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

by Ramesh Natarajan on May 29, 2008

Nagios

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
      gcc-3.4.6-8
      compat-gcc-32-3.2.3-47.3
      libgcc-3.4.6-8
      compat-libgcc-296-2.96-132.7.2
      compat-gcc-32-c++-3.2.3-47.3
      gcc-c++-3.4.6-8
  • Verify whether GD is installed
      [root@localhost]# rpm -qa gd
      gd-2.0.28-5.4E

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.


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{ 40 comments… read them below or add one }

1 jackie July 23, 2008 at 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?

2 Neal September 24, 2008 at 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. :)

3 Ian October 23, 2008 at 2:47 am

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

4 Siva December 4, 2008 at 6:43 pm

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

5 Balakumar December 25, 2008 at 10:43 am

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

6 kailas kadam June 29, 2009 at 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

7 Ian June 29, 2009 at 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.

8 gopi August 25, 2009 at 8:35 am

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

9 Arunkeerthan October 7, 2009 at 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..

10 Arunkeerthan October 7, 2009 at 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.

11 Ezudin December 18, 2009 at 4:21 am

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

12 Anonymous March 5, 2010 at 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: http://10.35.29.100/nagios/side.php
[Fri Mar 05 15:46:44 2010] [error] [client 10.35.45.116] Premature end of script headers: statusmap.cgi, referer: http://10.35.29.100/nagios/side.php))

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.

13 chin March 24, 2010 at 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?

14 Chris J May 6, 2010 at 6:58 pm

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

15 anurag sharma May 24, 2010 at 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
for
•connection-time
•keycache-hitrate
•qcache-hitrate
•tablecache-hitrate
•threadcache-hitrate
•tmp-disk-tables

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

16 Srini June 17, 2010 at 12:33 am

Hi,

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

You don’t have permission to access /nagios/cgi-bin/ on this server.
Apache/2.2.3 (Oracle) Server at 10.12.68.57 Port 80
*************************************************************************************

Appreciate your response asap.

Thanks in advance…,

17 KP June 23, 2010 at 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.

18 waqar azeem July 16, 2010 at 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)

19 Muhammad Salman October 10, 2010 at 3:16 pm

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

20 srini November 17, 2010 at 2:55 pm

Dear Sir

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

21 Navin March 4, 2011 at 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.

22 hima April 7, 2011 at 3:56 am

sir,

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

but in the browser
http://localhost/nagios/
showing
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,

23 Sridevi April 16, 2011 at 2:06 am

Hi,

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

Thanks in Advance.

24 Sridevi April 16, 2011 at 11:44 pm

Hi,

How to add multiple hosts in the nagios server.

25 srini May 11, 2011 at 5:12 am

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

26 soportesisstemas June 10, 2011 at 2:26 pm

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

27 banibrat June 27, 2011 at 9:03 am

Sir,
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

28 Udaya Sankar July 7, 2011 at 12:39 am

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

29 Romal July 28, 2011 at 5:47 am

Thanks it works :)

30 Ishara Fernando August 3, 2011 at 12:00 am

Ramesh,
I tried to install nagios in centos 5.6 but i get access denied message when i enter :
http://localhost/nagios/
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 !!!
THANKS

then the problem was solved

31 Ishara Fernando August 3, 2011 at 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

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

http://localhost/nagios/

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

DONE!!! ENJOY NAGIOS

ISHARA FERNANDO ( FROM: SRI LANKA )
<<<<>>>>

32 Janardhan September 26, 2011 at 11:06 pm

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

Thanks

33 Sachin Salunke November 23, 2011 at 6:34 am

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

34 ovais alam December 21, 2011 at 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
/usr/local/nagios/etc/objects/localhost.cfg

for new remote linux host.

35 Vijay December 22, 2011 at 7:46 am

Hi,

Very usefull post, nice one

36 Samuel March 2, 2012 at 10:14 am

Hi,
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.
Regards.

Samuel.

37 Fazeel October 14, 2012 at 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

***********************************************************

Thanks

38 Nagarjun May 23, 2013 at 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

39 Babin lonston July 26, 2013 at 12:04 pm

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

40 Mangala October 25, 2013 at 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

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