Docker network connectivity up until this point has relied on exposing individual services hosted in a container to the physical network. However, what if you want to expose a service from one container to another without exposing it to the Docker host? In this recipe we'll walk through how to map services between two containers running on the same Docker host.
You'll need access to a Docker host and an understanding of how your Docker host is connected to the network. In this recipe, we'll be using the docker1 host that we used in previous recipes. You'll want to make sure that you have access to view iptables rules to verify netfilter policies. If you wish to download and run example containers, your Docker host will also need access to the Internet. In some cases, the changes we make may require you to have root-level access to the system.