How to install Nagios in RHEL| Fedora | Centos

Nagios is the industry standard in enterprise-class monitoring for good reason. It allows you to gain insight into your network and fix problems before customers know they even exist. It’s stable, scalable, supported, and extensible.


1. First step : Install some Packages :

yum install httpd php

yum install gcc

yum install glibc glibc-common

yum install gd gd-devel

2. Create nagios user in box :

#/usr/sbin/useradd -m nagios

#passwd nagios

3. Add nagcmd group

/usr/sbin/groupadd nagcmd

/usr/sbin/usermod -a -G nagcmd nagios

/usr/sbin/usermod -a -G nagcmd apache

4. Now go to http://www.nagios.org download below files

nagios-3.1.0.tar.gz | nrpe-2.12.tar.gz | nagios-plugins-1.4.13.tar.gz

tar -zxvf  nagios-3.1.0.tar.gz

cd nagios-3.1.0

./configure --with-command-group=nagcmd

#make all; make install; make install-init; make install-config;
make install-commandmode; make install-webconf

5. Edit your email admin address in cantacts.cfg configuration file:

Go to

vi /usr/local/nagios/etc/objects/contacts.cfg 

If you want to use existing mail server like gmail, yahoo or own server then mention below like:
sSMTP Configuration

6. Create a nagiosadmin account for logging into the Nagios web interface assign to this you’ll need it later.

htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

7. Restart the httpd server :

#Service httpd restart

The second step : Extract and install plugins :

1.Go to you downloaded nagios tools

tar  -zxvf   nagios-plugins-1.4.13.tar.gz

cd nagios-plugins

./configure --with-nagios-user=nagios --with-nagios-group=nagios

make; make install

2.Now you have to add nagios to Chkconfig

chkconfig --add nagios

chkconfig nagios on

3. Verify if you have a good config of nagios with the command :

/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

4. Check if there are no errors displayed; then start nagios with command :

service nagios start

Run below command to get updated nagios logs.

tail -f /usr/local/nagios/var/nagios.log

5. Set Nagios Admin Panel Password

htpasswd -c /etc/nagios/passwd nagiosadmin

Please disable the selinux and iptables and ip6tables :
now open your browser and http://localhost/nagios or http://ip/nagios




This is what the Nagios admin panel looks like:




And you are all done!