restrict users to their home dir in the ssh

http://www.howtoforge.com/chroot_ssh_sftp_debian_etch

Check out your current bash binary:

# ls -la /bin/*bash*

if you see a "bash2" and don't see a sym-link for "rbash" then your system
is ready to be secured. Just create the needed symlink from rbash to
bash2:
# ln -s bash2 rbash

Now simply change your user's login shells in /etc/passwd from /bin/bash to
/bin/rbash