QUIC is a new transport protocol meant to be the replacement of the TCP + TLS, which is on top of UDP. Other the security mechanisms provided by TLS, QUIC itself has offered an extension for an endpoint to do an identity verification to the remote endpoint, to prevent from traffic amplification attack. It’s called address validation, and it would be done along side with initial handshakes between client and server. This post will briefly talked about how this is done within QUIC.