Server List Ping

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Revision as of 09:39, 26 October 2012 by Barneygale (talk) (Created page with "Minecraft supports querying the MOTD, player count, max players and server version via the usual port. Unlike Query, the server list ping interface is always enabled. == ...")
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Minecraft supports querying the MOTD, player count, max players and server version via the usual port. Unlike Query, the server list ping interface is always enabled.

Client -> Server

The client initiates a TCP connection to the minecraft server on the standard port. Instead of doing auth and logging in (as detailed in Protocol Encryption), it sends the two byte sequence FE 01. This is a 0xFE server list ping packet.

Server -> Client

The server responds with a 0xFF kick packet. The packet begins with a single byte identifier ff, then a two-byte big endian short giving the length of the proceeding string in characters. You can actually ignore the length because the server closes the connection after the response is sent.

After the first 3 bytes, the packet is a big-endian UCS-2 string. It begins with two characters: §1, followed by a null byte. On the wire these look like 00 a7 00 31 00 00.

The remainder is null character (that is 00 00) delimited fields:

  1. Protocol version (e.g. 47)
  2. Minecraft server version (e.g. 1.4.1)
  3. Message of the day (e.g. A Minecraft Server)
  4. Current player count
  5. Max players

The entire packet looks something like this:

                   <---> first character
   0000000: ff00 2300 a700 3100 0000 3400 3700 0000  ....§.1...4.7...
   0000010: 3100 2e00 3400 2e00 3200 0000 4100 2000  1...4...2...A. .
   0000020: 4d00 6900 6e00 6500 6300 7200 6100 6600  M.i.n.e.c.r.a.f.
   0000030: 7400 2000 5300 6500 7200 7600 6500 7200  t. .S.e.r.v.e.r.
   0000040: 0000 3000 0000 3200 30                   ..0...2.0

Sample code