FTP (File Transfer Protocol) and its file configuration

ftp function

It is used for file upload and download. It
belongs to the TCP protocol. Port number: 20
,
21. Port number: Data layer, used for file upload and download. 21 Port number: Control layer, used for account password verification and permission verification.

ftp three accounts

Anonymous, system, virtual account.
Anonymous account: login name: ftp, anonymous. You can log in without verifying the password.
System account: The account and password that already exist in the system are verified.
Virtual account

Ways of identifying:

Verified /etc/passwd and /etc/shadow
The verification is the user list (the user must be created by the system), which is equivalent to a white list. The
default root account does not allow login.
Virtual account: a predefined list of accounts. (The system has not been created before)

Anonymous account ftp creation:

[root@server ~]# yum -y install vsftpd

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Configuration file

[root@server ~]# vi /etc/vsftpd/vsftpd.conf

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Modify and add according to the above content;

Enable vsftpd service

[root@server ~]# systemctl start vsftpd

Create 2 test files

[root@server pub]# echo "abc123" > a.txt
[root@server pub]# echo "bcd123" > b.txt

Set permissions

[root@server ~]# chown -R ftp.ftp /var/ftp/pub/
[root@server ~]# chown -R 755 /var/ftp/pub

[root@server ~]# ftp 20.0.0.10

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System account ftp creation

[root@server ~]# vi /etc/vsftpd/vsftpd.conf

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Configure according to the above.
Use the client for authentication, the steps are similar to anonymous users

Virtual account ftp creation

Set up virtual account list

[root@server ~]# vi/etc/vsftpd/vusers.list

mike
123
john
234

Create a new virtual user account database

[root@server ~]# cd /etc/vsftpd
[root@server vsftpd]# db_load -T -t hash -F vusers.list vusers.db
[root@server ~]# file vusers.db

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Configuration file has been generated

Grant permissions

[root@server ~]# chmod 600 /etc/vsftpd/vusers.*

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Create virtual accounts and grant permissions

[root@server ~]# useradd -d /var/ftproot -s /sbin/nologin virtual
[root@server ~]# chmod 755 /var/ftproot

Configure it

[root@server ~]# vi /etc/pam.d/vsftpd.vu

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The configuration content is as above

Enter vsftpd for configuration

[root@server ~]# vi /etc/vsftpd/vsftpd.conf

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Modify the configuration according to the above content

Set up virtual account configuration file

[root@server ~]# mkdir /etc/vsftpd/vusers_dir/
[root@server ~]# cd /etc/vsftpd/vusers_dir/

Configure content

[root@server vusers_dir]# vi mike

anon_upload_enable=YES
anon_mkdir_write_enable=YES

The content of john is empty and will not be configured.
Then restart vsftpd

[root@server ~]# systemctl restart vsftpd

Use the client to verify

[root@server ~]# ftp 20.0.0.10

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Verified successfully