How to run QEMU full virtualization with bridged networking using NetworkManager under CentOS 8

In addition to the previously presented article on the subject Howto do QEMU full virtualization with bridged networking this one shows how to run a QEMU virtual machine with a bridge networking on the host server configured only by using the NetworkManager cli – nmcli.

It is worth mentioning the bridge interface presented in this article is a local bridge device for the server and no Internet addresses or real (or main or Internet-connected) network cards are bound to it. So no MAC addresses of slaved bridged devices will leave the server.
If a network bridge, which includes the Internet (main) server network device is needed, for example, to set real IPs in a virtual machine, there is another article on the bridge networking subject – Replace current interface configuration with a bridge device using nmcli (NetworkManager)


  1. Add bridge and TUN/TAP device.
  2. Install QEMU.
  3. Create QEMU local disk.
  4. Run a QEMU virtual server.

STEP 1) Add bridge and TUN/TAP device.

[root@srv ~]# nmcli connection add type bridge ifname br0 con-name br0 ipv4.method manual ipv4.addresses ""
Connection 'br0' (ad6878c8-1e06-4af8-a81f-1eb39e761df8) successfully added.
[root@srv ~]# nmcli connection up br0
Connection successfully activated (master waiting for slaves) (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/3)
[root@srv ~]# nmcli connection add type tun ifname tap0 con-name tap0 mode tap owner 0 ip4
Connection 'tap0' (dacee2be-a14b-4cf5-83d4-96d072a96725) successfully added.
[root@srv ~]# nmcli con add type bridge-slave ifname tap0 master br0
Connection 'bridge-slave-tap0' (66490382-b239-4eb2-ae1d-ee811e39596c) successfully added.
[root@srv ~]# nmcli con
NAME               UUID                                  TYPE      DEVICE 
System eno1        abf4c85b-57cc-4484-4fa9-b4a71689c359  ethernet  eno1   
br0                ad6878c8-1e06-4af8-a81f-1eb39e761df8  bridge    br0    
tap0               dacee2be-a14b-4cf5-83d4-96d072a96725  tun       tap0   
bridge-slave-tap0  66490382-b239-4eb2-ae1d-ee811e39596c  ethernet  -- 

First, a bridge device is added with manual IP. If the IP is skipped the bridge interface br0 would have DHCP enabled by default, which may not be the desired.
More detailed information on how to create and add TUN/TAP device with the NetworkManager here – Create bridge and add TUN/TAP device using NetworkManager nmcli under CentOS 8

STEP 2) Install QEMU.

Install the QEMU virtual tools under CentOS 8 Stream. At present, the QEMU version is 6.2, which is pretty new.
Keep on reading!

Virtualbox machine boots from usb drive

First, at present, booting from USB is impossible with VirtualBox! But there is a really easy workaround to use VMDK, which is just a container file describing physical devices (or files) to use in virtual machines like VirtualBox or VMware.
Because the USB is just another physical device attached to the machine this article will help to attach the USB drive to a virtual machine – Add a raw disk to a virtualbox virtual machine. Then boot from the newly attached disk.

Here is the quick tip for the USB drive:

  1. Attach the USB drive and find its device path. Under Windows, it would be something like “\\.\PhysicalDrive3” (open “Disk Management” if not sure) and under Linux it would be /dev/sdc, for example. This is the third disk device (including USB disk devices) connected to the machine.
  2. Make the VMDK from the USB physical device.
    Under Windows:

    VBoxManage.exe internalcommands createrawvmdk -filename "c:\Users\homer\.VirtualBox\windows11pro-install-usb.vmdk" -rawdisk \\.\PhysicalDrive3

    Under Linux:

    VBoxManage internalcommands createrawvmdk -filename /home/myuser/.VirtualBox/windows11pro-install-usb.vmdk.vmdk -rawdisk /dev/sdc
  3. Attach it the virtual machine: Settings -> Storage -> Storage Devices.

    First, a click on “Adds hard disk” would show a menu to add a new hard disk and then a click on “Add” (“Add Disk Image”) shows a file browse dialog to locate the VMDK file.

    main menu
    Storage Devices
  4. Boot from this device by selecting it manually from the boot menu (F12 would boot in Boot menu) or set the VMKD disk to be on the Port 0 in the above step.

For more details (not just the commands to generate the VMDK container file) follow the above URL to the proposed article – Add a raw disk to a virtualbox virtual machine