FOSS gamedev and creative worlds

I have played on singleplayer for a little while now, but today I decided to attempt to create a local server. It was not hard, and at first it looked fine, but it is definitely not. There is nothing like gravity. Pressing space allows me to travel as far as I want into the sky, while pressing shift will take me into the depths of the ground where I can see patches of rocks and lava pockets. Mining works like normal, but it is no fun without "natural laws." Can this be fixed somehow?

I play on Linux Mint, version 0.4.9. I have tried it several times and it repeats itself every time. I have played on a public server once or twice, on which it behaved normally...

Thanks for any help.

EDIT

After playing around some more, I realized that it is only the server game that behaves this way. Playing as a client behaves normally. Which is worked around easily enough, but is it meant to be this way?

Turn flying mode off.

Welcome to the MT forums.

I literally just read something about flying privileges. Thanks man.