Quick note on how to limit user's access with SFTP Jails on Ubuntu.

Access the ssh configuration file:

nano /etc/ssh/sshd_config

Modify so that it contains the line

Subsystem sftp internal-sftp

Add the following block to the end of the file:

Match group filetransfer
    ChrootDirectory %h
    X11Forwarding no
    AllowTcpForwarding no
    ForceCommand internal-sftp

Restart OpenSSH as follows:

/etc/init.d/ssh restart

Modify user account

If your goal is to give a client or designer access through SFTP to a domain folder, you can start by creating a group for the users- who will only have SFTP access:

    addgroup filetransfer

Next, you will have to create a new user account and relate it to the new group. This will create the user named fileuser and set its home directory to srv/www/[domain]/public_html:

sudo useradd -d /srv/www/[domain] [username]
sudo passwd [username]
sudo usermod -G filetransfer [username]
sudo chown [username]:[username] /srv/www/[domain]/public_html