Pre-release protocol
This page documents the changes from the last stable Minecraft release (currently 1.5.2, protocol 61) to the current pre-release, 13w17a (protocol 64). Note that this page contains bleeding-edge information that may not be completely or correctly documented.
He 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 occured to the respective packets there.
Contents
Protocol Version
13w25a: Protocol version is now 71. Changed packet: Increment Statistic (0xC8)
13w24b: Protocol version is now 70
13w24a: Protocol version is now 69. Changed functionality: Time Update (0x04)
13w23b: Protocol version is now 68.
13w22a: Protocol version is now 67. New packet: Entity Properties (0x2C); Changed packets: Chat Message (0x03)
13w18b: Protocol version is now 65.
13w16b: Protocol version is now 63. New packet: Steer Vehicle (0x1B)
13w16a: Protocol version is now 62. Changed packets: Update Health (0x08), Entity Action (0x17), Attach Entity (0x27), Player Abilities (0xCA)
New Packets
Steer Vehicle (0x1B)
Client to Server
Sent by client to steer the horse, minecart and boats. Horses listen to all directions, boats and minecarts only listen to the positive forward value in combination with the direction the player is looking in.
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x1B | Sideways | float | 0.98 | Positive to the left of the player |
| Forward | float | -0.98 | Positive forward | |
| Jump | bool | true | ||
| Unmount | bool | false | True when leaving the vehicle | |
| Total Size: | 11 bytes | |||
Entity Properties (0x2C)
Server to Client
Note: The server sends this packet to inform the user of its movement speed. Users move far too fast when this packet is not sent.
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x2C | EntityID | int | 195 | ? |
| Properties Count | int | 3 | Number of string/data pairs that follow. The remaining fields here are repeated this number of times. | |
| Key | string16 | "generic.Maxhealth" | ||
| Value | double | 20.0 | ||
| Total Size: | ? bytes | |||
Known 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 |
Changed Packets
Chat Message (0x03)
Client to Server
Unchanged
Server to Client
The chat string must now be a valid JSON object:
{"translate":"chat.type.announcement","using":["Server","hi"]}
{"color":"gray","italic":true,"translate":"chat.type.admin","using":["Server",{"translate":"commands.save.success"}]}
{"text":"§aOld style chat"}
Where translate is one of the following:
chat.type.admin: [%s: %s] chat.type.announcement: [%s] %s chat.type.emote: * %s %s chat.type.text: <%s> %s
Time Update (0x04)
Server to Client
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 | Field Name | Field Type | Example | Notes |
|---|---|---|---|---|
| 0x04 | Age of the world | long | 45464654 | In ticks; not changed by server commands |
| Time of Day | long | 21321 | The world (or region) time, in ticks. If negative the sun will stop moving at the Math.abs of the time. | |
| Total Size: | 17 Bytes | |||
Update Health (0x08)
Server to Client
Sent by the server to update/set the health of the player it is sent to. Added in protocol version 5.
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 | Field Name | Field Type | Example | Notes |
| 0x08 | Health | float | 20.0 | 0 or less = dead, 20 = full HP |
| Food | short | 20 | 0 - 20 | |
| Food Saturation | float | 5.0 | Seems to vary from 0.0 to 5.0 in integer increments | |
| Total Size: | 11 bytes | |||
Entity Action (0x13)
Client to Server
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 | Field Name | Field Type | Example | Notes |
| 0x13 | EID | int | 55534
|
Player ID |
| Action ID | byte | 1
|
The ID of the action, see below. | |
| Unknown | int | 0
|
Something to do with horses. Ranged from 0 -> 90 | |
| Total Size: | 10 bytes | |||
Action ID can be one of the following values:
| ID | Action |
|---|---|
| 1 | Crouch |
| 2 | Uncrouch |
| 3 | Leave bed |
| 4 | Start sprinting |
| 5 | Stop sprinting |
Attach Entity (0x27)
Server to Client
This packet is sent when a player has been attached to an entity (e.g. Minecart)
| Packet ID | Field Name | Field Type | Example | Notes |
| 0x27 | Entity ID | int | 1298
|
The player entity ID being attached |
| Vehicle ID | int | 1805
|
The vehicle entity ID attached to (-1 for unattaching) | |
| Leash | boolean | false
|
If set to true, leashes the entity to the vehicle | |
| Total Size: | 10 bytes | |||
Increment Statistic (0xC8)
Server to Client
| Packet ID | Field Name | Field Type | Example | Notes |
| 0xC8 | Statistic ID | int | 1003 | The ID of the statistic. See List of statistics. |
| Amount | int | 1 | The amount to increment the statistic. | |
| Total Size: | 9 bytes | |||
Player Abilities (0xCA)
Two-Way
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 | Field Name | Field Type | Example | Notes |
| 0xCA | Flags | byte | 5 | |
| Flying speed* | float | 0.05 | previous integer value divided by 250 | |
| Walking speed* | float | 0.1 | previous integer value divided by 250 | |
| Total Size: | 10 bytes | |||
The client ignores the walking speed and flying speed fields. Send an 0x2C packet as well.
Removed Packets
-None-
Changed Data Types
-None-
Protocol History
-None-
