8.2 KiB
Arch Linux with LUKS and btrfs on a Hetzner server (DRAFT)
Software
This guide shows how to set up the following software composition:
Requirements
Written for a Dedicated Hetzner server with the following hardware specifications:
CPU1: Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz (Cores 8)
Memory: 15973 MB
Disk /dev/sda: 3000 GB (=> 2794 GiB)
Disk /dev/sdb: 3000 GB (=> 2794 GiB)
Total capacity 5589 GiB with 2 Disks
Legend
The following symbols show in which environment the code is executed:
- 💻 Client
- 🚑 Hetzner Rescue System
- 👻 Chroot from Rescue System into Arch
- 💽 Arch OS
Guide
1. Configure and Install Image
1.1 Login to Hetzner Rescue System
💻 :
ssh root@your_server_ip
1.2 Create the /autosetup
🚑 :
nano /autosetup
Save the following content into this file:
## Hetzner Online GmbH - installimage - config
DRIVE1 /dev/sda
DRIVE2 /dev/sdb
## SOFTWARE RAID:
## activate software RAID? < 0 | 1 >
SWRAID 1
## Choose the level for the software RAID < 0 | 1 | 10 >
SWRAIDLEVEL 1
## BOOTLOADER:
BOOTLOADER grub
## HOSTNAME:
HOSTNAME hetzner-arch-luks
#Adapt the hostname to your needs
## PARTITIONS / FILESYSTEMS:
PART /boot btrfs 512M
PART lvm vg0 all
LV vg0 swap swap swap 8G
LV vg0 root / btrfs 10G
## OPERATING SYSTEM IMAGE:
IMAGE /root/.oldroot/nfs/install/../images/archlinux-latest-64-minimal.tar.gz
1.3 Install Image
🚑 :
installimage
1.4 Restart
🚑 :
reboot
2. Setup System
2.1 Login to server
💻 :
ssh-keygen -f "$HOME/.ssh/known_hosts" -R your_server_ip
ssh root@your_server_ip
2.2 Update the system
💽 :
pacman -Syyu
2.3 Install administration tools:
💽 :
pacman -S nano
3. Prepare System for Unlocking via SSH
3.1 Install software
💽 :
pacman -S busybox mkinitcpio-dropbear mkinitcpio-utils mkinitcpio-netconf
3.2 Copy authorized keys to dropbear
⚠️ I don't know if the following step is correct. Later during executing mkinitcpio -p linux the following error appears:
-> Running build hook: [dropbear]
Error: Unrecognised key type
Error reading key from '/etc/ssh/ssh_host_rsa_key'
Error: Unrecognised key type
Error reading key from '/etc/ssh/ssh_host_dsa_key'
Error: Unrecognised key type
Error reading key from '/etc/ssh/ssh_host_ecdsa_key'
I assume this is connected to this. The following links may help to solve the problem:
- https://github.com/grazzolini/mkinitcpio-dropbear/issues/8
- https://www.reddit.com/r/archlinux/comments/a8pcff/remote_unlock_encrypted_archlinux_with/
cp -v ~/.ssh/authorized_keys /etc/dropbear/root_key
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
systemctl enable sshd
3.3 Regenerate OpenSSH keys
💽 :
rm /etc/ssh/ssh_host_*
ssh-keygen -A -m PEM
3.4 Import SSH-keys to dropbear
💽 :
dropbearconvert openssh dropbear /etc/ssh/ssh_host_rsa_key /etc/dropbear/dropbear_rsa_host_key
3.5 Modify /etc/mkinitcpio.conf
💽 :
nano /etc/mkinitcpio.conf
Replace
Old:
HOOKS=(base udev autodetect modconf block mdadm_udev lvm2 filesystems keyboard fsck)
New:
HOOKS=(base udev autodetect modconf block mdadm_udev lvm2 netconf dropbear encryptssh filesystems keyboard fsck)
⚠️ In one of the guides the /etc/initramfs-tools/initramfs.conf get modified. Don't know how to implement this for mkinitcpio.
