[dm-crypt] change passphrase

[dm-crypt] change passphrase

[Biltong]

I have a raid-1 system running btrfs on top of luks.

I cannot remember my passphrase, but the system is running and I have
made a backup.

I'd like to add a new passphrase, and have followed the instructions
from 6.10 at
http://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQuestions#6._Backup_and_Data_Recovery

This worked for the first device, which seems to work with /dev/dm-0,
but I cannot work out what the device name for the second raid-1 member
is. The btrfs partition is on top of the luks device, and so I need to
change both.

The example shows:
  dmsetup table --target crypt --showkey /dev/mapper/c5

How do I know what to put in place of "/dev/mapper/c5"?

Many thanks.

-- 
  Biltong
  biltong@fastmail.fm

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Re: [dm-crypt] change passphrase

[Heiko Rosemann]

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Hash: SHA1

On 04/01/2014 09:02 PM, Biltong wrote:
> I have a raid-1 system running btrfs on top of luks.
> 
> I cannot remember my passphrase, but the system is running and I
> have made a backup.
> 
> I'd like to add a new passphrase, and have followed the
> instructions from 6.10 at
> 
http://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQuestions#6._Backup_and_Data_Recovery
> 
> This worked for the first device, which seems to work with
> /dev/dm-0, but I cannot work out what the device name for the
> second raid-1 member is. The btrfs partition is on top of the luks
> device, and so I need to change both.
> 

I'm not really clear on what your setup is, but there's basically two
choices:

1) encrypt 2 partitions separately (typically /dev/sdxy with x in a..z
and y in
1..) leading to /dev/mapper/a and /dev/mapper/b as links to /dev/dm-0
and /dev/dm-1
2) create RAID1 from /dev/mapper/a and /dev/mapper/b, causing /dev/md0
to appear
3) create btrfs (or whatever) on top of /dev/md0

or

1) create RAID1 from 2 partitions (typically /dev/sdxy as above) leading
to /dev/md0
2) encrypt /dev/md0 leading to /dev/mapper/a as a link to /dev/dm-0
3) create btrfs (or whatever) on top of /dev/dm-0


If you can't find /dev/dm-1, you might be using the second version. You
can also find some information in the output of the mount command (which
should show you the crypto device in the first and the RAID device in
the second scenario) and from /proc/mdstat showing /dev/mapper/a (or
/dev/dm-0) in the first and /dev/sdxy in the second case.

Good luck with the research,
Heiko

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Re: [dm-crypt] change passphrase

[Sven Eschenberg]

Additionally lsblk might come in handy to get an idea of the current
structure of the storage devices.

-Sven

On Tue, April 1, 2014 23:21, Heiko Rosemann wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 04/01/2014 09:02 PM, Biltong wrote:
>> I have a raid-1 system running btrfs on top of luks.
>>
>> I cannot remember my passphrase, but the system is running and I
>> have made a backup.
>>
>> I'd like to add a new passphrase, and have followed the
>> instructions from 6.10 at
>>
> http://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQuestions#6._Backup_and_Data_Recovery
>>
>> This worked for the first device, which seems to work with
>> /dev/dm-0, but I cannot work out what the device name for the
>> second raid-1 member is. The btrfs partition is on top of the luks
>> device, and so I need to change both.
>>
>
> I'm not really clear on what your setup is, but there's basically two
> choices:
>
> 1) encrypt 2 partitions separately (typically /dev/sdxy with x in a..z
> and y in
> 1..) leading to /dev/mapper/a and /dev/mapper/b as links to /dev/dm-0
> and /dev/dm-1
> 2) create RAID1 from /dev/mapper/a and /dev/mapper/b, causing /dev/md0
> to appear
> 3) create btrfs (or whatever) on top of /dev/md0
>
> or
>
> 1) create RAID1 from 2 partitions (typically /dev/sdxy as above) leading
> to /dev/md0
> 2) encrypt /dev/md0 leading to /dev/mapper/a as a link to /dev/dm-0
> 3) create btrfs (or whatever) on top of /dev/dm-0
>
>
> If you can't find /dev/dm-1, you might be using the second version. You
> can also find some information in the output of the mount command (which
> should show you the crypto device in the first and the RAID device in
> the second scenario) and from /proc/mdstat showing /dev/mapper/a (or
> /dev/dm-0) in the first and /dev/sdxy in the second case.
>
> Good luck with the research,
> Heiko
>
> - --
> eMails verschlüsseln mit PGP - privacy is your right!
> Mein PGP-Key zur Verifizierung: http://pgp.mit.edu
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1
> Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/
>
> iEYEARECAAYFAlM7LdQACgkQ/Vb5NagElAVK2gCgq7EVxGcc3sTlIgEF3M4oZH62
> LrQAn3kmHpBRcnjbWCbBsug5tQYKWS/s
> =lSG+
> -----END PGP SIGNATURE-----
>
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