Tag: qemu-kvm

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

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

It is worth mentioning the MacVTap is a virtual bridge, which will make the host and the guest device show up directly on the host switch. So when using QEMU, the guest virtualized system will be as if it is connected to the host switch with one limitation – the host and guest cannot communicate with each other. The IPs of the host won’t be reachable from the guest, so NAT (masquerade) between the host and guest is not possible with this setup. Still, if the NAT server is on another server or a real IP is planned for the guest, MacVTap is the right functionality to use with the QEMU guest system.

Summary

  1. Add MacVTap device in bridge mode with name macvtap0.
  2. Install QEMU.
  3. Create QEMU local disk.
  4. Run a QEMU virtual server.

STEP 1) Add MacVTap device in bridge mode with name macvtap0

[root@srv ~]# nmcli connection add type macvlan dev enp0s3 mode bridge tap yes ifname macvtap0 con-name macvtap0 ip4 0.0.0.0/24
Connection 'macvtap0' (7a5ef04c-ea98-4642-ac5d-4239f715f631) successfully added.
[root@srv ~]# nmcli con
NAME      UUID                                  TYPE      DEVICE   
enp0s3    09497bbf-da59-42b7-a72c-d69369760b36  ethernet  enp0s3   
macvtap0  7a5ef04c-ea98-4642-ac5d-4239f715f631  macvlan   macvtap0

First, create a MacVTap device with the name macvtap0 in bridge mode with the network interface enp0s3 a and a connection with the name macvtap0. The IP is set to manual mode.
More detailed information on how to create and add MacVTap device with the NetworkManager here – Create MacVTap 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!

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)

Summary

  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 "192.168.0.1/24"
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 0.0.0.0/24
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!