Of all the Linux network constructs we've reviewed in this book, VETH pairs are likely the most essential. Being namespace aware they allow you to connect a container in a unique namespace to any other namespace including the default. And while Docker handles all of this for you, it is useful to be able to determine where the ends of a VETH pair live and correlate them to determine what purpose a VETH pair is serving. In this recipe, we'll review in depth how to find and correlate the ends of a VETH pair.
In this recipe, we'll be using a single Docker host. It is assumed that Docker is installed and in its default configuration. You'll also need root-level access in order to inspect and change the hosts networking and firewall configuration.