NOTES_Nagios_client.txt

#### Problem Statement installing Nagios NRPE on Centos 7 
#### our client will be under 192.168.33.85 (democlient.sridemo.com)
### The steps are similar to that of adding Server (NOTES_Nagios_server_install.txt), 
### Except that LAMP and Nagios core will not be installed. You only need to install
### Plugins and NRPE (dependency xinetd to be installed)
### After doing the same, 
#Check permissions.. 
chown nagios.nagios /usr/local/nagios
chown -R nagios.nagios /usr/local/nagios/libexec

#Now open /etc/xinetd.d/nrpe file and add the localhost and IP address of the Nagios Monitoring Server.
#only_from = 127.0.0.1 localhost <nagios_ip_address>
#Next, open /etc/services file add the following entry for the NRPE daemon at the bottom of the file.
nrpe            5666/tcp                 NRPE
#Restart Xinetd 
service xinetd restart
#Verify NRPE Daemon Locally
netstat -at | grep nrpe
#tcp        0      0 *:nrpe                      *:*                         LISTEN
#If you get output similar to above, means it working correctly. If not, make sure to check the following things.
#Verify using  /usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 #To match only_fro


#Optional: 
Make sure that the Firewall on the local machine will allow the NRPE daemon to be accessed from remote servers. To do this, run the following iptables command.
 iptables -A INPUT -p tcp -m tcp --dport 5666 -j ACCEPT
 service iptables save
# Notes on Firewall on Centos: You cannot have both firewalld and iptables run at same time. So you need to stop firewalld and enable iptables
systemctl stop firewalld
systemctl mask firewalld
yum install iptables-services
systemctl enable iptables
systemctl [stop|start|restart] iptables
service iptables save
/usr/libexec/iptables/iptables.init save
# files of importance: /etc/sysconfig/ip6tables-config, /etc/sysconfig/ip4tables-config 

##### Next steps.. 

Verify using the local commands: 

/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c check_users
/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c check_load
/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c check_hda1
/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c check_total_procs
/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c check_zombie_procs


#### On servers
# Set up 2 files : hosts.cfg, services.cfg 
touch /usr/local/nagios/etc/objects/hosts.cfg
touch /usr/local/nagios/etc/objects/services.cfg
#edit the nagios.cfg file and ensure above 2 files are present
vi /usr/local/nagios/etc/nagios.cfg
cfg_file=/usr/local/nagios/etc/objects/hosts.cfg
cfg_file=/usr/local/nagios/etc/objects/services.cfg

#add below to hosts.cfg file
## Default Linux Host Template ##
define host{
name                            linux-box               ; Name of this template
use                             generic-host            ; Inherit default values
check_period                    24x7        
check_interval                  5       
retry_interval                  1       
max_check_attempts              10      
check_command                   check-host-alive
notification_period             24x7    
notification_interval           30      
notification_options            d,r     
contact_groups                  admins  
register                        0                       ; DONT REGISTER THIS - ITS A TEMPLATE
}

## Default
define host{
use                             linux-box               ; Inherit default values from a template
host_name                       democlient		        ; The name we're giving to this server
alias                           Centos7              ; A longer name for the server
address                         192.168.33.85            ; IP address of Remote Linux host
}

### services.cfg
define service{
        use                     generic-service
        host_name               democlient
        service_description     CPU Load
        check_command           check_nrpe!check_load
        }

define service{
        use                     generic-service
        host_name               democlient
        service_description     Total Processes
        check_command           check_nrpe!check_total_procs
        }

define service{
        use                     generic-service
        host_name               democlient
        service_description     Current Users
        check_command           check_nrpe!check_users
        }

define service{
        use                     generic-service
        host_name               democlient
        service_description     SSH Monitoring
        check_command           check_nrpe!check_ssh
        }

define service{
        use                     generic-service
        host_name               democlient
        service_description     FTP Monitoring
        check_command           check_nrpe!check_ftp
        }

#vi /usr/local/nagios/etc/objects/commands.cfg
#Validate config
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
service nagios restart