Pre-release protocol

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Under construction

In light of the recent release of Minecraft 1.9, this article still contains some changes between 1.8.9 and 1.9, which are currently being merged into Protocol. If you want to contribute, please coordinate with us in #mcdevs, and ping Fenhl before making any edits.

This page documents the changes from the last stable Minecraft release (currently 1.9, protocol 107) to the current pre-release (currently 1.9, protocol 107). Note that this page contains bleeding-edge information that may not be completely or correctly documented.

One who wishes to commandeer the merging of this into Protocol when an update is made must be sure to respect any changes that may have occurred to the respective packets there.

Contents

Data types

No changes so far.

Packets

ID Packet name Documentation
Play clientbound
0x17 Set Cooldown Current Pre
0x19 Named Sound Effect Current Pre
0x1B Entity Status Current Pre
0x1D Unload Chunk Current Pre
0x20 Chunk Data Current Pre
0x24 Map Current Pre
0x25 Entity Relative Move Current Pre
0x26 Entity Look And Relative Move Current Pre
0x29 Vehicle Move Current Pre
0x2C Combat Event Current Pre
0x2E Player Position And Look Current Pre
0x2F Use Bed Current Pre
0x3A Attach Entity Current Pre
0x3C Entity Equipment Current Pre
0x40 Set Passengers Current Pre
0x41 Teams Current Pre
0x47 Sound Effect Current Pre
0x4A Entity Teleport Current Pre
0x4B Entity Properties Current Pre
0x4C Entity Effect Current Pre
Play serverbound
0x00 Teleport Confirm Pre
0x14 0x01 Tab-Complete Current Pre
0x01 0x02 Chat Message Current (unchanged)
0x16 0x03 Client Status Current Pre
0x15 0x04 Client Settings Current Pre
0x0F 0x05 Confirm Transaction Current (unchanged)
0x11 0x06 Enchant Item Current (unchanged)
0x0E 0x07 Click Window Current (unchanged)
0x0D 0x08 Close Window Current (unchanged)
0x17 0x09 Plugin Message Current (unchanged)
0x02 0x0A Use Entity Current Pre
0x00 0x0B Keep Alive Current (unchanged)
0x04 0x0C Player Position Current (unchanged)
0x06 0x0D Player Position And Look Current (unchanged)
0x05 0x0E Player Look Current (unchanged)
0x03 0x0F Player Current (unchanged)
0x10 Vehicle Move (serverbound) Pre
0x11 Steer Boat Pre
0x13 0x12 Player Abilities Current (unchanged)
0x07 0x13 Player Digging Current Pre
0x0B 0x14 Entity Action Current Pre
0x0C 0x15 Steer Vehicle Current (unchanged)
0x19 0x16 Resource Pack Status Current (unchanged)
0x09 0x17 Held Item Change Current (unchanged)
0x10 0x18 Creative Inventory Action Current (unchanged)
0x12 0x19 Update Sign Current Pre
0x0A 0x1A Animation Current Pre
0x18 0x1B Spectate Current (unchanged)
0x08 0x1C Player Block Placement Current Pre
0x1D Use Item Pre
Status clientbound
0x00 Response Current (unchanged)
0x01 Pong Current (unchanged)
Status serverbound
0x00 Request Current (unchanged)
0x01 Ping Current (unchanged)
Login clientbound
0x00 Disconnect Current (unchanged)
0x01 Encryption Request Current (unchanged)
0x02 Login Success Current (unchanged)
0x03 Set Compression Current (unchanged)
Login serverbound
0x00 Login Start Current (unchanged)
0x01 Encryption Response Current (unchanged)

New/modified data types

None so far.

Handshaking

Clientbound

No changes so far.

Serverbound

No changes so far.

Play

Clientbound

Entity Relative Move

This packet is sent by the server when an entity moves less then 1024 blocks; if an entity moves more than 1024 blocks Entity Teleport should be sent instead.

This packet allows at most 1024 blocks movement in any direction, because short range is from -32768 to -32767.


