Learn how to install Nagios on CentOS 7 with this step-by-step guide. Set up this powerful monitoring tool to keep your systems and networks running smoothly. #centlinux #linux #nagios
Table of Contents
What is Nagios?
Nagios Core is a free and open source software application that provides monitoring and alerting services for servers, switches, applications and services. It monitors targets (i.e. hosts and services) and alerts users when something go wrong and alerts them a second time when the problem has been resolved. Nagios Core is primary application and monitoring and alerting engine, around that hundred of Nagios Projects are built.
In this article, we will install Nagios on CentOS 7. But before moving forward, it is required to have basic concepts of Nagios Core 4. Therefore, it is highly recommended that you should have Learning Nagios – Third Edition (PAID LINK). It will be really helpful for you during your Nagios journey.
System Specification
We have configured a CentOS 7 virtual machine with following specifications:
- Operating System – CentOS 7.6
- Nagios Core – 4.4.2
- Hostname – nagios-01.example.com
- IP Address: – 192.168.116.130/24
Install Nagios on CentOS 7
Connect to nagios-01.example.com using ssh.
Install prerequisite packages using yum command.
# yum install -y gcc glibc glibc-common wget unzip httpd php gd gd-devel perl postfix
Currently, Nagios Core does not compliance with SELinux, therefore we have to disable SELinux.
# sed -i 's/SELINUX=.*/SELINUX=disabled/g' /etc/selinux/config # setenforce 0
Create a directory for downloading Nagios Core source.
# mkdir setup
Download Nagios Core from https://www.nagios.org/downloads/nagios-core/.
# cd ~/setup # wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.2.tar.gz --2018-12-23 10:35:22-- https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.2.tar.gz Resolving assets.nagios.com (assets.nagios.com)... 72.14.181.71, 2600:3c00::f03c:91ff:fedf:b821 Connecting to assets.nagios.com (assets.nagios.com)|72.14.181.71|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 11301454 (11M) [application/x-gzip] Saving to: ânagios-4.4.2.tar.gzâ 100%[======================================>] 11,301,454 1.16MB/s in 10s 2018-12-23 10:35:34 (1.03 MB/s) - ânagios-4.4.2.tar.gzâ saved [11301454/11301454]
Extract downloaded source of Nagios Core.
# tar xf nagios-4.4.2.tar.gz
Compile and install Nagios Core from extracted source.
# cd ~/setup/nagios-4.4.2
# ./configure
config.status: creating t/Makefile
config.status: creating t-tap/Makefile
config.status: creating include/config.h
config.status: creating lib/snprintf.h
config.status: creating lib/iobroker.h
Creating sample config files in sample-config/ ...
*** Configuration summary for nagios 4.4.2 2018-08-16 ***:
General Options:
-------------------------
Nagios executable: nagios
Nagios user/group: nagios,nagios
Command user/group: nagios,nagios
Event Broker: yes
Install ${prefix}: /usr/local/nagios
Install ${includedir}: /usr/local/nagios/include/nagios
Lock file: /run/nagios.lock
Check result directory: /usr/local/nagios/var/spool/checkresults
Init directory: /lib/systemd/system
Apache conf.d directory: /etc/httpd/conf.d
Mail program: /usr/sbin/sendmail
Host OS: linux-gnu
IOBroker Method: epoll
Web Interface Options:
------------------------
HTML URL: http://localhost/nagios/
CGI URL: http://localhost/nagios/cgi-bin/
Traceroute (used by WAP):
Review the options above for accuracy. If they look okay,
type 'make all' to compile the main program and CGIs.
# make all
...
make[1]: Entering directory `/root/setup/nagios-4.4.2/worker'
cd ./ping && make all
make[2]: Entering directory `/root/setup/nagios-4.4.2/worker/ping'
gcc -I.. -I ../../include -I ../.. -g -O2 -DHAVE_CONFIG_H -o worker-ping worker-ping.c -L ../../lib -l nagios
make[2]: Leaving directory `/root/setup/nagios-4.4.2/worker/ping'
make[1]: Leaving directory `/root/setup/nagios-4.4.2/worker'
*** Compile finished ***
If the main program and CGIs compiled without any errors, you
can continue with testing or installing Nagios as follows (type
'make' without any arguments for a list of all possible options):
make test
- This runs the test suite
make install
- This installs the main program, CGIs, and HTML files
make install-init
- This installs the init script in /lib/systemd/system
make install-daemoninit
- This will initialize the init script
in /lib/systemd/system
make install-groups-users
- This adds the users and groups if they do not exist
make install-commandmode
- This installs and configures permissions on the
directory for holding the external command file
make install-config
- This installs *SAMPLE* config files in /usr/local/nagios/etc
You'll have to modify these sample files before you can
use Nagios. Read the HTML documentation for more info
on doing this. Pay particular attention to the docs on
object configuration files, as they determine what/how
things get monitored!
make install-webconf
- This installs the Apache config file for the Nagios
web interface
make install-exfoliation
- This installs the Exfoliation theme for the Nagios
web interface
make install-classicui
- This installs the classic theme for the Nagios
web interface
*** Support Notes *******************************************
If you have questions about configuring or running Nagios,
please make sure that you:
- Look at the sample config files
- Read the documentation on the Nagios Library at:
Nagios Library
Nagios Support Home
Create OS user and groups for Nagios Core.
# make install-groups-users groupadd -r nagios useradd -g nagios nagios # usermod -a -G nagios apache
Install Nagios on CentOS 7 now.
