Pocket Minecraft Protocol
Unlike the Minecraft protocol, this protocol uses UDP with (so far observed, at least) one message per packet. This makes the protocol easier to work with when it comes to packet serialization, and might offer latency improvements, but will inevitably have the usual UDP issues (packets lost, truncated, duplicated, out-of-order, etc.).
Servers listen on UDP port 19132.
Clients don't pick any specific port to listen on.
Please note that even where packet field names are written in this page, these are still largely hypothetical and could well be incorrect guesses. Some packets are fixed to the RakNet protocol, and will be marked as "RakNet Packet", which means that these packets will not change on future versions.
It has been determined that PM uses RakNet for its networking library, some documentation that seems relevant.
Contents
- 1 Terminology
- 2 Types
- 3 Packets
- 3.1 ID_UNCONNECTED_PING_OPEN_CONNECTIONS (0x02)
- 3.2 ID_OPEN_CONNECTION_REQUEST_1 (0x05)
- 3.3 ID_OPEN_CONNECTION_REPLY_1 (0x06)
- 3.4 ID_OPEN_CONNECTION_REQUEST_2 (0x07)
- 3.5 ID_OPEN_CONNECTION_REPLY_2 (0x08)
- 3.6 ID_INCOMPATIBLE_PROTOCOL_VERSION (0x1A)
- 3.7 ID_UNCONNECTED_PING_OPEN_CONNECTIONS (0x1C)
- 3.8 ID_ADVERTISE_SYSTEM (0x1D)
- 3.9 ID_RESERVED_7 (0x84)
- 3.10 Unknown (0x8C)
- 3.11 Unknown (0xC0)
- 4 Packet Dumps
Terminology
- PM
- Pocket Minecraft (aka Minecraft PE or Minecraft Pocket Edition)
Types
| Size | Range | Notes | |
|---|---|---|---|
| byte | 1 | -128 to 127 | Signed, two's complement |
| short | 2 | -32768 to 32767 | Signed, two's complement |
| int32 | 4 | -2147483648 to 2147483647 | Signed, two's complement |
| int64 | 8 | Maybe a double? | |
| MAGIC | 16 | 0x00ffff00fefefefefdfdfdfd12345678
|
always hex bytes 0x00ffff00fefefefefdfdfdfd12345678, corresponding to RakNet's default OFFLINE_MESSAGE_DATA_ID
|
| string | ≥ 1 | N/A | Prefixed by a short containing the length of the string in characters. It appears that only the following ASCII characters can be displayed: !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~ |
Packets
All packets start with a single byte that identifies the packet type, the rest of the packet follows it.
ID_UNCONNECTED_PING_OPEN_CONNECTIONS (0x02)
Client to Broadcast
RakNet Packet
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x02 | Ping ID | int64 | 0x00000000003c6d0d
|
Time since start in Milliseconds |
| MAGIC | MAGIC | |||
| Total Size: | 25 Bytes | |||
Clients start out by sending this packet to the IP broadcast address on port 19132 repeatedly (approx once per second) when joining a server was chosen on the main screen, and stops when the user selects a server (or leaves the screen). The ping ID from the client increases over time, and appears to be the number of milliseconds since the client program was started (might be used to measure server response latency).
ID_OPEN_CONNECTION_REQUEST_1 (0x05)
Client to Server
RakNet Packet
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x05 | MAGIC | MAGIC | ||
| Protocol Version | byte | 5
|
Currently 5 | |
| Null Payload | many 0x00 bytes | 0x00 * 1447
|
MTU (Maximum Transport Unit) | |
| Total Size: | 18 Bytes + lenght of Null Payload | |||
If the version is different than yours, reply with a [[#0x1A|ID_INCOMPATIBLE_PROTOCOL_VERSION (0x1A)]
Sent from client after it receives packet 0x1d. The client will repeatedly send this with reducing sizes until it successfully receives a reply. Observed behaviour is that the client will send packets ~0.5s apart in the following way, until it gets a 0x06 response packet, or reaches the end of these: 4 packets of Null Payload lenght of 1447 4 packets of Null Payload lenght of 1155 5 packets of Null Payload lenght of 531 If the server doesnt't reply the client, the client will display a "Connect Error" window
ID_OPEN_CONNECTION_REPLY_1 (0x06)
Server to Client
RakNet Packet
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x06 | MAGIC | MAGIC | ||
| Server ID | int64 | 0x00000000372cdc9e
|
This value seems to be constant for an installation of PM, or differs between the demo and full version. | |
| Server Security | byte | 0
|
Always 0 | |
| MTU Size | short | 1447
|
Lenght of 0x05. Used to determine packet loss and max UDP packet size (MTU) | |
| Total Size: | 28 Bytes | |||
Sent from server after it receives packet 0x05.
