Disabling anonymous comments

// Change in core/pages/ajax.php, case 'comment' into:
case "comment":     if($_POST["comment"]!="" && $_POST["ajax"]!=0 && USER_ID!='')
            {
                $engine_session->addcomment($_POST["id"], $_POST["comment"], $_POST["anonymous"]);
            }

// Change in themes/[theme_name]/tpl/comments.tpl (find by COMMENTS_HTML) by adding PHP code:

<div class="col-lg-12 comments" id="commentslist">
        <?php echo COMMENTS_HTML; ?>
      </div>
      <hr>
      <?php if(USER_ID!='') { ?>
      <div class="col-lg-12">
        <h3><?php echo langVar(416); ?>:</h3>
        <form method="post" id="commentForm" onsubmit="addComment('<?php echo MAIN_QUESTION_ID; ?>'); return false;">
          <div class="col-lg-10 col-sm-10 col-xs-9">
            <textarea name="comment" id="comment" maxlength="255" class="form-control" rows="2"></textarea>
          </div>
          <div class="col-lg-2 col-sm-2 col-xs-3">
            <a id="sendButton" class="btn btn-primary btn-sm" onclick="addComment('<?php echo MAIN_QUESTION_ID; ?>')"><?php echo langVar(417); ?> <i id="sendIndicator" class="fa fa-spinner fa-spin" style="display:none;"></i></a>
            <?php if(SESSION_STATUS!="") { ?>
              <div class="checkbox">
                <label>
                  <input type="checkbox" name="anonymous" value="1" id="anonymous"> <?php echo langVar(82); ?>
                </label>
              </div>
            <?php } else { ?>
              <div class="checkbox">
                <label>
                  <input name="anonymous" type="hidden" value="1" id="anonymous"> <?php echo langVar(82); ?>
                </label>
              </div>
            <?php } ?>
          </div>
        </form>
        <div id="commentSuccess" class="commentSuccess" style="display:none">
          <?php echo langVar(418); ?>. <a href="javascript://" onclick="commentAgain()" class="nofollow"><?php echo langVar(419); ?></a>
        </div>
      </div>
      <?php } ?>