"Connection Refused" on local network

[whitetree]

I've got my Nagios server configured with two NICs. One is a 192.168.1.xx and the other is my public IP xx.xx.xx.xx My remote servers that are not in my local network have no problem connecting and talking to Nagios using the public IP address. However the Windows machines in my local network get a "Connection Refused" status wether or not I use the public IP or the internal IP address. I have added a firewall exception for port 12489 AND THE NSClient++/exe is running.

How do I troubleshoot this?

[lmiltchev]

Did you add both IP addresses to the nsc.ini file (on this line)?

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allowed_hosts=

Note: After any change in the nsc.ini file, you must restart the nsclient++ service, so that the changes can take effect.

I would suggest testing it from the command line first. Run something simple from the command line and check the output, for example:

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# cd /usr/local/nagios/libexec
# ./check_nt -H <your_target_machine_IP_address> -s <your_password> -p 12489 -v MEMUSE -w 80 -c 90

[whitetree]

Did you add both IP addresses to the nsc.ini file (on this line)?

Code: Select all

allowed_hosts=

Note: After any change in the nsc.ini file, you must restart the nsclient++ service, so that the changes can take effect.

I would suggest testing it from the command line first. Run something simple from the command line and check the output, for example:

Code: Select all

# cd /usr/local/nagios/libexec
# ./check_nt -H <your_target_machine_IP_address> -s <your_password> -p 12489 -v MEMUSE -w 80 -c 90

Thanks for the quick reply. I did add both to the NSC.ini file and the command you suggested I run returned with [root@localhost libexec]# ./check_nt -H 192.168.1.9 -s <mypass> -p 12489 -v MEMUSE -w 80 -c 90
Connection refused
could not fetch information from server

[lmiltchev]

Can you telnet to port 12489 from your Nagios server?

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# telnet <target_machine_IP_address> 12489

Also, on your windows machine you can open a Command Prompt (Run->cmd.exe->Enter) and run:

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# netstat -an |find /i "listening" > c:openports.txt

You can then open the "openports.txt" file in a text editor and see if port 12489 is listening.

[whitetree]

Can you telnet to port 12489 from your Nagios server?

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# telnet <target_machine_IP_address> 12489

I cannot "connection refused"

Also, on your windows machine you can open a Command Prompt (Run->cmd.exe->Enter) and run:

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# netstat -an |find /i "listening" > c:openports.txt

You can then open the "openports.txt" file in a text editor and see if port 12489 is listening.

netstat does not show that the port is listening! even after I ran netsh to open the port with

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netsh firewall>set portopening tcp 12489
IMPORTANT: Command executed successfully.

I disabled the firewall completely and still cannot connect via telnet....

[scottwilkerson]

in your nsc.ini, in the [modules] section, make sure you have

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NSClientListener.dll

not

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;NSClientListener.dll

The NSClientListener.dll is what will listen on port 12489. If you make this change, restart the NSClient++ service and try again.

[whitetree]

in your nsc.ini, in the [modules] section, make sure you have

Code: Select all

NSClientListener.dll

not

Code: Select all

;NSClientListener.dll

The NSClientListener.dll is what will listen on port 12489. If you make this change, restart the NSClient++ service and try again.

Done. Still not listening...

One thing that is striking me as different is that the machine in my local network is requesting administrative permission every time I start and stop the service, whereas my remote servers did not...

EDIT: I uninstalled NSClient++ and reinstalled it as the Domain Admin account instead of my sysadmin user account. 12489 port is now open, i can telnet to it. The error message in Nagios has now changed to "could not fetch information from server"

[lmiltchev]

When you run your check from the command line, do you use the same password as the one listed in the nsc.ini file? You can play around with this - changing and/or temporarily removing the password altogether.

[whitetree]

When you run your check from the command line, do you use the same password as the one listed in the nsc.ini file? You can play around with this - changing and/or temporarily removing the password altogether.

There is no password set for this machine as it is internal.

[scottwilkerson]

There is no password set for this machine as it is internal.

Ludmil was referring to the passphrase in the nsc.ini and on the server. They need to share and use the same password