知行合一，止于至善
千里之行，始于足下；合抱之木，生于毫末；九层之台，起于累土MQTT协议简介
7月 4, 2023 |
Nix.Huang
tcpdump -nn -X -i ens33 port 1883
报文格式
| bit | 7-4 | 3 | 2-1 | 0 |
|---|---|---|---|---|
| byte1 | Message Type | DUP flag | QoS level | RETAIN |
| byte2 | Remaining Length | |||
CONNECT(0x1)
control + length + protocol name + Protocol Level +Connect Flags + keep alive +Payload
PUBLISH(3)
control + length + topic(length+name) + Packet identifier + payload
SUBSCRIBE(8)
control + length + Packet identifier + topic(length+name)
PINGREQ(12)
DISCONNECT(14)
参考文档
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