scriptbox/alpine-initramfs-dropbear

Alpine Initramfs Dropbear

This script took a huge references from:

• https://github.com/Deeplerg/fork-alpine-initramfs-dropbear

• https://github.com/mk-f/alpine-initramfs-dropbear

• https://gitlab.alpinelinux.org/alpine/mkinitfs/-/blob/master/initramfs-init.in

This script is modified from alpine/mkinitfs - initramfs-init.in

significant changes:

• Add dropbear

• After unlocked, kill all remainings dropbear and nlplug-findfs process, so no struck process reached the system.

Please install dropbear before continuing

1. copy dropbear/unlock_disk to /etc/dropbear/unlock_disk
   • Also Make sure /etc/dropbear/unlock_disk is executable! else dropbear will exit with "failed child"W
2. copy authorized_keys to /etc/dropbear/authorized_keys
3. copy features.d to /etc/mkinitfs/features.d

Note:

• if you're using Deeplerg/mk-f scripts before don't forget to change unlock_disk as i modified that one too.
• If you're using grub make sure to install syslinux and possibly checkout /etc/default/grub and commented CMDLINE that's conflicted with update-extlinux like GRUB_CMDLINE_LINUX_DEFAULT and default_kernel_opts after that grub-mkconfig -o /boot/grub/grub.cfg

/etc/mkinitfs.conf

features="ata base ide scsi usb virtio ext4 cryptsetup keymap dropbear network"

• features+= dropbear network

/etc/update-extlinux.conf

modules=sd-mod,usb-storage,ext4,ata_piix,virtio_net,e1000e,virtio_pci

• if network is not working (/sys/class/net/*/address not found etc.) try adding e1000e or virtio_net virtio_pci

default_kernel_opts="cryptroot=UUID=xxx cryptdm=root quiet rootfstype=ext4 dropbear=<dropbear_port> ip=<ip>>"

• ip= can be both static and dhcp(if supported) ip=<ip>::<gw>:<mask>::<interface> ip=dhcp

update-extlinux

mkinitfs -i path/to/initramfs-dropbear <Kernel Version(from /lib/modules) incase in emergency CD>

Full Diff:

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> setup_dropbear() {
>       local port="${KOPT_dropbear}"
>       local keys=""
> 
>       # set the unlock_disc script as shell for root
>       sed -i 's|\(root:x:0:0:root:/root:\).*$|\1/etc/dropbear/unlock_disk|' /etc/passwd
>       echo '/etc/dropbear/unlock_disk' > /etc/shells
> 
>       # transfer authorized_keys
>       mkdir /root/.ssh
>       cp /etc/dropbear/authorized_keys /root/.ssh/authorized_keys
> 
>       dropbear -R -E -s -j -k -p $port
> }
> 
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>       dropbear
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< if [ -n "$KOPT_cryptroot" ]; then
---
> if [ -n "$KOPT_dropbear" ]; then
>       if [ -n "$KOPT_cryptroot" ]; then
>               configure_ip
>               setup_dropbear
>       fi
> fi
> 
> # Add Workaround for dropbear
> if [ -n "$KOPT_cryptroot" ] && [ ! -b /dev/mapper/"${KOPT_cryptdm}" ]; then
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>       # Kill all struck nlplug-findfs jobs and dropbear
>       killall -9 nlplug-findfs
>       killall -9 dropbear
> 
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> 
>       # Kill all struck nlplug-findfs jobs and dropbear
>       killall -9 nlplug-findfs
>       killall -9 dropbear