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181 lines
6.4 KiB
ReStructuredText
181 lines
6.4 KiB
ReStructuredText
==============================
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Emergency backup recovery (v3)
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==============================
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This page describes how to perform an emergency restore of a backup
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created on Qubes R2 or later (which uses backup format version 3).
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The Qubes backup system has been designed with emergency disaster
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recovery in mind. No special Qubes-specific tools are required to access
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data backed up by Qubes. In the event a Qubes system is unavailable, you
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can access your data on any GNU/Linux system with the following
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procedure.
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**Note:** In the following example, the backup file is both *encrypted*
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and *compressed*.
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1. Untar the main backup file.
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.. code:: bash
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[user@restore ~]$ tar -i -xvf qubes-backup-2015-06-05T123456
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backup-header
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backup-header.hmac
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qubes.xml.000
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qubes.xml.000.hmac
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vm1/private.img.000
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vm1/private.img.000.hmac
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vm1/icon.png.000
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vm1/icon.png.000.hmac
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vm1/firewall.xml.000
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vm1/firewall.xml.000.hmac
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vm1/whitelisted-appmenus.list.000
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vm1/whitelisted-appmenus.list.000.hmac
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dom0-home/dom0user.000
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dom0-home/dom0user.000.hmac
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2. Set the backup passphrase environment variable. While this isn’t
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strictly required, it will be handy later and will avoid saving the
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passphrase in the shell’s history.
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.. code:: bash
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[user@restore ~]$ read -r backup_pass
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3. Verify the integrity of the ``backup-header`` file, which contains
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basic information about your backup.
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.. code:: bash
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[user@restore ~]$ openssl dgst -sha512 -hmac "$backup_pass" backup-header
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HMAC-SHA512(backup-header)= 5b266783e116fe3b2601a54c249ca5f5f96d421dfe6828eeaeb2dcd014e9e945c27b3d7b0f952f5d55c927318906d9c360f387b0e1f069bb8195e96543e2969c
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[user@restore ~]$ cat backup-header.hmac
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(stdin)= 5b266783e116fe3b2601a54c249ca5f5f96d421dfe6828eeaeb2dcd014e9e945c27b3d7b0f952f5d55c927318906d9c360f387b0e1f069bb8195e96543e2969c
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**Note:** The hash values should match. If they do not match, then
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the backup file may have been tampered with, or there may have been
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a storage error.
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**Note:** If your backup was hashed with a message digest algorithm
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other than ``sha512``, you must substitute the correct message
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digest command. This information is contained in the
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``backup-header`` file (see step 4), however it is not recommended
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to open this file until its integrity and authenticity has been
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verified (the current step). A complete list of supported message
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digest algorithms can be found with
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``openssl list-message-digest-algorithms``.
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4. Read the ``backup-header``. You’ll need some of this information
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later. The file will look similar to this:
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.. code:: bash
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[user@restore ~]$ cat backup-header
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version=3
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hmac-algorithm=SHA512
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crypto-algorithm=aes-256-cbc
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encrypted=True
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compressed=True
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compression-filter=gzip
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**Note:** If you see ``version=2`` here, go to :doc:`Emergency Backup Recovery - format version 2 </user/how-to-guides/backup-emergency-restore-v2>`
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instead.
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5. Verify the integrity of the ``private.img`` file which houses your
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data.
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.. code:: bash
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[user@restore ~]$ cd vm1/
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[user@restore vm1]$ openssl dgst -sha512 -hmac "$backup_pass" private.img.000
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HMAC-SHA512(private.img.000)= cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e
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[user@restore vm1]$ cat private.img.000.hmac
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(stdin)= cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e
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**Note:** The hash values should match. If they do not match, then
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the backup file may have been tampered with, or there may have been
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a storage error.
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**Note:** If your backup was hashed with a message digest algorithm
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other than ``sha512``, you must substitute the correct message
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digest command. This information is contained in the
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``backup-header`` file (see step 4). A complete list of supported
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message digest algorithms can be found with
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``openssl list-message-digest-algorithms``.
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6. Decrypt the ``private.img`` file.
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.. code:: bash
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[user@restore vm1]$ find -name 'private.img.*[0-9]' | sort -V | xargs cat | openssl enc -d -md MD5 -pass pass:"$backup_pass" -aes-256-cbc -out private.img.dec
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**Note:** If your backup was encrypted with a cipher algorithm other
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than ``aes-256-cbc``, you must substitute the correct cipher
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command. This information is contained in the ``backup-header`` file
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(see step 4). A complete list of supported cipher algorithms can be
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found with ``openssl list-cipher-algorithms``.
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7. Decompress the decrypted ``private.img`` file.
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.. code:: bash
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[user@restore vm1]$ zforce private.img.dec
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private.img.dec -- replaced with private.img.dec.gz
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[user@restore vm1]$ gunzip private.img.dec.gz
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**Note:** If your backup was compressed with a program other than
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``gzip``, you must substitute the correct compression program. This
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information is contained in the ``backup-header`` file (see step 4).
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For example, if you used ``bzip2``, then you should do this:
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.. code:: bash
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[user@restore vm1]$ mv private.img.dec private.img.dec.bz2
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[user@restore vm1]$ bunzip2 private.img.dec.bz2
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8. Untar the decrypted and decompressed ``private.img`` file.
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.. code:: bash
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[user@restore vm1]$ tar -xvf private.img.dec
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vm1/private.img
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9. Mount the private.img file and access your data.
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.. code:: bash
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[user@restore vm1]$ sudo mkdir /mnt/img
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[user@restore vm1]$ sudo mount -o loop vm1/private.img /mnt/img/
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[user@restore vm1]$ cat /mnt/img/home/user/your_data.txt
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This data has been successfully recovered!
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10. Success! If you wish to recover data from more than one VM in your
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backup, simply repeat steps 5–9 for each additional VM.
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**Note:** You may wish to store a copy of these instructions with
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your Qubes backups in the event that you fail to recall the above
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procedure while this web page is inaccessible. All Qubes
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documentation, including this page, is available in plain text
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format in the following Git repository:
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.. code:: bash
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https://github.com/QubesOS/qubes-doc.git
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