Nagios Install & Configuration
Nagios is one of the Open Source monitoring tool to monitor Networks, Servers and Services. Here I’m sharing the steps that I used to install and configure Nagios for a production environment.
Pre-Requesits:
OS : CentOS-6-x86_64
Step 1: Update all system software to the latest version
yum -y update
Step 2:Install Required dependencies
yum install -y httpd php gcc glibc glibc-common gd gd-devel make net-snmp
Step 3: Create a new user and group account for nagios and set a password.
useradd nagios groupadd nagcmd
Step 4: Add both the nagios user and the apache user to the group nagcmd .
usermod -G nagcmd nagios usermod -G nagcmd apache
Step 5: Download Nagios Core and Nagios Plugin
mkdir /root/nagios cd /root/nagios wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-4.2.0.tar.gz wget https://www.nagios-plugins.org/download/nagios-plugins-2.1.2.tar.gz
Step 6: Extract compressed files installation files and start installation process
tar -xvf nagios-4.2.0.tar.gz tar -xvf nagios-plugins-2.1.2.tar.gz cd nagios-4.2.0 ./configure --with-command-group=nagcmd make all make install make install-init make install-commandmode make install-config make install-webconf
Step 7: Set Password for Nagios Web admin user
htpasswd -s -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
Step 8: Restart Web service
service httpd start
Step 9: Install Nagios Plugins
cd /root/nagios cd nagios-plugins-2.1.2/ ./configure --with-nagios-user=nagios --with-nagios-group=nagios make make install
Step 10: Configure Nagios and Add Hots
Default nagios conf file location is : /usr/local/nagios/etc/nagios.cfg , there we are defining all other config file locations. By default main configuration files are:
I) /usr/local/nagios/etc/objects/contacts.cfg = Contact and contact group can be define here
Sample:
define contact{
contact_name nagiosadmin ;
use generic-contact ;
alias Nagios Admin ;
email nagios@localhost ;
}
define contact{
contact_name integral ;
use generic-contact ;
alias Integral Servers ;
email email@gmail.com ;
}
###############################################################################
# CONTACT GROUPS
###############################################################################
define contactgroup{
contactgroup_name admins
alias Nagios Administrators
members nagiosadmin
}
define contactgroup{
contactgroup_name integraladmins
alias Integralhost Nagios Administrators
members integral
}
II) /usr/local/nagios/etc/objects/groups.cfg = To defind host group here,
Sample:
define hostgroup{
hostgroup_name linux-shared ; The name of the hostgroup
alias Linux Shared Servers ; Long name of the group
members linux24.integralhost.net ; Comma separated list of hosts that belong to this group
}
III) /usr/local/nagios/etc/objects/commands.cfg – It contains object definitions that Nagios should use for monitoring
IV) /usr/local/nagios/etc/objects/servername.cfg = Host server details are defined here. We can place this file anywhere, but we should define it on nagios.cfg like below:
cfg_file=/usr/local/nagios/etc/objects/servername.cfg
Note: Rename “servername.cfg” with exact server host name. It will help admin to easily identify.
Sample:
###############################################################################
# HOST DEFINITION
###############################################################################
define host {
use generic-host
host_name server.domain.com
_localaddress server.domain.com
alias ibis
hostgroups linux-shared
address 104.255.67.38
check_period 24x7
check_interval 2
retry_interval 2
max_check_attempts 2
#check_command check_host
notification_period 24x7
notification_interval 2
notification_options d,u,r
notifications_enabled 1
contact_groups integraladmins
}
###############################################################################
# SERVICE DEFINITIONS
###############################################################################
# Define a service to "ping" the local machine
define service{
use local-service ; Name of service template to use
host_name server.domain.com
service_description PING
check_command check_ping!100.0,20%!500.0,60%
}
# Define a service to check the disk space of the root partition
# on the local machine. Warning if < 20% free, critical if
# < 10% free space on partition.
define service{
use local-service ; Name of service template to use
host_name server.domain.com
service_description Root Partition
check_command check_local_disk!20%!10%!/
}
# Define a service to check the number of currently logged in
# users on the local machine. Warning if > 20 users, critical
# if > 50 users.
define service{
use local-service ; Name of service template to use
host_name server.domain.com
service_description Current Users
check_command check_local_users!20!50
}
# Define a service to check the number of currently running procs
# on the local machine. Warning if > 250 processes, critical if
# > 400 processes.
define service{
use local-service ; Name of service template to use
host_name server.domain.com
service_description Total Processes
check_command check_local_procs!250!400!RSZDT
}
# Define a service to check the load on the local machine.
define service{
use local-service ; Name of service template to use
host_name server.domain.com
service_description Current Load
check_command check_local_load!5.0,4.0,3.0!10.0,6.0,4.0
}
# Define a service to check the swap usage the local machine.
# Critical if less than 10% of swap is free, warning if less than 20% is free
define service{
use local-service ; Name of service template to use
host_name server.domain.com
service_description Swap Usage
check_command check_local_swap!20!10
}
# Define a service to check SSH on the local machine.
# Disable notifications for this service by default, as not all users may have SSH enabled.
define service{
use local-service ; Name of service template to use
host_name server.domain.com
service_description SSH
check_command check_ssh
notifications_enabled 0
}
# Define a service to check HTTP on the local machine.
# Disable notifications for this service by default, as not all users may have HTTP enabled.
define service{
use local-service ; Name of service template to use
host_name server.domain.com
service_description HTTP
check_command check_http
notifications_enabled 0
}
Step 11: Verify Nagios config files:
Execute this before every nagios restart, since if there is any mistake in configuration files, below command will list them.
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Step 12: Restart Nagios:
/etc/init.d/nagios restart
Now you can access Nagios using the URL http://IPaddress/nagios .
Thank you!