I'm building a IPv6 enabled FTP container based on pure-ftpd and I have the problem that passive mode needs the client to connect on any port in the range of 30000 to 50000 to the server on the container.
Right now I don't have a solution for opening the port range for the container. With IPv4 I managed to do that with iptables and NAT, but for IPv6 the NAT table is empty. I see, that when I publish a port with IPv6, instead of using iptables like on IPv4, docker listens on that port. What kind of magic it does I don't know.
Maybe a solution would be to assign an address to the container, but I couldn't find a way to do that or I didn't see it.
What possible solutions are there, to forward the whole port range to the server in the container?