Protocol

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This page presents a dissection of the current stable Minecraft protocol. The current pre-release protocol is documented elsewhere. The protocol for Pocket Minecraft is substantially different, and is documented at Pocket Minecraft Protocol.

If you're having trouble, check out the FAQ or ask for help in the IRC channel (#mcdevs on irc.freenode.net).

Note: While you may use the contents of this page without restriction to create servers, clients, bots, etc… you still need to provide attribution to #mcdevs if you copy any of the contents of this page for publication elsewhere.

Warning.png As of 1.7 strings are now UTF-8 (prefixed with a VarInt giving the string's length in bytes) instead of UTF-16.

Warning.png As of 1.7.6 all UUIDs used in the protocol now contain '-'. The session server still returns them without

The changes between versions may be viewed at Protocol History

Contents

Definitions

Data types

All data sent over the network is big-endian, that is the bytes are sent from most significant byte to least significant byte. The majority of everyday computers are little-endian, therefore it may be necessary to change the endianness before sending data over the network.

Other than 'String' and 'Metadata', which are decoded with a custom function, these data formats are identical to those provided by the Java classes DataInputStream and DataOutputStream.

Size Range Notes
bool 1 0 or 1 Value can be either true (0x01) or false (0x00)
byte 1 -128 to 127 Signed, two's complement
short 2 -32768 to 32767 Signed, two's complement
int 4 -2147483648 to 2147483647 Signed, two's complement
long 8 -9223372036854775808 to 9223372036854775807 Signed, two's complement
128-bit integer 16 0 to 340282366920938463463374607431768211455 Unsigned, two's complement

Used in 0x2C to transmit UUIDs.

The vanilla Minecraft server internally sends this as two longs.

float 4

See this

Single-precision 32-bit IEEE 754 floating point
double 8

See this

Double-precision 64-bit IEEE 754 floating point
string ≥ 2
≤ 240
N/A UTF-8 String length prefixed with a VarInt
varInt Varies Protocol Buffer 32-bit Varint
metadata Varies See this
Slot Data Varies See slot data

Fixed-point numbers

Some fields may be stored as fixed-point numbers, where a certain number of bits represents the signed integer part (number to the left of the decimal point) and the rest represents the fractional part (to the right). Floating points (float and double9, in contrast, keep the number itself (mantissa) in one chunk, while the location of the decimal point (exponent) is stored beside it.

Essentially, while fixed-point numbers have lower range than floating points, their fractional precision is greater for higher values. This makes them ideal for representing global coordinates of an entity in Minecraft, as it's more important to store the integer part accurately than position them more precisely within a single block (or meter).

Coordinates are often represented as a 32-bit integer, where 5 of the least-significant bits are dedicated to the fractional part, and the rest store the integer part.

Java lacks support for fractional integers directly, but you can represent them as integers. To convert from a double to this integer representation, use the following formulas:

 abs_int = (int)double * 32;

And back again:

 double = (double)abs_int / 32;

Other definitions

Term Definition
Player When used in the singular, Player always refers to the client connected to the server
Entity Entity refers to any item, player, mob, minecart or boat in the world. This definition is subject to change as Notch extends the protocol
EID An EID - or Entity ID - is a unique 4-byte integer used to identify a specific entity
XYZ In this document, the axis names are the same as those used by Notch. Y points upwards, X points South, and Z points West.
See also: Units of Measurement

Packets

Protocol Version

1.7.2 - 4

1.7.6 - 5

Packet format

Field Name Field Type Notes
Length VarInt Length of packet data + length of the packet ID
Packet ID VarInt
Data

Handshaking

Serverbound

Handshake

This causes the server to switch into the target state.

Packet ID Category Bound To Field Name Field Type Notes
0x00 Handshake Server Protocol Version VarInt (4 as of 1.7.2)
Server Address (hostname or IP) String localhost
Server Port Unsigned Short 25565
Next state VarInt 1 for status, 2 for login

Play

Clientbound

Keep Alive

The server will frequently send out a keep-alive, each containing a random ID. The client must respond with the same packet. If the client does not respond to them for over 30 seconds, the server kicks the client. Vice versa, if the server does not send any keep-alives for 20 seconds, the client will disconnect and yields a "Timed out" exception.

Packet ID Category Bound To Field Name Field Type Notes
0x00 Play Client Keep Alive ID Int

Join Game

See Protocol Encryption for information on logging in.

Packet ID Category Bound To Field Name Field Type Notes
0x01 Play Client Entity ID Int The player's Entity ID
Gamemode Unsigned Byte 0: survival, 1: creative, 2: adventure. Bit 3 (0x8) is the hardcore flag
Dimension Byte -1: nether, 0: overworld, 1: end
Difficulty Unsigned Byte 0 thru 3 for Peaceful, Easy, Normal, Hard
Max Players Unsigned Byte Used by the client to draw the player list
Level Type String default, flat, largeBiomes, amplified, default_1_1

Warning.png If the Dimension isn't valid then the client will crash

Chat Message

Packet ID Category Bound To Field Name Field Type Notes
0x02 Play Client JSON Data String Chat, Limited to 32767 bytes

Warning.png Malformed JSON will disconnect the client

Time Update

Time is based on ticks, where 20 ticks happen every second. There are 24000 ticks in a day, making Minecraft days exactly 20 minutes long.

The time of day is based on the timestamp modulo 24000. 0 is sunrise, 6000 is noon, 12000 is sunset, and 18000 is midnight.

The default SMP server increments the time by 20 every second.

Packet ID Category Bound To Field Name Field Type Notes
0x03 Play Client Age of the world Long In ticks; not changed by server commands
Time of day Long The world (or region) time, in ticks. If negative the sun will stop moving at the Math.abs of the time

Entity Equipment

Packet ID Category Bound To Field Name Field Type Notes
0x04 Play Client EntityID Int Entity's ID
Slot Short Equipment slot: 0=held, 1-4=armor slot (1 - boots, 2 - leggings, 3 - chestplate, 4 - helmet)
Item Slot Item in slot format

Spawn Position

Sent by the server after login to specify the coordinates of the spawn point (the point at which players spawn at, and which the compass points to). It can be sent at any time to update the point compasses point at.

Packet ID Category Bound To Field Name Field Type Notes
0x05 Play Client X Int Spawn X in block coordinates
Y Int Spawn Y in block coordinates
Z Int Spawn Z in block coordinates

Update Health

Sent by the server to update/set the health of the player it is sent to.

