This repository contains scripts, build definitions and patches to build a minimal linux distribution running from initramfs. It's primary purpose is to teach the minimal requirements of a working linux system. If you just run our scripts you will end up with a small linux (between 5MB and 50MB) that allows you to login via SSH. Your phantasy and some scripts will expand this linux to a great deployment system or a platform for forensic analysis.
Our TinyCrossLinux is initially based on "Cross Linux from Scratch" (embedded). It uses an initramfs instead of a classic root file system. The boot scripts use a layout that is inspired by Berkeley Unix (BSD). Boot the system and take a look at /etc/rc.d
. The scripts here will be executed in the order they appear (they will be called with the argument "start"). At shutdown the scripts will be called in reverse order (with argument stop).
Scripts in this repository might be eventually moved to LessLinux' build process (I feel tempted not do to so to keep it simple). Currently only x86_64 is supported. ia32 and armhf (Raspberry Pi) will follow, but are of no major priority.
Scripts to build the toolchain itself. You probably will not need to add/modify scripts here.
Scripts to build binaries for the target filesystem. Add as you want, but do not forget that you are cross compiling. Define PKGNAME=...
and PKGVERSION=...
since those are read by the script build_stage0n.sh
.
These are scripts for tools and libraries that are not part of the base system. Softlink scripts of software you want to include to stage02. But be warned, you have to manually track dependencies, for example ntfs-3 needs fuse.
Script to assemble a bootable ISO image (isohybrid, might be dd'ed to an USB thumb drive). Currently BIOS only, UEFI will follow. Feel free to ad an overlay or similar sick things to this script - it is less than 40 lines anyway.
So to build TinyCrossLinux run
bash build_stage0n.sh # compiles everything
bash build_iso.sh # builds two ISO images
# one for BIOS - one for UEFI
Currently the following services provided by BusyBox or dropbearmulti are available. They are inactive by default, so use the bootparameters specified to enable them:
- SSHD
sshd=1
- you might want to add a permanent key to/etc/dropbear
- HTTPD
httpd=1
- searches for files in/srv/www
- TFTPD
tftpd=1
- serves files from/srv/tftp
- UDHCPD
udhcpd=1
- starts only in/etc/udhcpd.conf
is present
Run the command
openssl passwd -1
on an arbitary machine to create a password hash and replace the '!' in roots line in patches/etc-shadow
with the output.
Take a look at patches/etc-inittab
. Replace lines like
ttyN::respawn:/bin/ash
by
ttyN::respawn:/sbin/getty -l /bin/login 38400 ttyN
The build script stage02/0001_basefiles.sh
installs some of the startup scripts. Many of them are copied from the patches directory
. You might want to create stage02/0002_mybasefiles.sh
. Or you just expand the basefiles script.
This linux distribution will stay small and compact, thus I do not plan to add many features. I will add some build scripts to further expand the system for some rescue and forensic purposes:
- ddrescue
- ntfs-3g (ntfsclone etc.)
Changes to the boot scripts that will be eventually made:
- more flexible network configuration (allow specification of static IP via boot command line)
- more flexible module loading (blacklisting and allow to specify additional modules via boot command line)
I will also write a script to select certain modules and subdirectories from the kernels module tree to be able to reduce the size of the resulting ISO image without having to reconfigure the kernel.
Probably there are some. I already ran into those:
- You have to boot with a connected ethernet cable, otherwise udhcpc will try nearly forever to get a lease.
- Some firmware is missing - I will provide you with a script to automatically install firmware for the linux-firmware collection for kernel modules installed, in the meantime add those blobs by hand.