#!/bin/bash

Prefix='reboot'                         # Set a prefix for folder, keyfiles etc
Device='eth0'                           # Your network interface
Ip='10.0.0.99'                          # Your ip address
Subnet='255.255.255.0'                  # Your subnet mask
Gateway='10.0.0.1'                      # Your default gateway




##############################################################################################
#                                                                                            #
#                                    BELOW BE DRAGONS                                        #
#                                                                                            #
##############################################################################################


# Function for checking and replacing option values
function updateSettings
{
        File="$1"
        Pattern="$2"
        Replace="$3"

        if grep "${Pattern}" "${File}" >/dev/null;
        then
                # Pattern found, replace line
                sed -i s/.*${Pattern}.*/${Replace}/g "${File}"
                echo ""
        else
                # Pattern not found, append new
                echo "${Replace}" >> "${File}"
        fi
}


echo "Install dependencies"
apt-get -y install dropbear busybox
echo ""
echo ""



echo "Update /etc/initramfs-tools/initramfs.conf"
File="/etc/initramfs-tools/initramfs.conf"
updateSettings "${File}" "BUSYBOX=" "BUSYBOX=y"
updateSettings "${File}" "DROPBEAR=" "DROPBEAR=y"
updateSettings "${File}" "DEVICE=" "DEVICE=${Device}"
updateSettings "${File}" "IP=" "IP=${Ip}::${Gateway}:${Subnet}::${Device}:off"
echo ""
echo ""



echo "Creating host keys in /etc/initramfs-tools/etc/dropbear/"
rm "/etc/initramfs-tools/etc/dropbear/dropbear_dss_host_key"
rm "/etc/initramfs-tools/etc/dropbear/dropbear_rsa_host_key"
dropbearkey -t dss -f "/etc/initramfs-tools/etc/dropbear/dropbear_dss_host_key"
dropbearkey -t rsa -f "/etc/initramfs-tools/etc/dropbear/dropbear_rsa_host_key"
echo ""
echo ""



echo "Creating private and public keys"
rm -Rf "/etc/initramfs-tools/root/.ssh"
mkdir -p "/etc/initramfs-tools/root/.ssh"
mkdir -p "/root/${Prefix}"
dropbearkey -t rsa -f "/root/${Prefix}/${Prefix}_rsa.dropbear"
/usr/lib/dropbear/dropbearconvert dropbear openssh "/root/${Prefix}/${Prefix}_rsa.dropbear" "/root/${Prefix}/${Prefix}_rsa"
dropbearkey -y -f "/root/${Prefix}/${Prefix}_rsa.dropbear" | grep "^ssh-rsa " > "/root/${Prefix}/${Prefix}_rsa.pub"
cat "/root/${Prefix}/${Prefix}_rsa.pub" >> "/etc/initramfs-tools/root/.ssh/authorized_keys"
echo ""
echo ""



echo "Updating current initramfs"
update-initramfs -u


clear

echo ""
echo ""
echo "IMPORTANT: READ THE FOLLOWING LINES CAREFULLY!"
echo ""
echo ""

echo "SCP the new public key to your local machine. Run from your local machine the following command:"
echo "scp root@${Ip}:/root/${Prefix}/${Prefix}_rsa ~/.ssh/"
echo "This will store the private key in your ~/.ssh/ folder as ${Prefix}_rsa"
echo ""
echo ""


echo "To unlock the encrypted server after reboot run from the client:"
echo 'ssh -o "UserKnownHostsFile=~/.ssh/known_hosts.'${Prefix}'" -i ~/.ssh/'${Prefix}'_rsa root@'${Ip}' "echo -ne \"YOURENCRYPTIONPASSWORD\" >/lib/cryptsetup/passfifo"'
echo "Please replace YOURENCRYPTIONPASSWORD with the actual password for unlocking the root partition"