qubes-doc/en/common-tasks/backup-emergency-restore-v3.md

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doc	Emergency Backup Recovery - format version 3	/en/doc/backup-emergency-restore-v3/	/doc/BackupEmergencyRestoreV3/

Emergency Backup Recovery without Qubes - format version 3

This page describes how to perform an emergency restore of a backup created on Qubes R2 or later (which uses backup format version 3).

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. Untar the main backup file.

   [user@restore ~]$ tar -i -xvf qubes-backup-2015-06-05T123456
   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. Verify the integrity of the backup-header file, which contains basic information about your backup.

   [user@restore ~]$ openssl dgst -sha512 -hmac "your_passphrase" backup-header
   HMAC-SHA512(backup-header)= 5b266783e116fe3b2601a54c249ca5f5f96d421dfe6828eeaeb2dcd014e9e945c27b3d7b0f952f5d55c927318906d9c360f387b0e1f069bb8195e96543e2969c
   [user@restore ~]$ cat backup-header.hmac 
   (stdin)= 5b266783e116fe3b2601a54c249ca5f5f96d421dfe6828eeaeb2dcd014e9e945c27b3d7b0f952f5d55c927318906d9c360f387b0e1f069bb8195e96543e2969c
   

   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. This information is contained in the backup-header file (see step 3), however it is not recommended to open this file until its integrity and authenticity has been verified (the current step). A complete list of supported message digest algorithms can be found with openssl list-message-digest-algorithms.

3. 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=3
   hmac-algorithm=SHA512
   crypto-algorithm=aes-256-cbc
   encrypted=True
   compressed=True
   compression-filter=gzip
   

   Note: If you see version=2 here, go to Emergency Backup Recovery - format version 2 instead.

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

   [user@restore ~]$ cd vm1/
   [user@restore vm1]$ openssl dgst -sha512 -hmac "your_passphrase" 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. This information is contained in the backup-header file (see step 3). A complete list of supported message digest algorithms can be found with openssl list-message-digest-algorithms.

5. Decrypt the private.img file.

   [user@restore vm1]$ cat private.img.??? | openssl enc -d -pass pass:your_passphrase -aes-256-cbc -out private.img.dec
   

   Note: If your backup was encrypted with a cipher algorithm other than aes-256-cbc, you must substitute the correct cipher command. This information is contained in the backup-header file (see step 3). A complete list of supported cipher algorithms can be found with openssl list-cipher-algorithms.

6. Decompress the decrypted private.img file.

   [user@restore vm1]$ zforce private.img.dec
   private.img.dec -- replaced with private.img.dec.gz
   [user@restore vm1]$ gunzip private.img.dec.gz
   

   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).

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

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

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 4--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