Food saturation acts as a food "overcharge". Food values will not decrease while the saturation is over zero. Players logging in automatically get a saturation of 5.0. Eating food increases the saturation as well as the food bar.

Packet ID Category Bound To Field Name Field Type Notes
0x06 Play Client Health Float 0 or less = dead, 20 = full HP
Food Short 0 - 20
Food Saturation Float Seems to vary from 0.0 to 5.0 in integer increments

Respawn

To change the player's dimension (overworld/nether/end), send them a respawn packet with the appropriate dimension, followed by prechunks/chunks for the new dimension, and finally a position and look packet. You do not need to unload chunks, the client will do it automatically.

Packet ID Category Bound To Field Name Field Type Notes
0x07 Play Client Dimension Int -1: The Nether, 0: The Overworld, 1: The End
Difficulty Unsigned Byte 0 thru 3 for Peaceful, Easy, Normal, Hard.
Gamemode Unsigned Byte 0: survival, 1: creative, 2: adventure. The hardcore flag is not included
Level Type String Same as Join Game

Warning.png If the Dimension isn't valid then the client will crash

Warning.png Avoid changing player's dimension to same dimension they were already in, weird bugs can occur i.e. such player will be unable to attack other players in new world (fixes after their death and respawn)

Player Position And Look

Updates the players 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 units will result in the client being 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 of player (in degrees), standing at point (x0,z0) and looking towards point (x,z) one 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 Category Bound To Field Name Field Type Notes
0x08 Play Client X Double Absolute position
Y Double Absolute position (eyes pos)
Z Double Absolute position
Yaw Float Absolute rotation on the X Axis, in degrees
Pitch Float Absolute rotation on the Y Axis, in degrees
On Ground Bool True if the client is on the ground, False otherwise

Held Item Change

Sent to change the player's slot selection

Packet ID Category Bound To Field Name Field Type Notes
0x09 Play Client Slot Byte The slot which the player has selected (0-8)

Use Bed

This packet tells that a player goes to bed.

The client with the matching Entity ID will go into bed mode.

This Packet is sent to all nearby players including the one sent to bed.

Packet ID Category Bound To Field Name Field Type Notes
0x0A Play Client Entity ID Int Player ID
X Int Bed headboard X as block coordinate
Y Unsigned Byte Bed headboard Y as block coordinate
Z Int Bed headboard Z as block coordinate

Animation

Sent whenever an entity should change animation.

Packet ID Category Bound To Field Name Field Type Notes
0x0B Play Client Entity ID VarInt Player ID
Animation Unsigned Byte Animation ID

Animation can be one of the following values:

ID Animation
0 Swing arm
1 Damage animation
2 Leave bed
3 Eat food
4 Critical effect
5 Magic critical effect
102 (unknown)
104 Crouch
105 Uncrouch

Spawn Player

This packet is sent by the server when a player comes into visible range, not when a player joins.

Servers can, however, safely spawn player entities for players not in visible range. The client appears to handle it correctly.

When in online-mode the uuids must be valid and have valid skin blobs, in offline-mode uuid v3 is used.

For NPCs UUID v2 should be used. Note:

  <+Grum> i will never confirm this as a feature you know that :)
Packet ID Category Bound To Field Name Field Type Notes
0x0C Play Client Entity ID VarInt Player's Entity ID
Player UUID String Player's UUID
Player Name String Player's Name
Data count VarInt
Data Name String Name of the property as return by the session server's /hasJoined. E.g: textures
Value String Value of the property (base64) as return by the session server's /hasJoined
Signature String Signature of the property (base64) as return by the session server's /hasJoined.
X Int Player X as a Fixed-Point number
Y Int Player X as a Fixed-Point number
Z Int Player X as a Fixed-Point number
Yaw Byte Player rotation as a packed byte
Pitch Byte Player rotation as a packet byte
Current Item Short The item the player is currently holding. Note that this should be 0 for "no item", unlike -1 used in other packets. A negative value crashes clients.
Metadata Metadata The client will crash if no metadata is sent

Warning.png The client will crash if no metadata is sent Warning.png The client will disconnect if both UUID and Name are empty

Collect Item

Sent by the server when someone picks up an item lying on the ground - its sole purpose appears to be the animation of the item flying towards you. It doesn't destroy the entity in the client memory, and it doesn't add it to your inventory. The server only checks for items to be picked up after each Player Position and [Player Position & Look packet sent by the client.

Packet ID Category Bound To Field Name Field Type Notes
0x0D Play Client Collected Entity ID Int
Collector Entity ID Int

Spawn Object

Sent by the server when an Object/Vehicle is created.

Packet ID Category Bound To Field Name Field Type Notes
0x0E Play Client Entity ID VarInt Entity ID of the object
Type Byte The type of object (See Objects)
X Int X position as a Fixed-Point number
Y Int Y position as a Fixed-Point number
Z Int Z position as a Fixed-Point number
Pitch Byte The pitch in steps of 2p/256
Yaw Byte The yaw in steps of 2p/256
Data Object Data

Spawn Mob

Sent by the server when a Mob Entity is Spawned

Packet ID Category Bound To Field Name Field Type Notes
0x0F Play Client Entity ID VarInt Entity's ID
Type Unsigned Byte The type of mob. See Mobs
X Int X position as a Fixed-Point number
Y Int Y position as a Fixed-Point number
Z Int Z position as a Fixed-Point number
Yaw Byte The yaw in steps of 2p/256
Pitch Byte The pitch in steps of 2p/256
Head Pitch Byte The pitch in steps of 2p/256
Velocity X Short
Velocity Y Short
Velocity Z Short
Metadata Metadata

Spawn Painting

This packet shows location, name, and type of painting.

Calculating the center of an image: given a (width x height) grid of cells, with (0, 0) being the top left corner, the center is (max(0, width / 2 - 1), height / 2). E.g.

2x1 (1, 0) 4x4 (1, 2)


Packet ID Category Bound To Field Name Field Type Notes
0x10 Play Client Entity ID VarInt Entity's ID
Title String Name of the painting. Max length 13
X Int Center X coordinate
Y Int Center Y coordinate
Z Int Center Z coordinate
Direction Int Direction the painting faces (0 -z, 1 -x, 2 +z, 3 +x)

Spawn Experience Orb

Spawns one or more experience orbs.

