Catalog

FTP summary

FTP Function and working principle

experiment

Set user mode login

FTP 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

20 port ： For data transfer
21 port ： Used to transmit instructions （ Establishing a connection ）

FTP 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 FTP The client sends PORT Order to FTP server.Passive Pattern FTP The client sends PASV Order to FTP Server

FTP Function and working principle

FTP The role of ：

Internet The protocol used to transfer files remotely on .

FTP The pattern of ：

vsftp Full name (very secure FTP)

vsftp Pattern :c/s Pattern

FTP The server defaults to TCP Agreed 20、21 Port to communicate with the client ：

20 Ports are used to establish data connections , And transfer file data

21 Ports are used to establish control connections , And transmit FTP Control command

FTP Working principle and process

FTP Data connection is divided into active mode and passive mode

Active mode ： The server initiates the data connection actively

Passive mode ： The server passively waits for data connections

experiment

First, turn off the firewall

install vsftpd

open ftp service

Then enter vsftpd take vsftpd.conf File backup

then vim /etc/vsftpd/vsftpd.conf Compiling

write in ：

anon_upload_enable=YES： Allow anonymous users to upload files

anon_mkdir_write_enable=YES： Allow anonymous users to create （ Upload ） Catalog

anon_other_write_enable=YES： Allow deletion of , rename , Covering and other operations

And guarantee anonymous_enable=YES： Enable anonymous access （ Default on ）

write_enable=YES： Open server write permissions （ Default on ）

local_umask=022： Set the permission mask for anonymous users to upload data

Access is anonymous ftp Under the root directory of pub Set the maximum permissions for subdirectories So that anonymous users can upload data , And then restart ftp service

Get into /var/ftp/pub Create a new file 1.txt

open windows, Open command window , Connect to ftp 192.168.200.111（ virtual machine ip Address ）

Input password , Then enter pub Catalog , Check for 1.txt, then get 1.txt Download the file locally

Enter the folder to check , Create a new 2.txt, And write content

Then enter in the command window put 2.txt, Get the file back to the virtual machine

Enter the virtual machine to view pub Catalog , And look at the content , success

Set user mode login

Set up local user authentication access ftp, And prohibit switching to ftp Outside directory （ The default login root directory is the home directory of the local user ）

vim /etc/vsftpd/vsftpd.conf
local_enable=YES                # Enable local users
anonymous_enable=NO             # Turn off anonymous user access
write_enable=YES                # Open server write permissions （ To upload, you must enable ）
local_umask=077                 # It can be set that only the user of the host directory has the permission to upload files （ Unmask ）
chroot_local_user=YES           # Lock access to the user's Host Directory
allow_writeable_chroot=YES      # Allow restricted users to have write permission under their home directory
 
#anon_mkdir_write_enable=YES     notes
#anon_other_write_enable=YES     notes
 
systemctl restart vsftpd        # Restart the service

Create a new user fang, And give authority , Set the host directory

  Get into windows, Connect ftp, Sign in fang user , And get it back 1.txt and 2.txt

Get into fang Host Directory view , success