About Nagios Core
Perhaps you’ve heard it before, but let’s hear it again – “Nagios Is The Industry Standard In IT Infrastructure Monitoring”. It is used to for monitoring and alerting of your servers, switches applications and services. It is an open source system, network and application monitoring software. Open source also means it is fully customizable. You can change the way it looks and works too. You can write your own scripts and add custom checks.
Since we are installing the latest stable release of Nagios Core 3.5.0 (2013-03-15) on CentOS we will need to configure and compile it. It is possible to install Nagios Core on CentOS via RPM from EPEL repository, but the latest release available is 3.4.4 (2013-01-12).
UPDATE: Jump to the latest post on Nagios – Running Nagios Core 4.1.1. on CentOS 7
Let’s start with our How To install Nagios Core guide!
1. Install operating system
Install Linux operating system on a server. (I chose the latest CentOS 6.4 64bit – minimal install. Here is a How to install CentOS minimal.)
2. Install EPEL repository
rpm -ivh http://ftp-stud.hs-esslingen.de/pub/epel/6/i386/epel-release-6-8.noarch.rpm
3. Update operating system
Do a full update of newly installed CentOS 6.4 64bit.
4. Download Nagios Core
Download the latest tarball from http://www.nagios.org and transfer it to your CentOS server.
5. Install dependencies
yum install -y wget httpd php gcc glibc glibc-common gd gd-devel make net-snmp
6. Create Nagios user and group
useradd nagios groupadd nagcmd usermod -a -G nagcmd nagios
7. Extract tarball
tar -xvzf nagios-VERSION.tar.gz
8. Configure
cd nagios ./configure --with-command-group=nagcmd
9. Make
make all make install make install-init make install-config make install-commandmode make install-webconf
After running all of the above something like this should be printed out:
*** Configuration summary for nagios 3.5.0 03-15-2013 ***:
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/10. Check Nagios Core configuration
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Probably everything is OK so no errors are found.
11. Start services
/etc/init.d/nagios start /etc/init.d/httpd start
12. Install Nagios plugins
yum install nagios-plugins-all -y
13. Link eventhandlers
Since we configured and compiled the latest Nagios Core version on our CentOS the plugins installed via yum are installed on a different location. We can fix this by deleting libexec folder and link it to nagios plugins install location – copy eventhandlers folder
rm -rf /usr/local/nagios/libexec cd /usr/local/nagios/ ln -s /usr/lib64/nagios/plugins/ libexec chown nagios:nagios -R libexec
14. Create Nagios WEB user
htpasswd -s -c /usr/local/nagios/etc/htpasswd.users nagiosadmin service httpd restart
Nagios Core 3.5.0 on CentOS is finished. Your nagios instance should now be accessible if you point your browser to your server IP or hostname – something like http://hostname.domainname.com/nagios or http://IPADDR/nagios
The next step is to add your hosts and services to your Nagios configuration and start monitoring them! Read my Nagios configuration – How to configure Nagios guide.