**2. The structure of the internet: security from data Centre to the edge**

There is a proverb in the English language that says that a chain is only as strong as its weakest link. This applies directly as a basic principle of cybersecurity. Edge computing still requires communications to a central data centre, at least some of the time. It follows that it is necessary to consider carefully the WAN and LAN technologies used. **Figure 1** illustrates the networking technologies used and shows the position of edge computing within the wider fog computing environment, which we describe in a later part of this section. The section begins by discussing each networking technology separately and in doing so refers briefly to the history of the development of data networking technologies in general and to the development of the Internet in particular.
