#!/bin/bash
#
#  restore the standard MBR code to damaged hard drive
#  shellscript by oozie at poczta dot fm
#
#  Used generic MBR code from MSDOS 3.30 fdisk /mbr
#
#
####

if [ -z "$1" ]; then

cat << _EOF_
 
 Restore MBR with generic code
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Usage: $0 /dev/?d?
 
   where ?d? is one of your hard drives, e.g. /dev/sda

_EOF_

exit 0
fi

# 1. check for appropriate rights and existence of /dev/?d?

DISK="$1"

# check for appropriate rights

if [ "$UID" -ne "0" ]; then
echo "$0: you need to be root."
exit 1
fi

# checking for block device

if [ ! -b "$DISK" ]; then
echo "$0: $DISK is not a valid block device"
exit 1
fi

# let's start the fun - extact MBR generic code
NEWMBR=$(mktemp)
echo "[*] Extracting generic code to $NEWMBR"

umask 077
MBRBACKUP="/root/mbr-backup.`date +%H-%M-%S`"

printf \
"\xfa\x33\xc0\x8e\xd0\xbc\x00\x7c\x8b\xf4"\
"\x50\x07\x50\x1f\xfb\xfc\xbf\x00\x06\xb9"\
"\x00\x01\xf2\xa5\xea\x1d\x06\x00\x00\xbe"\
"\xbe\x07\xb3\x04\x80\x3c\x80\x74\x0e\x80"\
"\x3c\x00\x75\x1c\x83\xc6\x10\xfe\xcb\x75"\
"\xef\xcd\x18\x8b\x14\x8b\x4c\x02\x8b\xee"\
"\x83\xc6\x10\xfe\xcb\x74\x1a\x80\x3c\x00"\
"\x74\xf4\xbe\x8b\x06\xac\x3c\x00\x74\x0b"\
"\x56\xbb\x07\x00\xb4\x0e\xcd\x10\x5e\xeb"\
"\xf0\xeb\xfe\xbf\x05\x00\xbb\x00\x7c\xb8"\
"\x01\x02\x57\xcd\x13\x5f\x73\x0c\x33\xc0"\
"\xcd\x13\x4f\x75\xed\xbe\xa3\x06\xeb\xd3"\
"\xbe\xc2\x06\xbf\xfe\x7d\x81\x3d\x55\xaa"\
"\x75\xc7\x8b\xf5\xea\x00\x7c\x00\x00\x49"\
"\x6e\x76\x61\x6c\x69\x64\x20\x70\x61\x72"\
"\x74\x69\x74\x69\x6f\x6e\x20\x74\x61\x62"\
"\x6c\x65\x00\x45\x72\x72\x6f\x72\x20\x6c"\
"\x6f\x61\x64\x69\x6e\x67\x20\x6f\x70\x65"\
"\x72\x61\x74\x69\x6e\x67\x20\x73\x79\x73"\
"\x74\x65\x6d\x00\x4d\x69\x73\x73\x69\x6e"\
"\x67\x20\x6f\x70\x65\x72\x61\x74\x69\x6e"\
"\x67\x20\x73\x79\x73\x74\x65\x6d" > $NEWMBR

perl -e '{print "\0"x228}' >> $NEWMBR

printf \
"\x80\x01\x01\x00"\
"\x0b\x7f\xbf\xfd\x3f\x00\x00\x00\xc1\x40"\
"\x5e" >> $NEWMBR

perl -e '{print "\0"x49}' >> $NEWMBR


# 2. backup original MBR
echo "[*] Backing up MBR to $MBRBACKUP"
dd if=$DISK of=$MBRBACKUP count=1 bs=512 # > /dev/null  2>&1

# 3. rewrite original partition table from the harddrive to the
#    new mbr

echo "[*] Rewriting original partition table to the new MBR "
dd if=$MBRBACKUP of=$NEWMBR skip=446 seek=446 bs=1 count=64 #> /dev/null 2>&1
printf "\x55\xaa" >> $NEWMBR

# 4. write new mbr to the disk
echo -n "[?] Are you sure you want to write new MBR to the $DISK? [y/n] "
read SURE
if [ "$SURE" != "y" ]; then

echo "[-] I guess not."
exit 0

fi

echo "[*] Re-Writing MBR to the disk"
dd if=$NEWMBR of=$DISK bs=512 count=1
echo "-Done."

rm $NEWMBR