Werk #22160: CMC: no host check for hosts without a usable IPv6 address
| Component | The Checkmk Micro Core | ||
| Title | CMC: no host check for hosts without a usable IPv6 address | ||
| Date | Sep 22, 2026 | ||
| Level | Trivial Change | ||
| Class | Bug Fix | ||
| Compatibility | Compatible - no manual interaction needed | ||
| Checkmk versions & editions |
|
A host configured for IPv6 or dual stack whose address cannot be resolved, and
for which no explicit address is configured, is given the unspecified address
::. That address is not a destination, so no host check may be sent to it.
Until now the core recognised only the IPv4 form of this. For IPv4 the
unspecified address 0.0.0.0 was read as "this host has no address", and the
host check reported:
Failed to lookup IP address and no explicit IP address configured
For IPv6 the unspecified address was read as an ordinary address instead. The
core sent ICMP echo requests to :: and never received an answer it could
attribute to the host, so every check of such a host occupied a smart ping slot
for the full smart ping timeout and then reported:
No IP packet received for 15.921799 s (deadline is 15.000000 s)
The core now treats :: the same way it has always treated 0.0.0.0. Affected
hosts are reported as having no IP address, and no ICMP packets are sent for
them.
Hosts with the address family "No IP" were never affected, and hosts with a resolvable or explicitly configured address are unchanged.