How To Install Nagios 4.4.3 on CentOS 7/6 & RHEL 7/6

Nagios is the most widely used open source monitoring tools which help us to monitor the services and application that run’s on Windows, Linux, Routers and other network devices.

With the help of Nagios, you can monitor basic services and attributes. We can access the Nagios using web interface coming with the bundle and configuration need to be done on the file level.

Services List

This Tutorial describes how you can monitor private services and attributes of Linux/UNIX servers, such as:


  • CPU load
  • Memory usage
  • Disk usage
  • Logged in users
  • Running processes
  • etc.

Private Services

  • HTTP
  • FTP
  • SSH
  • SMTP
  • etc


Before installing the Nagios, the system needs to meet the requirements for installing Nagios. So install the Web Server (httpd), PHP, compilers and development libraries.

Install all packages in a single command.

yum -y install httpd php gcc glibc glibc-common wget perl gd gd-devel unzip zip

Create a nagios user and nagcmd group for allowing the external commands to be executed through the web interface, add the nagios and apache user to be a part of the nagcmd group.

useradd nagios
groupadd nagcmd
usermod -a -G nagcmd nagios
usermod -a -G nagcmd apache

Install Nagios Server

Download the latest version of Nagios Core using the terminal.

cd /tmp/
tar -zxvf nagios-4.4.3.tar.gz
cd /tmp/nagios-4.4.3

Compile and Install Nagios.

./configure --with-nagios-group=nagios --with-command-group=nagcmd
make all
make install
make install-init
make install-config
make install-commandmode

Install Nagios Web Interface

Install the Nagios web configuration using the following command.

make install-webconf

Run the following command to install a Nagios exfoliation theme

make install-exfoliation

Create a user account (nagiosadmin) for logging into the Nagios web interface. Remember the password that you assign to this user – you’ll need it later.

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

Restart Apache web server to make the new settings take effect.

### CentOS 7 / RHEL 7 ###

systemctl restart httpd
systemctl enable httpd

### CentOS 6 / RHEL 6 ###

service httpd start
chkconfig httpd on

Configure Nagios Server

Sample configuration files have now been installed in the /usr/local/nagios/etc directory. These sample files should work fine for getting started with Nagios. You’ll need to make just one change before you proceed.

Edit the /usr/local/nagios/etc/objects/contacts.cfg config file with your favorite editor and change the email address associated with the nagiosadmin contact definition to the address you’d like to use for receiving alerts.

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

Change the Email address field to receive the notification.

define contact{
        contact_name                    nagiosadmin             ; Short name of user
        use                             generic-contact         ; Inherit default values from generic-contact template (defined above)
        alias                           Nagios Admin            ; Full name of user

        email                        ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******

Install Nagios Plugins

Download Nagios Plugins to /tmp directory.

cd /tmp
tar -zxvf nagios-plugins-2.2.1.tar.gz
cd /tmp/nagios-plugins-2.2.1/

Compile and install the Nagios plugins.

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

Start Nagios Server

Verify the sample Nagios configuration files.

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


Nagios Core 4.4.3
Copyright (c) 2009-present Nagios Core Development Team and Community Contributors
Copyright (c) 1999-2009 Ethan Galstad
Last Modified: 2019-01-15
License: GPL

Reading configuration data...
   Read main config file okay...
   Read object config files okay...

Running pre-flight check on configuration data...

Checking objects...
        Checked 8 services.
        Checked 1 hosts.
        Checked 1 host groups.
        Checked 0 service groups.
        Checked 1 contacts.
        Checked 1 contact groups.
        Checked 24 commands.
        Checked 5 time periods.
        Checked 0 host escalations.
        Checked 0 service escalations.
Checking for circular paths...
        Checked 1 hosts
        Checked 0 service dependencies
        Checked 0 host dependencies
        Checked 5 timeperiods
Checking global event handlers...
Checking obsessive compulsive processor commands...
Checking misc settings...

Total Warnings: 0
Total Errors:   0

Things look okay - No serious problems were detected during the pre-flight check

If there are no errors, then start the Nagios service.

service nagios start

Start Nagios on system startup.

chkconfig nagios on


See if SELinux is in Enforcing mode.


Put SELinux in Permissive mode or disable it.

setenforce 0

To make this change permanent, you will have to modify /etc/selinux/config and reboot the system.


Make sure to allow web server access through the firewall.

### FirwallD ###

firewall-cmd --permanent --add-service=http
firewall-cmd --reload

### IP Tables ###

iptables -I INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
service iptables save

Access Nagios Web Interface

Now access the Nagios web interface using the following URL. You’ll be prompted for the username (nagiosadmin) and password you specified earlier.

Install Nagios 4.4.3 on CentOS 7 – Nagios Login Screen

Nagios console will look like below.

Install Nagios 4.4.3 on CentOS 7 – Nagios Portal

Click on Hosts in the left pane to get a list of systems being monitored by Nagios. We have not added any host to Nagios, So it simply monitors the localhost itself.

To monitor a remote Linux system,

READ: Monitor Remote Linux System with Nagios Server

Install Nagios 4.4.3 on CentOS 7 – Nagios Hosts List

Click on Services in the left pane to get the status of any services that are being monitored with Nagios.

Install Nagios 4.4.3 on CentOS 7 – Monitoring SServicesWith Nagios

In our next article, we will monitor Remote Linux System with Nagios Server.

That’s All.

centos 6centos 7monitoringmonitoring-toolsnagios
Comments (10)
Add Comment
  • Ahmed

    Hi Raj,

    i just have installed nagios, and it worked fine, but after restarting the centos VM. i was not able to login to nagios. i followed all your steps and after that i was able to login. but when i did the restart again and wasnt able to login to nagios.
    would you be able to guide me through what could be the issue.

    • Raj

      Dear Ahmed,

      I have updated the article, the following has been added extra in article.
      Auto start the services, Iptables entry, Make sure to disable selinux

      PS: Let me know

      • Ahmed

        Thanks Raj,
        yes that was the issue, and now it works fine.Thanks

  • space-hunter

    for check_http with SSL enabled,
    you have to install openssl-devel befor compile the nagios-plugins
    yum -y install openssl-devel

  • vikram devops

    Hi , getting command not found while executing below command on Centos 7. i have tried to fix this issue but in vain.Could you please help me out how to resolve this issue.

    firewall-cmd –permanent –zone=public –add-service=http
    firewall-cmd –reload

    • ITzGeek Web

      If you get command not found means, you don’t have firewalld installed. You further continue next step as it seems you don’t have iptables.

      • vikram devops

        thanks , issue has been resolved. but i am facing one more issue .

        I am unable to login web URL by using centos IP(ip addr) address.getting below mentioned issue

        Error: took too long to respond

        Selected ‘Automatically detect settings’ under Lan setting.

        is it required tomcat need to install on Local system ? or am i using incorrect IP address ?

        • ITzGeek Web


          1. Nagios service

          service nagios status

          2. Apache

          service httpd status

          3. If the CentOS has gui

          Use below URL

  • Adnan Khan

    thanks for the article, I was able to isntall and and configure nagios. However when I am navigating through the UI, the top url on the navigation bar stays same localhost/nagios.
    What can I do configure the nagios to change the URL on every click, if click on hosts, the url should change to hosts.

  • ITzGeek Web

    Have you done.

    ./configure –with-nagios-group=nagios –with-command-group=nagcmd
    make all
    make install
    make install-init
    make install-config
    make install-commandmode