[libvirt] A Big OOPS!!

[Gene Czarcinski]

A big OOPS!!!

On 10/23/2012 04:55 PM, Gene Czarcinski wrote:
> On 10/23/2012 04:10 PM, Laine Stump wrote:
>> I wouldn't worry about that quite yet. Let's wait until it's pushed
>> upstream. At the point, we'll probably want the first two (for F17 and
>> F18, which have dnsmasq-2.63 which according to you causes problems).
> Not me, Simon Kelley the dnsmasq developer/maintainer/etc.
>
> Rather than just pasting his comment here, got to look at the message 
> he wrote:
>
> http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2012q4/006415.html 
>
>
> There might be a way to make it work with just the gateway address 
> (that is what listen-address really is because dnsmasq does not really 
> need an address just the interface), but that is not how it was done.
After I sent the message, I just got something in from Simon Kelley 
which has some new info:
http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2012q4/006445.html

The heart of it is this:
--------------------------------------------------
> OK, so this is vaguely embarrassing. Having checked the actual code,
> rather than the changelog, I see that dnsmasq >=2.61 _already_ does the
> right thing. Setting --bind-interfaces* and a single --listen-address
> will cause the code to set SO_BINDTODEVICE on the DHCP socket(s).
>
> So, there is not a problem with the existing libvirt command line.
I disagree.  I believe that the problem still exists.

What Simon says implies that everything is OK and nothing needs to be 
done but consider this:

1. What harm does it do to add the interface=<> specification in 
addition to everything else?

2. Note that Simon states "Setting --bind-interfaces* and a single 
--listen-address ".  Well, I can define multiple IPv4 and/or IPv6 
listen-addresses to be on a single virtual interface.  From what Simon 
says, that means all bets are off.

3.  I suspect that many/most instances of dnsmasq only has a single 
address and that is why the problem has not manifested itself.

4.  I do not know if a v4 and v6 address counts as one or two.

Gene