A brief analysis of vsftpd service configuration in Linux (anonymous, user, virtual user)

[root@localhost ~]# yum install vsftpd -y ##Install service[root@localhost ~]# cd /etc/vsftpd/ ##This directory is the configuration file directory[root@localhost vsftpd]# ls
ftpusers user_list vsftpd.conf vsftpd_conf_migrate.sh
[root@localhost vsftpd]# systemctl start vsftpd ##Start vsftpd service[root@localhost vsftpd]# systemctl stop firewalld.service ##Close the firewall[root@localhost vsftpd]# setenforce 0 ##Close the enhanced function[root@localhost vsftpd]# ls /var/ftp/ ##Switch to the ftp directory pub
[root@localhost vsftpd]# echo "this is test" > /var/ftp/test.txt ##Add a text file

C:\Users\xy007>ftp 192.168.13.140 ##Access the ftp service and connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User (192.168.13.140:(none)): ftp ##Anonymous access 331 Please specify the password.
password: 
##Password without carriage return 230 Login successful.
ftp> pwd ##View the current path 257 "/" ##Root directory of ftp service ftp> ls -a ##View the contents of the directory 200 PORT command successful. Consider using PASV.
150 Here comes the directory listing.
.
..
pub
test.txt ##File in the server 226 Directory send OK.
ftp: received 25 bytes in 0.00 sec 25000.00 kb/sec.
ftp> get test.txt ##Download the file to the local computer (download to the disk you access, you can switch disks to download e:)
200 PORT command successful. Consider using PASV.
150 Opening BINARY mode data connection for test.txt (13 bytes).
226 Transfer complete.
ftp: received 13 bytes in 0.00 sec 13000.00 kb/sec.
ftp> put test1.txt ##Create a test1.txt in the C drive and upload it to Linux 200 PORT command successful. Consider using PASV.
550 Permission denied. ##This is the configuration of the vsftpd service in Linux with restricted permissions (anonymous, user, virtual user) 

[root@localhost ftp]# cd /etc/vsftpd/
[root@localhost vsftpd]# vim vsftpd.conf
##Find and enable the following options in the configuration file anonymous_enable=YES ##Enable anonymous users local_enable=YES ##Local users write_enable=YES ##Write permission local_umask=022 ##Local user reverse mask anon_upload_enable=YES ##Upload permission enabled anon_mkdir_write_enable=YES ##Enable directory creation and write access anon_other_write_enable=YES ##Add an other rename and delete permission [root@localhost vsftpd]# systemctl restart vsftpd ##Restart the service [root@localhost vsftpd]# cd /var/ftp/ ##Switch to the ftp directory [root@localhost ftp]# ls
pub test.txt
[root@localhost ftp]# ls -l
Total dosage 4
drwxr-xr-x. 2 root root 6 Oct 31 2018 pub
-rw-r--r--. 1 root root 13 November 5 19:14 test.txt
[root@localhost ftp]# chmod 777 pub ##Give the pub directory the maximum permissions. Note that you cannot directly give the ftp directory the maximum permissions.

C:\Users\xy007>ftp 192.168.13.140 ##Access the ftp service and connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User(192.168.13.140:(none)): ftp
331 Please specify the password.
password:
230 Login successful.
ftp> cd pub/ ##Switch to the pub directory 250 Directory successfully changed.
ftp> put test1.txt ##Upload file 200 PORT command successful. Consider using PASV.
150 Ok to send data.
226 Transfer complete.
ftp: sent 13 bytes in 0.03 s 0.41 kb/s.
ftp> by ##Exit 221 Goodbye.
##You can also use delete to delete files

[root@localhost ftp]# cd /var/ftp/pub ##Switch to the pub directory [root@localhost pub]# ls ##View the uploaded file test1.txt

[root@localhost pub]# useradd zhangsan ##Create a user and set the user password [root@localhost pub]# passwd zhangsan
[root@localhost pub]# useradd lisi ##Create a user and set the user password [root@localhost pub]# passwd lisi

C:\Users\xy007>ftp 192.168.13.140 ##Log in to the ftp service and connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User (192.168.13.140:(none)): zhangsan ##Use local user 331 Please specify the password.
password:
230 Login successful.
ftp> ls / ##View the directory files under user/ and go directly to the system root directory 200 PORT command successful. Consider using PASV.
150 Here comes the directory listing.
/bin
/boot
/dev
/etc
/home
/lib
/lib64
/media
/mnt
/opt
/proc
/root
/run
/sbin
/srv
/sys
/tmp
/usr
/var
226 Directory send OK.
ftp: received 126 bytes in 0.02 sec 7.88 kb/sec.