Packet ID Category Bound To Field Name Field Type Notes
0x11 Play Client Entity ID VarInt Entity's ID
X Int X position as a Fixed-Point number
Y Int Y position as a Fixed-Point number
Z Int Z position as a Fixed-Point number
Count Short The amount of experience this orb will reward once collected

Entity Velocity

Velocity is believed to be in units of 1/8000 of a block per server tick (50ms); for example, -1343 would move (-1343 / 8000) = -0.167875 blocks per tick (or -3,3575 blocks per second).

Packet ID Category Bound To Field Name Field Type Notes
0x12 Play Client Entity ID Int Entity's ID
Velocity X Short Velocity on the X axis
Velocity Y Short Velocity on the Y axis
Velocity Z Short Velocity on the Z axis

Destroy Entities

Sent by the server when an list of Entities is to be destroyed on the client.

Packet ID Category Bound To Field Name Field Type Notes
0x13 Play Client Count Byte Length of following array
Entity IDs Array of Int The list of entities of destroy

Entity

Most entity-related packets are subclasses of this packet. When sent from the server to the client, it may initialize the entry.

For player entities, either this packet or any move/look packet is sent every game tick. So the meaning of this packet is basically that the entity did not move/look since the last such packet.

Packet ID Category Bound To Field Name Field Type Notes
0x14 Play Client Entity ID Int Entity's ID

Entity Relative Move

This packet is sent by the server when an entity moves less then 4 blocks; if an entity moves more than 4 blocks Entity Teleport should be sent instead.

This packet allows at most four blocks movement in any direction, because byte range is from -128 to 127.

Packet ID Category Bound To Field Name Field Type Notes
0x15 Play Client Entity ID Int Entity's ID
DX Byte Change in X position as a Fixed-Point number
DY Byte Change in Y position as a Fixed-Point number
DZ Byte Change in Z position as a Fixed-Point number

Entity Look

This packet is sent by the server when an entity rotates. Example: "Yaw" field 64 means a 90 degree turn.

Packet ID Category Bound To Field Name Field Type Notes
0x16 Play Client Entity ID Int Entity's ID
Yaw Byte The X Axis rotation as a fraction of 360
Pitch Byte The Y Axis rotation as a fraction of 360

Entity Look and Relative Move

This packet is sent by the server when an entity rotates and moves. Since a byte range is limited from -128 to 127, and movement is offset of fixed-point numbers, this packet allows at most four blocks movement in any direction. (-128/32 == -4)

Packet ID Category Bound To Field Name Field Type Notes
0x17 Play Client Entity ID Int Entity's ID
DX Byte Change in X position as a Fixed-Point number
DY Byte Change in Y position as a Fixed-Point number
DZ Byte Change in Z position as a Fixed-Point number
Yaw Byte The X Axis rotation as a fraction of 360
Pitch Byte The Y Axis rotation as a fraction of 360

Entity Teleport

This packet is sent by the server when an entity moves more than 4 blocks.

Packet ID Category Bound To Field Name Field Type Notes
0x18 Play Client Entity ID Int Entity's ID
X Int X position as a Fixed-Point number
Y Int Y position as a Fixed-Point number
Z Int Z position as a Fixed-Point number
Yaw Byte The X Axis rotation as a fraction of 360
Pitch Byte The Y Axis rotation as a fraction of 360

Entity Head Look

Changes the direction an entity's head is facing.

Packet ID Category Bound To Field Name Field Type Notes
0x19 Play Client Entity ID Int Entity's ID
Head Yaw Byte Head yaw in steps of 2p/256

Entity Status

Packet ID Category Bound To Field Name Field Type Notes
0x1A Play Client Entity ID Int Entity's ID
Entity Status Byte See below
Entity Status Meaning
0 Something related to living entities?
1 Something related to the player entity?
2 Living Entity hurt
3 Living Entity dead
4 Iron Golem throwing up arms
6 Wolf/Ocelot/Horse taming - Spawn "heart" particles
7 Wolf/Ocelot/Horse tamed - Spawn "smoke" particles
8 Wolf shaking water - Trigger the shaking animation
9 (of self) Eating accepted by server
10 Sheep eating grass
11 Iron Golem handing over a rose
12 Villager mating - Spawn "heart" particles
13 Spawn particles indicating that a villager is angry and seeking revenge
14 Spawn happy particles near a villager
15 Witch animation - Spawn "magic" particles
16 Zombie converting into a villager by shaking violently
17 Firework exploding
18 Animal in love (ready to mate) - Spawn "heart" particles

Attach Entity

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

Packet ID Category Bound To Field Name Field Type Notes
0x1B Play Client Entity ID Int Entity's ID
Vehicle ID Int Vechicle's Entity ID
Leash Bool If true leashes the entity to the vehicle

Entity Metadata

Packet ID Category Bound To Field Name Field Type Notes
0x1C Play Client Entity ID Int Entity's ID
Metadata Metadata

Entity Effect

Packet ID Category Bound To Field Name Field Type Notes
0x1D Play Client Entity ID Int Entity's ID
Effect ID Byte See [[1]]
Amplifier Byte
Duration Short

Remove Entity Effect

Packet ID Category Bound To Field Name Field Type Notes
0x1E Play Client Entity ID Int Entity's ID
Effect ID Byte

Set Experience

Sent by the server when the client should change experience levels.

Packet ID Category Bound To Field Name Field Type Notes
0x1F Play Client Experience bar Float Between 0 and 1
Level Short
Total Experience Short

Entity Properties

Packet ID Category Bound To Field Name Field Type Notes
0x20 Play Client Entity ID Int Entity's ID
Count Int Length of following array
Properties Array of Property Data

Property Data structure:

Field Name Field Type Notes
Key String
Value Double
List Length Short Number of list elements that follow.
Modifiers Array of Modifier Data http://www.minecraftwiki.net/wiki/Attribute#Modifiers

Known key values:

Key Default Min Max Label
generic.maxHealth 20.0 0.0 Double.MaxValue 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 Movement Speed
generic.attackDamage 2.0 0.0 Double.MaxValue
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 128-bit integer
Amount Double
Operation Byte

Chunk Data

Chunks are not unloaded by the client automatically. To unload chunks, send this packet with ground-up continuous=true and no 16^3 chunks (eg. primary bit mask=0). The server does not send skylight information for nether-chunks, it's up to the client to know if the player is currently in the nether. You can also infer this information from the primary bitmask and the amount of uncompressed bytes sent.

