Broken dhcpv6 lease: explanation?

My router has two VLANs: one "lan" (ports 1-3) and one "guest" (port 4); connected to port 1, I've got a Samknows whitebox. The local wired clients are connected to this secondary switch.

Now, I don't need to access it directly and all is working fine, I'm just confused by the "broken" prefix in the hostname: what could it be? The box can be pinged using the IPV6 address from the "lan" and does not respond when pinged on the "guest" address, which is to be expected since port 1 is untagged and only belongs to "lan".

  • You completely blanked out the second lease, does it have the broken\ tag appended as well?
  • If not, why don't you suspect the SamKnows boxes?

If you click the image to enlarge it, you will see that both leases have "broken" as hostname prefix, the missing line in the middle refers to a different host.

Only difference is the subnet prefix in the address.

This is done by odhcpd when the received dhcpv6 client hostname tag is invalid, means containing illegal characters, wrong series of dots, overlong labels etc.

When such a hostname is detected, the prefix broken\x20 is prepended in the lease file to denote such cases and the name is not added to the autogenerated hosts file.

See https://git.openwrt.org/?p=project/odhcpd.git;a=commitdiff;h=881f66b0c2526bff6a2a51b30d314c512df813b4 for details.

In your case it seems that the clients use hostnames in the form SKWB8-$macaddr which is not a valid DNS label due to use of colons.

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Correct, and I assume it doesn't have broken\ appended on it?

So, as @jow noted, it seems your SamKnows device is requesting an invalid hostname.

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Yup, only samknows has this issue.
Thank you both, I'll see if I can get them to fix it but I'm good with this explanation.

Anyhow, it's still odd that there are two entries, one for each VLAN even if the box is only on one VLAN.

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