[Kea-users] Help! Kea 1.1 sends unicast, breaks iPXE

[Francis Dupont]

Attila Szalay writes:
> I'm not around my machine, but if I remember correctly there is a flag in
> the dhcp request that mandate using the broadcast in the answer. Without
> that flag the unicast is favored. So, the question is if that flag is set
> by the iPXE client? If yes, then it is definitely a bug in kea, otherwise
> I'm not sure.

=> there is such a flag (it is the only defined flag cf RFC 2131 figure 2
(format of flags) and section 4.1). Note that if it is set to 1 the
server or relay is required to use IP and link-layer broadcast, but
not the opposite (i.e., 0 does not imply unicast).

The ISC DHCP client built in standard way always sets this to 0 (*),
ISC DHCP relay and server follow it for bootp and dhcp,
Kea server too (cf Dhcpv4Srv::adjustRemoteAddr code).

(*) this suggests this flag is rarely set by clients in queries.

Regards

Francis Dupont <fdupont at isc.org>