Written on April 19, 2009 at 3:31 am by

Nagios Installation & Upgradation

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This post will cover step by step Nagios installation.
In current world everything is available online, every organization is trying to reduce their downtime. Almost all Data Centers are running hundreds of services. It is not possible for human being to monitor all services, this is where Nagios is useful. Administrator can use Nagios to monitor all hosts, services, network devices.

Nagios can be configured to check critical services on different time intervals. And can be used to send Email alerts to system admins.

Here I will cover installation, host & service configuration, service details, & upgradation.

Installation

Download Nagios & Nagios-plugins from http://www.nagios.org/download/
assuming you have stored source packages in /downloads/

(I prefer to use /tmp/ for package installation)

cd /tmp
tar zxvf /downloads/nagios-3.0.6.tar.gz
cd nagios-3.0.6/
./configure
make all
 
#nagios user
useradd nagios
 
#installs the main program, CGIs, and HTML files
make install
 
#installs init script in /etc/rc.d/init.d
make install-init
 
#installs and configures permissions on the directory for holding the external command file
make install-commandmode
 
#installs SAMPLE config files in /usr/local/nagios/etc
make install-config
 
#installs the Apache config file for the Nagios web interface
make install-webconf
#for Nagios web authentication.
htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

This was all required to start Nagios server.

service nagios restart
service httpd restart

Install nagios-plugins

cd /tmp
tar zxvf /downloads/nagios-plugins-1.4.13.tar.gz
cd nagios-plugins-1.4.13/
./configure --libexecdir=/usr/local/nagios/libexec/
make all
make install

This was all required to start Nagios server with limited available plugins.
By default during installation localhost is configured with few services.

You can access Nagios using http://nagios_server_ip/nagios (it will prompt you for authentication, use nagiosadmin as user & password you entered while creating htpasswd.users).
Nagios panel will display only localhost, if you can see status of localhost you can continue adding hosts & services.

Basic Configuration

To add more hosts.
I recommend to create separate host files in /usr/local/nagios/etc/objects/ e.g linux.cfg, windows.cfg, router.cfg etc. If you are planning to put all your services to monitor, you can segregate configuration files as per requirement. It helps to easily search & modify configuration whenever required.

You need to mention created .cfg files in /usr/local/nagios/etc/nagios.conf e.g cfg_file=/usr/local/nagios/etc/objects/linux.cfg This will guide Nagios to load manually created configuration files.

cd /usr/local/nagios/etc/objects
Followings is the contains of sample linux.cfg file.

#Linux
define host{
use generic-host ; Name of host template to use
host_name Linux
alias Linux
address 192.168.1.12
check_command check-host-alive
max_check_attempts 10
check_period 24x7
notification_interval 120
notification_period 24x7
notification_options d,r
contact_groups admins
}
 
#ping
define service{
use generic-service ; Name of service template to use
host_name Linux
service_description PING
is_volatile 0
check_period 24x7
max_check_attempts 4
normal_check_interval 5
retry_check_interval 1
contact_groups admins
notification_options w,u,c,r
notification_interval 960
notification_period 24x7
check_command check_ping!100.0,20%!500.0,60%
}
 
#http
define service{
use generic-service ; Name of service template to use
host_name Linux
service_description HTTP
is_volatile 0
check_period 24x7
max_check_attempts 4
normal_check_interval 5
retry_check_interval 1
contact_groups admins
notification_options w,u,c,r
notification_interval 960
notification_period 24x7
check_command check_http
}
 
#smtp
define service{
use generic-service ; Name of service template to use
host_name Linux
service_description SMTP
is_volatile 0
check_period 24x7
max_check_attempts 4
normal_check_interval 5
retry_check_interval 1
contact_groups admins
notification_options w,u,c,r
notification_interval 960
notification_period 24x7
check_command check_smtp
}
/usr/local/nagios/bin/nagios -v ../nagios.cfg #to check nagios configuration
service nagios reload

Click for service related details. Refer to section Service Definition
I have added Linux host in hostgroup available in localhost.cfg
Recommended way is to create separate groups.cfg.

Now you should be able to see Linux (host) on nagios panel.

To add more timeperiods & contacts you can refer to default config of timeperiods.cfg & contacts.cfg respectively.

Upgradation

tar zxvf /downloads/nagios-3.4.0.tar.gz 
cd nagios
./configure && make all
make install
make install-init
make install-commandmode
 
service nagios restart


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