UUID on offline mode - ok, you don't support, but tell me what happens

I know Bukkit don't support servers without authentication. But what happens with player UUID on offline modes? How are they determined and it'll change in what circunstance?

Any developer has any trick to keep track of players?

 

UUIDs will be generated differently compared to online-mode. Also UUID->PlayerName lookup might be a bit tricky, as you can't ask the Mojang Servers. (At least it was the last time I tested with offline-mode, there might be a change in CB that fixed this)

In result it will be kind of difficult to switch between both auth methods.

 

Maybe a last Ip - last name - last UUID and checking if the player knows its password (any authorization plugin) will work... But it'll be still tricky and not very stable.

 

If you set the online mode to false. The uuid will be a MD5 hash of the playername. This means:

• All players named "John" that join any offline mode server will all get the same UUID.
• The UUID of the "John" that has a premium account will not be the same as the offline UUID
• If the premium account "John" changes his name some other premium player can get his name thus changing the UUID that is related to the name "John"

On a offline mode server you dont need to track players by uuid since every playername has always the same uuid. You can also track them using a name based tracking plugin. like xauth or authme.

But you will lose the ability to see premium skins on your offline mode server. Because people will use your UUID on their client to fetch the skin from the mojang servers. Since the UUID is just a MD5 hash of the playername and not a premium UUID no skin is matched to your offline UUID so every player wont get your skin and all will be steves

 

Locked. Offline mode is not supported.