Packet ID State Bound To Field Name Field Type Notes
0x15 0x25 Play Client Entity ID VarInt
Delta X Byte Short Change in X position as a Fixed-Point number (currentX * 32 - prevX * 32) * 128
Delta Y Byte Short Change in Y position as a Fixed-Point number (currentY * 32 - prevY * 32) * 128
Delta Z Byte Short Change in Z position as a Fixed-Point number (currentZ * 32 - prevZ * 32) * 128
On Ground Boolean

Entity Look And Relative Move

This packet is sent by the server when an entity rotates and moves. Since a short range is limited from -32768 to 32767, and movement is offset of fixed-point numbers, this packet allows at most 1024 blocks movement in any direction. (-32768/32 == -1024)

Packet ID State Bound To Field Name Field Type Notes
0x17 0x26 Play Client Entity ID VarInt
Delta X Byte Short Change in X position as a Fixed-Point number (currentX * 32 - prevX * 32) * 128
Delta Y Byte Short Change in Y position as a Fixed-Point number (currentY * 32 - prevY * 32) * 128
Delta Z Byte Short Change in Z position as a Fixed-Point number (currentZ * 32 - prevZ * 32) * 128
Yaw Angle New angle, not a delta
Pitch Angle New angle, not a delta
On Ground Boolean

Vehicle Move

Note that all fields use absolute positioning and do not allow for relative positioning.

Packet ID State Bound To Field Name Field Type Notes
0x29 Play Client X Double Absolute position (X coordinate)
Y Double Absolute position (Y coordinate)
Z Double Absolute position (Z coordinate)
Yaw Float Absolute rotation on the vertical Axis, in degrees
Pitch Float Absolute rotation on the horizontal Axis, in degrees

Combat Event

Packet ID State Bound To Field Name Field Type Notes
0x42 0x2C Play Client Event VarInt Enum Determines the layout of the remaining packet
Event Field Name
0: enter combat no fields no fields
1: end combat Duration VarInt
Entity ID Int
2: entity dead Player ID VarInt
Entity ID Int
Message String Chat

Player Position And Look

Updates the player's position on the server.

If the distance between the last known position of the player on the server and the new position set by this packet is greater than 100 meters, the client will be kicked for “You moved too quickly :( (Hacking?)”.

Also if the fixed-point number of X or Z is set greater than 3.2E7D the client will be kicked for “Illegal position”.

Yaw is measured in degrees, and does not follow classical trigonometry rules. The unit circle of yaw on the XZ-plane starts at (0, 1) and turns counterclockwise, with 90 at (-1, 0), 180 at (0, -1) and 270 at (1, 0). Additionally, yaw is not clamped to between 0 and 360 degrees; any number is valid, including negative numbers and numbers greater than 360.

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

The yaw in degrees of a player standing at point (x0, z0) and looking towards point (x, z) can be calculated with:

l = x-x0
w = z-z0
c = sqrt( l*l + w*w )
alpha1 = -arcsin(l/c)/PI*180
alpha2 =  arccos(w/c)/PI*180
if alpha2 > 90 then
    yaw = 180 - alpha1
else
    yaw = alpha1

You can get a unit vector from a given yaw/pitch via:

x = -cos(pitch) * sin(yaw)
y = -sin(pitch)
z =  cos(pitch) * cos(yaw)
Packet ID State Bound To Field Name Field Type Notes
0x08 0x2E Play Client X Double Absolute or relative position, depending on Flags
Y Double Absolute or relative position, depending on Flags
Z Double Absolute or relative position, depending on Flags
Yaw Float Absolute or relative rotation on the X Axis, in degrees
Pitch Float Absolute or relative rotation on the Y Axis, in degrees
Flags Byte Bit field, see below
Teleport ID VarInt Client should confirm this packet with Teleport Confirm containing the same Teleport ID

About the Flags field:

<Dinnerbone> It's a bitfield, X/Y/Z/Y_ROT/X_ROT. If X is set, the x value is relative and not absolute.
Field Bit
X 0x01
Y 0x02
Z 0x04
Y_ROT 0x08
X_ROT 0x10

Attach Entity

This packet is sent when a player has been attached to an entity (e.g. Minecart).

