ssh jail?

[Jeffrey Ross]

I'm in the process of setting up an SSH jail, for the most part its
working as expected with one exception, I want to provide access to
/dev/ttyUSB0 through /dev/ttyUSB4 (not 2) via cu.

When I attempt to use "cu -lttyUSB0 -s9600" I always get "line in use"
even through it is not in use and from another account not restricted to
the "jail" I can successfully connect to the ttyUSB0.

I've tried creating $chroot/

run/
    lock/
    lockdev/
    uucp/
var/
    run -> symbolic link to $chroot/run
    lock -> symbolic link to $chroot/run/lock

and then matched the directory permissions so they are the same as the
"real" system.

ls -l $chroot/dev/ttyUSB?
    crwxrwxrwx 1 root dialout 188, 0 Jan 24 14:48 ttyUSB0
    crwxrwxrwx 1 root dialout 188, 1 Jan 24 14:49 ttyUSB1
    crwxrwxrwx 1 root dialout 188, 3 Jan 24 14:49 ttyUSB3
    crwxrwxrwx 1 root dialout 188, 4 Jan 24 14:49 ttyUSB4

The dialout group is 18 and the user is in group 18, initially I set the
permissions for the ttyUSB? to 660 before changing it to 777 as a last
ditch effort.

The "real" /dev/ttyUSB? -

ls -l /dev/ttyUSB?
    crw-rw---- 1 root dialout 188, 0 Jan 24 14:44 /dev/ttyUSB0
    crw-rw---- 1 root dialout 188, 1 Jan 23 21:48 /dev/ttyUSB1
    crw-rw---- 1 root dialout 188, 3 Jan 24 15:12 /dev/ttyUSB3
    crw-rw---- 1 root dialout 188, 4 Jan 23 21:48 /dev/ttyUSB4

I'm probably missing something simple and any suggestions would be
appreciated.

Thanks, Jeff