qubes-doc/common-tasks/backup-emergency-restore-v4.md

layout	title	permalink	redirect_from
doc	Emergency Backup Recovery - format version 4	/doc/backup-emergency-restore-v4/	/en/doc/backup-emergency-restore-v4/ /doc/BackupEmergencyRestoreV4/

Emergency Backup Recovery without Qubes - format version 4

This page describes how to perform an emergency restore of a backup created on Qubes R4.0 or later (which uses backup format version 4).

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 both encrypted and compressed.

1. Backup content is encrypted and integrity protected using scrypt utility. You need to obtain it to restore your data. If your distribution have it packaged (like on Debian), install the package standard way, otherwise you need to compile it yourself (verify its signature first!). Versions up to 1.2.0 (inclusive) do not support -P option for easier scripting - which means you'll need to enter the passphrase for each file separately, instead of using echo ... | scrypt.

2. Untar the main backup file.

   [user@restore ~]$ tar -i -xvf qubes-backup-2015-06-05T123456
   backup-header
   backup-header.hmac
   qubes.xml.000.enc
   vm1/private.img.000.enc
   vm1/private.img.001.enc
   vm1/private.img.002.enc
   vm1/icon.png.000.enc
   vm1/firewall.xml.000.enc
   vm1/whitelisted-appmenus.list.000.enc
   dom0-home/dom0user.000.enc
   

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

   read backup_pass
   

4. Verify integrity of backup-header. For compatibility reasons backup-header.hmac is in fact is an encrypted and integrity protected version of backup-header.

   [user@restore ~]$ echo "backup-header!$backup_pass" |\
       scrypt -P dec backup-header.hmac backup-header.verified && \
       diff -qs backup-header backup-header.verified
   Files backup-header and backup-header.verified are identical
   

   Note: If the above fail, it may be either mean that backup was tampered with, or it is in different format (see point 3 above). In that case, look into backup-header, at version field. If it contains anything else than version=4, go to other version of instruction: Emergency Backup Recovery - format version 2, Emergency Backup Recovery - format version 3

5. Read the backup-header. You'll need some of this information later. The file will look similar to this:

   [user@restore ~]$ cat backup-header
   version=4
   encrypted=True
   compressed=True
   compression-filter=gzip
   backup_id=20161020T123455-1234
   

6. Verify the integrity and decrypt the private.img file which houses your data.

   [user@restore ~]$ backup_id=20161020T123455-1234 # see backup-header above
   [user@restore ~]$ for f_enc in vm1/private.img.???.enc; do \
       f_dec=${f_enc%.enc}; \
       echo "$backup_id!$f_dec!$backup_pass" | scrypt -P dec $f_enc $f_dec || break; \
       done
   

   Note: If the above fail, most likely your backup is corrupted, or been tampered with.

7. Decompress and untar the decrypted private.img file.

   [user@restore ~]$ cat vm1/private.img.??? | gzip -d | tar -xv
   vm1/private.img
   

   Note: If your backup was compressed with a program other than gzip, you must substitute the correct compression program. This information is contained in the backup-header file (see step 3).

8. 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!
   

9. Success! If you wish to recover data from more than one VM in your backup, simply repeat steps 5--8 for each additional VM.

   Note: You may wish to store a 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. All Qubes documentation, including this page, is available in plain text format in the following Git repository:

   https://github.com/QubesOS/qubes-doc.git