Subsystem       sftp    internal-sftp

  ## You want to put only certain users (i.e users who belongs to
  ## sftpusers group) in the chroot jail environment. Add the following
  ## lines at the end of /etc/ssh/sshd_config

  Match Group sftpusers  ChrootDirectory /sftp/%u  ForceCommand internal-sftp

$ sudo service sshd restart