网络协议之FTP协议

FTP(File Transfer Protocol)

协议文档：RFC 959

1.1 FTP协议介绍

FTP协议基于TCP/IP协议实现，处于应用层。

FTP协议为C/S架构，每一次FTP连接，命令和数据分别通过两个端口进行通信。

FTP Server占用命令端口21和数据传输端口20。

FTP Client发起命令，FTP Server被动响应，但是数据传输可以由任意一方发起。

FTP Client首先使用一个随机的端口，向FTP Server的命令端口（端口号20）告知自己的端口号，FTP Server向该端口号发送应答消息。

1.2 FTP命令

ABOR - abort a file transfer

CWD - change working directory

DELE - delete a remote file

LIST - list remote files

MDTM - return the modifucation time of a file

MKD - make a remote directory

NLST - name list of remote directory

PASS - send password

PASV - enter passive mode

PORT - open a data port

PWD - print working directory

QUIT - terminate the connection

RETR - retrieve a remote file

RMD - remove a remote directory

RNFR - rename from

RNTO - rename to

SITE - site-specific commands

SIZE - return the size of a file

STOR - store a file on the remote host

TYPE - set transfer type

USER - send username