dhcpcd-discuss

Hi Roy,

On 2015-01-06 6:57, Roy Marples wrote:

> Hi Joachim
>
> On Tuesday 30 Dec 2014 10:04:49 Joachim Achtzehnter wrote:
> > This is an answer only if one wanted to disable autonomous
> > auto-configuration globally as a policy for the subnet, but this wasn't
> > my question. Sorry, I should have made this clear.
> >
> > The question is about client-side configuration. On a subnet where the
> > router allows both autonomous and managed address configuration we want
> > to configure a host such that it only configures the address assigned by
> > DHCP, but not generate addresses autonomously based on the hardware
> > address or randomized (privacy extension).
>
> It helps if I read messages like this if not concentrating on Christmas :)
>
> OK, so basically if Auto is set AND Managed is set, you want an option to
> ignore Auto.

Yes, exactly. The addrconf RFC says that "Creation of global and 
site-local addresses and configuration of other parameters as described 
in this section SHOULD be locally configurable. However, the processing 
described below MUST be enabled by default."

So the standards do not object to having an option for a local system to 
opt-out of stateless auto-configuration. On Linux systems, this is 
usually controlled by the autoconf kernel parameter, which my original 
patch tried to honour.

> Here is a patch which allows this, but before I commit it, a question.
> If we set this new option and receive a RA with Managed set so DHCPv6 is
> kicking off but a new RA appears without Managed set but with prefixes and auto
> flags set, should dhcpcd ignore these also or generate SLAAC addresses for
> them?

Yes, otherwise the option would be pointless. When this option is 
engaged no other global scope addresses should be configured, except the 
one negotiated with a DHCP server.

We have a similar use case when the local administrator wants to assign 
an address manually, and not have anything assigned automatically, 
except for the link-local address. Of course, in this case we simply 
don't call the DHCP client.

Thanks,

Joachim


> BTW, this patch I committed earlier may be of some use to you.
> http://roy.marples.name/projects/dhcpcd/ci/107e7a1a749390472a7b13d8e23b896e1d0fffe5?sbs=0
>
> Thanks
>
> Roy

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