See also: SMP Map Format

Packet ID Category Bound To Field Name Field Type Notes
0x21 Play Client Chunk X Int Chunk X coordinate
Chunk Z Int Chunk Z coordinate
Ground-Up continuous Boolean This is True if the packet represents all sections in this vertical column, where the primary bit map specifies exactly which sections are included, and which are air
Primary bit map Unsigned Short Bitmask with 1 for every 16x16x16 section which data follows in the compressed data.
Add bit map Unsigned Short Same as above, but this is used exclusively for the 'add' portion of the payload
Compressed size Int Size of compressed chunk data
Compressed data Byte array The chunk data is compressed using Zlib Deflate

Multi Block Change

Packet ID Category Bound To Field Name Field Type Notes
0x22 Play Client Chunk X Int Chunk X coordinate
Chunk Z Int Chunk Z Coordinate
Record count Short The number of blocks affected
Data size Int The total size of the data, in bytes. Should always be 4*record count
Records Array of Records

Record

Bit mask Width Meaning
00 00 00 0F 4 bits Block metadata
00 00 FF F0 12 bits Block ID
00 FF 00 00 8 bits Y co-ordinate
0F 00 00 00 4 bits Z co-ordinate, relative to chunk
F0 00 00 00 4 bits X co-ordinate, relative to chunk

Block Change

Packet ID Category Bound To Field Name Field Type Notes
0x23 Play Client X Int Block X Coordinate
Y Unsigned Byte Block Y Coordinate
Z Int Block Z Coordinate
Block ID VarInt The new block ID for the block
Block Metadata Unsigned Byte The new metadata for the block

Block Action

This packet is used for a number of things:

  • Chests opening and closing
  • Pistons pushing and pulling
  • Note blocks playing

See Also: Block Actions

Packet ID Category Bound To Field Name Field Type Notes
0x24 Play Client X Int Block X Coordinate
Y Short Block Y Coordinate
Z Int Block Z Coordinate
Byte 1 Unsigned Byte Varies depending on block - see Block_Actions
Byte 2 Unsigned Byte Varies depending on block - see Block_Actions
Block Type VarInt The block type for the block

Block Break Animation

0-9 are the displayable destroy stages and each other number means that there is no animation on this coordinate.

You can also set an animation to air! The animation will still be visible.

If you need to display several break animations at the same time you have to give each of them a unique Entity ID.

Also if you set the coordinates to a special block like water, it won't show the actual break animation, but some other interesting effects. (Water will lose its transparency)

Packet ID Category Bound To Field Name Field Type Notes
0x25 Play Client Entity ID VarInt Entity's ID
X Int Block Position
Y Int
Z Int
Destroy Stage Byte 0 - 9

Map Chunk Bulk

See also: SMP Map Format

To reduce the number of bytes this packet is used to send chunks together for better compression results.

Packet ID Category Bound To Field Name Field Type Notes
0x26 Play Client Chunk column count Short The number of chunk in this packet
Data length Int The size of the data field
Sky light sent Bool Whether or not the chunk data contains a light nibble array. This is true in the main world, false in the end + nether
Data Byte Array Compressed chunk data
Meta information Meta See below

Meta

Field Name Field Type Notes
Chunk X Int The X Coordinate of the chunk
Chunk Z Int The Z Coordinate of the chunk
Primary bitmap Unsigned Short A bitmap which specifies which sections are not empty in this chunk
Add bitmap Unsigned Short A bitmap which specifies which sections need add information because of very high block ids. not yet used

Explosion

Sent when an explosion occurs (creepers, TNT, and ghast fireballs).

Each block in Records is set to air. Coordinates for each axis in record is int(X) + record.x

Packet ID Category Bound To Field Name Field Type Notes
0x27 Play Client X Float
Y Float
Z Float
Radius Float Currently unused in the client
Record count Int This is the count, not the size. The size is 3 times this value.
Records (Byte, Byte, Byte) × count Each record is 3 signed bytes long, each bytes are the XYZ (respectively) offsets of affected blocks.
Player Motion X Float X velocity of the player being pushed by the explosion
Player Motion Y Float Y velocity of the player being pushed by the explosion
Player Motion Z Float Z velocity of the player being pushed by the explosion

Effect

Sent when a client is to play a sound or particle effect.

By default, the minecraft client adjusts the volume of sound effects based on distance. The final boolean field is used to disable this, and instead the effect is played from 2 blocks away in the correct direction. Currently this is only used for effects 1013 and 1018 (mob.wither.spawn and mob.enderdragon.end, respectively), and is ignored for any other value by the client.

Packet ID Category Bound To Field Name Field Type Notes
0x28 Play Client Effect ID Int The ID of the effect, see below.
X Int The X location of the effect
Y Byte The Y location of the effect
Z Int The Z location of the effect
Data Int Extra data for certain effects, see below.
Disable relative volume Bool See above
Effects
ID Name
Sound
1000 random.click
1001 random.click
1002 random.bow
1003 random.door_open or random.door_close (50/50 chance)
1004 random.fizz
1005 Play a music disc. Data Record ID
(1006 not assigned)
1007 mob.ghast.charge
1008 mob.ghast.fireball
1009 mob.ghast.fireball, but with a lower volume.
1010 mob.zombie.wood
1011 mob.zombie.metal
1012 mob.zombie.woodbreak
1013 mob.wither.spawn
1014 mob.wither.shoot
1015 mob.bat.takeoff
1016 mob.zombie.infect
1017 mob.zombie.unfect
1018 mob.enderdragon.end
1020 random.anvil_break
1021 random.anvil_use
1022 random.anvil_land
Particle
2000 Spawns 10 smoke particles, e.g. from a fire. Data direction, see below
2001 Block break. Data Block ID
2002 Splash potion. Particle effect + glass break sound. Data Potion ID
2003 Eye of ender entity break animation - particles and sound
2004 Mob spawn particle effect: smoke + flames
2005 Spawn "happy villager" effect (green crosses), used for bonemealing vegetation.
2005 Spawn fall particles (when player hits ground). Data fall damage taken for particle speed

Smoke directions:

ID Direction
0 South - East
1 South
2 South - West
3 East
4 (Up or middle ?)
5 West
6 North - East
7 North
8 North - West

Sound Effect

Used to play a sound effect on the client.

All known sound effect names can be seen here.

