Minecraft:RakNet

RakNet is a networking library and protocol for multiplayer games. It runs over UDP and provides connection management, configurable reliability and ordering, sequencing, and fragmentation.

UDP does not guarantee delivery or ordering. RakNet supports different delivery modes, so applications can request reliability or ordering when needed.

The source code for RakNet is available in the archived source repository.

Use in Bedrock Edition

Minecraft:NetherNet became the default transport for Minecraft:Bedrock Dedicated Server in Minecraft:26.50.<ref>Template:Cite</ref> RakNet is deprecated in Minecraft:26.60, which removes client support for it.<ref>Template:Cite</ref>

Libraries

The following libraries implement RakNet. Supported features and protocol versions vary between implementations.

Name	Description	Language	License
go-raknet	RakNet implementation written in Go.	Go	MIT
RakNet	Asynchronous RakNet implementation written in Rust.	Rust	Apache-2.0
PieRakNet	RakNet implementation written in Python.	Python	GPL-3.0
Cloudburst Network	Network components used by CloudburstMC projects.	Java	Apache-2.0
rak-net	Python RakNet implementation originally developed for Podrum.	Python	GPL-2.0
JRakNet	Java implementation of the RakNet protocol.	Java	MIT
netty-raknet	RakNet implementation for Netty.	Java	MIT
JRakLibPlus	RakNet server library based on RakLib and JRakLib.	Java	LGPL-3.0
RakLib	Lightweight PHP RakNet server implementation.	PHP	GPL-3.0
raknet	UDP networking library for Node.js that follows the RakNet protocol.	JavaScript	MIT
PyRakLib	Python port of RakLib that follows the RakNet protocol.	Python	GPL
rust-raknet	RakNet implementation written in Rust.	Rust	MIT
Baltica	Bedrock toolkit that includes a RakNet implementation.	TypeScript	See repository
RakNet.Py	RakNet implementation written in Python.	Python	GPL-2.0
LavishMC RakNet	C++ fork of the original RakNet implementation.	C++	BSD
RakNet (original)	Original C++ RakNet implementation.	C++	BSD-2-Clause

Data types

The types below describe the packet layouts on this page. Multi-byte integers are big-endian unless stated otherwise; 24-bit indices are little-endian. Address structures have their own byte order.<ref>RakNet: BitStream go-raknet: Frame encoding</ref>

Type	Size	Description
Byte	1 byte	Unsigned 8-bit value.
Boolean	1 byte	Template:Cd is false; Template:Cd is true.
Short	2 bytes	Signed 16-bit integer.
Unsigned Short	2 bytes	Unsigned 16-bit integer.
Int	4 bytes	Signed 32-bit integer.
Unsigned Int	4 bytes	Unsigned 32-bit integer.
Long	8 bytes	64-bit integer. Whether it represents a signed value depends on the field.
uint24le	3 bytes	Unsigned 24-bit little-endian integer, used for datagram sequence numbers and frame indices.
String	Variable	An unsigned 16-bit byte length followed by that many string bytes.
Magic	16 bytes	The fixed Template:Cd value used in offline packets.<ref>RakNet: RakPeer.cpp</ref>
Address	7 bytes (IPv4); 29 bytes (IPv6)	Encodes the address family, address and port. IPv4 address bytes are inverted; the port is big-endian. IPv6 also includes address-family, flow-info and scope fields.<ref name="address-format">go-raknet: Address encoding</ref>

Handshake sequence

The handshake begins with unconnected UDP packets and continues with connection-control messages carried inside RakNet frames.<ref>RakNet: RakPeer.cpp go-raknet: Connection messages</ref>

1. C→S: Open Connection Request 1
2. S→C: Open Connection Reply 1 (or Incompatible Protocol)
3. C→S: Open Connection Request 2
4. S→C: Open Connection Reply 2. The peers can now exchange framed connection-control messages.
5. C→S: Connection Request
6. S→C: Connection Request Accepted
7. C→S: New Incoming Connection

After this exchange, the RakNet connection is established. Connection Request, Connection Request Accepted, and New Incoming Connection are themselves carried inside frames. In Minecraft:Bedrock Edition, game packets are carried in RakNet frames as described at Game Packet.