Packet ID State Bound To Field Name Field Type Notes
0x1B 0x3A Play Client Entity ID Int Attached entity's EID
Vehicle ID Int Vechicle's Entity ID. Set to -1 to detach
Leash Boolean If true leashes the entity to the vehicle

Entity Equipment

Packet ID State Bound To Field Name Field Type Notes
0x04 0x3C Play Client Entity ID VarInt Entity's EID
Slot Short VarInt Enum Equipment slot. 0: main hand, 1: off hand, 1–4 2–5: armor slot (2: boots, 3: leggings, 4: chestplate, 5: helmet)
Item Slot

Set Passengers

Packet ID State Bound To Field Name Field Type Notes
0x40 Play Client Entity ID VarInt Vehicle's EID
Passenger Count VarInt Number of passengers in the array.
Passengers Array of VarInt EIDs of entity's passengers

Teams

Creates and updates teams.

Packet ID State Bound To Field Name Field Type Notes
0x3E 0x41 Play Client Team Name String A unique name for the team. (Shared with scoreboard).
Mode Byte Enum 0: create team, 1: remove team, 2: update team info; 3: add players to team; 4: remove players from team
Team Display Name Optional String Only if Mode is 0 or 2.
Team Prefix Optional String Only if Mode is 0 or 2. Displayed before the players' name that are part of this team.
Team Suffix Optional String Only if Mode is 0 or 2. Displayed after the players' name that are part of this team.
Friendly Fire Optional Byte Only if Mode is 0 or 2. 0 for off, 1 for on, 3 for seeing friendly invisibles.
Name Tag Visibility Optional String Only if Mode is 0 or 2. always, hideForOtherTeams, hideForOwnTeam, never.
Collision Rule Optional String Only if Mode is 0 or 2. always, pushOtherTeams, pushOwnTeam, never
Color Optional Byte Only if Mode is 0 or 2. Same as Chat colors.
Player Count Optional VarInt Only if Mode is 0 or 3 or 4. Number of players in the array.
Players Optional Array of String Only if Mode is 0 or 3 or 4. Players to be added/remove from the team. Max 40 characters so may be uuid's later.

Sound Effect

Packet ID State Bound To Field Name Field Type Notes
0x47 Play Client Sound ID VarInt ID of hardcoded sound event (events)
Sound Category VarInt Enum The category that this sound will be played from (current categories)
Effect Position X Int Effect X multiplied by 8
Effect Position Y Int Effect Y multiplied by 8
Effect Position Z Int Effect Z multiplied by 8
Volume Float 1.0 is 100%, capped between 0.0 and 1.0 by vanilla client
Pitch Unsigned Byte Float multiplied by 63.5, capped between 0.5 and 2.0 by vanilla client

Entity Teleport

This packet is sent by the server when an entity moves more than 1024 blocks.

Packet ID State Bound To Field Name Field Type Notes
0x18 0x4A Play Client Entity ID VarInt
X Int Double
Y Int Double
Z Int Double
Yaw Angle New angle, not a delta
Pitch Angle New angle, not a delta
On Ground Boolean

Entity Properties

Packet ID State Bound To Field Name Field Type Notes
0x20 0x4B Play Client Entity ID VarInt
Number Of Properties Int Number of elements in the following array
Property Key Array String See below
Value Double See below
Number Of Modifiers VarInt Number of elements in the following array
Modifiers Array of Modifier Data See Attribute#Modifiers. Modifier Data defined below.

Known Key values (see also Attribute#Modifiers):

Key Default Min Max Label
generic.maxHealth 20.0 0.0 Double.MaxValue 1024.0 Max Health
generic.followRange 32.0 0.0 2048.0 Follow Range
generic.knockbackResistance 0.0 0.0 1.0 Knockback Resistance
generic.movementSpeed 0.699999988079071 0.0 Double.MaxValue 1024.0 Movement Speed
generic.attackDamage 2.0 0.0 Double.MaxValue 2048.0 Attack Damage
generic.attackSpeed 4.0 0.0 1024.0 Attack Speed
horse.jumpStrength 0.7 0.0 2.0 Jump Strength
zombie.spawnReinforcements 0.0 0.0 1.0 Spawn Reinforcements Chance

Modifier Data structure:

Field Name Field Type Notes
UUID UUID
Amount Double
Operation Byte

Entity Effect

Packet ID State Bound To Field Name Field Type Notes
0x1D 0x4C Play Client Entity ID VarInt
Effect ID Byte See this table
Amplifier Byte Notchian client displays effect level as Amplifier + 1
Duration VarInt Seconds
Hide Particles Boolean Byte

Map Chunk Bulk

Replaced by multiple Chunk Data packets.

