本文目录导读：
在计算机网络中，文件传输协议（FTP）是一种广泛使用的网络协议，用于在计算机之间传输文件，FTP服务器作为文件传输的核心，承载着用户上传、下载、管理文件的职责，为了更好地理解FTP服务器的工作流程，本文将结合流程图，对FTP服务器的工作原理进行详细解析。
FTP服务器工作流程概述
FTP服务器工作流程主要包括以下几个阶段：
1、客户端连接到FTP服务器
2、用户身份验证
图片来源于网络，如有侵权联系删除
3、选择文件传输类型
4、文件传输
5、客户端断开连接
FTP服务器工作流程详解
1、客户端连接到FTP服务器
客户端需要通过FTP客户端软件（如FileZilla、FlashFXP等）连接到FTP服务器，客户端软件会向FTP服务器发送一个TCP连接请求，请求建立控制连接。
2、用户身份验证
在客户端与FTP服务器建立控制连接后，客户端需要向服务器发送用户名和密码进行身份验证，服务器收到请求后，会根据用户名和密码验证用户的合法性，如果验证成功，服务器会返回一个“230 Login successful”消息；如果验证失败，则会返回一个“530 Login incorrect”消息。
图片来源于网络，如有侵权联系删除
3、选择文件传输类型
身份验证成功后，客户端需要选择文件传输类型，FTP协议支持两种传输模式：ASCII模式和二进制模式。
- ASCII模式：适用于文本文件传输，服务器会将文件转换为本地系统的默认编码。
- 二进制模式：适用于二进制文件传输，服务器会保持文件原始的二进制格式。
客户端发送“TYPE”命令，服务器收到后返回相应的“230”或“425”消息。
4、文件传输
在完成文件传输类型选择后，客户端可以通过发送“PUT”或“GET”命令来上传或下载文件，服务器收到命令后，会根据客户端的要求进行文件传输。
图片来源于网络，如有侵权联系删除
- 上传文件：客户端发送“PUT”命令，指定本地文件路径，服务器将文件上传到指定路径。
- 下载文件：客户端发送“GET”命令，指定服务器文件路径，服务器将文件下载到本地。
文件传输过程中，服务器会实时反馈传输状态，如“226 Transfer complete”表示文件传输成功。
5、客户端断开连接
文件传输完成后，客户端可以发送“QUIT”命令，通知服务器断开连接，服务器收到命令后，会返回一个“221 Goodbye”消息，并关闭控制连接。
ftp服务器流程图分析
以下是FTP服务器工作流程的流程图：
[开始] --> [客户端连接到FTP服务器] --> [用户身份验证]
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| | 标签： #ftp服务器流程图
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