Jail in chroot in debian 7.5 - Privileges Separation problem

Question

I'm trying to create a jail for a user in my server. Let's call the user "juser".

What do I want to achieve? I want an ssh user to be jailed in his home folder and not have any access (whatsoever) on my server's root directory.

For that, I'm following the tutorial given in here.

Everything went fine, until the step of Privileges Separation. Now I don't want to disable privilage separation as it is a security threat to the system.

The other solution is in the next line in the tutorial:

If you don't disable Privilege Separation you will need an /etc/passwd which includes the user's UID inside the chroot for Privilege Separation to work properly.

But I don't know how to do this! In /etc/passwd I have for juser:

juser:x:5002:5002::/home/juser:/bin/sh

How do I implement what is said in the quoted sentence?

Answer 1

Let us say the chroot is in /path/to/chroot. Then you need:

1. A directory etc in /path/to/chroot, and

2. A file called passwd in /path/to/chroot/etc, with at least one entry:

   juser:x:5002:5002::/some/path:/some/shell
   

3. And both:
   • /path/to/chroot/some/path
   • /path/to/chroot/some/shell (The shell must be present, along with any necessary libraries and such.)