[clug] IPv6 for home

Paul Wayper paulway at mabula.net
Thu Dec 29 19:39:25 MST 2011

Hash: SHA1

On 12/30/2011 11:44 AM, Michael Still wrote:
> Dear Internet. I am confused by your new fangled IPv6. Personally, I
> think we should have jumped to IPv8, but I was overruled on that. So,
> given the current schmozzle we find ourselves in, please advise:

Congratulations to Scott Ferguson for writing an amusing reply.  I'm going to
go rad and be serious for a change :-)

>  - I have a DSL modem. Because Telstra are evil, it only gets 3.3mbit to
> the Internet, but that doesn't seem relevant. However, it does claim to
> get an IPv6 address, which is exciting.

If it's not an FE80::/16 address - most likely something in the 2001::/16
range - then you're good to go.  IPv6 has the concept of different address
ranges covering the same machine, usually for different networks.  FE80::/16
are 'link-local' addresses randomly decided by the network stack that are only
supposed to work on the local network.

So you've got a gateway; so far so good.  That bit took me a while.

>  - I have a machine on the network (not the DSL modem) which hands out
> IPv4 DHCP leases, as well as acting as a DNS server.

I'm assuming from your description that that machine isn't the same as your
router with the IPv6 address.  That's OK, as I understand it.

> I'd like IPv6 to just magically work for the home network, and be able
> to route packets to the Internets. I'd also like to keep DNS resolution
> going via the home DNS server if possible, as DNS latency is a big
> performance problem for me.
> So, how should I do that?
> - Should I run a DHCPv6 server on the DHCP machine? Does that really
> mean running two copies of ISC dhcpd?

Yes, sadly, because AFAICS there's two versions of dhcpd.

Alternately, you can run a route advertising daemon (radvd) on your DHCP/DNS
server.  It looks out for IPv6 "what are the local route?" packets and replies
with "you can pick one in this range, and the router is this address"
responses.  If the gateway and the radvd server are the same machine, then the
config is easier, but there's no reason why they can't be separate AFAICS.

> - Should I obtain an address range for use in my house, or should I just
> use the netblock Internode hands my modem?

You've already got one, it should be right to go.

> Please do my homework for me. I'm obsessed with the desire to experience
> animated turtles, but not obsessed enough to have done any research at all.

OK, install radvd and set up an /etc/radvd.conf file looking something like this:

interface eth0
  AdvSendAdvert on;
  prefix 2001:mika:lsip:rnge::/64
    AdvOnLink on;
    AdvAutonomous on;

Your homework is to work out what bits to change and, possibly, what I've left
out.  Steve Walsh may be able to help there too :-)

Have fun,

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