Lan Worlds

Beginning with 1.3.1 minecraft introduces lan worlds. A player can open his single player map to allow other players in the local network to join. The minecraft client will open a random port and listen at it and behaves like a server. Other players in the local network will see this lan world in their server list.

The client who hosts the lan world will send a udp broadcast every second to the udp broadcast address 224.0.2.60:4445. Other clients in the local network will wait for such broadcasts and show incoming entries in the server browser. This is a example of a lan world datagram packet:

[MOTD]pdelvo - world[/MOTD][AD]192.168.2.42:15380[/AD]

Here are examples how to send and receive these packets: C# Example [1]