As you probably know, VerneMQ has different options when it comes to Authentication and Authorization. But let's take a step back here, and look into Authorization only (the more complex issue of both). We'll go through a couple of basic questions ...
Let's have a look together at a nice little feature that makes integration between proxy components like load balancers and VerneMQ a little bit easier. HAProxy was the first to implement it, and you can find the current specification of the protocol ...
TCP buffers are probably not the main and first thing you think about when you start working with VerneMQ.
But, oh my, are they essential!
MQTT is a TCP based protocol, and VerneMQ is TCP/TLS server-based software. Knowing your ways around TCP stuff ...