[Dnsmasq-discuss] IPV6 RA configuration

kim-dnsmasq at bluemoose.org.uk kim-dnsmasq at bluemoose.org.uk
Sat Dec 29 13:37:50 GMT 2012


Back again - further digging, I think I've got it going with RA's from the
router (M bit set off, O bit set on which makes sense) and the wide-dhcp6
(dhcp6s) dhcp server on Debian - with single line config that seems to work.

 

So I'm just misunderstanding how to setup a DHCPV6 only dnsmasq, without it
making RA's.?

 

From: dnsmasq-discuss-bounces at lists.thekelleys.org.uk
[mailto:dnsmasq-discuss-bounces at lists.thekelleys.org.uk] On Behalf Of
kim-dnsmasq at bluemoose.org.uk
Sent: 29 December 2012 10:01
To: dnsmasq-discuss at lists.thekelleys.org.uk
Subject: [Dnsmasq-discuss] IPV6 RA configuration

 

Hi,

 

This may be a simple lack of comprehension on my part (I'm convinced IPV6
will be easier for those who never new V4. J) but can someone please point
me in the right direction.

 

I think I'm trying to configure dnsmasq to send a router advertisement
pointing to a different system (ie not itself).  I can't see a way to do
that - which may mean it's a bad idea!

 

Background - I've got a Billion DSL router and a Debian box - the Billion
has native IPV4 and V6 to the world (thank you A&A), internally it actually
runs dnsmasq I believe, but it's not trivial to get a shell so I've left
that alone.    The Debian box is running anyway so I use that as an internal
DNS with dnsmasq (just updated to 2.65 from the sid deb packages, although
I'm still on squeeze) , and as a NAT gateway for all the sorts of things
which are popping up with RJ45's on these days I don't want to give public
V4's.  

 

IPV4 - fine - dnsmasq on Debian handles DHCP for the NAT range, and happily
hands out details telling those things to use the debian box as a gateway.
Via MAC based tags, a few others get given a fixed IP and default gateway
straight to the Billion router - all well.

 

Initially the Billion came setup for V6 -running both router advertisements
and DHCPV6 - which would be fine, but of course it sets IPV6 DNS to only the
external ISP servers, so any internal only hosts (printers etc) aren't
listed.  So if a host does DNS over V4 it can see all the printers etc, if
it uses V6 it only sees the public DNS.   Now I know I could go and set up
every single device in the A&A public DNS, and that would fix it but that
feels silly - all I want is to have the IPV6 config point to the internal
Debian dnsmasq and all will be fine.

 

The billion seems to run dnsmasq, radvd and dhcp6s, but I can't easily get
shell access to edit to the config files directly, so I 've turned them off
in the web interface and I'm trying to advertise the right config from
dnsmasq on the debian box.

 

 

I'm happy using V6 autoconfig addresses (seems half the point of V6 for
clients) but I think I need to send router advertisments pointing the
default gateway directly to the Billion router, not to the Debian box where
dnsmasq is running (no reason to send the packets via Debian as no NAT
involved in V6).   I then need to use DHCPV6 to set the DNS server to the
debian box and all will be well.

 

I can't find a way to specify the default gateway sent in the RA from
dnsmasq - entirely logically it sends its own address and only that.

 

 

I tried to get clever and turn RA's back on from the Billion router and
disable them on dnsmasq - leaving DHCPV6 on Debian to set DNS and turning it
off on the router - it sort of works but only some of the time which makes
me think I've missed the point.

 

 

Any thoughts? - are RA's inherently only ever set to the router they are
sent from?   What's the best way to set up a network with the DNS on one box
and the router on another.

 

Thanks in advance - sorry this is such a long mail!

 

Cheers

Kim

 

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