changing root password

[Richard P. Williamson]

Hello all,

I've got a 4.8R system that I use for development of a 'freebsd-small'
type network device.  The network device environment runs out of
memory, the kernel and an mfsroot.gz image coming from a 32Mb pccard
Compact Flash drive.

The mfsroot.gz development image is stored as a vnconfig vn0
virtual node, called 'mfsroot', on the development machine.

Everything boots and I can do what I want with the system.

The problem is that I need to be able to set the root password
of the device, from the development machine prior to moving to
the actual device.

So I (or rather, 'root') mount(s) the virtual fs node:

% vnconfig vn0 mfsroot
% mount /dev/vn0 /mnt

(under /mnt now is a partially functional FreeBSD 4.8R based
installation, including /etc/master.passwd, etc)

And then change the root directory to the mount point:

% chroot /mnt

And then try to change the password:

% passwd
Type new password:
Retype new password:
...
%

The behavior I'm seeing is that the /original/ /etc/ password 
files and databases are updated, and not the [/mnt]/etc/ password
files.

Am I expecting incorrectly?  Am I going to be able to change the
network device's root password before moving to the actual device
from the development machine, or will it be necessary to put 
/usr/bin/passwd onto the network device?

Thanks in advance,
rip