Return ignore during dhcprequest for unknown subnets

Tue Jun 4 06:12:50 UTC 2024

Hi

Isc-dhcpd ignores dhcprequest from clients that come from an unknown segment. In the logs it looks like this:

DHCPREQUEST for 10.65.1.179 from MAC:ADDR via 10.65.0.1: ignored (unknown subnet).

What I get from kea-dhcp4 is this:

ERROR [kea-dhcp4.bad-packets/435270.139990395717376] DHCP4_PACKET_NAK_0001 [hwtype=1 MAC:ADDR], cid=[MAC:ADDR], tid=0x52eec91a: failed to select a subnet for incoming packet, src 10.65.0.1, type DHCPREQUEST

ERROR [kea-dhcp4.bad-packets/435270.139990395717376] DHCP4_PACKET_NAK_0001 [hwtype=1 MAC:ADDR], cid=[MAC:ADDR], tid=0x52eec91b: failed to select a subnet for incoming packet, src 10.65.0.1, type DHCPDISCOVER

Kea sends dhcpnak to clients from subnets it is not configured to serve. If the same client keeps coming back, it will not get an IP address. This is what is happening.
It would be very helpful if kea would ignore these requests, much like isc-dhcp does. Is it possible to configure this?

I am aware of dhcp helpers. There would be no such logs if we had dhcp helpers in our network. Currently, we don’t. Our network guys work (and the hardware vendor) work on it.

Thanks,
Philipp
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