[Kea-users] kea-dhcp4 and interface binding

[Francis Dupont]

There is no good solution: Kea uses LPF raw sockets on Linux by default
with a fallback socket which is used to:
 1- send some packets back
 2- avoid the kernel to return ICMP port unreachables because no socket
  is bound to the service port
The result is that it is complex and sometime impossible to run multiple
DHCP services on the same system. BTW unfortunately it is not a new
problem...

Some extra comments:
 - the openFallbackSocket() method is generic so does not use the Linux
  specific SO_BINDTODEVICE.
 - SO_REUSEADDR won't help on Linux because its implementation is broken:
  when set to 1 it simply disables conflict detection.
 - I saw the word NAT in your message: if dnsmasq is run behind a NAT the
  best solution is to translate the DHCP server port and to use for
  dnsmasq this alternate port.

Regards

Francis Dupont <fdupont at isc.org>