0

We've just completed a deployment and migration from Exchange 2010 to Exchange 2016.

Our ticket system connects to an Exchange mailbox to generate tickets. Connections from the ticket system to Exchange are failing with a timeout error.

The server running the ticket system is CentOS 7. I SSH'd into it, opened telnet and was able to connect to our Exchange 2016 servers. After connecting I get no response to "HELLO" or "EHLO" and then get disconnected due to inactivity.

Using 3 other CentOS servers, one on the same subnet as the ticket system box, I was able to successfully telnet into Exchange and get a response to my "HELLO" and "EHLO".

Why would Exchange 2016 be ignoring a single server trying to connect to it?

I checked the SMTP logs and found nothing in there but the connection and eventual timeout.

I checked the IP block list in Exchange and it's blank.

There are no firewalls/IDS/IPS involved between Exchange and the ticket system.

1 Answer 1

0

Found the problem.

It appears when the server was built, months to year(s) ago. A typo was made in the subnet mask on the ethernet configuration.

Should have been /21 but was /32 instead

The new Exchange servers are on the same subset as the server with the issue.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .