code: public void setActive()
          throws IOException, ServerException, ClientException {
          Session local = localServer.getSession();
          if (local.serverAddress == null) {
              throw new ClientException(ClientException.CALL_PASSIVE_FIRST);
          }
          setActive(local.serverAddress);
      }
docs: Sets remote server active, telling it to connect to the client.
  setLocalPassive() must be called beforehand.