Ever wanted to be able to boot Linux1 over the network using an Ethernet cable but without setting up a PXE? Now you only need a SMB server that can be installed anywhere!
SKUF Network Boot System allows you to boot the Arch Linux2 operating system on a computer connected to network via Ethernet using USB flash drive (100MB minimum) and a SMB file share.
Caution
The only supported distribution is Arch Linux™. Other shitty systems like Debian, Ubuntu, Manjaro, Fedora, openSUSE, etc. are NOT supported and NEVER WILL BE.
Two computers in the same network:
Server:
- Running SMB file server
- Your user on the SMB server has a password. Users without password or anonymous access are not supported
Client:
- Connected to network via Ethernet cable. Wireless is not supported.
- A USB stick/CD/DVD with the
skuflinux
image (you can also use Ventoy) - Brain not poisoned with beer so you have enough brain cells to read this manual
Caution
Prebuilt binaries and ISO images will NEVER be available due to possible security risks. Read the build instructions carefully.
Note
The example illustrates how the server
and client
work together.
Server — a computer with the SMB
server running.
Client — a computer that will boot the system from the server
over the network using a cable
You have a USB flash drive/CD/DVD with an ISO image of skuflinux
on it. You have two PCs in your room/college/office. First one is the one you will be sitting at. The other one is running SMB server with a directory that you have write access to. That directory contains filesystem image with the Arch Linux distribution and the skuf
package installed.
After booting from USB drive with skuflinux
you will be prompted to enter SMB server address and port, user credentials and path to filesystem image. Now SKUF script will do the following:
- Obtain an IP address using
dhcpcd
- Mount the SMB directory
- Mount the image volume with Arch Linux
- Generate an encrypted string with your answers to the questions asked earlier
- Load kernel and initramfs from a previously mounted Arch Linux image into RAM
- Unmount SMB and image volume with Arch Linux
- Execute kexec
Now when the kernel and initramfs of your Arch Linux were loaded from SMB server, SKUF mounts system image again:
- The newly booted system obtaining IP address again
- The previously encrypted string contained your answers to the questions. It was passed to the kernel command line (
/proc/cmdline
) in encrypted form, and will now be decrypted, so you don't have to write it all over again. - Mounting the SMB directory again
- Once the Arch Linux image volume is mounted, SKUF executes switch_root and system is booted. Congratulations!
Caution
The only supported distribution is Arch Linux™. Other shitty systems like Debian, Ubuntu, Manjaro, Fedora, openSUSE, etc. are NOT supported and NEVER WILL BE.
arch-install-scripts
archiso
base
base-devel
binutils
clang
orgcc
musl
kernel-api-headers
kernel-headers-musl
Clone this repository using git:
git clone https://github.com/BiteDasher/skuf
cd skuf
Tune encryption obfuscation and encryption password (see Customization instructions):
vim tune.password
vim tune.crypt
Setup defaults for ISO
(optional):
vim defaults
Run configuraion sripts:
./tune_crypt.sh
./tune_password.sh
./setup_defaults.sh
Build SKUF:
./build_rootfs_tar.sh
./build_package.sh
./setup_repo.sh
./build_iso.sh
./create_image.sh SIZE_IN_GIGABYTES additional_packages
# For sparse file, use ./create_image.sh -s
Note
Basic installation of Arch Linux without GUI or any additional software takes about 1 GB.
Done! 💪🎉 Now write skuflinux-smth.iso
to your USB drive, put arch.ext4
into your directory on SMB server and try SKUF Network Boot System.
String for /proc/cmdline
is encrypted using OpenSSL. You need to specify encryption password and number of iterations in the tune.password
file in following format:
ITERATIONS_COUNT PASSWORD
Note
For an example, see the tune.passwordX
file
String that is encrypted through OpenSSL is eventually turned into a base64 string. You can obfuscate this string by swapping these letters. Write pairs of letters in the following format to the tune.crypt
file:
A B
X Y
I O
Note
For an example, see the tune.cryptX
file
When you booted up the skuflinux
ISO image from your media device, you will be asked questions like: SMB server address, SMB server port, SMB protocol version and so on. Edit the defaults
file if you want to preset them manually.
