Nagios is an open source monitoring tool that provides a monitoring environment to keep a tab on your network and machines, be it is in data-centre or in a small lab. Nagios alerts the system administrator when something went wrong and helps us to reduce downtime and business losses. We are going to setup nagios 3.5.1 in a freshly installed CentOS 6.7 and the installation process will work on Scientific Linux 6.X as well as RHEL 6.X
Install necessary epel repository for CentOS 6
Nagios will not be found in CentOS official repository. To install Nagios, we need to install EPEL repository and update.
sudo rpm -iUvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
Install dependencies & Nagios Packages
sudo yum install httpd php php-cli gcc glibc glibc-common gd gd-devel net-snmp
Once we completed our dependencies installation we may proceed to install nagios packages as followed
sudo yum install nagios* -y
Turn on http service
sudo service httpd start sudo chkconfig httpd on
By default , http port is blocked hence you will need to unblock port 80 for web service.
sudo iptables -I INPUT 5 -p tcp -m tcp --dport 80 -j ACCEPT sudo service iptables save sudo service iptables restart
Configuring Nagios Contact
Edit the admin mail address in the nagios contact file to receive alerts from nagios server.
By default, nagios admin area will be accessible from any source hence if you like to restrict to specific source you may update the following. Example here shown that we only permit access to nagios administration console from Host with 100.100.100.100/32
Set password for user [nagiosadmin] with the following command
htpasswd /etc/nagios/passwd nagiosadmin
Restart httpd service now to apply all new changes
sudo service httpd restart
Start nagios service and let them start automatically on every boot
sudo service nagios start chkconfig nagios on
Now we are ready to test our nagios installation by accessing the following url with the userid and password we set earlier [ nagiosadmin and the password ]
Congratulation! Our Nagios server is ready for action
We will be updating another tutorial based on nagios Core 4.1.1 and including changing the theme in our next follow up.