Docker Configuration via /etc/docker/daemon.json

{
        "iptables": false,
        "ip-masq": false,
        "userland-proxy": false
}

iptables -A FORWARD -s $dockernetwork -m tcp -p tcp -m conntrack --ctstate NEW -j ACCEPT

{
        "dns": ["192.168.100.254"]
}

{
    "ipv6": true,
    "fixed-cidr-v6": "fd00:fd00::/64"
}

Just “ipv6” is not enough - docker daemon will not start with an error message about non-overlapping IPv6 network.