Table of SKUF variables:
Variable | Meaning |
---|---|
SAMBA_ADDRESS |
Address of the SMB server where the client directory with the Arch Linux image is located |
SAMBA_PORT |
SMB server port |
SAMBA_VERSION |
SMB server protocol version |
SAMBA_DOMAIN |
Domain for the SMB server (default domain is WORKGROUP ) |
VOLUME_PATH |
Path to the directory on the SMB server where the client Arch Linux image volume and swap file are located(see Tips and Tricks) |
VOLUME_FILENAME |
Arch Linux image volume name that is located in VOLUME_PATH |
SWAP_FILENAME |
swap file name that is located in VOLUME_PATH |
SAMBA_EXTRA_MOUNT_OPTS |
Additional SMB mount options. Applies to both step 1 and step 2 of SKUF boot process |
VOLUME_EXTRA_MOUNT_OPTS |
Additional client Arch Linux image volume mount options. Applies to both step 1 and step 2 of SKUF boot process |
CHECK_FS |
Whether to check the integrity of a file system image with Arch Linux. Accepts Yes or No . Applies only to step 2 |
EXTRA_KERNEL_OPTS |
Additional linux kernel options |
PATH_TO_NEW_KERNEL |
Path to the new kernel that will be loaded using kexec. The new kernel must be in the Arch Linux image that is lies on SMB server |
PATH_TO_NEW_INITRAMFS |
Path to the new initramfs that will be loaded using kexec alongside kernel. The new initramfs must be in the Arch Linux image that is lies on SMB server |
MAX_SMB_RETRY_COUNT |
Maximum number of attempts to re-enter SMB credentials if the first mount attempt failed. Applies only to step 1 |
-
You can place a swap file next to the Arch Linux image volume so you can use it on your system. The swap file will be connected over the network as a loop device.
-
You can use Plymouth in step 2. Add
splash
toEXTRA_KERNEL_OPTS
to thedefaults
file, also don't forget to addHOOKS=(... plymouth ...)
to theskuf_src/mkinitcpio.conf
and installplymouth
package. -
In step 1, you can write
@u@
and@fu@
in the path to the client(your) directory, in the path to the image volume file and in the swap file. If you login as[email protected]
,@u@
will bejohn
and@fu@
will be[email protected]
. -
After building the ISO image and creating a file system image with Arch Linux you can execute
sudo ./clean.sh
to remove unnedeed files. -
Password for
root
andtest
users inarch.ext4
is0000
-
If you enter something incorrectly while entering SMB address, kernel path, etc. at step 1 and fall into the interactive shell, write
reboot -f
. No, you cannot restart the script. Train your attention. -
If the client computer has
UEFI
, you can installSKUF
on aFAT32 EFI
partition so you don't have to use a USB flash drive/CD/DVD. To do this, mountskuflinux-smth.iso
somewhere (like /mnt), then copy/mnt/skuf/boot/x86_64/{vmlinuz-linux,initramfs-linux.img}
toFAT32 EFI
partition and executeefibootmgr -c -d /dev/sdX -p Y -u 'initrd=\initramfs-linux.img' -l '\vmlinuz-linux' -L 'SKUF'
where /dev/sdX is the target disk and Y is the targetFAT32 EFI
partition number.
skuf_demo.mp4
Huge thanks to the Arch Linux development team for their awesome distribution, archiso and mkinitcpio utilities. They made the creation of this project much easier.
Footnotes
-
The registered trademark Linux® is used pursuant to a sublicense from LMI, the exclusive licensee of Linus Torvalds, owner of the mark on a world-wide basis. ↩
-
Copyright © 2002-2024 Judd Vinet, Aaron Griffin and Levente Polyák. The Arch Linux name and logo are recognized trademarks. Some rights reserved. ↩