archlinux-initrd-ssh-cryptsetup/README.md

Personal ArchLinux package combining dropbear and cryptsetup in initrd for unlocking LUKS-encrypted devices either locally (boot console) or remotely over SSH. The code was reworked from dropbear_initrd_encrypt.

Installation

After cloning the repo, installation is done as for an AUR package.

Configuration

As explained upon installation, the following things need to be done:

• add the SSH public key to /etc/dropbear/initrd.authorized_keys
• add the ip= kernel command parameter to the bootloader configuration (see https://wiki.archlinux.org/index.php/Mkinitcpio#Using_net)
• in the HOOKS section of /etc/mkinitcpio.conf, add ssh-cryptsetup before filesystems; then rebuild the initramfs: mkinitcpio -p linux

The LUKS-encrypted devices to unlock are derived from /etc/crypttab.

Some options can be set in /etc/initcpio/sshcs_env (file is sourced in initrd shell):

• sshcs_opt_timeout_ipconfig: time (in seconds) to configure IP
  • default: 10 seconds
• sshcs_opt_listen: SSH listening port
  • default: 22
• sshcs_opt_timeout_poweroff: time (in seconds) to unlock devices before automatic powering off
  • default (and minimum value): 2 minutes
  • negative value to deactivate

For example:

sshcs_opt_timeout_ipconfig=30
sshcs_opt_listen=2222
sshcs_opt_timeout_poweroff=-1

Building notes

1. Modify the sources (features in src, and/or package building files)
2. If src was modified
   • archive the src folder in $pkgname-$pkgver.tar.xz file; e.g.: tar -cJf initrd-ssh-cryptsetup-0.4.tar.xz src
   • upload the archive on the online repository (pointed by PKGBUILD)
3. Update PKGBUILD
   • bump pkgver if src was modified, or pkgrel if building files were modified
   • refresh md5sums if necessary (based on md5sum initrd-ssh-cryptsetup-*.tar.xz initrd-ssh-cryptsetup.install output)
4. Delete generated archive file if any