By default Digitalocean add some custom rc.d scripts for network configuration to your droplet.
You can just append the content of /etc/rc.digitalocean.d/droplet.conf to your /etc/rc.conf
In my case the public ipv4 address is 184.108.40.206 and my first ipv6 address
defaultrouter="220.127.116.11"# ipv6 address are shortend for readabilityipv6_defaultrouter="2a03:b0c0:2:d0::1"ifconfig_vtnet0="inet 18.104.22.168 netmask 255.255.192.0"ifconfig_vtnet0_ipv6="inet6 2a03:b0c0:2:d0::2a5:f001 prefixlen 64"
Digitalocean provides these days for native Ipv6 for the most of its datacenters.
Unlike other hoster they are very spare, when distributing Ipv6
Addresses and only route 16 addresses per droplet (xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxx1 until xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxf).
To make use of these additional ip addresses they have to be assigned to your network interface vtnet0: