≡ Menu

Nagios 3.0 Jumpstart Guide For Linux – Overview, Installation and Configuration


Let us discuss the overview, installation and configuration of Nagios, a powerful open source monitoring solution for host and services.
I. Overview of nagios

II. 8 steps for installing nagios on Linux:

  1. Download the nagios and plugins
  2. Take care of the prerequisites
  3. Create user and group for nagios
  4. Install nagios
  5. Configure the web interface
  6. Compile and install nagios plugins
  7. Start Nagios
  8. Login to web interface

III. Configuration files overview

I. Overview of Nagios

Nagios is a host and service monitor tool. Following are some of the features of nagios.

  • Monitor equipments such as servers, switches, routers, firewalls, power supply etc.
  • Monitor services such as disk space, cpu usage, memory usage, temperature of the equipment, HTTP, Mail, SSH etc.
  • Nagios can monitor pretty much anything. for e.g. host, services, databases, applications etc.
  • Nagios has an extensible plugin interface for monitoring user defined services. There are lot of plugins available for Nagios. Visit NagiosPlugins and NagiosExchange for review the available user developed plugins.
  • It can send out various notifications ( email, pager etc.) when the problem occurs and get resolved.
  • Web interface to view current status, notifications, problem history, log files etc.

Following is a partial screenshot of the nagios web dashboard:

Nagios Web UI
Fig: Nagios Web UI (click on the image to enlarge)

II. 8 steps for installing nagios on Linux:

1. Download the nagios and plugins

Download following files from Nagios.org and move to /home/downloads

  • nagios-3.0.1.tar.gz
  • nagios-plugins-1.4.11.tar.gz

2. Take care of the prerequisites

  • Make sure apache is working on the server by verifying from browser: http://localhost
  • Verify whether gcc is installed
      [root@localhost]#rpm -qa | grep gcc
  • Verify whether GD is installed
      [root@localhost]# rpm -qa gd

3. Create user and group for nagios

[root@localhost]# useradd nagios
[root@localhost]# passwd nagios
[root@localhost]# groupadd nagcmd
[root@localhost]# usermod -G nagcmd nagios
[root@localhost]# usermod -G nagcmd apache

4. Install nagios

[root@localhost]# tar xvf nagios-3.0.1.tar.gz
[root@localhost]# cd nagios-3.0.1
[root@localhost]# ./configure --with-command-group=nagcmd
[root@localhost]# make all
[root@localhost]# make install
[root@localhost]# make install-config
[root@localhost]# make install-commandmode

Following are some additional parameters that you can pass to ./configure to customize your installation. I used only --with-command-group as shown above.

	--prefix		/opt/nagios	Where to put the Nagios files
	--with-cgiurl		/nagios/cgi-bin	Web server url where the cgi's will be available
	--with-htmurl		/nagios		Web server url where nagios will be available
	--with-nagios-user	nagios		user account under which Nagios will run
	--with-nagios-group	nagios		group account under which Nagios will run
	--with-command-group	nagcmd		group account which will allow the apache user to submit
						commands to Nagios

At the end of the configure output, it will display a summary as shown below:

*** Configuration summary for nagios 3.0.1 05-28-2008 ***:

General Options:
Nagios executable:  nagios
Nagios user/group:  nagios,nagios
Command user/group:  nagios,nagcmd
Embedded Perl:  no
Event Broker:  yes
Install ${prefix}:  /usr/local/nagios
Lock file:  ${prefix}/var/nagios.lock
Check result directory:  ${prefix}/var/spool/checkresults
Init directory:  /etc/rc.d/init.d
Apache conf.d directory:  /etc/httpd/conf.d
Mail program:  /bin/mail
Host OS:  linux-gnu

Web Interface Options:
HTML URL:  http://localhost/nagios/
CGI URL:  http://localhost/nagios/cgi-bin/
Traceroute (used by WAP):  /bin/traceroute

5. Configure the web interface.

[root@localhost]# make install-webconf
[root@localhost# htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
New password:
Re-type new password:
Adding password for user nagiosadmin

6. Compile and install nagios plugins

[root@localhost]# tar xvf nagios-plugins-1.4.11.tar.gz
[root@localhost]# cd nagios-plugins-1.4.11
[root@localhost]# ./configure --with-nagios-user=nagios --with-nagios-group=nagios
[root@localhost]# make
[root@localhost]# make install

Note: On Red Hat, the ./configure command mentioned above did not work and was hanging at the when it was displaying the message: checking for redhat spopen problem… Add –enable-redhat-pthread-workaround to the ./configure command as a work-around for the above problem as shown below.

