> Any time you have a UDP-based protocol where a small packet to the server results in a large packet from the server will be exploited

In other news, water is wet.

Seriously folks, if you don't already know this you shouldn't be designing any protocols. Datagram or stream-based.

> That's one reason for the TCP three-way handshake.

And its horrendous latency.

All of the mitigations for that open up resource exhaustion attacks; frying pan, meet fire.

There's no free lunch. Datagram protocols are not going away.