之前講到的PUBREC、PUBREC、PUBREL、PUBCOMP等等，都是MQTT控制封包類型的一種，總共定義了16種。
Server：MQTT Broker
Client：發佈者、訂閱者
| 名稱 | 值 | 流向 | 說明 |
|---|---|---|---|
| Reserved | 0 | Forbidden | 保留 |
| CONNECT | 1 | Client to Server | Connection request |
| CONNACK | 2 | Server to Client | Connect acknowledgment |
| PUBLISH | 3 | Client to Server or Server to Client | Publish message |
| PUBACK | 4 | Client to Server or Server to Client | Publish acknowledgment (QoS 1) |
| PUBREC | 5 | Client to Server or Server to Client | Publish received (QoS 2 delivery part 1) |
| PUBREL | 6 | Client to Server or Server to Client | Publish release (QoS 2 delivery part 2) |
| PUBCOMP | 7 | Client to Server or Server to Client | Publish complete (QoS 2 delivery part 3) |
| SUBSCRIBE | 8 | Client to Server | Subscribe request |
| SUBACK | 9 | Server to Client | Subscribe acknowledgment |
| UNSUBSCRIBE | 10 | Client to Server | Unsubscribe request |
| UNSUBACK | 11 | Server to Client | Unsubscribe acknowledgment |
| PINGREQ | 12 | Client to Server | PING request |
| PINGRESP | 13 | Server to Client | PING response |
| DISCONNECT | 14 | Client to Server or Server to Client | Disconnect notification |
| AUTH | 15 | Client to Server or Server to Client | Authentication exchange |
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