QEMU bridging interface

czezz · 05-17-2017, 07:45 AM

Hi,

Code:

[Internet] - [ROUTER] - [physical host]
                                     |___[Virtualbox guest OS: Ubuntu]
                                                                    |___[QEMU guest OS: Raspbian]

Picture/topology: https://www.dropbox.com/s/ow13aeaawc...gram1.png?dl=0

In my LAN there is PC with VirtualBox. GuestOS: Ubuntu and with NIC setup as: bridged adapter.
That makes Ubuntu to be like an another physical host in the LAN.
Then, inside of Ubuntu, I am running QEMU with guest OS: Raspbian.
On Ubuntu I have bridged eth0 so QEMU's guest OS is also like an another host in the LAN.

Bridging Ubuntu's eth0 for qemu's guest os:

Code:

# ip link add br0 type bridge
# ip addr flush dev eth0
# link set eth0 master br0
# /usr/sbin/tunctl -u $(whoami)
# /usr/sbin/tunctl -t tap0
# ip link set dev br0 up
# ip link set dev tap0 up
# dhclient br0 (or assign it manually)

And this is how I start QEMU guest OS:

Code:

qemu-system-arm -kernel kernel-qemu-4.4.34-jessie -cpu arm1176 -m 256 -M versatilepb -no-reboot -serial stdio -append "root=/dev/sda2 panic=1" -hda ~/qemu_vms/2017-04-10-raspbian-jessie-lite.img -net nic,macaddr=00:16:3e:00:00:01 -net tap,ifname=tap0,script=no,downscript=no

Raspbian receives IP address from Router/DHCP server. I can see that in Router's dhcp.leases AND on Raspbian - it has IP assigned.

Problem:
Raspbian reaches Ubuntu (eg. ping or SSH) and reverse Ubuntu reaches Raspbian.
Raspbian does not reach neither router/gateway(192.168.1.1) nor any physical hosts of the LAN.

Question:
Can anyone please have look on the way I prepare bridge on Ubuntu for qemu? Maybe I have missed something?
I was also wondering that bridging already bridged interface might be a problem BUT eventually Raspbian receives IP address from DHCP server / router.

jefro · 05-17-2017, 01:23 PM

Hello. I might as well start off with a dumb question. Why don't you just run qemu on host?

Not sure I've ever read that you could double bridge like that. Not sure what would happen. As you can see you have some connection or seemingly some connection.

I might try it once with nat on both client and sub-client.

However since it does partly work, I'd imagine some problem with ping or subnet or port permissions maybe.

czezz · 05-18-2017, 02:56 AM

Hello,
that question is little bit off topic but the answer is I have no permission to install anything on HOST (obviously that would be the right way

).

There are no firewalls at any step (up to router's WAN interface) and also from Ubuntu guest OS (like i have written before) I can reach both sites: router and qemu guest os.
Also please note: qemu guest os receives DHCP address from ROUTER.

The reason why I am posting this here is bridging procedure. Can anyone please have a look at it and say is it a right way to bridge interface (for guest OS) ?