GRUB - Rescue BootLoader on a USB Flash Drive

My goal is to just have a GRUB bootloader (without a Linux instalation) on a USB Flash Drive to:

• Boot OS with Bootloaders without entering the BIOS
• Boot OS with Broken Boot Loaders
• Boot Linux Live CDs

 

Installing the GRUB Boot Loader

Run a live CD like Ubuntu, a boot i without installing it.

First list your disks in order to identify you USB Flash Drive

    sudo fdisk -l

if you have trouble identifying you USB Flash Drive just run the command above without the USB Flash Drive, the insert it and list again, compare the outputs, and the extra disk is you USB Flash Drive.

My USB Flash Drive is “sdb1” (b=second HD | 1=first partition), now let’s make a folder to mount the usb flash drive (my Flash Drive was formated with the ext4 filesystem), and mount it:

    sudo mkdir /mnt/USB
    sudo mount /dev/sdb1 /mnt/USB

Now let’s just install the the bootloader

    sudo grub-install --force --removable --boot-directory=/mnt/USB/boot /dev/sdb

boot code goes on /dev/sdb and grub files on /mnt/USB/boot.

 

Set Up the Grub Configuration FIle

Now just create/edit the grub config file

    nano /mnt/USB/boot/grub/grub.cfg

and input the following configuration:

grub.cfg
_____________________________________________

set timeout=10
set default=0

menuentry "#### Boot OS with Bootloaders without entering the BIOS ####" {set root=(hd1)}

menuentry "HD0 (First HD – This USB Flash Drive)" {
set root=(hd0)
chainloader +1
}

menuentry "HD1 (Second HD)" {
set root=(hd1)
chainloader +1
}

menuentry "HD2 (Third HD)" {
set root=(hd2)
chainloader +1
}

menuentry "HD3 (Fourth HD)" {
set root=(hd3)
chainloader +1
}

 

menuentry "#### Boot OS with Broken Boot Loaders ####" {set root=(hd1)}

menuentry "Ubuntu 16.04 (HD1 - First HD)"  {

    insmod part_msdos
    insmod ext2
    set root=(hd1,msdos1)

    echo 'Loading Linux Kernel...'
    linux /boot/vmlinuz-4.4.0-24-generic root=/dev/sda1
       
    echo 'Loading Initial Ramdisk ...'
    initrd /boot/initrd.img-4.4.0-24-generic
    boot
}

menuentry "Windows XP/7/10 (HD1 - First HD)"  {

    insmod part_msdos
    insmod ntfs
    set root=(hd1,msdos1)

    drivemap -s (hd0) ${root}
    chainloader +1
}

 

menuentry "#### Boot Linux Live CDs ####" {set root=(hd1)}
   
menuentry "Ubuntu 16.04 ISO (On This USB PEN Drive)" {

    set isofile="/ubuntu-16.04-desktop-amd64.iso"
    loopback loop (hd0,msdos1)$isofile
    linux (loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=$isofile noprompt noeject
    initrd (loop)/casper/initrd.lz
}

This is what it looks like:

You migth need to adjust some things if you have more disks, partitions or diferent linux distro. To make it easyer I have put the things you migth need to change in bold.

The above config was for the following setup

• One USB Flash Drive (with Grub Installed)
  • hd0,msdos1 - First HD | First Partition – MBR Geometry
  • This is was my USB Flash Drive
• One Hard Drive for OS
  • hd1,msdos1 – Second HD | First Partition – MBR Geometry
  • This is the Disk with the OS

If you have trouble Identifying you disks and partion you can press ‘c’, on the grub menu, to get the GRUB command line and run “ls” :

this was very hepfull, specially identifying the the name for the MBR partitions aka “msdos” .

Related Links

• http://www.pendrivelinux.com/install-grub2-on-usb-from-ubuntu-linux/
• https://www.gnu.org/software/grub/manual/html_node/Chain_002dloading.html
• http://ubuntuhandbook.org/index.php/2014/04/install-grub-customizer-ubuntu-1404/

Windows – SSH SOCKS Proxy

If you have a Raspberry Pi or any Linux machine at home, you can use it as an SSH Proxy with the help of SSH and exit to the Internet via you home conection/IP.

Some of the advantages are:

• Privacy (SSH Traffic is Encrypted)
• Bypassing Local Security Policies (Access Blocked Services)

no aditional configuration needed on the SSH server

You only need to forward port 22 on your internet router to the linux host on your LAN (no aditional configuration needed on youre Linux SSH server).

Now that you have port 22 forwarded to you Linux in you home Lan, from somewhere on the Internet setup an Dynamic SSH Tunnel on Putty like show bellow (replace the 98.125.80.38  with your own Public IP):

The tunnel will remain working as long this Putty windows is open:

Now on your Browser (or any other aplication that supports it) you must configure the Socks Proxy to point to the local end of the Dynamic SSH Tunnel, and that’s it.

Now all your browser’s traffic will be sent to the local port 8080 wich SSH wil tunnel it to you home where it will exit via you linux machine.

Here I show how to set up the Socks Proxy on IE (Internet Explorer).

