KVM Networking Hell

[Jamie McDonald]

Soren,

Thanks for your response and well spotted with the network mask, must have
got tired staying up playing with this so late!!

I have updated the network address on the host the /etc/network/interfaces
file now reads

## START /etc/network/interfaces file on HOST ##

auto eth0
iface eth0 inet manual

auto br0
iface br0 inet static
        address 88.208.249.44
        network 88.208.248.0
        netmask 255.255.252.0
        gateway 88.208.248.1
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0
        bridge_maxwait 0

## END /etc/network/interfaces file on HOST ##

These changes have been enabled and I can still ssh between both the host
and the guest, but still no external conectivity for the guest.

The routing table on the guest is as follows

## START routing table ##

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
88.208.248.0    0.0.0.0         255.255.252.0   U     0      0        0 eth0
0.0.0.0         88.208.248.1    0.0.0.0         UG    100    0        0 eth0

## END routing table ##

Any more ideas?

Kind Regards,
Jamie.


On Tue, Jun 8, 2010 at 11:31 PM, Soren Hansen <soren at ubuntu.com> wrote:

> On Tue, Jun 08, 2010 at 10:49:04PM +0100, Jamie McDonald wrote:
> > #### START /etc/network/interfaces on HOST ####
> >
> > auto eth0
> > iface eth0 inet manual
> >
> > auto br0
> > iface br0 inet static
> >         address 88.208.249.44
> >         network 88.208.249.0
> >         netmask 255.255.252.0
> >         gateway 88.208.248.1
>
> I probably doesn't matter, but that address with that netmask doesn't
> give that network.
>
> > auto eth0
> > iface eth0 inet static
> >     address 88.208.249.45
> >     netmask 255.255.252.0
> >     network 88.208.248.0
> >     broadcast 88.208.251.255
> >     gateway 88.208.248.1
>
> This adds up, though :)
>
> > Symptoms
> > ----------------
> > I can now ssh from the host into the guest (from the host) and from the
> > guest to the host, however try as I might I cannot get the guest to
> access
> > the outside world or the host to pass packets to the guest.
>
> It is not the job of the host to do any of this, really.
>
> > As you can see, the bridge is working and when I start the VM from
> > virsh# the vnet0 adapter is created, however no tap0 is being created.
>
> vnet0 is the tap device. This is the expected behaviour.
>
> > As far as I am aware you should not need ipv4 forwarding enabled in
> > the Kernel for bridged networks
>
> That's correct.
>
> > If any of you could shed any light on this issue (since I can't seem
> > to find anyone else with the issue) it would be most appreciated.
>
> Off the top of my (arguably quite tired) head, it looks good. Can I see
> the routing table in the guest?
>
>
> --
> Soren Hansen
> Ubuntu Developer
> http://www.ubuntu.com/
>
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