Give permission to a SSH user only to a specific directory and block terminal access !!

How do I restrict the user to only be able to do anything within that folder? (ie: that folder is the user's root and they cannot view/edit anything higher in the directory tree)

Step-1: adding a new group

sudo addgroup sftptsl

Step-2: Create the chroot directory

sudo mkdir /var/www/html/user-dir/

sudo chmod g+rx /var/www/html/user-dir/

Step-3: Create the group-writable directory

sudo mkdir -p /var/www/html/user-dir/working-dir1/

sudo chmod g+rwx /var/www/html/user-dir/working-dir1/

Step-4: Give them both to the new group.

sudo chgrp -R sftptsl /var/www/html/user-dir/

Step-5: create an user and asign to this group 

sudo adduser --ingroup sftptsl sftpuser

## group change

You can also assign an existing user to the group

usermod -g primarygroupname username

usermod -G secondarygroupname username

-g (primary group assigned to the users)

-G (Other groups the user belongs to)

Step-6: Open the SSH configuration file from "/etc/ssh/sshd_config", add the below text end of the file

Match Group sftptsl

  # Force the connection to use SFTP and chroot to the required directory.

  ForceCommand internal-sftp

  ChrootDirectory /var/www/html/user-dir/

  # Disable tunneling, authentication agent, TCP and X11 forwarding.

  PermitTunnel no

  AllowAgentForwarding no

  AllowTcpForwarding no

  X11Forwarding no

Step-7: Check it is working or not by using filezilla or any remote file browser.