Introduction: This tutorial demonstrates how to allocate a portion of your IPv6 address pool to your libvirt guests using bridges, ensuring that each guest has its unique public IPv6 address.
Prerequisites:
- Dedicated server with libvirt installed
- A /64 IPv6 subnet (e.g., 2001:0db8:abcd::/64)
Before We Begin: Before starting, ensure you have the following information:
- Your IPv6 subnet address (e.g., 2001:0db8:abcd::/64)
Step 1 - Install Required Packages
Begin by installing the necessary packages, including bridge-utils and ifupdown. These are required alongside your existing libvirt installation:
sudo apt install bridge-utils ifupdown
Step 2 - Create the Bridge Interface
Next, create the bridge interface using the installed packages:
sudo brctl addbr br0
Step 2.1 - Assign a Subnet
Now, assign a /96 subnet to the bridge. This should provide ample addresses for your VMs:
sudo ip addr add 2001:0db8:abcd:1::1/96 dev br0
Step 2.2 - Set It Up
Activate the bridge interface:
ip link set br0 up
Step 3 - Add the Interface to a VM
Attach the bridge to a VM by using virsh:
sudo virsh
Inside virsh, edit the domain configuration for your VM:
edit --domain <name of the VM>
Add the following XML entry to the devices node, modifying it as needed:
<interface type='bridge'>
<source bridge='br0'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
</interface>
Please adjust the address values based on your specific configuration.
Step 4 - Set Up Your VM
Configure the network interface within your VM to use the allocated IPv6 address:
auto enp7s0
iface enp7s0 inet6 static
address 2001:0db8:abcd:1::2
netmask 96
gateway 2001:0db8:abcd:1::1
Modify the values accordingly to match your network configuration. In the case of a Windows guest, configure the network settings through the Windows Settings app.
Step 4.1 - Activate the Configuration
Activate the configuration by restarting the networking service:
sudo systemctl restart networking
Your networking should be reestablished in a few seconds, without interrupting your SSH session.
Conclusion: You can now SSH into your libvirt guests using their static IPv6 addresses. To make your bridge configuration persistent across reboots, add it to the /etc/network/interfaces file. Additionally, consider installing a DHCP server to automate address assignments if needed.
