we have updated our server from “2.3.0p24.cee” to “2.3.0p31.cee” and now we have about 25-30 Windows Servers where I receive a “Communication failed: [Errno 111] Connection refused” error.
There were no other changes and not all within a firewall group are affaced so I don’t think it’s a firewall problem.
At the moment I don’t know where I have to look.
A reboot fixes the problem - restarting the cmk-service does not. I can’t reboot all the servers bacause it’s a critival environment.
CMK version: 2.3.0p31 OS version: Ubuntu 20.04 LTS
Error message: [agent] Communication failed: [Errno 111] Connection refused
You are talking about Windows clients. I suggest to check FW on these Windows servers anyway. Maybe they had patching activity in paralell with your cmk upgrade? Sometimes bigest patches on Windows can turn on Windows local FW. You need an open connection (Incoming) TCP port 6556. Also try telnet from your cmk server to your affected servers via port 6556.
From other hand I suggest to contact with your FW team and ask them for check the trafic from your CMK server to affected Windows systems andask if they can see any drops.
No firewall changes, I’ve checked that. Rebooting the server solves the Problem.
For me the problem is caused by the software update of the agent on the host via the agent bakery. Maybe something sometimes went wrong with that version update.