Re: [PATCH 0/2] IPv6 conntrack support for neighbour discovery

[Patrick McHardy <kaber@trash.net>]

Yasuyuki KOZAKAI wrote:
> From: Eric Leblond <eric@inl.fr>
> Date: Fri, 23 Jan 2009 11:51:30 +0100
> 
>>> I prefer 'NEW' rather than 'UNTRACKED' as other protocols which
>>> validation is unclear. So another solution is to let the connection
>>> tracking subsystem to create a new conntrack and to make
>>> nf_contrack_proto_icmpv6 assign 0 as timeout. How do you think ?
>> If we do that, we can have nfnetlink messages (NEW, DESTROY) send to
>> userspace. Personnaly, I don't think they are necessary. But there is an
>> other issue: as we can't invert the tuple, the information provided to
>> userspace will be false.
>>
>> Once we agree on this last point, I will send a reworked patchset (with
>> at least the removal of sysctl stuff).
> 
> Thank you. I understand why ICMPv6 packets are special here and
> I agree to assign UNTRACKED to them. Indeed non-invertible tuple might
> bring issues.

How about adding a flag to indicate that only one direction of
the tuple exists? It makes sense to support this for other kinds
of simplex flows as well in my opinion and it somewhat goes in the
same direction as the patch I talked about during the workshop
to have only a single tuple within the conntrack and have reply
tuples or potentially other tuples that relate to a connection
within the ct_extend area. And using NEW and having netlink
events seems more consistent to me.