Tools > Internet Options > Connections > LAN Settings > Proxy Server > Advanced

You can go on your browser to:

• http://whatismyipaddress.com/

to confirm see Public IP and confirm from wich connection you entering the internet

Linux – Howto Boot an ISO from GRUB

Linux’s GRUB2 boot loader can boot Linux ISO files directly from your hard drive. Boot Linux live CDs or even install Linux on another hard drive partition without burning it to disc or booting from a USB drive.

We performed this process on Ubuntu 14.04 — Ubuntu and Ubuntu-based Linux distributions have good support for this. Other Linux distributions should work similarly.

This trick requires you have a Linux system installed on your hard drive. Your computer must be using the GRUB2 boot loader, which is a standard boot loader on most Linux systems. Sorry, you can’t boot a Linux ISO file directly from a Windows system using the Windows boot loader.

Download the ISO files you want to use and store them on your Linux partition. GRUB2 should support most Linux systems. if you want to use them in a live environment without installing them to your hard drive, be sure to download the “live CD” versions of each Linux ISO. Many Linux-based bootable utility discs should also work.

 

Check the Contents of the ISO File

You may need to look inside the ISO file to determine exactly where specific files are. For example, you can do this by opening the ISO file with the Archive Manager/File Roller graphical application that comes with Ubuntu and other GNOME-based desktop environments. In the Nautilus file manager, right-click the ISO file and select Open with Archive Manager.

Locate the kernel file and the initrd image. If you’re using a Ubuntu ISO file, you’ll find these files inside the casper folder — the vmlinuz file is the Linux kernel and the initrd file is the initrd image. You’ll need to know their location inside the ISO file later.

 

Determine the Hard Drive Partition’s Path

GRUB uses a different “device name” scheme than Linux does. On a Linux system, /dev/sda1 is the first partition on the first hard disk — a means the first hard disk and 1 means its first partition. In GRUB, (hd0,1) is equivalent to /dev/sda0. The 0 means the first hard disk, while the1 means the first partition on it. In other words, in a GRUB device name, the disk numbers start counting at 0 and the partition num6ers start counting at 1 — yes, it’s unnecessarily confusing. For example, (hd3,6) refers to the sixth partition on the fourth hard disk.

You can use the fdisk -l command to view this information. On Ubuntu, open a Terminal and run the following command:

sudo fdisk -l

You’ll see a list of Linux device paths, which you can convert to GRUB device names on your own. For example, below we can see the system partition is /dev/sda1 — so that’s (hd0,1) for GRUB.

 

Create the GRUB2 Boot Entry

The easiest way to add a custom boot entry is to edit the /etc/grub.d/40_custom script. This file is designed for user-added custom boot entries. After editing the file, the contents of your /etc/defaults/grub file and the /etc/grub.d/ scripts will be combined to create a /boot/grub/grub.cfg file — you shouldn’t edit this file by hand. It’s designed to be automatically generated from settings you specify in other files.

You’ll need to open the /etc/grub.d/40_custom file for editing with root privileges. On Ubuntu, you can do this by opening a Terminal window and running the following command:

sudo gedit /etc/grub.d/40_custom

Feel free to open the file in your favorite text editor. For example, you could replace “gedit” with “nano” in the command to open the file in the Nano text editor.

Unless you’ve added other custom boot entries, you should see a mostly empty file. You’ll need to add one or more ISO-booting sections to the file below the commented lines.

Here’s how you can boot an Ubuntu or Ubuntu-based distribution from an ISO file. We tested this with Ubuntu 14.04:

menuentry “Ubuntu 14.04 ISO” {
set isofile=”/home/name/Downloads/ubuntu-14.04.1-desktop-amd64.iso”
loopback loop (hd0,1)$isofile
linux (loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=${isofile} quiet splash
initrd (loop)/casper/initrd.lz
}

Customize the boot entry to contain your desiredmenu entry name, the correct path to the ISO file on your computer, and the device name of the hard disk and partition containing the ISO file. If the vmlinuz and initrd files have different names or paths, be sure to specify the correct path to those files, too.

(If you have a separate /home/ partition, omit the /home bit, like so: set isofile=”/name/Downloads/${isoname}”).

Important Note: Different Linux distributions require different boot entries with different boot options. The GRUB Live ISO Multiboot project offers a variety of menu entries for different Linux distributions. You should be able to adapt these example menu entries for the ISO file you want to boot. You can also just perform a web search for the name and release number of the Linux distribution you want to boot along with “boot from ISO in GRUB” to find more information.

If you want to add more ISO boot options, add additional sections to the file.

Save the file when you’re done. Return to a Terminal window and run the following command:

sudo update-grub

The next time you boot your computer, you’ll see the ISO boot entry and you can choose it to boot the ISO file. You may have to hold Shift while booting to see the GRUB menu.

If you see an error message or a black screen when you attempt to boot the ISO file, you misconfigured the boot entry somehow. Even if you got the ISO file path and device name right, the paths to the vmlinuz and intird files on the ISO file may not be correct or the Linux system you’re booting may require different options.

Taken From: http://www.howtogeek.com/196933/how-to-boot-linux-iso-images-directly-from-your-hard-drive/