[root@localhost]# ./configure --with-nagios-user=nagios --with-nagios-group=nagios --enable-redhat-pthread-workaround

7. Start Nagios

  • Add the nagios to the startup routine:
      [root@localhost]# chkconfig --add nagios
      [root@localhost]# chkconfig nagios on
  • Verify to make sure there are no errors in the nagios configuration file:
      [root@localhost]# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

      Total Warnings: 0
      Total Errors:   0
      Things look okay - No serious problems were detected during the pre-flight check
  • Start the nagios
      [root@localhost]# service nagios start
      Starting nagios: done.

8. Login to web interface

Nagios Web URL: http://localhost/nagios/
Use the userid, password that was created from step#5 above.

III. Configuration files overview

The first configuration to modify is to change the default value of email address in /usr/local/nagios/etc/objects/contacts.cfg file to your email address.

Following are the three major configuration files located under /usr/local/nagios/etc

  1. nagios.cfg – This is the primary Nagios configuration file where lot of global parameters that controls the nagios can be defined.
  2. cgi.cfg – This files has configuration information for nagios web interface.
  3. resource.cfg – If you have to pass some sensitive information (username, password etc.) to a plugin to monitor a specific service, you can define them here. This file is readable only by nagios user and group.

Following are the other configuration files under /usr/local/nagios/etc/objects directory:

  • contacts.cfg: All the contacts who needs to be notified should be defined here. You can specify name, email address, what type of notifications they need to receive and what is the time period this particular contact should be receiving notifications etc.
  • commands.cfg – All the commands to check services are defined here. You can use $HOSTNAME$ and $HOSTADDRESS$ macro on the command execution that will substitute the corresponding hostname or host ip-address automatically.
  • timeperiods.cfg – Define the timeperiods. for e.g. if you want a service to be monitored only during the business hours, define a time period called businesshours and specify the hours that you would like to monitor.
  • templates.cfg – Multiple host or service definition that has similar characteristics can use a template, where all the common characteristics can be defined. Use template is a time saver.
  • localhost.cfg – Defines the monitoring for the local host. This is a sample configuration file that comes with nagios installation that you can use as a baseline to define other hosts that you would like to monitor.
  • printer.cfg – Sample config file for printer
  • switch.cfg – Sample config file for switch
  • windows.cfg – Sample config file for a windows machine

I will discuss about the steps to configure a remote Linux Host and Windows Host for monitoring through nagios in upcoming posts.

Best Nagios Book

Nagios Core 3 eBook – I’ve been using Nagios for several years, and I can sleep peacefully at night knowing that Nagios is monitoring all my systems and will warn me about any potential issue, before it becomes critical. I strongly recommend that you read Nagios Core 3 ebook to gain detailed understanding on Nagios. Since Nagios is free software, spending few dollars on the book can be the best investment you can make.

Awesome Nagios Articles

Following are few awesome Nagios articles that you might find helpful.

If you enjoyed this article, you might also like..

  1. 50 Linux Sysadmin Tutorials
  2. 50 Most Frequently Used Linux Commands (With Examples)
  3. Top 25 Best Linux Performance Monitoring and Debugging Tools
  4. Mommy, I found it! – 15 Practical Linux Find Command Examples
  5. Linux 101 Hacks 2nd Edition eBook Linux 101 Hacks Book

Bash 101 Hacks Book Sed and Awk 101 Hacks Book Nagios Core 3 Book Vim 101 Hacks Book

{ 40 comments… add one }

  • jackie July 23, 2008, 9:10 am

    I cant find any documentation about how to add further hosts. i have nagios running, monitoring the local host and another pc, using the localhost.cfg and windows.cfg file. How to add more hosts? I tried to create another file and declared it in the nagios.cfg file but doesnt work. any ideas?

  • Neal September 24, 2008, 9:07 am

    I think you missed a command. Step 4 should also include “make install-init” otherwise step 7 will fail. Otherwise perfect post, thank you! Saved me a bit of hair pulling. :)

  • Ian October 23, 2008, 2:47 am

    There are also very useful quick start guides for Fedora, openSUSE and Ubuntu in the Nagios documentation :)

  • Siva December 4, 2008, 6:43 pm

    Hi, I had configured the windows.cfg file for one server. How do I configure for multiple servers?

  • Balakumar December 25, 2008, 10:43 am

    Thank u so much for nice article.It is very understandable.

  • kailas kadam June 29, 2009, 10:55 pm

    i configured nagios . when i was starting the NAGIOS service it is showing the error like unrecgnised service can u help me what is the service for nagios

    waiting for reply

  • Ian June 29, 2009, 11:29 pm

    What does chkconfig –list | grep nagios show? If it shows nothing you need to go through the install guide again and check all the steps.

  • gopi August 25, 2009, 8:35 am

    Thanks I have successfully configured nagios by reading the above. but before trying this i installed through rpm which failed.

