about the script /etc/qemu-ifup with nmcli command

[Eduardo Habkost]

On Wed, Oct 21, 2020 at 06:31:50PM +0800, Yalan Zhang wrote:
> Hi,
> 
> I have tried the qemu-ifup script as below with nmcli command as brctl is
> deprecated on rhel8, but the guest network can not work.
> I think the script needs update. Could you please help to have a look?
> Thank you in advance.
> 
> 1. prepare a linux bridge on the host named br0;
> 
> 2. prepare the qemu-ifup script as below:
> # cat /etc/qemu-ifup
> #!/bin/bash
> # A br0 bridge should be already set up.
> # Compare with:
> # http://en.wikibooks.org/wiki/QEMU/Networking#qemu-ifup
> #
> # For the bridge setup, see:
> # http://wiki.libvirt.org/page/Networking#Fedora.2FRHEL_Bridging
> # http://gist.github.com/393525
> ip link set "$1" up
> nmcli c add type bridge-slave ifname $1 con-name $1 master br0 autoconnect
> yes
> 
> 3. start vm with below interface setting:
> # virsh dumpxml rh | grep /interface -B5
>     <interface type='ethernet'>
>       <mac address='52:54:00:79:ba:dd'/>
>       <script path='/etc/qemu-ifup'/>

I don't know how to make the script work, but I don't understand
why you are using <script> instead of <source bridge='...'> as
documented at
http://wiki.libvirt.org/page/Networking#Fedora.2FRHEL_Bridging


>       <model type='virtio'/>
>       <address type='pci' domain='0x0000' bus='0x04' slot='0x00'
> function='0x0'/>
>     </interface>
> # virsh start rh
> Domain rh started
> 
> 4.check on guest, the interface can not get dhcp ip address;
> 
> 5. check on host,
> # nmcli con
> NAME    UUID                                  TYPE      DEVICE
> br0     f68f73c7-10ee-40c1-bb09-3366d11ac896  bridge    br0
> ...
> vnet0   90a48d77-dccc-4b59-98f5-09f8cbd62458  ethernet  --
> 
> # nmcli dev
> DEVICE      TYPE      STATE                   CONNECTION
> br0         bridge    connected               br0
> ...
> vnet0       tun       unmanaged               --
> 
> 6. hotplug a bridge type interface and compare the tap devices:
> # virsh attach-interface rh bridge br0 --model virtio
> Interface attached successfully
> 
> # nmcli con
> NAME    UUID                                  TYPE      DEVICE
> br0     f68f73c7-10ee-40c1-bb09-3366d11ac896  bridge    br0
> vnet1   07c2a1f8-396f-4d5f-b61f-ef2ddb42ed93  tun       vnet1    --->the
> hot-plugged one
> ...
> vnet0   90a48d77-dccc-4b59-98f5-09f8cbd62458  ethernet  --       ----> the
> ethernet one
> 
> # nmcli dev
> DEVICE      TYPE      STATE                   CONNECTION
> vnet1       tun       connected (externally)  vnet1         --->the
> hot-plugged one
> vnet0       tun       unmanaged               --     ----> the ethernet one
> ...
> 
> 7. from the outputs above, the back-end tun device for ethernet type
> interface is unmanaged.
> I don't know how to update the script to fix it. Could you please help?
> 
> 
> -------
> Best Regards,
> Yalan Zhang
> IRC: yalzhang

-- 
Eduardo