SFTP jail

summary:

In /etc/ssh/sshd_config :

You need to configure OpenSSH to use its internal SFTP subsystem.

Subsystem sftp internal-sftp

Then, I configured chroot()ing in a match rule.

Match User ftpuser
         ChrootDirectory /var/www/html
         X11Forwarding no
         AllowTcpForwarding no
         ForceCommand internal-sftp

create user

useradd ftpuser -g apache

chown root:root /var/www/html

usermod -d / ftpuser

detail : http://www.debian-administration.org/articles/590