  • Arunkeerthan October 7, 2009, 2:18 am

    I configured Nagios no errors and warnings.But when i tried to start the Nagios service its saying “unrecognized service Nagios” .Please help me out in this issue..

  • Arunkeerthan October 7, 2009, 11:13 am

    “make install-init” chould be added to step 4 in RHEL.Otherwise its not working step 7 fails.I dont know about the other distros.
    Thanks for the wonderful post.

  • Ezudin December 18, 2009, 4:21 am

    For installation on Ubuntu server see: https://help.ubuntu.com/9.10/serverguide/C/nagios.html

  • Anonymous March 5, 2010, 7:15 am

    Thanks I have successfully configured nagios but i got some error

    (( (13)Permission denied: exec of ‘/usr/local/nagios/sbin/statusmap.cgi’ failed, referer:
    [Fri Mar 05 15:46:44 2010] [error] [client] Premature end of script headers: statusmap.cgi, referer:

    I got a solution for this error here is the udpate. pelase run this command.

    #chcon -R system_u:object_r:httpd_sys_script_exec_t /usr/local/nagios/sbin

    it will solve the problem.

    Once again thanks.

  • chin March 24, 2010, 9:19 am

    Hi i got 403 forbidden error for nagios like::::

    You don’t have permission to access /nagios/ on this server.
    Apache/2.2.3 (Red Hat) Server at localhost Port 80

    can any one help me please?

  • Chris J May 6, 2010, 6:58 pm

    Thanks for the great post!!!
    Just would like to add you will need to restart httpd before you start nagios

  • anurag sharma May 24, 2010, 7:55 am

    Dear Sir

    I am daily visitor of your your great site and also i am getting your daily newsletters on my mail.i am a big fan of yours.
    Please sir include some other post in nagios like monitoring MySql

    your configuration steps for all topics are very clear.
    I hape you will consider my request.

  • Srini June 17, 2010, 12:33 am


    I am getting the below error. Anyone help me to sort it out.

    You don’t have permission to access /nagios/cgi-bin/ on this server.
    Apache/2.2.3 (Oracle) Server at Port 80

    Appreciate your response asap.

    Thanks in advance…,

  • KP June 23, 2010, 3:42 am

    Hi, it’s not working.

    i did as per your instruction, but still http://localhost/nagios/ not opening in ocal syste.

    please help on this.

  • waqar azeem July 16, 2010, 12:42 pm

    Please note that php is also the prerequisite for nagios to work.
    Verify you have PHP installed and enabled. Verify index.php is listed
    as a DirectoryIndex within httpd.conf or conf.d/php.conf (depending on
    your OS/distribution)

  • Muhammad Salman October 10, 2010, 3:16 pm

    Its great, i dont have words for you, you explain every step v.well.

  • srini November 17, 2010, 2:55 pm

    Dear Sir

    Could you help me out with steps of notification of email and sms and for plotting graps

  • Navin March 4, 2011, 6:19 am

    How do i setup Nagios to monitor websites on the Internet and alert if they are not reachable, Please assist with the steps to setup this as i have tried them but not successfully with it.

  • hima April 7, 2011, 3:56 am


    Thank you very much,
    the installation steps are very clear,
    i did as u wrote,
    service nagios start also working

    but in the browser
    The requested URL /nagios was not found on this server.
    Apache/2.2.3 (Red Hat) Server at localhost Port 80
    please help me,
    thanks in advance,

  • Sridevi April 16, 2011, 2:06 am


    I am getting the error “500 Internal Server Error” after login.
    Can you please help me out.

    Thanks in Advance.

  • Sridevi April 16, 2011, 11:44 pm


    How to add multiple hosts in the nagios server.

  • srini May 11, 2011, 5:12 am

    Can you help me out, how to install nagios on windows.where can i get this software.

  • soportesisstemas June 10, 2011, 2:26 pm

    Hello I`d like to know if nagios has some type of documentation, guide or installation manual in spanish?

  • banibrat June 27, 2011, 9:03 am

    thank u very mach,
    Can you provide me the installation step in RHEL5.5
    YOU can provide me the step-by-step installation guide of nagios

  • Udaya Sankar July 7, 2011, 12:39 am

    To establish the Nagios Service
    first we have to use this command make install-init before chkconfig –add nagios

  • Romal July 28, 2011, 5:47 am

    Thanks it works :)

  • Ishara Fernando August 3, 2011, 12:00 am

    I tried to install nagios in centos 5.6 but i get access denied message when i enter :
    so what i did was i installed php :
    then entered the following command as root user:
    yum install php
    /usr/sbin/setenforce 0
    chcon -R -t httpd_sys_content_t /usr/local/nagios/sbin/
    chcon -R -t httpd_sys_content_t /usr/local/nagios/share/
    /sbin/service httpd restart
    /sbin/service nagios restart

