Nagios Support Forum

Posted: **Fri Feb 11, 2022 11:33 am**

Hi,

We want to monitor Linux Server using NCPA which is a DMZ server.
As when we trying to telnet to port 5693 we are getting Connection refused
The change has been implemented for port opening on DMZ server but still we are getting Connection refused.
what might be issue?

Also please let us know whether we can monitor Mail queue on Linux

Thanks

Posted: **Fri Feb 11, 2022 5:51 pm**

Hi lanxessinfy,

Connection refused usually means a reset packet was received which often implies that nothing is listening on that port. On the remote system you can get list of the sockets in a listen state using either of the following commands (depending upon what's installed).

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ss -ln

or

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netstat -n --listening

And you can verify that NCPA listener is resident with a ps command.

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ps -ax | grep ncpa

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centos-stream-log-6-230@~{150:0} ps -ax |grep ncpa 
1413886 ?        Sl    11:10 /usr/local/ncpa/ncpa_listener --start
1413892 ?        S      1:57 /usr/local/ncpa/ncpa_passive --start
3539652 pts/1    S+     0:00 grep --color=auto ncpa
centos-stream-log-6-230@~{151:0} ss -nl | grep 5693 
tcp   LISTEN 0      128                                                         *:5693                   *:*               
centos-stream-log-6-230@~{152:0}  netstat -n --listening | grep 5693 
tcp6       0      0 :::5693                 :::*                    LISTEN     
centos-stream-log-6-230@~{153:0}

Hope this is useful.

Thanks and Best Regards,
Keith

Posted: **Sat Feb 12, 2022 4:40 am**

Hi,

Can we monitor Mail queue on linux?
If yes, please let us know how we can do that

Thanks

Posted: **Mon Feb 14, 2022 11:59 am**

Hi lanxessinfy,

Monitoring the mail queue on a Linux system will depend upon the MTA you are using. Nagios does have a plugin, check_mailq, that uses the mailq command to monitor the queue.

https://nagios-plugins.org/doc/man/check_mailq.html

If that doesn't work with your MTA you can always search for community supplied plugins on our exchange site:

https://exchange.nagios.org/

Finally - you always have the option of writing your own plugin. I'll append links to our plugin API as well as development guidelines:

Plugin API page:
https://assets.nagios.com/downloads/nag ... inapi.html

Plugin Development Guidelines:
http://nagios-plugins.org/doc/guidelines.html

Thanks and Best Regards,
Keith

Posted: **Tue Feb 15, 2022 12:01 am**

HI,

We are able to telnet to the server.

But how can we monitor Postfix Mailq using NCPA?

Using check_mailq am unable to monitor different host

Please provide us the suitable solution.

Thanks!

Posted: **Tue Feb 15, 2022 1:37 pm**

Hi lanxessinfy,

Please find below our knowledge base article on using scripts/plugins with NCPA:

https://support.nagios.com/kb/article/n ... a-722.html

After installing the plugin on the remote machine you should be able to run the check_mailq plugin via NCPA. Depending up the distribution you are using on the target system you may be able to install packages provided by your OS distribution or you can build from source.

Example of plugin installation using CentOS7.9:

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yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm 
yum install nagios-plugins-mailq.x86_64

And here is our guide for installing from source:

https://support.nagios.com/kb/article/n ... e-569.html

Thanks and Best Regards,
Keith

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