On Thu Sep 12 15:56:23 2013, jpopelka@redhat.com wrote:

=> a simple question: is the problem for multicast or
unicast packets (it should work for multicast packets
but for unicast packets it has no chance to work with
a single global socket bound to *.port)?

> When there are more 'dhclient -6' instances running
> (one instance per network interface),
> always only one of them gets all the packets
> (even those destined for the other instances).
> The exact behavior depends on linux kernel version, either only the
> first or only the last started instance gets all the packets,
> but the problem remains.

=> IMHO the correct behaviour should be to have bind()
rejected but it implies SO_REUSEPORT to be implemented
and SO_REUSEADDR fixed. I don't know if it will help here
but at least it will align with the BSD (and IMHO correct)
behaviour...

> I think the problem is that DHCPv6 part of if_register_socket() binds to
> address from local_address6 variable but this variable has never been
> initialized so it's always 0.

=> local_address* is for agents (i.e., relays and servers).
In fact this part of the code is essentially for agents.

> I don't know the internals, so the patch can be completely wrong
> but up to now it's seemed to fix the problem and not cause any others.
> I'll update it if I find something better.

=> I am afraid it will break agents via the multicast receive.

> See also
> http://serverfault.com/questions/471076/ipv6-two-interfaces-with-dhclient

=> it will be tested too as the goal is to have
something which supports any partition of clients
over multiple interfaces.