    SUccessful !!!

    then the problem was solved

  • Ishara Fernando August 3, 2011, 12:26 am

    If you guys are using centos 5.6
    then follow the steps below:

    su root:

    yum install httpd php

    yum install gcc-3.4.6-8 compat-gcc* libgcc* compat-libgcc* compat-gcc-32* gcc-c++* glibc* glibc-common*

    yum install gd gd-devel

    /usr/sbin/useradd -m nagios

    passwd nagios

    /usr/sbin/groupadd nagcmd

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

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

    Download nagios and nagios-plugins as follows:

    wget http://nchc.dl.sourceforge.net/project/nagios/nagios-3.x/nagios-3.3.1/nagios-3.3.1.tar.gz

    wget http://space.dl.sourceforge.net/project/nagiosplug/nagiosplug/1.4.15/nagios-plugins-1.4.15.tar.gz
    eg: if you are downloading as a user called, ishara: then enter the command:

    cd /home/ishara/Downloads

    Extract and Install nagios as follows:

    tar xvf nagios-3.3.1.tar.gz

    cd nagios*
    ./configure –with-command-group=nagcmd
    make all

    make install

    make install-init

    make install-config

    make install-commandmode

    make install-webconf

    Now provide a password for the username called nagiosadmin: run the following command:

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

    /sbin/service httpd restart

    Now let’s install the nagios-plugins as follows: Enter

    tar xvf nagios-plugins-1.4.15.tar.gz

    cd nagios-plugins*

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


    make install

    Add nagios service to the startup as follows: Enter:

    chkconfig —add nagios

    chkconfig nagios on

    To disable SELinux to permissive mode: Enter:

    /usr/sbin/setenforce 0

    chcon -R -t httpd_sys_content_t /usr/local/nagios/sbin/

    chcon -R -t httpd_sys_content_t /usr/local/nagios/share/

    All work done in the terminal now in and now in firefox or any web-browser, type


    Enter username : nagiosadmin and the relevant password you entered above:



  • Janardhan September 26, 2011, 11:06 pm

    Its nice tutorial and understandable i succeded in installation and configuration.


  • Sachin Salunke November 23, 2011, 6:34 am

    content is really good & usefull , request you to review and improve documentation regarding of Nagios ….

  • ovais alam December 21, 2011, 8:01 pm

    if you want to add one more windows then add another host entry and services. in /usr/local/nagios/etc/objects/windows.cfg
    for new system

    if you wan to add more linux machines then add host entries and services in

    for new remote linux host.

  • Vijay December 22, 2011, 7:46 am


    Very usefull post, nice one

  • Samuel March 2, 2012, 10:14 am

    After step 5 I get this error, “No rule to make target ‘install-webconf’. Stop”.

    What can be wrong?

    Can any one help me please?

    Thanks in advance.


  • Fazeel October 14, 2012, 3:17 am

    Hi …I get this error while compling plugin……can anyone help .me ….

    ./configure ……. Ok
    make giving the bellow error after compiling

    Making all in plugins
    make[2]: Entering directory `/media/ubisrvr/nagios-plugins-1.4.16/plugins’
    rm -f check_ftp
    ln -s check_tcp check_ftp
    ln: creating symbolic link `check_ftp’ to `check_tcp': Read-only file system
    make[2]: *** [check_ftp] Error 1
    make[2]: Leaving directory `/media/ubisrvr/nagios-plugins-1.4.16/plugins’
    make[1]: *** [all-recursive] Error 1
    make[1]: Leaving directory `/media/ubisrvr/nagios-plugins-1.4.16′
    make: *** [all] Error 2



  • Nagarjun May 23, 2013, 6:15 am

    How to monitor apache tom cat and mysql using nagios.
    it would be great it any step by step procedure is give like the above

    thank you very much

  • Babin lonston July 26, 2013, 12:04 pm

    have a look at this guys for adding more Object need to get monitored. and this for monitoring Public services.

  • Mangala October 25, 2013, 9:13 am

    This article is really very helpful…thanks…
    There are some points which needs to be taken care to make it work.
    1. The server must have php installed (if not, the webpage won’t display properly).
    –> You can install PHP using : “yum install php -y” command in red hat linux
    2. Modify, “httpd.conf” file:
    –> Replace “DirectoryIndex index.html index.html.var” with “DirectoryIndex index.php index.html index.html.var” (web interface looks for index.php, not index.html)
    3. Set index.php file permission to 644
    –> chmod 644 /usr/local/nagios/share/index.php
    4. On Redhat linux use below command for nagios configuration
    –> ./configure –with-nagios-user=nagios –with-nagios-group=nagios –enable-redhat-pthread-workaround

Leave a Comment