Windows: cmk-agent-ctl not binding to port 6556 (sometimes)

Troubleshooting
1

CMK version: 2.1.0.p6 cee
OS version: Windows Server 2016/2019

Hi,

we’ve updates to CMK 2.1.0.p6 cee.
The windows agents were built via bakery. A single msi file is used for more than 100 Windows Servers (2016 + 2019). For some reason CheckMKService is running on all servers (check_mk_agent.exe + cmk-agent-ctl.exe), but only 2/3 of the servers are reachable via port 6556. That means, about 30 servers are not monitored at the moment.
Via “netstat -ano” I’ve seen, there is no process listening on port 6556. To be sure there are no old configs etc. I’ve deinstalled the Agent and deleted %programdata%\checkmk as well as %ProgramFiles(x86)%\checkmk. After that I’ve installed the same MSI again. For some servers that was the trick and they’re listening again. Most servers are still not listening on port 6556.

The service is running as “Local system”. I blieve it’s any kind of permission issue. Sometimes it was working after using an admistrative user. Mostly not. Sometime it was working via commandline ‘“C:\Program Files (x86)\checkmk\service\check_mk_agent.exe” adhoc -show’ - mostly not.

Does anybody has an idea what’s wrong there?

Many thanks,
Thomas
PS: The servers were rebooted, of course :wink:

2

Hello,

I have the same problem on Windows and linux servers.

For me it always helps if I reinstall the agent with the following command

Cmk-update-agent -v -f

Then after one minute in most cases the port is bound.

Unfortunately I do not know a better solution at the moment

3

Hi,

I did some additional tests. Over all I think it has something to do with plugin-handling.

Before that I have removed the complete old CheckMK Stuff from servers.

Reproduceable behaviour:

  • Baked agent installed
  • Service is running. check_mk_agent.exe and cmk-agent-ctl.exe are show in process explorer
  • port 6556 is NOT bound to any process
  • Service stopped
  • complete content of %programdata%\checkmk\agent\plugins delete
  • Service startet
  • port 6556 is bound to process cmk-agent-ctl.exe
4

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