The host network

There exist occasions where we want to run a container in the network namespace of the host. This can be necessary when we need to run some software in a container that is used to analyze or debug the host network's traffic. But keep in mind that these are very specific scenarios. When running business software in containers, there is no good reason to ever run the respective containers attached to the host's network. For security reasons, it is strongly recommended that you do not run any such container attached to the host network on a production or production-like environment.

That said, how can we run a container inside the network namespace of the host? Simply by attaching the container to the host network:

$ docker container run --rm -it --network host alpine:latest /bin/sh

If we now use the ip tool to analyze the network namespace from within the container, we will see that we get exactly the same picture as we would if we were running the ip tool directly on the host...