We consider the authentication of IoT devices for every transaction and develop a fast and secure authentication protocol. Our key idea is to leverage highly secure Physically Unclonable Functions (PUFs) and high-speed programmable switch and offload PUF-based authentication protocol to the switch. By doing so, it enables authentication of every transaction at network speed. In this work, we demonstrate the feasibility of our idea by offloading the authentication protocol to a programmable switch with Tofino, XDP and Server.