php ftp连接上传文件，为什么提示Opening ASCII mode data connection

[qq_41265012]

  $source = fopen("txt123.txt","r");
  $conn = ftp_connect("ip") or die("Could not connect");
  ftp_login($conn,"ftp账号","ftp密码");
  echo ftp_fput($conn,"txt321.txt",$source,FTP_ASCII);
  ftp_close($conn);

为什么提示Opening ASCII mode data connection，哪里错误了？

[桂浮云]

http://php.net/manual/zh/function.ftp-put.php User Contributed Notes部分有对此问题的说明。 启动被动模式即可： ftp_pasv($resource, true);