc glibc glibc-common make gettext automake autoconf wget openssl-devel net-snmp net-snmp-utils epel-release
yum install -y perl-Net-SNMP

 

===== RHEL 5.x | Oracle Linux 5.x =====

cd /tmp
wget http://archives.fedoraproject.org/pub/archive/epel/epel-release-latest-5.noarch.rpm
rpm -ihv epel-release-latest-5.noarch.rpm
yum install -y gcc glibc glibc-common make gettext automake wget openssl-devel net-snmp net-snmp-utils
yum install -y perl-Net-SNMP
wget http://ftp.gnu.org/gnu/autoconf/autoconf-2.60.tar.gz
tar xzf autoconf-2.60.tar.gz
cd /tmp/autoconf-2.60
./configure
make
make install

 

===== RHEL 6.x | Oracle Linux 6.x =====

cd /tmp
wget https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm
rpm -ihv epel-release-latest-6.noarch.rpm
yum install -y gcc glibc glibc-common make gettext automake autoconf wget openssl-devel net-snmp net-snmp-utils
yum install -y perl-Net-SNMP

 

===== RHEL 7.x =====

cd /tmp
wget https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ihv epel-release-latest-7.noarch.rpm
subscription-manager repos --enable=rhel-7-server-optional-rpms
yum install -y gcc glibc glibc-common make gettext automake autoconf wget openssl-devel net-snmp net-snmp-utils
yum install -y perl-Net-SNMP

 

===== Oracle Linux 7.x =====

yum install -y yum-utils
yum-config-manager --enable ol7_optional_latest
cd /tmp
wget https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ihv epel-release-latest-7.noarch.rpm
yum install -y gcc glibc glibc-common make gettext automake autoconf wget openssl-devel net-snmp net-snmp-utils
yum install -y perl-Net-SNMP

 

Downloading the Source

cd /tmp
wget --no-check-certificate -O nagios-plugins.tar.gz https://github.com/nagios-plugins/nagios-plugins/archive/release-2.2.1.tar.gz
tar zxf nagios-plugins.tar.gz

 

Compile + Install

cd /tmp/nagios-plugins-release-2.2.1/
./tools/setup
./configure
make
make install

 

Test NRPE + Plugins

Now you can check that NRPE is executing plugins correctly. The default configuration file /usr/local/nagios/etc/nrpe.cfg has the following command defined in it:

command[check_load]=/usr/local/nagios/libexec/check_load -w 15,10,5 -c 30,25,20

 

Using the check_load command to test NRPE:

/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c check_load

 

You should see the output similar to the following:

OK - load average: 0.01, 0.13, 0.12|load1=0.010;15.000;30.000;0; load5=0.130;10.000;25.000;0; load15=0.120;5.000;20.000;0;

 

You can also test from your Nagios host by executing the same command above, but instead of 127.0.0.1 you will need to replace that with the IP Address / DNS name of the machine with NRPE running.