apt-get install proftpd openssl
Add user (default group named "websitename" will be created)
adduser websitename
Next we need to make the directory protected from removing and renaming its content by any user, so we will change the directory permissions as follows:
chmod -R 1777 /var/www/html/websitename
nano /etc/proftpd/proftpd.conf
Make changes like as shown
# Set off to disable IPv6 support which is annoying on IPv4 only boxes.
UseIPv6 off
# Use this to jail all users in their homes.
DefaultRoot /var/www/html/websitename websitename
DefaultRoot ~
# Save and exit
service proftpd restart
nano /etc/ssh/sshd_config
Make changes like as shown
# Privilege Separation is turned on for security
[...]
DenyGroups websitename
service ssh restart