Firewalls and Edge Security Gateways

Edge computing offers significant advantages for latency-sensitive, bandwidth-constrained applications. However, its distributed architecture and proximity to heterogeneous, often resource-limited devices introduce unique security challenges. This chapter focuses on the evolving role of firewalls as critical components of access control and threat mitigation at the edge. We begin by revisiting foundational models of network-layer firewalls, with an emphasis on structured rule analysis and decision diagrams. Building upon this, we examine how firewalls can be modularized and deployed across multiple edge devices, supporting both centralized and collaborative architectures. As security demands become more dynamic and context-dependent, we explore the shift toward application-layer and next-generation firewalls that are capable of deep packet inspection and complex policy enforcement. The final section presents the integration of machine learning techniques, enabling adaptive, intelligent firewalls that can detect anomalies, respond to emerging threats, and enforce context-aware policies in real time. Throughout, we highlight both the theoretical underpinnings and practical constraints of deploying such systems in edge environments. This chapter aims to equip researchers and practitioners with a structured understanding of firewall evolution and its pivotal role in edge security.