How to lock down simutrans player in network game ?

[missingpiece]

To the networking guys of you this questions : how do I lock down the default simutrans player so that players connecting to the server are required to chose another slot ?

I've read that as being a best practice somewhere in the networking tutorials, and I agree, but it lacked a description of how to do that... 

[Dwachs]

you have to set a password for this player.