This article explains the reason why an user with super-user login class cannot perform the "mount" command, and shows the condition required to execute the "mount" command on an UNIX system.
An user with super-user login class cannot perform the mount command on an SRX device.
super-user
mount
The disk device files in /dev are owned by an user with root login class, and group ownership belongs to the operator group, with 640 permissions (rw-r-----). That means that the user root has exclusive access write to the device node, and members of the operator group can only read from it. The mount command cannot perform root-level actions on its own, so the invoking user must be root login class, so that the mount command can execute both read/write operations, to/from the SRX device. root@100-2% ls -l /dev/da* crw-r----- 1 root operator 0, 46 Jan 31 20:16 /dev/da0 crw-r----- 1 root operator 0, 47 Jan 31 20:16 /dev/da0s1 crw-r----- 1 root operator 0, 51 Jan 31 20:16 /dev/da0s1a crw-r----- 1 root operator 0, 52 Jan 31 20:16 /dev/da0s1c crw-r----- 1 root operator 0, 48 Jan 31 20:16 /dev/da0s2 crw-r----- 1 root operator 0, 53 Jan 31 20:16 /dev/da0s2a crw-r----- 1 root operator 0, 54 Jan 31 20:16 /dev/da0s2c crw-r----- 1 root operator 0, 49 Jan 31 20:16 /dev/da0s3 Here you see that /dev/da files belong to root user (or operator group). Accounts created as super-user accounts in Junos do not get added to the operator UNIX system group. Create an user Test with super-user class, and login with that user: % % whoami Test % % mount -t msdosfs /dev/da1s1 /tmp/usb mount_msdosfs: /dev/da1s1: Operation not permitted % % id uid=2000(Test) gid=20(staff) groups=20(staff), 0(wheel), 10(field), 11(floppy)
/dev
root
operator
write
read
root@100-2% ls -l /dev/da* crw-r----- 1 root operator 0, 46 Jan 31 20:16 /dev/da0 crw-r----- 1 root operator 0, 47 Jan 31 20:16 /dev/da0s1 crw-r----- 1 root operator 0, 51 Jan 31 20:16 /dev/da0s1a crw-r----- 1 root operator 0, 52 Jan 31 20:16 /dev/da0s1c crw-r----- 1 root operator 0, 48 Jan 31 20:16 /dev/da0s2 crw-r----- 1 root operator 0, 53 Jan 31 20:16 /dev/da0s2a crw-r----- 1 root operator 0, 54 Jan 31 20:16 /dev/da0s2c crw-r----- 1 root operator 0, 49 Jan 31 20:16 /dev/da0s3
/dev/da
Test
% % whoami Test % % mount -t msdosfs /dev/da1s1 /tmp/usb mount_msdosfs: /dev/da1s1: Operation not permitted % % id uid=2000(Test) gid=20(staff) groups=20(staff), 0(wheel), 10(field), 11(floppy)
Now do a su to root:
su to root:
% % su Password: root@100-2% root@100-2% whoami root root@100-2% id uid=0(root) gid=0(wheel) groups=0(wheel), 5(operator), 10(field), 11(floppy), 31(guest), 73(config) root@100-2% root@100-2% root@100-2% mount -t msdosfs /dev/da1s1 /tmp/usb root@100-2% root@100-2%
operator.
su to root).