e to this issue TLSv1.3 and DTLS include a stateless cookie mechanism. The idea is that when a client attempts to connect to a server it sends a ClientHello message. The server responds with a HelloRetryRequest (in TLSv1.3) or a HelloVerifyRequest (in DTLS) which contains a unique cookie. The client then resends the ClientHello, but this time includes the cookie in the message thus proving that the client is capable of receiving messages sent to that address. All of this can be done by the server without al