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Re: IPv6 support in debian installer


On Sat, 2011-01-22 at 21:16 +1100, Matthew Palmer wrote:
> Hi Martin,
> Thanks for giving my changes a test, and especially for your detailed
> feedback.

Np.  I'm one of those users already wanting IPv6-only installer support!
So  +1 :)

(I'll just remove what I don't have any further comments on from now on)

> I was aware of the existence of rDNS-in-RA, but I didn't know what tool (if
> any) on Linux handled it.  Looks like rdnssd is the way to go.  Do you
> happen to know what radvd magic is required to send out RAs with the rDNS
> servers in, so I can test it (and avoid having to run DHCPv6 at home)?

The radvd package on squeeze comes with two examples
(in /usr/share/doc/radvd/examples/ IIRC). The longer one of those has a
RDNSS snippet towards the end of the file that I used today in radvd.
(and tcpdump printed the info with the verbose flag, but I haven't tried
it further)

> Going out to DHCPv6 is on the todo list (a fair way down, because it
> involves getting udebs of wide-dhcp6c sorted).  I hadn't intended on
> examining the RA for bit6, but I can't imagine it'll be massively
> complicated.

A fair amount of IPv6-networks will probably use DHCPv6 for DNS
provisioning (win7 works with RA (without included DNS fields) +
stateless DHCPv6 for DNS, etc.  Just saying this so you are aware, and
realize that the utility of the IPv6-only installation support will be
definitively larger if picking resolvers from DNS is supported.
  At any rate, I believe you can use rdisc6 of Remis ndisc6-suite to
investigate the RA fields more closely.  Set it up and try it out :) I
will tomorrow (bedtime now).

> >   4) eventually and finally complete support for auto-configuration of
> > all IPv6-only network settings, which I admit is far from trivial.
> I'm up for handling anything that d-i handles for IPv4, pretty much, but I'm
> not planning on going all out with every possible bit of network
> configuration (SIP servers?  Naaaah).

Oh, that's not what I meant. :)  I meant address/gateway/resolver only,
but the hard part being using a variety of means to find them.

> My overall mental map of netcfg is:
>   for each interface
>     attempt to autoconfigure v4/v6
>     if autoconfiguration succeeded
>       consider the network config all done
>   if autoconfig failed for all interfaces
>     ask for interface to configure manually
>     configure that interface manually
>   ensure we have gateway, DNS, hostname, domain name, ask for it if
>   necessary
>   write out all settings

Looks good, thanks for sharing (and sorry for pestering you with my
20-seconds mental product.. ;) )

> My philosophy with netcfg is to configure the network only as far as is
> required to complete the rest of the installation process.  So, if we find
> working IPv4, I don't want to deal with IPv6.  Similarly, if we find
> autoconfigured IPv6, I'm not going to ask about manually configuring IPv4. 
> If we find one interface that works, I'm not going to ask about all the
> other interfaces and whether the user would like to configure those as well
> just now.

Sounds very reasonable to me.

> Since it's rare for people to have v6-only networks, I guess nobody's really
> worried about it too much.  I don't have a need for it myself, I'm just
> doing this partially as an intellectual exercise, but I also think it's
> getting to the point where people *are* going to have v6-only networks soon,
> and I'd really prefer it if d-i wasn't the only reason someone had to setup
> a v4 infrastructure.

v6-only networks are on the rise, rest assured.  Might not be your
typical home network, but they're coming. :)
  Irregardless, the ease with which autoconfiguration can be done with
IPv6 (with globally unique addresses!) makes for a very easy networking
experience -- integrating this into the installation is just superb.
Plug and play comes home.  I have plenty experience with IPv6 just
working while IPv4 continues to be a hassle.

> >   7. When I can login I see that there is a configured address from
> >   /etc/network/interfaces, as well as a RA-configured address.  A method
> >   of specifying a inet6-section in /etc/network/interfaces without any
> >   address (SLAAC should come from kernel) is needed.
> Weeeeell... if you don't put anything into /e/n/interfaces for the
> interface, it doesn't come up, so the kernel doesn't autoconfigure it.  I'd
> like it if ifupdown had a 'slaac' interface type, so I could just put "iface
> eth0 inet6 slaac" and be done with it, but in the meantime I'll settle for
> what I'm planning to do now:
> # This is a SLAAC-configured interface
> iface eth0 inet6 manual
> 	post-up ip link set eth0 up
> 	down ip link set eth0 down

Right.  I'm well aware :)   I agree that a slaac stanza/option is
mandated for IPv6 in 'interfaces'.  If nothing else to let you avoid
that hack above.  .oO( I wonder how many minutes it will take to add
that... )

> Keep an eye on the mailing list for further announcements.


Again, thank you for making this (~today of all days)!


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