[Dnsmasq-discuss] IPv6: selective RAs

Simon Kelley simon at thekelleys.org.uk
Wed Sep 12 15:24:09 BST 2012


On 12/09/12 14:20, Lutz Preßler wrote:
> Hello Simon!
> 
> Am Mittwoch, 12. September 2012 schrieb Simon Kelley:
>> On 12/09/12 13:04, Lutz Preßler wrote:
>>> I don't see a way to have RAs only for certain clients like
>>> radvd (from radvd.conf.5:)
>>> "By  default  radvd will send route advertisements so that every node on the
>>> link can use them.  The list of clients (IPv6 address) to advertise to,
>>> and accept route solicitations from can be configured.  If done, radvd
> [...]
>>> "
>>>
>>> Is this a feature you would implement?
>>
>> I don't think this is an appropriate feature for dnsmasq, the philosophy
>> is that it should provide a basic RA service for networks which are
>> really using DHCPv6 for the complex stuff.
> I understand that. But maybe I have to explain the motiavation: clients,
> which are in principle IPv6 capable but habe broken or incomplete implementations
> (e.g. Windows XP, some Linux distros, Android). It would be good to be able
> to black- or whitelist within dnsmasq (and not with packet filter rules).
> I said RA - but this also extends to DHCPv6 as there are clients which
> (not conforming to current RFCs) do DHCPv6 despite having received no RA.
> 

You can black or white list for DHCPv6 with the --dhcp-ignore (but it
might be difficult to blacklist for DHCpv6 and allow DHCPv4 - that could
be fixed.)

You can't black or whitelist RA's
>>
>>> Only sending stateful DHCPv6 but no RAs is not possible either, is it?
>>
>> If you configure DHCPv6 for a subnet, you get stateful DHCPv6 but no RA.
>> That should combine with radvd fine, I think.
> Sorry, this was a type: I meant "only stateLESS DHCPv6".
>

OK, but my statement is still valid stateless DHCPv6 is just different
requests from the client if you configure DHCPv6 you get both. If you
then configure radvd to send the correct bits in RAs, clients will ask
for stateless rather than stateful DHCPv6.

Simon.


> Lutz
> 




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