Hi Werner,
re: "For example with netstat I can see, that 2437 is a used port. I am wondering that I could recognize that this port is used by my testprogram istself"
It really wouldn't do any good. When you make a call on an EJB, it filters down to Remoting, which, if it can't find a pooled connection to reuse, will create a new socket, leading to ServerSocket.accept() returning a socket on the server.
It seems like something is preventing the client from completing the initialization of the connection, but I can't imagine what it is. You could use Wireshark to monitor what bytes, if any, get sent from the client to the server.
-Ron