This article is going to elaborate the whole process to install KVM on Debian 12, with Bridge network.

With the power of bridge network, each VM will have its own LAN IP, and we can connect to the VM directly from other hosts in the same LAN.

Install dependency packages

Install QEMU deps

  • Install qemu with GUI

    sudo apt install qemu-system libvirt-daemon-system virt-manager aqemu

  • Install qemu without GUI

    sudo apt install --no-install-recommends qemu-system libvirt-clients libvirt-daemon-system virtinst

Install bridge network deps

sudo apt install dnsmasq-base bridge-utils firewalld

Create bridge network

KVM use NAT as the default network type, we need to create the bridge network first, and create the VM with the bridge network.

Install deps

sudo apt-get install bridge-utils

Create br0 interface

The bridge network br0 will assign a static IP, and bridged to the ethernet port enp1s0f0. Here are the config files:

  • /etc/network/interfaces.d/br0

    auto br0
iface br0 inet static
    address 192.168.1.180
    broadcast 192.168.1.255
    netmask 255.255.254.0
    gateway 192.168.0.1
    dns-nameservers 192.168.0.1 192.168.1.180
    bridge_ports enp1s0f0
    bridge_stp off
    bridge_waitport 0
    bridge_fd 0
    bridge_maxwait 0

  • /etc/network/interfaces.d/enp1s0f0

    iface enp1s0f0 inet manual

after creating the above files, we need to restart the networking service

systemctl restart networking

Disable net filter

create file /etc/sysctl.d/99-netfilter-bridge.conf

net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0

load br_netfilter module

sudo modprobe br_netfilter

load br netfilter at boot with /etc/modules-load.d/br_netfilter.conf

br_netfilter

load netfilter setting:

sysctl -p /etc/sysctl.d/99-netfilter-bridge.conf

Create virtual network

create file in any place: bridged-network.xml

<network>
    <name>bridged-network</name>
    <forward mode="bridge" />
    <bridge name="br0" />
</network>

create virtual network with above xml

sudo virsh net-define bridged-network.xml
sudo virsh net-start bridged-network
sudo virsh net-autostart bridged-network

check network created or not

sudo virsh net-list

Create VM with bridge network

sudo virt-install \
  --vcpus=1 \
  --memory=1024 \
  --cdrom=debian-12-amd64-DVD-1.iso \
  --disk size=7 \
  --os-variant=debian12 \
  --network network=bridged-network

References