I hope you know to install Nagios monitoring server on CentOS, this post describes to configure the Nagios client in Ubuntu machine. Its, very simple steps to install, 

Create a new user with password : nagios

# adduser nagios    


Update and install necessary packages,



# sudo apt-get update -y



# sudo apt-get install  gcc perl libtool openssl libssl-dev -y


Download Nagios-Plugin and nrpe latest version,



# wget http://www.nagios-plugins.org/download/nagios-plugins-2.1.1.tar.gz



# wget http://liquidtelecom.dl.sourceforge.net/project/nagios/nrpe-2.x/nrpe-2.15/nrpe-2.15.tar.gz


Extract the Nagios-plugins package and configure,



# tar -zxvf nagios-plugins-2.1.1.tar.gz



# cd /root/nagios-plugins-2.1.1



# ./configure



# make



# make install


Change ownership on below directories



# chown  -R nagios.nagios /usr/local/nagios



# chown -R nagios.nagios /usr/local/nagios/libexec


Install xinetd package,

# apt-get install xinetd -y


check the xinetd status and start it if doesn't start.



# service xinetd status



# service xinetd start

 


Now, extract nrpe package and install





# tar -zxvf /root/nrpe-2.15.tar.gz



# cd /root/nrpe-2.15



# ./configure --with-ssl=/usr/bin/openssl --with-ssl-lib=/usr/lib/x86_64-linux-gnu



# make all



# make install-plugin



# make install-daemon



# make install-daemon-config



# make install-xinetd


Installation process has been completed, let begin to configure,

You need to add the  below line in services file



# vim  /etc/services



nrpe                5666/tcp      # NRPE 


Note : Assume that suppose to your Nagios IP address is 192.168.10.10,

open nrpe file and add nagios IP Address



# vim /etc/xinetd.d/nrpe

        only_from  = 127.0.0.1  192.168.10.10


Open  main configure file in remote-client nrpe.cfg, append Nagios-server ip to  allowed_host



# vim /usr/local/nagios/etc/nrpe.cfg



allowed_hosts=127.0.0.1