Packets

Offline packet IDs identify UDP datagrams; connected message IDs identify the payload inside a frame. The handshake tables below describe the layout with RakNet security disabled. Optional security handshakes and connection passwords are not included. Field details can vary by implementation.<ref>RakNet: Message identifiers go-raknet: Frame encoding</ref>

Unconnected Ping

The client sends this packet to discover a server. ID Template:Cd is a regular unconnected ping; Template:Cd asks for a response only when the server is accepting new connections. The server replies with Unconnected Pong.

Packet ID	Field Name	Field Type
0x01, 0x02	Time	Long
	Magic	Magic
	Client GUID	Long

Unconnected Pong

The server sends this in response to an unconnected ping. It echoes the ping time and includes its GUID and a server ID string. In Minecraft:Bedrock Edition, that string contains server-list information in a semicolon-delimited format; its fields can vary by game version.

Packet ID	Field Name	Field Type	Notes
0x1c	Time	Long
	Server GUID	Long
	Magic	Magic
	Server ID String	String	Carries server-list information.

Connected Ping

This packet measures latency on an established connection. It is commonly sent unreliably.

Packet ID	Field Name	Field Type
0x00	Time	Long

Connected Pong

The receiver replies with the original ping time and its own response time. It is commonly sent unreliably.

Packet ID	Field Name	Field Type
0x03	Ping Time	Long
	Pong Time	Long

Open Connection Request 1

The first packet in the handshake sequence, sent by the client to the server.

Packet ID	Field Name	Field Type	Notes
0x05	Magic	Magic
	Protocol version	Byte	RakNet protocol version used by the client; separate from the Bedrock game protocol version.
	Padding	Zero bytes	Zero padding used to probe the path MTU.

The MTU is inferred from the datagram length, including IP and UDP overhead; it is not a numeric field in this request. The server replies with the selected MTU, or sends Incompatible Protocol if it does not support the client's RakNet protocol version.

Open Connection Reply 1

The second packet in the handshake sequence, sent by the server to the client.

Packet ID	Field Name	Field Type	Notes
0x06	Magic	Magic
	Server GUID	Long
	Use security	Boolean	False for the layout shown here.
	MTU	Unsigned Short	Selected MTU for the connection.

Open Connection Request 2

The third packet in the handshake sequence, sent by the client to the server.

Packet ID	Field Name	Field Type
0x07	Magic	Magic
	Server Address	Address
	MTU	Unsigned Short
	Client GUID	Long

Open Connection Reply 2

The fourth packet in the handshake sequence, sent by the server to the client.

Packet ID	Field Name	Field Type	Notes
0x08	Magic	Magic
	Server GUID	Long
	Client Address	Address
	MTU	Unsigned Short
	Encryption enabled	Boolean	False for the layout shown here.

Connection Request

The client sends this framed message after Open Connection Reply 2 to continue the RakNet handshake.

Packet ID	Field Name	Field Type
0x09	GUID	Long
	Time	Long
	Use security	Boolean

Connection Request Accepted

The server sends this packet to accept the client's connection request.

Packet ID	Field Name	Field Type	Notes
0x10	Client address	Address
	System index	Unsigned Short	System index assigned by the server.
	Internal addresses	Address array	Internal server addresses; the count varies by implementation, commonly 10 or 20.<ref name="accepted-addresses">go-raknet: Connection Request Accepted</ref>
	Request time	Long	Timestamp from the corresponding Connection Request.
	Time	Long	Server acceptance time.

New Incoming Connection

The client sends this packet to confirm that it received the server's acceptance.

Packet ID	Field Name	Field Type	Notes
0x13	Server address	Address
	Internal addresses	Address array	Internal client addresses; the count varies by implementation, commonly 10 or 20.<ref>go-raknet: New Incoming Connection</ref>
	Ping time	Long	Server acceptance timestamp echoed by the client.
	Pong time	Long	Time at which the client sends this message.

