SNMP services show as a discovery warning but vanish in service discovery

Troubleshooting
,
1

CMK version: 2.4.0p9

OS version: Rocky 9.6

Target device: OPNsense 25.7.1_1-amd64 via os-net-snmp plugin.

Services from SNMP aren’t showing up in the discovery page.

Check_MK service reports [snmp] Success. cmk --debug -vvn hostname shows all the SNMP data. Check_MK Discovery shows the services as “services unmonitored” and a periodic discovery rule does eventually add new services. SNMP is working!

But the discovery page just is not. It says “[snmp]: Got no data” and if I hit rescan I see all the SNMP services that periodic discovery added have “vanished”.

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If I click host icons or check_mk service icons and select “Download SNMP walk” I get the following message and an empty 0 byte download.

	
Fetching 'walk'...
Failed: Failed to fetch data from [hostname]: cannot access local variable 'oid' where it is not associated with a value

Job finished.
 Click on the icon to download the agent output.

So SNMP is sorta working but also sorta broken and I can’t figure out where it’s gone wrong.

2

Have you tried a “Remove all/Find new” (sometimes called Tabula Rasa)? That forces CheckMK to remove and recreate the SNMP data cache

3

Hmm, not a bad guess. But no, just turns my “vanished services” back into no services at all and I still have " [snmp]: Got no data". :frowning: Thanks though.

4

cmk -II -vv --debug <hostname> complete ok? The II (two capital i) is a tabula rasa discovery. You might need to restart the site or make some dummy change to be able to due a UI change activation after to make sure the updates found by the command are applied.

5

That prints the expected pages and pages and pages of SNMP info, finishing off with

  Trying discovery with: proxmox_ve_vm_info, hr_cpu, hr_fs, snmp_info, proxmox_ve_vm_backup_status, proxmox_ve_vm_snapshot_age, proxmox_ve_mem_usage, ps, uptime, if64, hr_ps, docker_container_status_uptime, mem_used
  1 hr_cpu
 14 hr_fs
  7 if64
  1 mem_used
  1 proxmox_ve_mem_usage
  1 proxmox_ve_vm_backup_status
  1 proxmox_ve_vm_info
  1 proxmox_ve_vm_snapshot_age
  1 snmp_info
  1 uptime
SUCCESS - Found 29 services

Activating changes makes the services appear.

So the CLI discovery works, just not the web page for it.

6

When was the last time the site was restarted? It seems like a running config vs saved config conflict that I’ve run into before. Make sure all changes are applied before restarting the site

7

Oh no that long ago.

But I think this turns out to be just one of those things. I cloned the host (changing the hostname, going through a bit of a renaming) and service discovery just WORKED. Everything is fine now. :person_shrugging:

I appreciate your effort though :smile: Thank you!