Re: Device to use with cryptsetup Buster encrypted lvm

[john doe <johndoe65534@mail.com>]

On 10/4/2020 4:52 PM, David Wright wrote:
> On Sun 04 Oct 2020 at 16:39:38 (+0200), john doe wrote:
> > On 10/4/2020 4:35 PM, David Wright wrote:
> > > On Sun 04 Oct 2020 at 16:16:33 (+0200), john doe wrote:
> > > > I just installed Debian Buster with encrypted LVM.
> > > >
> > > > In my fstab file, I have:
> > > > # <file system> <mount point>   <type>  <options>       <dump>  <pass>
> > > > /dev/mapper/try02--vg-root /               ext4    errors=remount-ro 0
> > > >        1
> > > >
> > > > I can't figure out what device I should pass to cryptsetup to avoid the
> > > > below error:
> > > >
> > > > $ cryptsetup -v luksAddKey /dev/mapper/try02--vg-root /etc/keys/root.key
> > > > --key-slot=1
> > > > Device /dev/mapper/try02--vg-root doesn't exist or access denied.
> > > > Command failed with code -4 (wrong device or file specified).
> > > >
> > > >
> > > > How can I know what device cryptsetupt will accept?
> > >
> > > It looks as if you're trying to add the key to the decrypted device,
> > > ie the /dev/mapper/ device that gets mounted as /.
> > > You add keys to the encrypted device, ie the device that contains the
> > > encrypted filesystem, the argument you used in the command
> > > # cryptsetup luksFormat <this-device>
> >
> > The debian -installer has done that for me, I don't understand how I can
> > get the encrypted device.
>
> I've not done that with the installer. I would expect there to be
> an entry in /etc/crypttab for the root filesystem, so that it gets
> mounted at boot time. It's the second field in that line.

In /etc/crypttab, the first column in the file has the device name
followed by '_crypt'.
Alternatively, use the UUID from the second column with the uuid option
of the blkid command.

$ blkid -U <UUID>


Thanks to you David and to 'Ulf Volmer <u.volmer@u-v.de>'.


I appriciated.


--
John Doe