This demo-oriented talk showcases the capabilities and functionality of NEST (Network Enforced Session Types): a tool for generating and deploying network-level runtime monitors that enforce application-level protocols based on session type specifications. NEST monitors can be deployed in networks where hosts cannot trust each other: its network-level enforcement can block faulty traffic before it reaches the destination host. We show that NEST monitors can accurately enforce non-trivial protocols while operating within the limitations of network devices supporting the P4 standard for software-defined networking (e.g. limited expressiveness and memory).