code: protected void readInitialReplies() throws IOException, ServerException {
          Reply reply = null;
          try {
              reply = read();
          } catch (FTPReplyParseException rpe) {
              throw ServerException.embedFTPReplyParseException(
                                  rpe,
                                  "Received faulty initial reply");
          }
  
          if (Reply.isPositivePreliminary(reply)) {
              try {
                  reply = read();
              } catch (FTPReplyParseException rpe) {
                  throw ServerException.embedFTPReplyParseException(
                                          rpe,
                                          "Received faulty second reply");
              }
          }
  
          if (!Reply.isPositiveCompletion(reply)) {
              close();
              throw ServerException.embedUnexpectedReplyCodeException(
                                  new UnexpectedReplyCodeException(reply),
                                  "Server refused connection.");
          }
      }
docs: (that the server sends after opening control ch.)