Custom sounds may be added by resource packs

Packet ID Category Bound To Field Name Field Type Notes
0x29 Play Client Sound name String
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 is 100%, can be more
Pitch Unsigned Byte 63 is 100%, can be more

Particle

Displays the named particle

Packet ID Category Bound To Field Name Field Type Notes
0x2A Play Client Particle name String The name of the particle to create. A list can be found here
X Float X position of the particle
Y Float Y position of the particle
Z Float Z position of the particle
Offset X Float This is added to the X position after being multiplied by random.nextGaussian()
Offset Y Float This is added to the Y position after being multiplied by random.nextGaussian()
Offset Z Float This is added to the Z position after being multiplied by random.nextGaussian()
Particle data Float The data of each particle
Number of particles Int The number of particles to create

Change Game State

It appears when a bed can't be used as a spawn point and when the rain state changes.

The class has an array of strings linked to reason codes 0, 1, 2, and 3 but only the codes for 1 and 2 are null.

Packet ID Category Bound To Field Name Field Type Notes
0x2B Play Client Reason Unsigned Byte
Value Float Depends on reason

Reason codes

Code Effect Notes
0 Invalid Bed "tile.bed.notValid"
1 End raining
2 Begin raining
3 Change game mode "gameMode.changed" 0 - Survival, 1 - Creative, 2 - Adventure
4 Enter credits
5 Demo messages 0 - Show welcome to demo screen, 101 - Tell movement controls, 102 - Tell jump control, 103 - Tell inventory control
6 Arrow hitting player Appears to be played when an arrow strikes another player in Multiplayer
7 Fade value The current darkness value. 1 = Dark, 0 = Bright, Setting the value higher causes the game to change color and freeze
8 Fade time Time in ticks for the sky to fade

Spawn Global Entity

With this packet, the server notifies the client of thunderbolts striking within a 512 block radius around the player. The coordinates specify where exactly the thunderbolt strikes.

Packet ID Category Bound To Field Name Field Type Notes
0x2C Play Client Entity ID VarInt The entity ID of the thunderbolt
Type Byte The global entity type, currently always 1 for thunderbolt.
X Int Thunderbolt X a fixed-point number
Y Int Thunderbolt Y a fixed-point number
Z Int Thunderbolt Z a fixed-point number

Open Window

This is sent to the client when it should open an inventory, such as a chest, workbench, or furnace. This message is not sent anywhere for clients opening their own inventory.

Packet ID Category Bound To Field Name Field Type Notes
0x2D Play Client Window id Unsigned Byte A unique id number for the window to be displayed. Notchian server implementation is a counter, starting at 1.
Inventory Type Unsigned Byte The window type to use for display. Check below
Window title String The title of the window.
Number of Slots Unsigned Byte Number of slots in the window (excluding the number of slots in the player inventory).
Use provided window title Bool If false, the client will look up a string like "window.minecart". If true, the client uses what the server provides.
Entity ID Int EntityHorse's entityId. Only sent when window type is equal to 11 (AnimalChest).

See inventory windows for further information.

Close Window

This packet is sent from the server to the client when a window is forcibly closed, such as when a chest is destroyed while it's open.

Note, notchian clients send a close window message with window id 0 to close their inventory even though there is never an Open Window message for inventory.

Packet ID Category Bound To Field Name Field Type Notes
0x2E Play Client Window ID Unsigned Byte This is the id of the window that was closed. 0 for inventory.

Set Slot

Sent by the server when an item in a slot (in a window) is added/removed.

Packet ID Category Bound To Field Name Field Type Notes
0x2F Play Client Window ID Byte The window which is being updated. 0 for player inventory. Note that all known window types include the player inventory. This packet will only be sent for the currently opened window while the player is performing actions, even if it affects the player inventory. After the window is closed, a number of these packets are sent to update the player's inventory window (0).
Slot Short The slot that should be updated
Slot data Slot

Window Items

The inventory slots

Sent by the server when an item in a slot (in a window) is added/removed. This includes the main inventory, equipped armour and crafting slots.

Packet ID Category Bound To Field Name Field Type Notes
0x30 Play Client Window ID Unsigned Byte The id of window which items are being sent for. 0 for player inventory.
Count Short The number of slots (see below)
Slot data Array of Slots

See inventory windows for further information about how slots are indexed.

Window Property

Packet ID Category Bound To Field Name Field Type Notes
0x31 Play Client Window ID Unsigned Byte The id of the window.
Property Short Which property should be updated.
Value Short The new value for the property.

Furnace

Properties:

  • 0: Progress arrow
  • 1: Fire icon (fuel)

Values:

  • 0-200 for progress arrow
  • 0-200 for fuel indicator

Ranges are presumably in in-game ticks

Enchantment Table

Properties: 0, 1 or 2 depending on the "enchantment slot" being given.

Values: The enchantment's level.

Beacon

  • 0: Power level
  • 1: Potion effect one
  • 2: Potion effect two

Anvil

  • 0: Maximum cost

Brewing Stand

  • 0: Brew time

Confirm Transaction

A packet from the server indicating whether a request from the client was accepted, or whether there was a conflict (due to lag). This packet is also sent from the client to the server in response to a server transaction rejection packet.

Packet ID Category Bound To Field Name Field Type Notes
0x32 Play Client Window ID Unsigned Byte The id of the window that the action occurred in.
Action number Short Every action that is to be accepted has a unique number. This field corresponds to that number.
Accepted Bool Whether the action was accepted.

Update Sign

This message is sent from the server to the client whenever a sign is discovered or created. This message is NOT sent when a sign is destroyed or unloaded.

Packet ID Category Bound To Field Name Field Type Notes
0x33 Play Client X Int Block X Coordinate
Y Short Block Y Coordinate
Z Int Block Z Coordinate
Line 1 String First line of text in the sign
Line 2 String Second line of text in the sign
Line 3 String Third line of text in the sign
Line 4 String Fourth line of text in the sign

Maps

If the first byte of the array is 0, the next two bytes are X start and Y start and the rest of the bytes are the colors in that column.

If the first byte of the array is 1, the rest of the bytes are in groups of three: (data, x, y). The lower half of the data is the type (always 0 under vanilla) and the upper half is the direction.

If the first byte of the array is 2, the second byte is the map scale.

Packet ID Category Bound To Field Name Field Type Notes
0x34 Play Client Item Damage VarInt The damage value of the map being modified
Length Short Length of following byte array
Data Byte Array Array data

Update Block Entity

Essentially a block update on a block entity.

