在Linux系统上完成一个文件传输协议（FTP）的简单实现。通过本实验，深入了解FTP协议的原理和协议细节，学会利用socket接口设计实现简单的应用层协议，掌握TCP/IP网络应用程序的基本设计方法和实现技巧。在Linux系统上使用socket接口实现FTP客户端程序，严格按照RFC959，使客户端可以连接至服务器，并且可以进行一些FTP的基本操作，如列出目录、下载文件等。从FTP协议的实现角度来看，客户端与服务器的命令通道和数据通道需要分离。-In the Linux system to complete a file transfer protocol (FTP) simple to achieve. Through this experiment, in-depth understanding of the principles of FTP protocol and protocol details, learn to use simple socket interface design application layer protocol, master TCP/IP network application design and implementation of basic skills. In the Linux system using the socket interface FTP client application, in strict accordance with RFC959, so that clients can connect to the server, and can do some basic FTP operations, such as listing directories, download files. FTP protocol implementation from the perspective of the client and the server' s command channel and data channels are separated.