Old:
BUSYBOX=auto
New:
BUSYBOX=y
4. Activate Encryption
4.1 Activate Rescue System
Activate the rescue system https://robot.your-server.de/server
4.2 Reboot
💽 :
reboot
4.3 Login to the rescue system
💻 :
ssh-keygen -f "$HOME/.ssh/known_hosts" -R your_server_ip
ssh root@your_server_ip
4.4 Mount the "system"
🚑 :
vgscan -v
vgchange -a y
mount /dev/mapper/vg0-root /mnt
4.5 Copy "system"
🚑 :
echo 0 >/proc/sys/dev/raid/speed_limit_max
mkdir /oldroot
cp -va /mnt/. /oldroot/.
echo 200000 >/proc/sys/dev/raid/speed_limit_max
4.6 Unmount the "system"
🚑 :
umount /mnt
4.7 Delete decrypted LVM-Volume-Group
🚑 :
vgremove vg0
4.8 Check drive state
🚑 :
cat /proc/mdstat
4.9 Encrypt MD1 by executing
🚑 :
cryptsetup --cipher aes-xts-plain64 --key-size 256 --hash sha256 --iter-time=10000 luksFormat /dev/md1
cryptsetup luksOpen /dev/md1 cryptroot
pvcreate /dev/mapper/cryptroot
vgcreate vg0 /dev/mapper/cryptroot
lvcreate -n swap -L8G vg0
lvcreate -n root -L10G vg0
mkfs.btrfs /dev/vg0/root
mkswap /dev/vg0/swap
4.10 Mount encrypted
🚑 :
mount /dev/vg0/root /mnt
4.12 Copy "system"
🚑 :
echo 0 >/proc/sys/dev/raid/speed_limit_max
cp -av /oldroot/. /mnt/.
echo 200000 >/proc/sys/dev/raid/speed_limit_max
4.13 Integrate Finale Installation
🚑 :
mount /dev/md0 /mnt/boot
mount --bind /dev /mnt/dev
mount --bind /sys /mnt/sys
mount --bind /proc /mnt/proc
chroot /mnt
4.14
👻 :
echo "cryptroot /dev/md1 none luks" >> /etc/crypttab
4.15 Create an initial ramdisk
👻 :
mkinitcpio -p linux
5 Grub
5.1 Install Grub
👻 :
pacman -S grub
5.2 Configure /etc/default/grub
👻 :
nano /etc/default/grub
⚠️ I'm not shure if the following is correct. Please check out this link . I appreciate feedback 💕
⚠️ I don't know if the raid also needs to be configured in the GRUB_CMDLINE_LINUX parameter.
Change the following parameters:
GRUB_CMDLINE_LINUX="cryptdevice=/dev/md1:cryptroot ip=dhcp"
GRUB_ENABLE_CRYPTODISK=y # Not secure if necessary
ℹ️ Further information.
5.3 Make and Install on Hard-drives
👻 :
grub-mkconfig -o /boot/grub/grub.cfg
grub-install /dev/sda
grub-install /dev/sdb
5.4 Restart System
👻 🚑 :
exit
umount /mnt/boot /mnt/proc /mnt/sys /mnt/dev
umount /mnt
sync
reboot
6. Encryption Procedure
6.1 Decrypt server
💻 :
ssh -o UserKnownHostsFile=/dev/null root@your_server_ip
cryptroot-unlock
exit
6.2 Login to server
💻 :
ssh-keygen -f "$HOME/.ssh/known_hosts" -R your_server_ip
ssh root@your_server_ip
7. Debugging
7.1 Login to System from Rescue System
🚑 :
cryptsetup luksOpen /dev/md1 cryptroot
mount /dev/vg0/root /mnt
mount /dev/md0 /mnt/boot
mount --bind /dev /mnt/dev
mount --bind /sys /mnt/sys
mount --bind /proc /mnt/proc
chroot /mnt
7.2 Logout from chroot environment
👻 🚑 :
exit
umount /mnt/boot /mnt/proc /mnt/sys /mnt/dev
umount /mnt
sync
reboot
7.3 Regenerate GRUB and Arch
👻 :
mkinitcpio -p linux
grub-mkconfig -o /boot/grub/grub.cfg
grub-install /dev/sda
grub-install /dev/sdb
Sources
The code is adapted from the following guides:
- http://daemons-point.com/blog/2019/10/20/hetzner-verschluesselt/
- https://www.howtoforge.com/using-the-btrfs-filesystem-with-raid1-with-ubuntu-12.10-on-a-hetzner-server
- https://code.trafficking.agency/arch-linux-remote-unlock-root-volume-with-mdraid-and-dmcrypt.html
- https://wiki.archlinux.org/index.php/Dm-crypt/Specialties#Remote_unlocking_(hooks:_netconf,_dropbear,_tinyssh,_ppp)
- https://gist.github.com/pezz/5310082