Packet ID Category Bound To Field Name Field Type Notes
0x35 Play Client X Int
Y Short
Z Int
Action Unsigned Byte The type of update to perform
Data length Short Varies
NBT Data Byte Array Present if data length > 0. Compressed with gzip. Varies, but based on the NBT chunk storage format as can be found in the Minecraft Wiki (http://www.minecraftwiki.net/Chunk_Format)

Actions

  • 1: Set mob displayed inside a mob spawner
  • 2: Set command block text (command and last execution status)
  • 3: Set rotation and skin of mob head
  • 4: Set type of flower in flower pot

Sign Editor Open

Sent on placement of sign.

Packet ID Category Bound To Field Name Field Type Notes
0x36 Play Client X Int X in block coordinates
Y Int Y in block coordinates
Z Int Z in block coordinates

Statistics

Packet ID Category Bound To Field Name Field Type Notes
0x37 Play Client Count VarInt Number of entries
Entry Statistic's name String https://gist.github.com/thinkofdeath/a1842c21a0cf2e1fb5e0
Value VarInt The amount to set it to

Player List Item

Sent by the notchian server to update the user list (<tab> in the client).

Packet ID Category Bound To Field Name Field Type Notes
0x38 Play Client Player name String Supports chat colouring, limited to 16 characters.
Online Bool The client will remove the user from the list if false.
Ping Short Ping, presumably in ms.

Player Abilities

The latter 2 floats are used to indicate the walking and flying speeds respectively, while the first byte is used to determine the value of 4 booleans.

The flags are whether damage is disabled (god mode, 8, bit 3), whether the player can fly (4, bit 2), whether the player is flying (2, bit 1), and whether the player is in creative mode (1, bit 0).

To get the values of these booleans, simply AND (&) the byte with 1,2,4 and 8 respectively, to get the 0 or 1 bitwise value. To set them OR (|) them with their repspective masks.

Packet ID Category Bound To Field Name Field Type Notes
0x39 Play Client Flags Byte
Flying speed Float previous integer value divided by 250
Walking speed Float previous integer value divided by 250

Tab-Complete

The server responds with a list of auto-completions of the last word sent to it. In the case of regular chat, this is a player username. Command names and parameters are also supported.

Packet ID Category Bound To Field Name Field Type Notes
0x3A Play Client Count VarInt Number of following strings
Match String One eligible command, note that each command is sent separately instead of in a single string, hence the need for Count

Scoreboard Objective

This is sent to the client when it should create a new scoreboard or remove one.

Packet ID Category Bound To Field Name Field Type Notes
0x3B Play Client Objective name String An unique name for the objective
Objective value String The text to be displayed for the score.
Create/Remove Byte 0 to create the scoreboard. 1 to remove the scoreboard. 2 to update the display text.

Update Score

This is sent to the client when it should update a scoreboard item.

Packet ID Category Bound To Field Name Field Type Notes
0x3C Play Client Item Name String An unique name to be displayed in the list.
Update/Remove Byte 0 to create/update an item. 1 to remove an item.
Score Name String The unique name for the scoreboard to be updated. Only sent when Update/Remove does not equal 1.
Value Int The score to be displayed next to the entry. Only sent when Update/Remove does not equal 1.

Warning.png The final String and Int are only sent if the Update/Remove Byte does not equal 1

Display Scoreboard

This is sent to the client when it should display a scoreboard.

Packet ID Category Bound To Field Name Field Type Notes
0x3D Play Client Position Byte The position of the scoreboard. 0 = list, 1 = sidebar, 2 = belowName.
Score Name String The unique name for the scoreboard to be displayed.

Teams

Creates and updates teams.

Packet ID Category Bound To Field Name Field Type Notes
0x3E Play Client Team Name String A unique name for the team. (Shared with scoreboard).
Mode Byte If 0 then the team is created.

If 1 then the team is removed.

If 2 the team team information is updated.

If 3 then new players are added to the team.

If 4 then players are removed from the team.

Team Display Name String Only if Mode = 0 or 2.
Team Prefix String Only if Mode = 0 or 2. Displayed before the players' name that are part of this team.
Team Suffix String Only if Mode = 0 or 2. Displayed after the players' name that are part of this team.
Friendly fire Byte Only if Mode = 0 or 2; 0 for off, 1 for on, 3 for seeing friendly invisibles
Player count Short Only if Mode = 0 or 3 or 4. Number of players in the array
Players Array of strings Only if Mode = 0 or 3 or 4. Players to be added/remove from the team.

Plugin Message

Mods and plugins can use this to send their data. Minecraft itself uses a number of plugin channels. These internal channels are prefixed with MC|.

More documentation on this: http://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Packet ID Category Bound To Field Name Field Type Notes
0x3F Play Client Channel String Name of the "channel" used to send the data.
Length Short Length of the following byte array
Data Byte Array Any data.

Disconnect

Sent by the server before it disconnects a client. The server assumes that the sender has already closed the connection by the time the packet arrives.

Packet ID Category Bound To Field Name Field Type Notes
0x40 Play Client Reason String Displayed to the client when the connection terminates. Must be valid JSON.

Serverbound

Keep Alive

The server will frequently send out a keep-alive, each containing a random ID. The client must respond with the same packet.

Packet ID Category Bound To Field Name Field Type Notes
0x00 Play Server Keep Alive ID Int

Chat Message

The default server will check the message to see if it begins with a '/'. If it doesn't, the username of the sender is prepended and sent to all other clients (including the original sender). If it does, the server assumes it to be a command and attempts to process it. A message longer than 100 characters will cause the server to kick the client. This change was initially done by allowing the client to not slice the message up to 119 (the previous limit), without changes to the server. For this reason, the vanilla server kept the code to cut messages at 119, but this isn't a protocol limitation and can be ignored.

For more information, see Chat.

Packet ID Category Bound To Field Name Field Type Notes
0x01 Play Server Message String

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 Category Bound To Field Name Field Type Notes
0x02 Play Server Target Int
Mouse Byte 0 = Right-click, 1 = Left-click

Player

This packet is used to indicate whether the player is on ground (walking/swimming), or airborne (jumping/falling).

When dropping from sufficient height, fall damage is applied when this state goes from False to True. The amount of damage applied is based on the point where it last changed from True to False. Note that there are several movement related packets containing this state.