Update Entity NBT

Wasn't used for anything.

Serverbound

Teleport Confirm

Sent by client as confirmation of Player Position And Look packet.

Packet ID State Bound To Field Name Field Type Notes
0x00 Play Server Teleport ID VarInt

Tab-Complete

Sent when the user presses tab while writing text.

Packet ID State Bound To Field Name Field Type Notes
0x14 0x01 Play Server Text String All text behind the cursor (e.g. to the left of the cursor in left-to-right languages like English)
Assume Command Boolean If true, the server will parse Text as a command even if it doesn't start with a /. Used in the command block GUI.
Has Position Boolean
Looked At Block Optional Position The position of the block being looked at. Only sent if Has Position is true.

Client Status

Sent when the client is ready to complete login and when the client is ready to respawn after death.

Packet ID State Bound To Field Name Field Type Notes
0x16 0x03 Play Server Action ID VarInt Enum See below

Action ID values:

Action ID Action
0 Perform respawn
1 Request stats
2 Taking Inventory achievement Open Inventory

Client Settings

Sent when the player connects, or when settings are changed.

Packet ID State Bound To Field Name Field Type Notes
0x15 0x04 Play Server Locale String e.g. en_GB
View Distance Byte Client-side render distance, in chunks
Chat Mode Byte VarInt Enum 0: enabled, 1: commands only, 2: hidden
Chat Colors Boolean “Colors” multiplayer setting
Displayed Skin Parts Unsigned Byte Skin parts, see note below
Main Hand VarInt Enum 0: Left, 1: Right

Displayed Skin Parts flags:

  • Bit 0 (0x01): Cape enabled
  • Bit 1 (0x02): Jacket enabled
  • Bit 2 (0x04): Left Sleeve enabled
  • Bit 3 (0x08): Right Sleeve enabled
  • Bit 4 (0x10): Left Pants Leg enabled
  • Bit 5 (0x20): Right Pants Leg enabled
  • Bit 6 (0x40): Hat enabled

The most significant bit (bit 7, 0x80) appears to be unused.

Use Entity

This packet is sent from the client to the server when the client attacks or right-clicks another entity (a player, minecart, etc).

A Notchian server only accepts this packet if the entity being attacked/used is visible without obstruction and within a 4-unit radius of the player's position.

Note that middle-click in creative mode is interpreted by the client and sent as a Creative Inventory Action packet instead.

Packet ID State Bound To Field Name Field Type Notes
0x02 0x0A Play Server Target VarInt
Type VarInt Enum 0: interact, 1: attack, 2: interact at
Target X Optional Float Only if Type is interact at
Target Y Optional Float Only if Type is interact at
Target Z Optional Float Only if Type is interact at
Hand Optional VarInt Enum Only if Type is interact or interact at; 0: main hand, 1: off hand

Vehicle Move (serverbound)

Sent when a player moves in a vehicle. Fields are the same as in Player Position And Look. Note that all fields use absolute positioning and do not allow for relative positioning.

Packet ID State Bound To Field Name Field Type Notes
0x10 Play Server X Double Absolute position (X coordinate)
Y Double Absolute position (Y coordinate)
Z Double Absolute position (Z coordinate)
Yaw Float Absolute rotation on the vertical Axis, in degrees
Pitch Float Absolute rotation on the horizontal Axis, in degrees

Steer Boat

Packet ID State Bound To Field Name Field Type Notes
0x11 Play Server Boolean Unknown
Boolean Unknown 2

Player Digging

Sent when the player mines a block. A Notchian server only accepts digging packets with coordinates within a 6-unit radius of the player's position.

