I just upgraded a few Debian 11.3 VMs to 2.1.0. Port 6556 is not open on just one of the VMs so it is no longer monitored. The VM successfully registered with my server, however the following message is repeated on the VM’s logs:
cmk-agent-ctl[3883704]: ERROR [cmk_agent_ctl] Address family not supported by protocol (os error 97)
I have uninstalled the agent and reinstalled the agent with no luck.
Any thoughts?
Ok, what’s the output (on the host) of:
ss -tulpn | grep 6556
cmk-agent-ctl status
BTW: Might it be some enforced IPv4 environment?
Well a bit more digging around yielded the following…
Disabling ipv6 at the kernel level via ‘GRUB_CMDLINE_LINUX_DEFAULT=“ipv6.disable=1”’ in /etc/default/grub and “update-grub -o /boot/grub/grub.cfg” causes the issue.
Re-enabling ipv6 via grub.cfg and disabling ipv6 in sysctl via “echo ‘net.ipv6.conf.all.disable_ipv6 = 1’ >> /etc/sysctl.conf” and reboot fixes the issue.
That’s what I feared / suspected. But we could not reproduce this in our test environments. Would you mind providing us with a complete output of dmesg immediately after boot?
** NOTE:
I incorrectly stated in my initial post that this was a VM. The host in question is an old ECS Liva X mini PC.
Attached is a dmesg capture after a fresh reboot. This reboot was after the fix I mentioned above.
dmesg.txt (52.7 KB)
Let me know if you need any more info. I would like to disable ipv6 at the kernel level as it just seems like a more elegant solution to me.
Hi,
thanks for reporting this, the issue has been fixed: Agent controller: Fix agent data transport for IPv4-only hosts
Best, Jörg
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