[root@localhost pub]# vim /etc/vsftpd/vsftpd.conf ##Modify the configuration file chroot_local_user=YES ##Enable the module to restrict local access to system directories allow_writeable_chroot=YES ##Add write permissions [root@localhost pub]# systemctl restart vsftpd ##Restart the service

C:\Users\xy007>ftp 192.168.13.140 ##Access ftp
Connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User (192.168.13.140:(none)): zhangsan ##User zhangsan
331 Please specify the password.
password:
230 Login successful.
ftp> cd / ##Switch to the system root directory 250 Directory successfully changed.
ftp> ls ## Check and find that it is still in the user's home directory. Other directories of the system cannot be accessed, which enhances security. 200 PORT command successful. Consider using PASV.
150 Here comes the directory listing.
226 Directory send OK.
Set to allow or deny specified users to access ftp
1. Set user-list (deny by default) to allow or deny specific users to log in to FTP
[root@localhost pub]# cd /etc/vsftpd/ ##Switch to the vsftpd configuration file directory [root@localhost vsftpd]# vim vsftpd.conf

userlist_enable=YES ##Confirm that user-list is enabled [root@localhost vsftpd]# ls
ftpusers user_list vsftpd.conf vsftpd_conf_migrate.sh
[root@localhost vsftpd]# echo "zhangsan" >> user-list ##Add user zhangsan to the list [root@localhost vsftpd]# systemctl restart vsftpd ##Restart service 2 and test it with the test machine cmd C:\Users\xy007>ftp 192.168.13.140
Connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User (192.168.13.140:(none)): zhangsan ##Log in using zhangsan 530 Permission denied.
Login failed. ##Directly refuse to log in to ftp>

[root@localhost ftp]# cd /etc/vsftpd/
[root@localhost vsftpd]# vim vsftpd.conf ##Configure vsftpd configuration file userlist_enable=YES
userlist_deny=NO ##Add list to allow [root@localhost vsftpd]# systemctl restart vsftpd ##Restart service

C:\Users\xy007>ftp 192.168.13.140
Connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User (192.168.13.140:(none)): zhangsan ##Use zhangsan to log in to 331. Please specify the password.
password:
230 Login successful. ##Login successful ftp> by
221 Goodbye.

C:\Users\xy007>ftp 192.168.13.140
Connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User (192.168.13.140:(none)): lisi ##Log in using lisi 530 Permission denied.
Login failed. ##Login failed

[root@localhost vsftpd]# cd /etc/vsftpd/ ##Switch to the configuration file directory [root@localhost vsftpd]# vim vuser ##Create a virtual user file lisa ##Odd-numbered user name 123123 ##Even-numbered password tom
123123

[root@localhost vsftpd]# db_load -T -t hash -f vuser vuser.db ##Convert vuser to a database file ##T conversion, t type, f specified file [root@localhost vsftpd]# chmod 600 vuser ##For security reasons, do not let others see it, set permissions [root@localhost vsftpd]# chmod 600 vuser.db

[root@localhost vsftpd]# useradd -d /opt/vuser -s /sbin/nologin vuser 
##Create a system user, specify the home directory, and cannot log in [root@localhost vsftpd]# vim /etc/pam.d/vsftpd.vu ##Compile the pam authentication module auth required pam_userdb.so db=/etc/vsftpd/vuser ##Identify the converted database file account required pam_userdb.so db=/etc/vsftpd/vuser ##Connect to the password service

[root@localhost vsftpd]# vim vsftpd.conf ##Modify the configuration file##The big G goes to the last line#pam_service_name=vsftpd ##Comment##Add the following three lines guest_enable=YES ##Enable guest user access guest_username=vuser ##Use the vuser username pam_service_name=vsftpd.vu ##pam module [root@localhost vsftpd]# systemctl restart vsftpd ##Restart the service

C:\Users\xy007>ftp 192.168.13.140
Connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User (192.168.13.140:(none)): tom ##Login using virtual user tom 331 Please specify the password.
password:
230 Login successful.
ftp> put test1.txt ##Upload a file 200 PORT command successful. Consider using PASV.
150 Ok to send data.
226 Transfer complete.
ftp: sent 13 bytes in 0.00 sec 13000.00 kb/sec.
##The permission to view the file is 600
[root@localhost vsftpd]# ls -l /opt/vuser/
Total dosage 4
-rw------. 1 vuser vuser 13 November 5 22:51 test1.txt

[root@localhost vsftpd]# vim vsftpd.conf 
##Add user_config_dir=/etc/vsftpd/vu_dir to the last line of the big G ##Individual user configuration folder [root@localhost vsftpd]# mkdir vu_dir ##Create a folder [root@localhost vsftpd]# cd vu_dir/
[root@localhost vu_dir]# vim lisa ##Create a user profile in the configuration folder anon_umask=022 ##Specify permissions for uploaded files [root@localhost vu_dir]# systemctl restart vsftpd ##Restart the service

C:\Users\xy007>ftp 192.168.13.140
Connect to 192.168.13.140.
220 (vsFTPd 3.0.2)
200 Always in UTF8 mode.
User (192.168.13.140:(none)): lisa ##Login to 331 using lisa. Please specify the password.
password:
230 Login successful.
ftp> put 111.txt ##Upload file 200 PORT command successful. Consider using PASV.
150 Ok to send data.
226 Transfer complete.
ftp: sent 13 bytes in 0.00 sec 13000.00 kb/sec.

[root@localhost vu_dir]# ls -l /opt/vuser/ ##View the total usage of uploaded file permissions 8
-rw-r--r--. 1 vuser vuser 13 November 5 22:58 111.txt ##lisa upload file permissions 644
-rw------. 1 vuser vuser 13 November 5 22:51 test1.txt ##tom uploads file permissions 600