Packet ID State Bound To Field Name Field Type Notes
0x07 0x13 Play Server Status Byte Enum The action the player is taking against the block (see below)
Location Position Block position
Face Byte Enum The face being hit (see below)

Status can be one of seven values:

Value Meaning Notes
0 Started digging
1 Cancelled digging Sent when the player lets go of the Mine Block key (default: left click)
2 Finished digging Sent when the client thinks it is finished
3 Drop item stack Triggered by using the Drop Item key (default: Q) with the modifier to drop the entire selected stack (default: depends on OS). Location is always set to 0/0/0, Face is always set to -Y.
4 Drop item Triggered by using the Drop Item key (default: Q). Location is always set to 0/0/0, Face is always set to -Y.
5 Shoot arrow / finish eating Location is always set to 0/0/0, Face is always set to Special.
6 Swap item in hand Used to swap or assign an item to the second hand. Location is always set to 0/0/0, Face is always set to -Y.

The Face field can be one of the following values, representing the face being hit (or the Special value used for “shoot arrow / finish eating”):

Value Offset Face
0 -Y Bottom
1 +Y Top
2 -Z North
3 +Z South
4 -X West
5 +X East
255 Special

Entity Action

Sent at least when crouching, leaving a bed, or sprinting. To send action animation to client use 0x28. The client will send this with Action ID = 3 when “Leave Bed” is clicked.

Packet ID State Bound To Field Name Field Type Notes
0x0B 0x14 Play Server Entity ID VarInt Player ID
Action ID VarInt Enum The ID of the action, see below
Jump Boost VarInt Horse jump boost. Ranged from 0 to 100.

Action ID can be one of the following values:

ID Action
0 Crouch
1 Uncrouch
2 Leave bed
3 Start sprinting
4 Stop sprinting
5 Start Jump with horse
6 Stop Jump with horse
7 Open ridden horse inventory
8 Start Elytra Flying

“Open inventory” is now sent via the Client Status packet.

Update Sign

This message is sent from the client to the server when the “Done” button is pushed after placing a sign.

Packet ID State Bound To Field Name Field Type Notes
0x12 0x19 Play Server Location Position Block Coordinates
Line 1 Chat String First line of text in the sign
Line 2 Chat String Second line of text in the sign
Line 3 Chat String Third line of text in the sign
Line 4 Chat String Fourth line of text in the sign

Animation

Sent when the player's arm swings.

Packet ID State Bound To Field Name Field Type Notes
0x0A 0x1A Play Server Hand VarInt Enum Hand used for the animation

Player Block Placement

Packet ID State Bound To Field Name Field Type Notes
0x08 0x1C Play Server Location Position Block position
Face Byte VarInt Enum The face on which the block is placed (as documented at Player Digging)
Held Item Slot
Hand VarInt Enum The hand from which the block is placed; 0: main hand, 1: off hand
Cursor Position X Unsigned Byte The position of the crosshair on the block, from 0 to 15 increasing from west to east
Cursor Position Y Unsigned Byte The position of the crosshair on the block, from 0 to 15 increasing from bottom to top
Cursor Position Z Unsigned Byte The position of the crosshair on the block, from 0 to 15 increasing from north to south

In normal operation (i.e. placing a block), this packet is sent once, with the values set normally.

The Cursor Position X/Y/Z fields (also known as in-block coordinates) are calculated using raytracing. The unit corresponds to one pixel in the default resource pack. For example, let's say a slab is being placed against the south face of a full block. The Cursor Position X will be higher if the player was pointing near the right (east) edge of the face, lower if pointing near the left. The Cursor Position Y will be used to determine whether it will appear as a bottom slab (values 0–7) or as a top slab (values 8–15). The Cursor Position Z should be 15 since the player was looking at the southernmost part of the block.

This packet has a special case where X, Y, Z, and Direction are all -1. (Note that Y is unsigned so set to 255.) This special packet indicates that the currently held item for the player should have its state updated such as eating food, pulling back bows, using buckets, etc.

Special note on using buckets: When using buckets, the Notchian client might send two packets: first a normal and then a special case. The first normal packet is sent when you're looking at a block (e.g. the water you want to scoop up). This normal packet does not appear to do anything with a Notchian server. The second, special case packet appears to perform the action — based on current position/orientation and with a distance check — it appears that buckets can only be used within a radius of 6 units.

Use Item

Sent when pressing the Use Item key (default: right click) with an item in hand.

Packet ID State Bound To Field Name Field Type Notes
0x1D Play Server Hand VarInt Enum Hand used for the animation

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.