[virt-tools-list] virt-manager only adecuate for IPv4 networks?

[Daniel P. Berrange]

On Fri, Oct 03, 2014 at 06:59:56AM -0300, Hugo Osvaldo Barrera wrote:
> On 2014-10-03 10:39, Daniel P. Berrange wrote:
> > On Fri, Oct 03, 2014 at 06:28:44AM -0300, Hugo Osvaldo Barrera wrote:
> > > I've been trying to set up a simple VM with network (Internet) connectivity on
> > > my laptop.
> > > 
> > > I've come across series of issues, after which I'm starting to believe that
> > > virt-manager is oriented towards IPv4-only networks, since non of it's options
> > > work with IPv6: NAT has (luckily/finally) obsoleted by IPv6 and bridging does
> > > not work on wireless networks.
> > > 
> > > I've seen some guides here and there were users configured their machines as
> > > routers, with radvd, manual routing, etc. That's a bit of a pain because:
> > > 
> > >  * It requires a not-so-short series of steps which I must redo every time I
> > >    connect to a different network (since I'll have different IP addresses,
> > >    different routes, etc).
> > >  * The whole point of virt-manager is to make this "user friendly", and not so
> > >    complicated.
> > > 
> > > Am I missing something? Are there any plans to address this in future? Is there
> > > something I can do to work around this?
> > 
> > Given the lack of NAT for IPv6 what behaviour would you suggest
> > virt manager attempt to do for IPv6 ?  If there are suggestions
> > we're listening, but I've not heard any satisfactory suggestions
> > for a "just works" setup with IPv6 that's on a par with what we
> > are able todo with IPv4 NAT.
> > 
> > Regards,
> > Daniel
> > -- 
> > |: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
> > |: http://libvirt.org              -o-             http://virt-manager.org :|
> > |: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
> > |: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|
> 
> IMO, the real problem is that wireless clients can't have two MACs (and hence,
> can't bridge). But I don't see that changing in future.
> 
> I think what would work aroundn this issue is:
> 
>  * Grab a second IP address on the host machine on the same subnet. eg: my
>  machine gets it's IP via RA. It's quite possible to simply grab a second IP on
>  the same subnet that RA is advertising.
>  * Set up something like radvd on the virtual network that's set up for the
>  guest. Give it that same IP, and forward any DNS that were picked up via RA.
>  * Forward all traffic to this second IP to the guest machine.
> 
> This doesn't seem to conflict with any standard (AFAIK), and should work fine
> on roaming clients (eg: laptops). I think the only scenario where this may not
> work is were static IPs are used and there's no RA present.

So this would require virt-manager or libvirt to be actively monitoring
for change of IP addresses and then reconfigure radvd with the new address
info. It also sounds like it would only work with a single guest, or require
the host to acquire an extra IP address per guest. So this isn't exactly
straightforward compared to our current NAT setup.

For a while I've thought it would be nice to have a Proxy-ARP setup for
IPv4, basically that's IPv4 level bridging instead of ethernet level
bridging. There does seem to be a similar-ish concept for IPv6 called
proxy NDP, but from what I can see that still requires manual routing
table setup for each address.

  http://www.ipsidixit.net/2010/03/24/239/

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|