Disconnection Notification

This packet notifies the other peer that the sender is disconnecting.

Packet ID	Field Name	Field Type	Notes
0x15	No payload		Signals that the sender is disconnecting.

Incompatible Protocol

The server sends this packet when it does not support the RakNet protocol version used by the client.

Packet ID	Field Name	Field Type
0x19	Protocol	Byte
	Magic	Magic
	Server GUID	Long

Frame Set Packet

This packet carries one or more frames between connected peers.

Packet ID	Field Name			Field Type	Notes
0x80–0x9f	Sequence number			uint24le	Used for building ACK and NACK ranges
	Frames	Flags		Byte	Top 3 bits give the reliability type, fourth bit is 1 when the frame is fragmented and part of a compound.
		Body bit length		Unsigned Short	Length of this frame's body in bits.
		Reliable frame index		uint24le	Only if reliable, used for detecting frame level duplication
		Sequenced frame index		uint24le	Only if sequenced, used for discarding out-of-date packets
		Order (if ordered or sequenced)	Ordered frame index	uint24le	Tells the receiver the correct order in which to deliver frames to the application
			Order channel	Byte	Maximum of 32 channels
		Fragment (only if fragmented)	Compound size	Unsigned Int	Number of fragments in the split message.
			Compound ID	Unsigned Short	Identifies which compound this fragment is part of
			Index	Unsigned Int	Zero-based index of this fragment in the split message.
		Body	ceil(length/8) bytes

A frame-set header has bit Template:Cd set and ACK/NACK bits Template:Cd clear. The remaining bits are flags, so the header is not a fixed message ID. A frame set can contain multiple frames.<ref name="frames">go-raknet: Frame encoding</ref>

The reliability values transmitted in the frame header are as follows:

ID	Name	Reliable	Sequenced	Ordered
0	unreliable
1	unreliable sequenced		x
2	reliable	x
3	reliable ordered	x		x
4	reliable sequenced	x	x

The original RakNet API also defines receipt modes 5, 6, and 7. These are encoded as wire values 0, 2, and 3 respectively; receipt notification is handled locally.<ref>RakNet: Reliability layer</ref>

Sequenced delivery discards older packets when a newer packet has arrived. Ordered delivery preserves the order of reliable packets within a channel.

Game Packet

This Bedrock-specific message carries a batch of game packets inside a RakNet frame.

Packet ID	Field Name	Field Type	Notes
0xfe	Body	bytes	In Minecraft:Bedrock Edition, the body contains a batch of game packets. Framing and compression are described in Bedrock Edition protocol.

Packet definitions are listed at Minecraft:Bedrock Edition protocol/Packets.

NACK

This packet reports datagrams that were not received so the sender can retransmit them when required.

Packet ID	Field Name			Field Type	Notes
0xa0	Record count			Unsigned Short	Number of records in the packet
	Records	Is Single?		boolean	False for range, True for no range
		No Range, if is_single == true	Sequence number	uint24le	Datagram sequence number in this record.
		Range, if is_single == false	Start Sequence number	uint24le	First datagram sequence number in the inclusive range.
			End Sequence number	uint24le	Last datagram sequence number in the inclusive range.

A NACK reports frame-set sequence numbers that were not received, prompting retransmission where required.

ACK

This packet acknowledges datagrams received from the other peer.

Packet ID	Field Name			Field Type	Notes
0xc0	Record count			Unsigned Short	Number of records in the packet
	Records	Is Single?		boolean	False for range, True for no range
		No Range, if is_single == true	Sequence number	uint24le	Datagram sequence number in this record.
		Range, if is_single == false	Start Sequence number	uint24le	First datagram sequence number in the inclusive range.
			End Sequence number	uint24le	Last datagram sequence number in the inclusive range.

An ACK reports frame-set sequence numbers that were received. Both ACK and NACK packets can contain multiple records.