[dm-crypt] recovering forgotten passwords for 2 LVs

ken gebser at mousecar.com
Tue Aug 23 13:59:48 CEST 2011

On 08/22/2011 06:53 PM Milan Broz wrote:
> On 08/23/2011 12:33 AM, ken wrote:
> ....

Because "cryptsetup luksOpen ..." didn't work, I didn't think the rest
of the commands you mentioned would work.  But it seems they do, even
when "cryptsetup luksOpen ..." fails.  So...

> 4) paste here output of "blkid /dev/mapper/*"

# blkid /dev/mapper/*
UUID="aa98849e-f2fe-42b5-b28e-6df9230ebac8" TYPE="ext3"
/dev/mapper/VolGroup00-LogVol01: TYPE="swap"

> Maybe you can add also "blkid /dev/sd*" so we can be sure what's
> type of partitions you have there - the grub entry you mentioned
> does not match the device on /dev/sda5.

# blkid /dev/sd*
/dev/sda1: SEC_TYPE="msdos" LABEL="DellUtility" UUID="07D4-0612" TYPE="vfat"
/dev/sda2: TYPE="ntfs"
/dev/sda3: LABEL="/boot" UUID="3043a9bc-cee8-4e8f-8f96-5725ad0a5db1"
SEC_TYPE="ext2" TYPE="ext3"
/dev/sda5: UUID="074c3369-bd66-4afa-97ad-973769aeb208" TYPE="crypt_LUKS"

Here's that grub menu entry again... in case someone no longer has that

title CentOS (2.6.18-238.12.1.el5)
        root (hd0,2)
        kernel /vmlinuz-2.6.18-238.12.1.el5 ro
root=/dev/mapper/luks-3d723b4f-0184-438d-9cb9-9ebff16e683a rhgb quiet
        initrd /initrd-2.6.18-238.12.1.el5.img

I can think of no reason for the mismatch.  As said, all of this booted
and ran fine until one evening when I put the system into hibernate;
when I brought it back out of hibernate and was prompted for the two
passphrases, I couldn't remember them.  That was a week or so ago.

> (I would say paste here output of "lsblk -f" but this command is not
> yet in CentOS5.)

Is it in RH6/CentOS6?

Thanks, Milan

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