How to configure IPv6 connectivitiy using networkd

networkd is the network manager of systemd and can be used as an alternative to the configuration of IPv6 using a standalone DHCP client.

1. To configure networkd, start by creating a backup of the current network configuration:

   sudo mv /etc/network/interfaces /etc/network/interfaces.backup
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2. Enable networkd by using the systemctl command. Do not start the service yet, as the server is currently still running on the old configuration and may become unreachable if networkd is started at this step.

   systemctl enable systemd-networkd.service
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3. Create a new file called dummy0.netdev in the /etc/systemd/network directory and open it in a text editor, i.e. nano.

   sudo nano /etc/systemd/network/dummy0.netdev
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4. Copy the following content into the file, save it, and exit the text editor:

   [NetDev]
   Name=dummy0
   Kind=dummy
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5. Create a new file dummy0.network and open it in nano:

   sudo nano /etc/systemd/network/dummy0.network
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6. Copy the following content into the file, save it and exit the text editor:

   [Match]
   Name=dummy0
   [Network]
   IPv6PrefixDelegation=dhcpv6
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7. Find the name of your public Internet interface using the ip link show command. In this example, the name of the interface is enp1s0f0. Take a note of it, as it will be required in the next steps.
8. Create a new file called <interface_name>.network and open it in a text editor

   sudo nano /etc/systemd/network/enp1s0f0.network
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9. Copy the following content in the file, edit it towards your configuration before saving the file and exiting the text editor.

   [Match]
   #The name must correspond to your interface name
   Name=enp1s0
   
   [Network]
   DHCP=ipv6
   IPv6AcceptRA=True
   # IPv4 of the Dedibox
   Address=<ip_of_your_dedibox>/<netmask>
   # IPv6 of the Dedibox
   Address=<your_ipv6_address>/<netmask>
   
   [Route]
   # The gateway is either your dedibox ip ending on .1 (i.e. x.y.z.1) for the physical host or 62.210.0.1 for any VM running on a Dedibox
   Gateway=<gateway_ip>
   GatewayOnlink=yes
   
   [DHCP]
   ClientIdentifier=duid-only
   DUIDType=link-layer
   # Onine by Scaleway DUID without 00:03 at the begginnig
   DUIDRawData=<Online by Scaleway DUID>
   ForceDHCPv6PDOtherInformation=yes
   
   [IPv6AcceptRA]
   UseOnLinkPrefix=False
   UseAutonomousPrefix=False
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10. Reboot the machine to activate the new configuration.

    sudo reboot
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