Hello. There is no program for this.
Type /jo servernamehere and type /passwd (passwordhere) to set a password to the server.
Oh and without brackets. It will make the server private and only those with the pass can enter. Type /pass passhere to authorize and enter.
In addition to this you can also click the multiplayer option on the main menu and in the bottom right hand corner and click "create".
Then you type in the server name, and that should work
She/They
Yeah, I only don't like erthtkv2 because of the mod's name. Make it "tkv2," and the mod will instantly become more popular. This is a valid reason as the name of the mod is still an important feature that no one seems to have yet discussed.