# make install
/usr/bin/install -c -m 775 -o nagios -g nagios -d /usr/local/nagios/libexec
/usr/bin/install -c -m 775 -o nagios -g nagios -d /usr/local/nagios/var
/usr/bin/install -c -m 775 -o nagios -g nagios -d /usr/local/nagios/var/archives
/usr/bin/install -c -m 775 -o nagios -g nagios -d /usr/local/nagios/var/spool/checkresults
chmod g+s /usr/local/nagios/var/spool/checkresults
*** Main program, CGIs and HTML files installed ***
You can continue with installing Nagios as follows (type 'make'
without any arguments for a list of all possible options):
make install-init
- This installs the init script in /lib/systemd/system
make install-commandmode
- This installs and configures permissions on the
directory for holding the external command file
make install-config
- This installs sample config files in /usr/local/nagios/etc
make[1]: Leaving directory `/root/setup/nagios-4.4.2'
Install Nagios Core service.
# make install-daemoninit /usr/bin/install -c -m 755 -d -o root -g root /lib/systemd/system /usr/bin/install -c -m 755 -o root -g root startup/default-service /lib/systemd/system/nagios.service Created symlink from /etc/systemd/system/multi-user.target.wants/nagios.service to /usr/lib/systemd/system/nagios.service. *** Init script installed ***
Enable httpd service.
# systemctl enable httpd.service Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.
Install and configure external command file.
# make install-commandmode /usr/bin/install -c -m 775 -o nagios -g nagios -d /usr/local/nagios/var/rw chmod g+s /usr/local/nagios/var/rw *** External command directory configured ***
Install Sample configuration files for Nagios Core.
# make install-config /usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/windows.cfg /usr/local/nagios/etc/objects/windows.cfg /usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/printer.cfg /usr/local/nagios/etc/objects/printer.cfg /usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/switch.cfg /usr/local/nagios/etc/objects/switch.cfg *** Config files installed *** Remember, these are *SAMPLE* config files. You'll need to read the documentation for more information on how to actually define services, hosts, etc. to fit your particular needs.
Add Nagios Core configurations to Apache Web Server.
# make install-webconf
/usr/bin/install -c -m 644 sample-config/httpd.conf /etc/httpd/conf.d/nagios.conf
if [ 0 -eq 1 ]; then
ln -s /etc/httpd/conf.d/nagios.conf /etc/apache2/sites-enabled/nagios.conf;
fi
*** Nagios/Apache conf file installed ***
Configure Linux Firewall
Configure Linux Firewall to allow http service.
# firewall-cmd --permanent --add-service=http success # firewall-cmd --reload success
Setup Basic HTTP Authentication
Nagios does not have integrated user authentication, therefore, we have to use Basic HTTP authentication for this purpose.
Create an admin user for Nagios Core Web UI.
# htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin New password: Re-type new password: Adding password for user nagiosadmin
Start httpd & nagios services.
# systemctl start httpd.service # systemctl start nagios.service Warning: nagios.service changed on disk. Run 'systemctl daemon-reload' to reload units. # systemctl daemon-reload
Access Nagios Web Interface
Browse URL http://192.168.116.130/nagios to connect with Nagios Core Web UI.
Login using nagiosadmin user.
Go to services page.
You can see that all the services are unavailable. It is because we don’t have installed Nagios Plugins on our CentOS 7 server.
Install Nagios Plugins on CentOS 7
Install prerequisite packages for Nagios Plugins using yum command.
# yum install -y perl-Net-SNMP gcc glibc glibc-common make gettext automake autoconf wget openssl-devel net-snmp net-snmp-utils epel-release
Download Nagios Plugins from https://www.nagios.org/downloads/nagios-plugins/.
# cd ~/setup # wget https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz --2018-12-23 10:37:19-- https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz Resolving nagios-plugins.org (nagios-plugins.org)... 72.14.186.43 Connecting to nagios-plugins.org (nagios-plugins.org)|72.14.186.43|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 2728818 (2.6M) [application/x-gzip] Saving to: ânagios-plugins-2.2.1.tar.gzâ 100%[======================================>] 2,728,818 813KB/s in 3.3s 2018-12-23 10:37:24 (813 KB/s) - ânagios-plugins-2.2.1.tar.gzâ saved [2728818/2728818]
Extract downloaded source of Nagios Plugins.
# cd ~/setup # tar xf nagios-plugins-2.2.1.tar.gz
Compile Nagios Plugins source.
# cd ~/setup/nagios-plugins-2.2.1 # ./configure ... config.status: executing libtool commands config.status: executing po-directories commands config.status: creating po/POTFILES config.status: creating po/Makefile
Install Nagios Plugins by executing following command.
# make ... make[2]: Nothing to be done for `all'. make[2]: Leaving directory `/root/setup/nagios-plugins-2.2.1/po' make[2]: Entering directory `/root/setup/nagios-plugins-2.2.1' make[2]: Leaving directory `/root/setup/nagios-plugins-2.2.1' make[1]: Leaving directory `/root/setup/nagios-plugins-2.2.1' # make install ... make[2]: Entering directory `/root/setup/nagios-plugins-2.2.1' make[2]: Nothing to be done for `install-exec-am'. make[2]: Nothing to be done for `install-data-am'. make[2]: Leaving directory `/root/setup/nagios-plugins-2.2.1' make[1]: Leaving directory `/root/setup/nagios-plugins-2.2.1'
Go to Nagios Web UI and open services page.
You can see that, now all the services are in OK state now. (Note: Keep patience, Nagios Core takes a while to collect data for each service)
Recommended Training for You:
Final Thoughts
Installing Nagios on CentOS 7 ensures you have a robust monitoring solution for your systems and networks. By following this guide, you should now have Nagios up and running efficiently.
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