IP listening

[R.L. Reingard]

hello
i tried commands with $ netstat, but do not get what i like to see. i want  
to understand what program / utility i have to use to simple get to know  
the following.

to which IP address(es) the machine is connected at the moment? (nice  
would be if it could be shown continously refreshed)
AND
which IP address does search a connection to the machine at the moment?  
(and at what door / ports do they knock?)

truly unexperienced i am in this regard.

thank you for sharing with me.
René