Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.1) to the current pre-release

New packets

Entity Head Look (0x23)

Changes the direction an entity's head is facing.

Packet ID	Field Name	Field Type	Example	Notes
0x23	Entity ID	int
	Head Yaw	byte		Head yaw in steps of 2π/256
Total Size:	6 bytes

Update Tile Entity (0x84)

Essentially a block update on a tile entity.

Packet ID	Field Name	Field Type	Example	Notes
0x84	X	int
	Y	short
	Z	int
	Action	byte		The type of update to perform
	Custom 1	int		Varies
	Custom 2	int		Varies
	Custom 3	int		Varies
Total Size:	24 bytes

Actions

• 1: Set mob displayed inside a mob spawner. Custom 1 contains the mob type

Changed packets

Handshake (0x02)

Client to Server

The hostname and port were added to this packet, most likely to allow virtual hosting .(sample implementation)

Packet ID	Field Name	Field Type	Example	Notes
0x02	UsernameAndHost	string	TkTech;localhost:25565	The username of the player attempting to connect, and the host he is connecting to, seperated by a semicolon.
Total Size:	3 bytes + length of strings

Mob Spawn (0x18)

New byte field: head yaw

This needs confirmation!

Packet ID	Field Name	Field Type	Example	Notes
0x18	EID	int	446	Entity ID
	Type	byte	91	The type of mob. See Entities#Mobs
	X	int	13366	The Absolute Integer X Position of the object
	Y	int	2176	The Absolute Integer Y Position of the object
	Z	int	1680	The Absolute Integer Z Position of the object
	Yaw	byte	-27	The yaw in steps of 2π/256
	Pitch	byte	0	The pitch in steps of 2π/256
	Head Yaw	byte		Head yaw in steps of 2π/256
	Metadata	Metadata	127	Varies by mob, see Entities
Total Size:	21 bytes + Metadata (at least 1)

Other changes

Protocol version is now 25.

Protocol History

2012-02-09

• 12w06a
• Protocol version is now 25
• New packet: 0x84

2012-01-26

• 12w04a
• Protocol version has not been changed
• Handshake Packet by client (0x02) now contains the server host and port
• Window Open Packet (0x64): WindowTitle is now longer than accepted by older clients. Contains a keyword such as "container.furnace"

2012-01-19

• 12w03a
• Protocol version is now 24
• New packet: 0x23
• MobSpawn: new field, 1 byte inserted before metadata.