The FireBrick has some specific features which are not found in many brokers.
- Concurrent MQTT and MQTTS operation - which can be separate or allow messages between the two.
- Feature to expire session states after a period when not connected.
- Feature to expire retained messages after a period when not connected. Very useful if you use MQTT to provision and reconfigure devices as otherwise old retained messages can linger forever.
- Not yet, but MQTT/MQTTS client with option to relay/aggregate clients to an external server.
- Integration with internal FireBrick features (see below).
- Allows weaker ciphers (RSA negotiation rather the DH) as common on ESP8266 TLS builds (can be disabled).
