I found a solution to show all forums in index and not see topics if user group don't have permission (similar to phpbb view forum option), i dont know how secure is it
open index.php and search
$result = $db->query('SELECT c.id AS cid, c.cat_name, f.id AS fid, f.forum_name, f.forum_desc, f.redirect_url, f.moderators, f.num_topics, f.num_posts, f.last_post, f.last_post_id, f.last_poster FROM '.$db->prefix.'categories AS c INNER JOIN '.$db->prefix.'forums AS f ON c.id=f.cat_id LEFT JOIN '.$db->prefix.'forum_perms AS fp ON (fp.forum_id=f.id AND fp.group_id='.$pun_user['g_id'].') WHERE fp.read_forum IS NULL OR fp.read_forum=1 ORDER BY c.disp_position, c.id, f.disp_position', true) or error('Unable to fetch category/forum list', __FILE__, __LINE__, $db->error());
change to
$result = $db->query('SELECT c.id AS cid, c.cat_name, f.id AS fid, f.forum_name, f.forum_desc, f.redirect_url, f.moderators, f.num_topics, f.num_posts, f.last_post, f.last_post_id, f.last_poster FROM '.$db->prefix.'categories AS c INNER JOIN '.$db->prefix.'forums AS f ON c.id=f.cat_id LEFT JOIN '.$db->prefix.'forum_perms AS fp ON (fp.forum_id=f.id AND fp.group_id='.$pun_user['g_id'].') WHERE fp.read_forum IS NULL OR fp.read_forum=1 OR fp.read_forum=0 ORDER BY c.disp_position, c.id, f.disp_position', true) or error('Unable to fetch category/forum list', __FILE__, __LINE__, $db->error());
Now it say 'Bad request' when user group don't have permission to see private forum, I need to change message to 'No permission' in this case...