MQTTs

MQTTs refers to the secure variant of the Message Queuing Telemetry Transport (MQTT) protocol, achieved by using TLS/SSL to protect communications in transit. It preserves the lightweight publish-subscribe model of MQTT while providing encryption, integrity, and authentication for data exchanged between clients and brokers.

In MQTTs, a client establishes a TLS-secured TCP connection to a broker, typically on a port such as 8883. Once connected, clients publish messages to topics and subscribe to topics to receive messages. Messages are delivered according to the chosen Quality of Service level (0, 1, or 2). MQTT also supports retained messages, Last Will and Testament, and session options that influence message delivery and state. The broker routes messages from publishers to subscribers based on topic filters rather than client identities.

Security and deployment: TLS provides confidentiality and data integrity, while optional client authentication can be enforced with certificates. Authentication methods include TLS client certificates, usernames/passwords, and access control lists managed by the broker. Best practices include enforcing TLS, validating broker certificates, using strong cipher suites, and considering mutual TLS for device authentication. Proper certificate management, regular revocation checks, and appropriate keep-alive settings help maintain secure connections.

Deployment and ecosystem: MQTTs is widely supported by brokers and client libraries across many platforms and languages. Popular brokers include Mosquitto, EMQX, and HiveMQ, among others. It is widely used in IoT, home automation, and telemetry systems where secure, scalable pub/sub messaging is required.