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FTP experiment and overview

2022-07-23 12:54:00 【Y firm materialist】

Catalog

One 、 summary

1.1FYP It's a file transfer protocol

1.2Passive Pattern

1.3standard Pattern

1.4 Data connection mode

Two 、 build FTP

1. install FTP service

2. Modify the configuration file

3. Opening service , Turn off firewalls and enhanced security ！！！！

3、 ... and 、 verification

One 、 summary

FTP (File TransferProtocol, File transfer protocol ） Is a typical c/s Application layer protocol of architecture , The server software is required 、 The two parts of the client software jointly realize the file transfer function .FTP The connection between the client and the server is reliable , Connection oriented , It provides reliable guarantee for data transmission .tcp agreement :20,21 port

1.1FYP It's a file transfer protocol

It supports two modes , One way is called standard( That is to say active, Active way ), One is Passive( That is to say PASV, Passive way ).Standard Pattern rlP The client sends PORT Order to FTP server.Passive Pattern FTP The client sends PASV Order to FTP serverstandard Pattern FTP The client first communicates with lFTP Server Of TCP21 Port establish connection , Send commands through this channel , When the client needs to receive data, it will send it on this channel PORT command .PORT The command contains what port the client uses to receive data . When transmitting data , Server side through their own TCP 20 Port send data .FTPserver A new connection must be established with the client to transmit data .

1.2Passive Pattern

When establishing control channels and standard Similar model , When the client sends through this channel PASV When ordered ,FTP
server Open a window located in 1024 and 5000 And notify the client of the request to transmit data on this port , then FTP server Data will be transmitted through this port , This is the time FTP server There is no longer a need to establish a new connection with the client .

1.3standard Pattern

FTP The client first communicates with FTP Server Of TCP
21 Port establish connection , Send commands through this channel , When the client needs to receive data, it will send it on this channel PORT command .
PORT The command contains what port the client uses to receive data . When transmitting data , Server side through their own TcP[20 Port send data ,FTP
server A new connection must be established with the client to transmit data .