Nagios Support Forum

Hi Team,

We have enabled monitoring on a windows host, monitoring was working fine but now we are receiving attached error message i.e connection refused.

I have restarted the NSClient++ service on remote host, but still the issue persists.

I have checked below points in the NSC.ini file
1. NSClientListener.dll is uncommented.
2. File consists of nagios ip in allowed host address section as shown below:

;# ALLOWED HOST ADDRESSES
; This is a comma-delimited list of IP address of hosts that are allowed to talk to the all daemons.
; If leave this blank anyone can access the deamon remotly (NSClient still requires a valid password).
; The syntax is host or ip/mask so 192.168.0.0/24 will allow anyone on that subnet access
;allowed_hosts=127.0.0.1/32
;
;# USE THIS FILE
; Use the INI file as opposed to the registry if this is 0 and the use_reg in the registry is set to 1
; the registry will be used instead.
use_file=1
allowed_hosts=10.147.108.45
password=nag1osadm1n
;

3. NSClient port 12489 is mentioned in the NSC.ini file

[NSClient]
;# ALLOWED HOST ADDRESSES
; This is a comma-delimited list of IP address of hosts that are allowed to talk to NSClient deamon.
; If you leave this blank the global version will be used instead.
;allowed_hosts=
;
;# NSCLIENT PORT NUMBER
; This is the port the NSClientListener.dll will listen to.
;port=12489
;

4. I have executed a command "netstat -an" on remote host, refer the attachment for the output.

Kindly let us know your comments on this.

Can you check your Windows Firewall rules? Windows update may have altered them.

From the Nagios machine, what is the result of a nmap 10.148.186.140?

Hi Team,

Windows firewalls is already turned off in server level.

What firewall rules to be checked; if the details are provided, we can request network team to check.

Please find the attached snapshot consisting the nmap command output.

What is the operating system version you are trying to run the NSClient++ on?

Take a look at this document for configuring the NSClient++ for your system.
https://assets.nagios.com/downloads/nag ... ios-XI.pdf

Please find the snapshot for the configuration of remote host.

And I went through the link, but I am not able to suspect anything in my NSC.ini configuration file, it seems to be as expected.

Can you post the entire NSC.ini file in code wraps?

Hi Team,

Please find the attached NSC.ini file.

Kindly let us know What firewall rules to be checked; if the details are provided, we can request network team to check.

Looking at your previous post, it looks like port 12489 is not open. Please have your network team check this, as NSClient uses that port.

As per the network team, port 12489 is already open.

Kindly can you let me know how can I crosscheck from Nagios end whether the port 12489 is open or not.

Port 12489 should be used "by default" regardless of the fact it is commented out in the NSC.ini. Just to be on a safe side, change this: to this: save, exit, and restart NSClient++ service. Make sure the service is indeed running.
[root@localhost ~]# nmap 192.168.5.18 -p 12489

Check if the port is open by running the following command on the Nagios XI server:
Example: If this doesn't work, you may try to reinstall NSClient++ agent on the Windows server, maybe try a newer version.