[Dnsmasq-discuss] IPV6 RA configuration

[kim-dnsmasq at bluemoose.org.uk]

Thanks for the confirmation - I tried that briefly yesterday and it seemed
to work but I had some issues with Win7 after resuming from standby and with
an android device so I assumed something was up

I'll give dhcp6s another day or so (so far so good) and if that's stable
I'll turn it off and go back to dnsmasq and try and catch it in the act and
come up with a better problem report! :-)

I think my earlier question about how to send RA's with configurable default
routes may have been foolish - it makes sense that a router would always
send it's own RA (rather by definition in the name RA...!) - providing the O
bit is there the DHCP server can be anywhere on the subnet to handle other
stuff.  

I can't currently think of another use case which would need to be able to
effectively spoof an RA on behalf of a router which wasn't sending them, but
there may be one...?


Thanks again
Kim

-----Original Message-----
From: dnsmasq-discuss-bounces at lists.thekelleys.org.uk
[mailto:dnsmasq-discuss-bounces at lists.thekelleys.org.uk] On Behalf Of Simon
Kelley
Sent: 29 December 2012 20:46
To: dnsmasq-discuss at lists.thekelleys.org.uk
Subject: Re: [Dnsmasq-discuss] IPV6 RA configuration

On 29/12/12 13:37, kim-dnsmasq at bluemoose.org.uk wrote:
> 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.?

I'm catching up with the longer questions below, but this one is easy:

If you don't supply

enable-ra

or mention ra in any dhcp-range, than dnsmasq will not supply RA. 
Dnsmasq always logs when it send an RA, so verifying this should be fairly
easy.

Cheers,

Simon.

>
> *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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