Configuring Windows hosts with Nagios 3.5 - Part 1

If you need to Monitor a Windows host using Nagios , the default Nagios plugins have a build in command to do so.You will need to configure your windows host with a small client ( NSClient - find more at www.nsclient.org ) that does the actual monitoring of the host.

There are basically two things that you have to do here,

I.) Configure the Nagios Server to Monitor the Host

II.) Install NSClient in the Host Machine

Lets see how the Nagios Configuration can be done to accept the messages sent from the NSClient that is running on the windows host.The following is a brief of what you have to do.

1. Verify check_nt command and windows-server template
2. Uncomment windows.cfg in /usr/local/nagios/etc/nagios.cfg
3. Modify /usr/local/nagios/etc/objects/windows.cfg
4. Define windows services that should be monitored.
5. Enable Password Protection
6. Verify Configuration and Restart Nagios.

1. Verify check_nt command and windows-server template

Verify that the check_nt is enabled under /usr/local/nagios/etc/objects/commands.cfg

# 'check_nt' command definition
define command{
command_name    check_nt
command_line    $USER1$/check_nt -H $HOSTADDRESS$ -p 12489 -v $ARG1$ $ARG2$
}

# Windows host definition template - This is NOT a real host, just a template!
define host{
name                    windows-server  ; The name of this host template
use                     generic-host    ; Inherit default values from the generic-host template
check_period            24x7            ; By default, Windows servers are monitored round the clock
check_interval          5               ; Actively check the server every 5 minutes
retry_interval          1               ; Schedule host check retries at 1 minute intervals
max_check_attempts      10              ; Check each server 10 times (max)
check_command           check-host-alive        ; Default command to check if servers are "alive"
notification_period     24x7            ; Send notification out at any time - day or night
notification_interval   30              ; Resend notifications every 30 minutes
notification_options    d,r             ; Only send notifications for specific host states
contact_groups          admins          ; Notifications get sent to the admins by default
hostgroups              windows-servers ; Host groups that Windows servers should be a member of
register                0               ; DONT REGISTER THIS - ITS JUST A TEMPLATE
}

2. Uncomment windows.cfg in /usr/local/nagios/etc/nagios.cfg

It should look like this 

# Definitions for monitoring a Windows machine
cfg_file=/usr/local/nagios/etc/objects/windows.cfg

3. Modify /usr/local/nagios/etc/objects/windows.cfg

By default a sample host definition for a windows server is given under windows.cfg, modify this to reflect the appropriate windows server that needs to be monitored through nagios.

# Define a host for the Windows machine we'll be monitoring
# Change the host_name, alias, and address to fit your situation

define host{
use             windows-server              ; Inherit default values from a template
host_name   remote-windows-host      ; The name we're giving to this host
alias            Remote Windows Host     ; A longer name associated with the host
address       192.168.1.4                   ; IP address of the remote windows host }                                                                                             

4. Define windows services that should be monitored.

Following are the default windows services that are already enabled in the sample windows.cfg. Make sure to update the host_name on these services to reflect the host_name defined in the above step.If you want to add more services use the guide at http://nagiosplugins.org/man/check_nt

define service{

use                     generic-service
host_name               remote-windows-host
service_description     NSClient++ Version
check_command           check_nt!CLIENTVERSION
}
define service{
use                     generic-service
host_name               remote-windows-host
service_description     Uptime
check_command           check_nt!UPTIME
}
define service{
use                     generic-service
host_name               remote-windows-host
service_description     CPU Load
check_command           check_nt!CPULOAD!-l 5,80,90
}
define service{
use                     generic-service
host_name               remote-windows-host
service_description     Memory Usage
check_command           check_nt!MEMUSE!-w 80 -c 90
}
define service{
use                     generic-service
host_name               remote-windows-host
service_description     C:\ Drive Space
check_command           check_nt!USEDDISKSPACE!-l c -w 80 -c 90
}
define service{
use                     generic-service
host_name               remote-windows-host
service_description     W3SVC
check_command           check_nt!SERVICESTATE!-d SHOWALL -l W3SVC
}
define service{
use                     generic-service
host_name               remote-windows-host
service_description     Explorer
check_command           check_nt!PROCSTATE!-d SHOWALL -l Explorer.exe
}

5. Enable Password Protection

If you specified a password in the NSC.ini file of the NSClient++ configuration file on the Windows machine, you’ll need to modify the check_nt command definition to include the password. Modify the /usr/local/nagios/etc/commands.cfg file and add password as shown below.

define command{
command_name check_nt
command_line $USER1$/check_nt -H $HOSTADDRESS$ -p 12489 -s My2Secure$Password -v $ARG1$ $ARG2$
}

6. Verify Configuration and Restart Nagios.

Verify the nagios configuration files as shown below.

[nagios-server]# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Total Warnings: 0
Total Errors:   0

Things look okay - No serious problems were detected during the pre-flight check

Restart nagios as shown below.

[nagios-server]# /etc/rc.d/init.d/nagios stop
Stopping nagios: .done.

[nagios-server]# /etc/rc.d/init.d/nagios start
Starting nagios: done.

Verify the status of the services running on the remote windows host via Nagios ..................................................................................................................................

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