private void ForwardedPort_Closing(object sender, EventArgs eventArgs)
{
// signal to the client that we will not send anything anymore; this should also interrupt the
// blocking receive in Bind if the client sends FIN/ACK in time
ShutdownSocket(SocketShutdown.Send);
// if the FIN/ACK is not sent in time by the remote client, then interrupt the blocking receive
// by closing the socket
CloseSocket();
}