从命令行终端获得ftp 服务器的域名或 IP 地址字符串，转换为网络字节序的二进制

格式的IP 地址。

使用上述IP 地址和默认的21端口，创建一个到ftp 服务器的TCP 连接，用于传输

所有的控制命令。

在传输控制命令的TCP 连接中循环处理，将用户端的标准输入解释为FTP 协议的

控制命令并发送，根据ftp 服务器回复的响应命令执行一些本地操作或远程控制。

准备进行数据传输时，创建一个新的 TCP 连接，根据需要，将接收到的数据发送到

标准输出或存储到文件中。数据传输结束后，关闭这个TCP 连接。

用户退出时，释放内存等资源，关闭用于传输控制命令的TCP 连接，退出程序。-From the command line terminal access to the ftp server domain name or IP address of the string is converted to the IP address of the network byte order binary format. Use the IP address and default port 21, to create a TCP connection to the ftp server for the transmission of all control commands. 3 loop in the TCP connection of the transmission of control commands, the client　s standard input is interpreted as control commands and sends the FTP protocol ftp server reply to the response command to perform some local or remote control. Ready for data transmission, to create a new TCP connection, according to need, will receive the data sent to standard output or stored to a file. Close the TCP connection after the data transmission. 5 when the user exits the release of memory and other resources to close the TCP connection used to transmit control commands to exit the program.