LUKS - Linux Unified Key Setup: Difference between revisions

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==Encrypted swap on LVM==
==Encrypted swap on LVM==
===Create logical volume for swap===
===Create logical volume for swap===
<source lang=bash>
<syntaxhighlight lang=bash>
# lvcreate -L 2g -n lv-swap vg-root
# lvcreate -L 2g -n lv-swap vg-root
   Logical volume "lv-swap" created
   Logical volume "lv-swap" created
</syntaxhighlight>
</syntaxhighlight>


<source lang=bash>
<syntaxhighlight lang=bash>
# lvs /dev/vg-root/lv-swap
# lvs /dev/vg-root/lv-swap
   LV      VG      Attr      LSize Pool Origin Data%  Move Log Copy%  Convert
   LV      VG      Attr      LSize Pool Origin Data%  Move Log Copy%  Convert
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'''This step will erase all of your data from the disk after the mkswap command!!!'''
'''This step will erase all of your data from the disk after the mkswap command!!!'''
So be sure you pick the right one!
So be sure you pick the right one!
<source lang=bash>
<syntaxhighlight lang=bash>
# mkswap /dev/vg-root/lv-swap
# mkswap /dev/vg-root/lv-swap
mkswap: /dev/vg-root/lv-swap: warning: don't erase bootbits sectors
mkswap: /dev/vg-root/lv-swap: warning: don't erase bootbits sectors
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Put this in your /etc/crypttab :
Put this in your /etc/crypttab :
<source lang=bash>
<syntaxhighlight lang=bash>
cryptswap1 UUID=4764e516-d025-41de-ab5b-72070a3ae765 /dev/urandom swap,cipher=aes-cbc-essiv:sha256,offset=40,noearly
cryptswap1 UUID=4764e516-d025-41de-ab5b-72070a3ae765 /dev/urandom swap,cipher=aes-cbc-essiv:sha256,offset=40,noearly
</syntaxhighlight>
</syntaxhighlight>
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====Start the crypted partition====
====Start the crypted partition====
<source lang=bash>
<syntaxhighlight lang=bash>
# cryptdisks_start cryptswap1
# cryptdisks_start cryptswap1
  * Starting crypto disk...
  * Starting crypto disk...
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====Check the status====
====Check the status====
<source lang=bash>
<syntaxhighlight lang=bash>
# cryptsetup status cryptswap1
# cryptsetup status cryptswap1
/dev/mapper/cryptswap1 is active.
/dev/mapper/cryptswap1 is active.
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====Make the swapFS====
====Make the swapFS====
<source lang=bash>
<syntaxhighlight lang=bash>
# mkswap /dev/mapper/cryptswap1
# mkswap /dev/mapper/cryptswap1
mkswap: /dev/mapper/cryptswap1: warning: don't erase bootbits sectors
mkswap: /dev/mapper/cryptswap1: warning: don't erase bootbits sectors
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===Edit the /etc/fstab===
===Edit the /etc/fstab===
<source lang=bash>
<syntaxhighlight lang=bash>
# vit /etc/fstab
# vit /etc/fstab
...
...

Revision as of 23:32, 25 November 2021

Kategorie:Linux Kategorie:Security

Encrypted swap on LVM

Create logical volume for swap

# lvcreate -L 2g -n lv-swap vg-root
  Logical volume "lv-swap" created
# lvs /dev/vg-root/lv-swap
  LV      VG      Attr      LSize Pool Origin Data%  Move Log Copy%  Convert
  lv-swap vg-root -wi-ao--- 2.00g

Create and get the UUID

This step will erase all of your data from the disk after the mkswap command!!! So be sure you pick the right one!

# mkswap /dev/vg-root/lv-swap
mkswap: /dev/vg-root/lv-swap: warning: don't erase bootbits sectors
        on whole disk. Use -f to force.
Setting up swapspace version 1, size = 2097148 KiB
no label, UUID=4764e516-d025-41de-ab5b-72070a3ae765

Save this UUID for the next step!!!

Create the crypted swap

Put this in your /etc/crypttab :

cryptswap1 UUID=4764e516-d025-41de-ab5b-72070a3ae765 /dev/urandom swap,cipher=aes-cbc-essiv:sha256,offset=40,noearly

The UUID is the one from mkswap before!!!

Important things:

  1. offset=40 : Save the region where your UUID is written on disk.
  2. noearly  : Avoid race conditions of the init scripts (cryptdisks and cryptdisks-early).

Start the crypted partition

# cryptdisks_start cryptswap1
 * Starting crypto disk...
 * cryptswap1 (starting)..
 * cryptswap1 (started)...

Check the status

# cryptsetup status cryptswap1
/dev/mapper/cryptswap1 is active.
  type:    PLAIN
  cipher:  aes-cbc-essiv:sha256
  keysize: 256 bits
  device:  /dev/mapper/vg--root-lv--swap
  offset:  40 sectors
  size:    4194264 sectors
  mode:    read/write

Make the swapFS

# mkswap /dev/mapper/cryptswap1
mkswap: /dev/mapper/cryptswap1: warning: don't erase bootbits sectors
        on whole disk. Use -f to force.
Setting up swapspace version 1, size = 2097128 KiB
no label, UUID=ccdd1d28-0504-4682-8ece-8b6ef381d7e9

This new UUID has no relevance for /etc/crypttab.

Edit the /etc/fstab

# vit /etc/fstab
...
/dev/mapper/cryptswap1 none swap sw 0 0

Reboot to test your settings.