我查了MSDN，其中说：When an FTP client passes a command to an FTP server and the client is in active mode, the client also passes a port on which it listens for the response from the server. If the client is sending a command that does not require a data port (such as the syst command), the client does not set up a data port. The ls command, also called the list command, requires a data port to return the data. If the server is expecting a data port from the client, and the server does not receive a data port, the server generates the 425 error.
但是并不有给出解决方案，我试着先传送PASV命令，但结果还是报425错。
为什么？？