ID_OPEN_CONNECTION_REQUEST_2 (0x07)
Client to Server
RakNet Packet
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x07 | MAGIC | MAGIC | ||
| Security + Cookie | 1 + 4 bytes | 0x043f57fefd
|
Unused, constant value | |
| Server UDP Port | short | 19132
|
||
| MTU Size | short | 1464
|
||
| Client ID | int64 | 0x00000000372cdc9e
|
The Client / Server ID will be the same for a given device | |
| Total Size: | 34 Bytes | |||
Sent from client in response to packet 0x06.
ID_OPEN_CONNECTION_REPLY_2 (0x08)
Server to Client
RakNet Packet
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x08 | MAGIC | MAGIC | ||
| Server ID | int64 | 0x00000000372cdc9e
|
||
| Client UDP Port | short | 46946
|
||
| MTU Size | short | 1464
|
||
| Security | byte | 0
|
Always 0 | |
| Total Size: | 30 Bytes | |||
Sent from server in response to packet 0x07.
ID_INCOMPATIBLE_PROTOCOL_VERSION (0x1A)
Server to Client
RakNet Packet
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x1A | Protocol Version | byte | 5
|
|
| MAGIC | MAGIC | |||
| Server ID | int64 | 0x00000000372cdc9e
|
||
| Total Size: | 26 Bytes | |||
ID_UNCONNECTED_PING_OPEN_CONNECTIONS (0x1C)
Server to Client
RakNet Packet
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x1C | Ping ID | int64 | 0x00000000003c6d0d
|
Time since start in Milliseconds |
| Server ID | int64 | 0x00000000372cdc9e
|
||
| MAGIC | MAGIC | |||
| Data | string | MCCPP;Demo;Steve
|
Used to send the username (MCCPP;Demo; + username) | |
| Total Size: | 35 Bytes + lenght of string | |||
Server sends this packet in response to a 0x02 packet. Depends of the version to send a 0x1D or a 0x1C If the Server is invisible, this packet will be sent without username
ID_ADVERTISE_SYSTEM (0x1D)
Server to Client
RakNet Packet
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x1D | Ping ID | int64 | 0x00000000003c6d0d
|
Time since start in Milliseconds |
| Server ID | int64 | 0x00000000372cdc9e
|
||
| MAGIC | MAGIC | |||
| Data | string | MCCPP;Demo;Steve
|
Used to send the username (MCCPP;Demo; + username) | |
| Total Size: | 35 Bytes + lenght of string | |||
Same as ID_UNCONNECTED_PING_OPEN_CONNECTIONS (0x1C), but with the Packet ID changed. Depends of the version to send a 0x1D or a 0x1C
ID_RESERVED_7 (0x84)
Two-Way
This packet is part of the real Minecraft PE implementation. The structure can change anytime.
This packet has a partial unknown structure
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x84 | Packet Order ID | byte? | 2
|
Could be used to reorder packets |
| Unknown | variable | |||
| Total Size: | ? Bytes | |||
Sent after 0x08, and 0xC0. Packet Order is independient from server/client
Different 0x84 values sent in a session, use this to help understand this packet
Unknown (0x8C)
Server to Client
This packet is part of the real Minecraft PE implementation. The structure can change anytime.
This packet has a partial unknown structure, but it seems to complement the packet 0x84. Packet Order count continues from the last value of 0x84. Could be Chunk Data
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x8C | Packet Order ID | byte? | 57
|
Could be used to reorder packets |
| Unknown | variable | |||
| Total Size: | 1 + ? Bytes | |||
Sent after 0x84
Unknown (0xC0)
Two-Way
This packet is part of the real Minecraft PE implementation. The structure can change anytime.
| Packet ID | Field Name | Field Type | Example | Notes |
| 0xC0 | Ping ID | 6 bytes | 0x000101000000
|
|
| Total Size: | 7 Bytes | |||
Sent by the Client after the first 0x84. Then, the Server replies with the same packet
Packet Dumps
Due to the lack of information about the protocol, packet dumps are welcome. You can also post here pcap files of Client <-> Server sessions
