0x3F S3FPacketCustomPayload

Sends a plugin channel message from server to client. Used for mod/plugin communication.

Clientbound (Server → Client) · PLAY · net/minecraft/network/play/server/S3FPacketCustomPayload.java
pluginmoddingchannel

Fields

FieldTypeDescription
channelStringPlugin channel name
dataPacketBufferChannel-specific payload

Wire Encoding

FieldTypeNotes
ChannelStringPlugin channel identifier
Data Lengthshort
Databyte[]Channel-specific payload

MCP References

MCPNetHandlerPlayClient.handleCustomPayload()

Handler Interface

HNDINetHandlerPlayClient

Notes

Common channels: "MC|Brand" (server brand), "MC|AdvCmd" (command block update), "MC|TrList" (villager trades), "MC|RPack" (resource pack).

implementation Implementation Cases

BrandDetector (Flux B39.11 (Brand detection), Lycoris 1.0 (Brand detection))

Read server brand from "MC|Brand" channel. Detect anti-cheat plugins from custom payloads.

Vanilla hook: EventReceivePacket
ServerCrasher (Flux B39.11 (Brand detection), Lycoris 1.0 (Brand detection))

Read server brand from "MC|Brand" channel. Detect anti-cheat plugins from custom payloads.

Vanilla hook: EventReceivePacket
AntiCheatDetector (Flux B39.11 (Brand detection), Lycoris 1.0 (Brand detection))

Read server brand from "MC|Brand" channel. Detect anti-cheat plugins from custom payloads.

Vanilla hook: EventReceivePacket
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