Ubuntu 18.04 uses netplan to configure the network. All my servers run behind an OPNSense Firewall that runs a DHCP server for IPv4 and has static leases applied.
Since I don't run a IPv6 DHCP server, I have to configure IPv6 manually on all my servers. I did some research to figure out how to get it working with netplan. And guess what, it is easier than I thought.
network: ethernets: ens18: dhcp4: yes dhcp6: no addresses: - <IPv6 address> gateway6: <IPv6 gateway address> version: 2
I think the setup is pretty self explainary but let me explain it to you. First we enable dhcp for IPv4 and disable dhcp for ipv6.
dhcp4: yes dhcp6: no
In the last step we apply the fixed ipv6 address and save the file. After a reboot, the server should have the correct ip addresses. Terms