Packet ID Category Bound To Field Name Field Type Notes
0x03 Play Server On Ground Bool True if the client is on the ground, False otherwise

Player Position

Updates the players XYZ position on the server. If HeadY - FeetY is less than 0.1 or greater than 1.65, the stance is illegal and the client will be kicked with the message “Illegal Stance”. 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 units will result in the client being 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"

Packet ID Category Bound To Field Name Field Type Notes
0x04 Play Server X Double Absolute position
FeetY Double Absolute feet position, normally HeadY - 1.62. Used to modify the players bounding box when going up stairs, crouching, etc…
HeadY Double Absolute head position
Z Double Absolute position
On Ground Bool True if the client is on the ground, False otherwise

Player Look

The unit circle for yaw
The unit circle of yaw, redrawn

Updates the direction the player is looking in.

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 of player (in degrees), standing at point (x0,z0) and looking towards point (x,z) one 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

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

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 Category Bound To Field Name Field Type Notes
0x05 Play Server Yaw Float Absolute rotation on the X Axis, in degrees
Pitch Float Absolute rotation on the Y Axis, in degrees
On Ground Bool True if the client is on the ground, False otherwise

Player Position And Look

A combination of Player Look and Player position.

Packet ID Category Bound To Field Name Field Type Notes
0x06 Play Server X Double Absolute position
FeetY Double Absolute feet position. Is normally HeadY - 1.62. Used to modify the players bounding box when going up stairs, crouching, etc…
HeadY Double Absolute head position
Z Double Absolute position
Yaw Float Absolute rotation on the X Axis, in degrees
Pitch Float Absolute rotation on the Y Axis, in degrees
On Ground Bool True if the client is on the ground, False otherwise

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 Category Bound To Field Name Field Type Notes
0x07 Play Server Status Byte The action the player is taking against the block (see below)
X Int Block position
Y Unsigned Byte Block position
Z Int Block position
Face Byte The face being hit (see below)

Status can (currently) be one of six values:

Meaning Value
Started digging 0
Cancelled digging 1
Finished digging 2
Drop item stack 3
Drop item 4
Shoot arrow / finish eating 5

Notchian clients send a 0 (started digging) when they start digging and a 2 (finished digging) once they think they are finished. If digging is aborted, the client simply send a 1 (Cancel digging).

Status code 4 (drop item) is a special case. In-game, when you use the Drop Item command (keypress 'q'), a dig packet with a status of 4, and all other values set to 0, is sent from client to server. Status code 3 is similar, but drops the entire stack.

Status code 5 (shoot arrow / finish eating) is also a special case. The x, y and z fields are all set to 0 like above, with the exception of the face field, which is set to 255.

The face can be one of six values, representing the face being hit:

Value 0 1 2 3 4 5
Offset -Y +Y -Z +Z -X +X

In 1.7.3, when a player opens a door with left click the server receives Packet 0xE+start digging and opens the door.

Player Block Placement

Packet ID Category Bound To Field Name Field Type Notes
0x08 Play Server X Int Block position
Y Unsigned Byte Block position
Z Int Block position
Direction Byte The offset to use for block/item placement (see below)
Held item Slot
Cursor position X Byte The position of the crosshair on the block
Cursor position Y Byte
Cursor position Z Byte

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

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, shooting bows, using buckets, etc.

In a Notchian Beta client, the block or item ID corresponds to whatever the client is currently holding, and the client sends one of these packets any time a right-click is issued on a surface, so no assumptions can be made about the safety of the ID. However, with the implementation of server-side inventory, a Notchian server seems to ignore the item ID, instead operating on server-side inventory information and holding selection. The client has been observed (1.2.5 and 1.3.2) to send both real item IDs and -1 in a single session.

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.

Held Item Change

Sent when the player changes the slot selection

Packet ID Category Bound To Field Name Field Type Notes
0x09 Play Server Slot Short The slot which the player has selected (0-8)

Animation

Packet ID Category Bound To Field Name Field Type Notes
0x0A Play Server Entity ID Int Player ID
Animation Byte Animation ID


Animation can be one of the following values:

ID Animation
0 No animation
1 Swing arm
2 Damage animation
3 Leave bed
5 Eat food
6 Critical effect
7 Magic critical effect
102 (unknown)
104 Crouch
105 Uncrouch

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 Category Bound To Field Name Field Type Notes
0x0B Play Server Entity ID Int Player ID
Action ID Byte The ID of the action, see below.
Jump Boost Int Horse jump boost. Ranged from 0 -> 100.

Action ID can be one of the following values:

ID Action
1 Crouch
2 Uncrouch
3 Leave bed
4 Start sprinting
5 Stop sprinting
6 Horse jump
5 Horse interaction ?

Steer Vehicle

Packet ID Category Bound To Field Name Field Type Notes
0x0C Play Server Sideways Float Positive to the left of the player
Forward Float Positive forward
Jump Bool
Unmount Bool True when leaving the vehicle

Close Window

This packet is sent by the client when closing a window.

Note, notchian clients send a close window message with window id 0 to close their inventory even though there is never an Open Window message for inventory.

Packet ID Category Bound To Field Name Field Type Notes
0x0D Play Server Window id byte This is the id of the window that was closed. 0 for inventory.


Click Window

This packet is sent by the player when it clicks on a slot in a window.

Packet ID Category Bound To Field Name Field Type Notes
0x0E Play Server Window ID Byte The id of the window which was clicked. 0 for player inventory.
Slot Short The clicked slot. See below.
Button Byte The button used in the click. See below.
Action number Short A unique number for the action, used for transaction handling (See the Transaction packet).
Mode Byte Inventory operation mode. See below.
Clicked item Slot

See inventory windows for further information about how slots are indexed.

When right-clicking on a stack of items, half the stack will be picked up and half left in the slot. If the stack is an odd number, the half left in the slot will be smaller of the amounts.

The Action number is actually a counter, starting at 1. This number is used by the server as a transaction ID to send back a Transaction packet.

The distinct type of click performed by the client is determined by the combination of the "Mode" and "Button" fields.

