I am trying to set up a ssh-chroot jail on one of my NAS servers. The system runs on NAS4Free (which is based on nanobsd). The user should be able to run only one command, which is a bash-script that opens ssh to another server and executes one command there.
To setup the chroot I have this in my sshd config.
Match User op ChrootDirectory %h X11Forwarding no AllowTcpForwarding no
The script has this line in it:
ssh -i /.ssh/id_rsa backup@$externalresource -t "/mnt/storage/backup/run_project.sh '$1' '$2'"
I can log in to that chroot using ssh but when I run the script it gives the following error when trying to execute the ssh command in it.
Couldn't open /dev/null: Operation not supported
The same happens, when I try to run ssh plain within the chroot
[I have no name!@nas /]$ ssh Couldn't open /dev/null: Operation not supported
/dev/null looks as this:
$ ls -la dev/ total 8 drwx--x--x 2 root staff 512 Nov 29 18:16 . drwxr-xr-x 8 root staff 512 Nov 29 18:06 .. crw-rw-rw- 1 root staff 0x18 Nov 29 18:16 null
Without the 666 permissions I get a /dev/null permission denied error of course.
I created dev/null using
mknod dev/null c 2 2
I have tried to find an explaination why /dev/null returns operation not permitted but have not found anything that helps.
Could someone please explain how to fix this?