How to unlock crypto root partition in Debian Linux over SSH (and more)
Early-ssh is a simple initramfs-tools hook script which provides an SSH server at boottime (in the initramfs) before the root filesystem gets mounted, so you will be able to do a numerous things, such as:
unlocking crypto devices – even your root can be an encrypted filesystem
assembling/altering mdadm RAID arrays
checking the root filesystem in read-write mode, [...]