As we saw in the last recipe, one of the major differences with IPv6 support in Docker is the lack of the firewall integration. Without that integration, we lose things like outbound masquerade and full port publishing capabilities. And while this may not be necessary in all cases, there is a certain convenience factor that is lost when not using this. For instance, when running in IPv4 only mode, an administrator could install Docker and immediately connect your containers to the outside network. This is because the container was only ever seen through the Docker host's IP addresses for both inbound (published port) and outbound (masquerade) connectivity. This meant that there was no need to inform the outside network about additional subnets because the outside network only ever saw the Docker host's IP addresses. In the IPv6 model, the outside network has to know about the container subnets in order to route to them. In this chapter, we'll review how to configure...