Mode Button Slot Trigger
0 0 Normal Left mouse click
1 Normal Right mouse click
1 0 Normal Shift + left mouse click
1 Normal Shift + right mouse click (Identical behavior)
2 0 Normal Number key 1
1 Normal Number key 2
2 Normal Number key 3
... ... ...
8 Normal Number key 9
3 2 Normal Middle click
4 0 Normal Drop key (Q)
1 Normal Ctrl + Drop key (Ctrl-Q)
0 -999 Left click outside inventory holding nothing (No-op)
1 -999 Right click outside inventory holding nothing (No-op)
5 0 -999 Starting left mouse drag (Or middle mouse)
4 -999 Starting right mouse drag
1 Normal Add slot for left-mouse drag
5 Normal Add slot for right-mouse drag
2 -999 Ending left mouse drag
6 -999 Ending right mouse drag
6 0 Normal Double click

Starting from version 1.5, "painting mode" is available for use in inventory windows. It is done by picking up stack of something (more than 1 items), then holding mouse button (left, right or middle) and dragging holded stack over empty (or same type in case of right button ) slots. In that case client sends the following to server after mouse button release (omitting first pickup packet which is sent as usual):

  1. packet with mode 5, slot -999 , button (0 for left | 4 for right);
  2. packet for every slot painted on, mode is still 5, button (1 | 5);
  3. packet with mode 5, slot -999, button (2 | 6);

If any of the painting packets other than the "progress" ones are sent out of order (for example, a start, some slots, then another start; or a left-click in the middle) the painting status will be reset.

Confirm Transaction

Packet ID Category Bound To Field Name Field Type Notes
0x0F Play Server Window ID Byte The id of the window that the action occurred in.
Action number Short Every action that is to be accepted has a unique number. This field corresponds to that number.
Accepted Bool Whether the action was accepted.

Creative Inventory Action

While the user is in the standard inventory (i.e., not a crafting bench) on a creative-mode server then the server will send this packet:

  • If an item is dropped into the quick bar
  • If an item is picked up from the quick bar (item id is -1)
Packet ID Category Bound To Field Name Field Type Notes
0x10 Play Server Slot Short Inventory slot
Clicked item Slot

Enchant Item

Packet ID Category Bound To Field Name Field Type Notes
0x11 Play Server Window ID Byte The ID sent by Open Window
Enchantment Byte The position of the enchantment on the enchantment table window, starting with 0 as the topmost one.

Update Sign

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

Packet ID Category Bound To Field Name Field Type Notes
0x12 Play Server X Int Block X Coordinate
Y Short Block Y Coordinate
Z Int Block Z Coordinate
Line 1 String First line of text in the sign
Line 2 String Second line of text in the sign
Line 3 String Third line of text in the sign
Line 4 String Fourth line of text in the sign

Player Abilities

The latter 2 bytes are used to indicate the walking and flying speeds respectively, while the first byte is used to determine the value of 4 booleans.

The flags are whether damage is disabled (god mode, 8, bit 3), whether the player can fly (4, bit 2), whether the player is flying (2, bit 1), and whether the player is in creative mode (1, bit 0).

To get the values of these booleans, simply AND (&) the byte with 1,2,4 and 8 respectively, to get the 0 or 1 bitwise value. To set them OR (|) them with their repspective masks. The vanilla client sends this packet when the player starts/stops flying with the second parameter changed accordingly. All other parameters are ignored by the vanilla server.

Packet ID Category Bound To Field Name Field Type Notes
0x13 Play Server Flags Byte
Flying speed Float previous integer value divided by 250
Walking speed Float previous integer value divided by 250

Tab-Complete

Sent when the user presses [tab] while writing text. The payload contains all text behind the cursor.

Packet ID Category Bound To Field Name Field Type Notes
0x14 Play Server Text String

Client Settings

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

Packet ID Category Bound To Field Name Field Type Notes
0x15 Play Server Locale String en_GB
View distance Byte Client-side render distance(chunks)
Chat flags Byte Chat settings. See notes below.
Chat colours Bool "Colours" multiplayer setting
Difficulty Byte Client-side difficulty from options.txt
Show Cape Bool Show Cape multiplayer setting

Chat flags has several values packed into one byte.

Chat Enabled: Bits 0-1. 00: Enabled. 01: Commands only. 10: Hidden.

Client Status

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

Packet ID Category Bound To Field Name Field Type Notes
0x16 Play Server Action ID Byte See below

Action ID values:

Action ID Name
0 Perform respawn
1 Request stats
2 Open inventory achievement

Plugin Message

Mods and plugins can use this to send their data. Minecraft itself uses a number of plugin channels. These internal channels are prefixed with MC|.

More documentation on this: http://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Packet ID Category Bound To Field Name Field Type Notes
0x17 Play Server Channel String Name of the "channel" used to send the data.
Length Short Length of the following byte array
Data Byte Array Any data.

Status

The status ping works as follows.

   C->S : Handshake State=1
   C->S : Request
   S->C : Response
   C->S : Ping
   S->C : Ping

Clientbound

Response

Packet ID Category Bound To Field Name Field Type Notes
0x00 Status Client JSON Response String https://gist.github.com/thinkofdeath/6927216


Ping

Packet ID Category Bound To Field Name Field Type Notes
0x01 Status Client Time Long Should be the same as sent by the client

Serverbound

Request

Packet ID Category Bound To Field Name Field Type Notes
0x00 Status Server


Ping

Packet ID Category Bound To Field Name Field Type Notes
0x01 Status Server Time Long

Login

The login process is as follows:

   C->S : Handshake State=2
   C->S : Login Start
   S->C : Encryption Key Request
   (Client Auth)
   C->S : Encryption Key Response
   (Server Auth, Both enable encryption)
   S->C : Login Success

For unauthenticated and* localhost connections there is no encryption. In that case Login Start is directly followed by Login Success.

* It could be that only one of the two conditions is enough for an unencrypted connection.

See Protocol Encryption for details.

Clientbound

Disconnect

Packet ID Category Bound To Field Name Field Type Notes
0x00 Login Client JSON Data String

Encryption Request

Packet ID Category Bound To Field Name Field Type Notes
0x01 Login Client Server ID String appears to be empty as of 1.7.x
Length Short length of public key
Public Key Byte array
Length Short length of verify token
Verify Token Byte array

See Protocol Encryption for details.

Login Success

Packet ID Category Bound To Field Name Field Type Notes
0x02 Login Client UUID String
Username String

Serverbound

Login Start

Packet ID Category Bound To Field Name Field Type Notes
0x00 Login Server Name String

Encryption Response

Packet ID Category Bound To Field Name Field Type Notes
0x01 Login Server Length Short length of shared secret
Shared Secret Byte array
Length Short length of verify token
Verify Token Byte array

See Protocol Encryption for details.

See Also

Retrieved from "http://wiki.vg/index.php?title=Protocol&oldid=5939"