说明：  设计和实现FTP服务器，主要是遵从FTP协议标准实现FTP服务器 允许现有标准的FTP客户端与它互连互通 支持上传和下载文件。
(Design and implementation of an FTP server, mainly to achieve compliance with the standard FTP protocol FTP server allows existing standard FTP client with its interconnection support for uploading and downloading files)