Nagios Web Interface through firewall

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Nagios Web Interface through firewall

Postby Andreb1972 » Mon May 13, 2019 5:52 pm

Hello,

I have installed Nagios Core 4.4.3 with HTTP on Ubuntu 18.04. The installation is in our DMZ monitoring a number of servers. The web interface works well as long as it is used from a machine in the DMZ. I have opened Port 22 and 80 so that we can monitor the environment from the internal network, so there is a firewall between my network and the Nagios server.

Issue: If I access the Web Interface from the internal machine using "http://nagiosserver/nagios", then the browser waits for some time (60s), then gives a "Connection Reset" or "Can't reach this page".

I tried to make the site a VirtualHost, and then used "http://nagiosserver/" The main page loads, but I noticed that none of the CGI scripts are able to execute. e.g. The Status Check in the middle of the page eventually returns "net::ERR_CONNECTION_RESET". If I select any of the sidebar links, none of the pages are able to load also with the same error.
To confuse the issue, I installed NagiosGraph, which also uses CGI scripts, and this appears to work fine using "http://nagiosserver/nagiosgraph"

The Ubuntu firewall has been disabled
Tried Chrome, IE and Edge
Tried different client machine
Checked Nagios file permissions
I matched the file permissions with the NagiosGraph
Followed numerous threads configuring <Directory> Require all granted </Directory>

I thought I had a firewall issue, but the Nagiosgraph cgi's wok fine, so don't think it is that, but I am not sure what else to check.

Any ideas what I can check?
Andreb1972
 
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Re: Nagios Web Interface through firewall

Postby npolovenko » Tue May 14, 2019 4:11 pm

Hello, @Andreb1972. Can you upload the /var/log/httpd/error_log and the Apache configuration file /etc/httpd/conf.d/nagios.conf? Are you using the same IP address to access nagios from the inside of the DMZ and from the outside?
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Re: Nagios Web Interface through firewall

Postby Andreb1972 » Tue May 14, 2019 7:05 pm

My Apache2 does not use httpd.conf, so I think you want the apache2.conf.

The same IP Address is used from all environments.
Attachments
nagios.conf
(2.01 KiB) Downloaded 9 times
apache2.conf
(7.06 KiB) Downloaded 9 times
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Re: Nagios Web Interface through firewall

Postby ssax » Wed May 15, 2019 3:59 pm

More than likely this is because you didn't setup any DNS records for nagioslogserver.

From the internal machine, what does this command output?

Code: Select all
nslookup nagioslogserver
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Re: Nagios Web Interface through firewall

Postby Andreb1972 » Wed May 15, 2019 9:14 pm

I have no DNS records for nagioslogserver, as this is not installed. I see no reference to this in the Core documentation.
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Re: Nagios Web Interface through firewall

Postby Andreb1972 » Thu May 16, 2019 4:03 pm

Resolved. The IT team found a firewall rule blocking certain nagios script execution.
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Re: Nagios Web Interface through firewall

Postby npolovenko » Thu May 16, 2019 4:40 pm

@Andreb1972, Glad you were able to resolve this. I will be closing this thread.
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