qubes-doc/user/how-to-guides/backup-emergency-restore-v2.md

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en	doc	/doc/backup-emergency-restore-v2/	/en/doc/backup-emergency-restore-v2/ /doc/BackupEmergencyRestoreV2/	207	Emergency backup recovery (v2)

This page describes how to perform emergency restore of backup created on Qubes R2 Beta3 or earlier (which uses backup format 2).

The Qubes backup system has been designed with emergency disaster recovery in mind. No special Qubes-specific tools are required to access data backed up by Qubes. In the event a Qubes system is unavailable, you can access your data on any GNU/Linux system with the following procedure.

Note: In the following example, the backup file is assumed to be both encrypted and compressed.

1. Untar the main backup file.

   [user@restore ~]$ tar -i -xvf qubes-backup-2013-12-26-123456
   backup-header
   backup-header.hmac
   qubes.xml.000
   qubes.xml.000.hmac
   vm1/private.img.000
   vm1/private.img.000.hmac
   vm1/icon.png.000
   vm1/icon.png.000.hmac
   vm1/firewall.xml.000
   vm1/firewall.xml.000.hmac
   vm1/whitelisted-appmenus.list.000
   vm1/whitelisted-appmenus.list.000.hmac
   dom0-home/dom0user.000
   dom0-home/dom0user.000.hmac
   

2. Set the backup passphrase environment variable. While this isn't strictly required, it will be handy later and will avoid saving the passphrase in the shell's history.

   [user@restore ~]$ read -r backup_pass
   

3. Verify the integrity of the private.img file which houses your data.

   [user@restore ~]$ cd vm1/
   [user@restore vm1]$ openssl dgst -sha512 -hmac "$backup_pass" private.img.000
   HMAC-SHA512(private.img.000)= cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e
   [user@restore vm1]$ cat private.img.000.hmac
   (stdin)= cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e
   

Note: The hash values should match. If they do not match, then the backup file may have been tampered with, or there may have been a storage error.

Note: If your backup was hashed with a message digest algorithm other than sha512, you must substitute the correct message digest command. A complete list of supported message digest algorithms can be found with openssl list-message-digest-algorithms.

4. Decrypt the private.img file.

   [user@restore vm1]$ openssl enc -d -pass pass:"$backup_pass" -aes-256-cbc -in private.img.000 -out private.img.dec.000
   

Note: For multi-part files, a loop can be used:

find -name 'private.img.*' | sort -V | while read f; do
  openssl enc -d -pass pass:"$backup_pass" -aes-256-cbc -in $f -out
${f/.img/.img.dec}
done

Note: If your backup was encrypted with a cipher algorithm other than aes-256-cbc, you must substitute the correct cipher command. A complete list of supported cipher algorithms can be found with openssl list-cipher-algorithms.

5. Decompress the decrypted private.img file.

   [user@restore vm1]$ zforce private.img.dec.*
   [user@restore vm1]$ gunzip private.img.dec.000.gz
   

Note: If your backup was compressed with a program other than gzip, you must substitute the correct compression program.

6. Untar the decrypted and decompressed private.img file.

   [user@restore vm1]$ tar -M -xvf private.img.dec.000
   vm1/private.img
   

   Note: For multi-part files, a script is required:

   1. Create a new-volume-script:

      #!/bin/sh
      name=`expr $TAR_ARCHIVE : '\(.*\)\..*'`
      suffix=`printf %03d $[ $TAR_VOLUME - 1 ]`
      echo $name.$suffix >&$TAR_FD
      

   2. chmod +x new-volume-script.

   3. tar --new-volume-script=./new-volume-script -xvf private.img.dec.000. (The --new-volume-script option enables multi-volume untaring.)

7. Mount the private.img file and access your data.

   [user@restore vm1]$ sudo mkdir /mnt/img
   [user@restore vm1]$ sudo mount -o loop vm1/private.img /mnt/img/
   [user@restore vm1]$ cat /mnt/img/home/user/your_data.txt
   This data has been successfully recovered!
   

Note: You may wish to store a plain text copy of these instructions with your Qubes backups in the event that you fail to recall the above procedure while this web page is inaccessible. You may obtain a plaintext version of this file in Git repository housing all the documentation on Github