The largely distributed nature of fog computing (FC) provides a major attack surface with increased possibilities for attackers. Compared to networks with higher centralization, securing an FC network represents a significant challenge. This issue is complicated since edge nodes are usually resource-constrained and cannot resort to sophisticated cryptographic solutions. Furthermore, the deployment of a public key infrastructure is complicated considering the large number of connected devices. In this chapter, we investigate the challenges and possibilities of wireless communications in fog computing. In particular, we investigate the advantages provided by the adoption of physical layer security (PLS) techniques. Thanks to PLS and the combination of beyond 5G technologies, we show how an FC network can be secured using low-complexity PLS solutions viable for resource-constrained devices. We also show how PLS solutions can guarantee important features in an FC network, such as authorization and location verification.