I have the port opened correctly. However when I try to connect using 'localhost', the command prompt says I'm connected...and then promptly kicks me, saying I need to log in. Obviously I am logged in, or else I wouldn't be able to access it in the first place. In the actual minecraft window it says it's crashed and shows several NullPointerExceptions. I'll provide screenshots if needed.
I've tried google for this, nothing helpful comes up.