Open ports are shown as blocked

Question

Hello,

I have a question regarding the installation of an Exchange Server 2016. Currently, I am getting error messages at testconnectivity.microsoft.com regarding closed ports:

"Testing TCP port 443 on host autodiscover.DOMAIN:TLD to ensure it's listening and open.
The specified port is either blocked, not listening, or not producing the expected response.
Additional DetailsA network error occurred while communicating with the remote host."

and

"Testing TCP port 80 on host autodiscover.DOMAIN.TLD to ensure it's listening and open.
The specified port is either blocked, not listening, or not producing the expected response.
Additional Details
A network error occurred while communicating with the remote host."

The result of a port scan on the firewall server (with a Windows Firewall) is that all ports are shown as closed, although 1) the respective e-mail ports are explicitly opened in the firewall and 2) services are listening on these ports (by port forwarding to the email server).

What could be the reason for the ports being shown as blocked? How can I resolve the issue? Thank you in adavance!

Answer 1

Might also try
https://www.canyouseeme.org/

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Answer 2

Hi ,

In order to narrow down the issue, please temporarily disable windows firewall and other third-party software, then test autodiscover again and check the results.

Best Regards,

Candy

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Answer 3

Even after temporarily disabling the Windows firewall the test with https://testconnectivity.microsoft.com returns the same error messages. The same holds for the port scan. Therefore, it is independent of the firewall configurations.

However, the problem does not seem to be related only to the e-mail server. Behind the firewall server, for instance, there is also a Linux server that I was previously able to log on to via SSH without any problems. However, this has also not worked for quite some now. Presumably, some accidentally set Windows configurations are responsible for this.

Although all ports are shown as closed to the outside (I have also tested this with https://www.canyouseeme.org), I can connect to the firewall server via VPN and then connect to all servers via Remote Desktop.

I do not yet understand what could be the cause of this behaviour. What other Windows settings can have an effect on the ports?

Answer 4

have also tested this with https://www.canyouseeme.org),

Next step is to do a netstat -aon and confirm the correct process listens on the port.

--please don't forget to Accept as answer if the reply is helpful--