No IPv6 connectivity from docker container

Solution 1:

So after waiting two weeks for an answer and researching another few hours after opening up a bounty i found the solution.

1. Set up a new IPv6 enabled network and assign a subnet available to me (a /80 of my /64)

   docker network create --ipv6 --subnet=w:x:y:z:aaaa::/80 myfancynetwork
   

   Now start a container and connect it to the new network. Find out it's IP address. Let's say it's w:x:y:z:aaaa::5 in this example.

2. Enable proxy_ndp

   sysctl net.ipv6.conf.eth0.proxy_ndp=1
   

   You may also configure this setting via /etc/sysctl.conf, to make it persistent.

3. Add proxy to make my host (IPv6 enable) to respond to Neighbour Sollicitation messages from my router (like: "hey, who's hosting w:x:y:z:aaaa::5?") with Neighbour Advertisement messages ("that would be me!").

   ip -6 neigh add proxy w:x:y:z:aaaa::5 dev eth0
   

   ndppd may help you to automatically advertize any hosts on your network.

Bam, that's it.