Creating a live boot-able operating system with Ubuntu linux and a USB flash drive

Using the open source Linux Ubuntu operating system and a USB drive we can create a boot-able device that is useful for a variety of security and Bitcoin applications. The latest version of Ubuntu is Ubuntu Desktop 24.04.1 and can be downloaded here. You can also download older versions of Ubuntu here. What you are downloading is called an “iso image” and it is a .iso file with the image of the Ubuntu operating system used for installation or trying out the OS. The goal of this tutorial is not to install the OS on your hard-drive, we are simply going to “try ubuntu” and test it out from the USB drive. This is a much simpler process than installation and allows you to keep your regular hard drive unaffected, allowing you to switch back and forth, for example between your windows hard drive and Ubuntu USB drive for different purposes.

There are a few different ways to create a boot-able USB drive. Here is a tutorial for MacOS. Here is a tutorial for Ubuntu. I will provide an easier way to do it on linux below using the disk utility. But first is to explain it for windows users:

For Windows Users:

I suggest windows users create the boot-able Ubuntu USB drive using the Universal USB installer found here. Currently version 2.0.2.5 is available and you can see the download button here. Also you are going to need the Ubuntu .iso file also linked here and above.

Once you download these two files, you can then plug an empty USB drive into your computer. The drive should be at least 8GB to handle the iso file. This is the USB we are going to make into a boot-able Ubuntu drive. The drive will be dedicated to the Ubuntu Operating System and you will not be able to save anything else on it(since we are not creating a partition), and all the contents will be erased. Once the drive is plugged into your computer, windows may prompt you to scan or format the drive. I would cancel/skip that option as it can sometimes cause problems with the process. If you have trouble getting the USB-installer to work in the later steps, then you can try to format the drive first and try again. Once the drive is plugged in and ready, go ahead and locate and launch the universal-USB-installer. Once launched, click “I agree”, and it will bring you to the setup menu.

From the first dropdown menu in step1 select the drive that you have already plugged into the computer. Make sure the USB drive was plugged into your USB slot prior to the launch of the USB-installer so that it will detect the drive. Once the drive is selected from the dropdown in step1, if the drive was not used as a boot-able device before, it will display a box to “prepare this device”. If you click on the box then it will format the device with an exFAT formatted partition and bootloader files that allow you to install multiple operating systems on this one device. Once ready you can proceed to the next step, where in step2 you can select Ubuntu as the linux distribution you will be installing onto the drive. In step3 you will click the browse button and then navigate to the Ubuntu .iso image file you downloaded earlier and select it. Step4 is to create a persistent storage option, but you can skip that and leave it at 0MB for simplicity. Once ready, click the “create” button and then wait for the installer to complete which usually takes several minutes. Follow the prompts until the process is finished and then you can eject the USB drive and it will be ready to use as a boot-able device.

For Linux users: Now if you were using linux or ubuntu already and want to create boot-able drives you can just use the disk utility option. Click on the bottom left start menu, and then type in “disk” until you see the disk utility icon show up and click it, you will see a screen like this. Now plug in your blank USB drive and it will appear in the disk utility list. Find it in the list and make sure you select the proper drive and then click the button with 3 dots on the top right and then click “restore disk image”. Then it asks you to select the image to restore, you want to select the Ubuntu or other .iso image of your choosing then click “start restoring”. It will take many minutes. Once complete, the USB should be ready for booting.

Booting into the USB ubuntu OS:

Once finished you are ready to go on to the next step which is booting the computer into the USB Ubuntu operating system. This part is simple, but can be tricky because everyone’s system is different. The first thing you can do is power off your machine. Then plug the Ubuntu USB drive into the computer. Then press the power button to boot the system and see if the system will automatically boot into ubuntu. There is a good chance it will, but also a good chance it won’t work and you will boot into your main hard-drive or operating system as usual.

If Ubuntu failed to boot, then power off the computer, and try again, but this time when rebooting, you want to enter the BIOS menu on boot. Every computer has a BIOS menu where you can select boot settings. On most computers you press and hold the F12 key while booting, sometimes it is a different F key, or on some Sony laptops it is the “assist” key that allows you to get into the BIOS menu. Often there is a message telling you how to enter BIOS on boot, and you usually have a few seconds time limit where you need to press a certain key or it will boot into your system as normal. With a little research you can probably figure it out for whatever model computer you are using. Just do a google search for your computer model and how to boot into BIOS if you have trouble. Once you get into the BIOS menu, you will most likely see a blue screen like this.

Before changing/experimenting with any settings on the BIOS menu, it is a good idea to take a photo of the current BIOS settings, so you can always revert them back to the original settings if needed. Use the tab button/arrows, or mouse and the space bar to navigate to the “boot” tab. Then you want to make sure boot options will enable you to boot into USB. So check to see if “external boot device” is enabled. If it is “disabled”, navigate to it and change it to “enabled”. Also look at the “boot priority”. You want to make sure “external device” is the number one priority, otherwise it will prioritize booting from your hard-drive. So use the tab key and space bar to rearrange the order of the boot priority list so external boot is on top. The other option you may have to switch is “boot mode”. You may have to change boot mode from “UEFI” to “legacy” mode to get the USB to boot on some systems. You can experiment with both UEFI and legacy mode, restart and see if it will boot into the Ubuntu USB drive. Don’t worry about screwing your system up with the BIOS settings, it won’t harm anything. If you want to boot back into your hard drive just make sure the Ubuntu USB media is removed first. If any issues arise later, you can always boot back into BIOS and change the settings back to the original.

So once you successfully get Ubuntu to boot, you will encounter a screen like this. It varies depending on Ubuntu version. Click through the prompts and eventually choose the “try ubuntu” option. You don’t want to install ubuntu on your main hard-drive, so press the “try ubuntu” button instead. This will allow you to test out and try the Ubuntu OS on the USB device without installing it on your hard drive. After pressing the try Ubuntu button, the operating system will boot and you will see a desktop like this. If you wanted to connect Ubuntu to the internet on the top right you could then start surfing around the internet using firefox browser from the sidebar.

If you want to keep the environment cold and secure for Bitcoin security applications, then make sure to never connect the internet. Make sure your computer is not plugged into any ethernet cables. Also if you have an external switch for wifi or bluetooth make sure to turn it off manually.

As an added precaution you can go to the top right and click the little downward white triangle. You will see it say “wifi-not connected” which is good for our purposes. But for added safety go ahead and select the option to “Turn off” wifi. Then underneath this, it shows blue tooth connections and says “on”. Now select the option to turn blue tooth off as well. Now it will show you that airplane mode is on. Once you see that airplane icon in the top right you know you are good and a cold environment has been created. Now it is safe for example to begin the process of generating Bitcoin cold storage keys.

You have now created and booted into a USB live boot-able device, and created a cold environment. When the Ubuntu USB system is turned off all the activity you did will basically be erased and lost. Nothing can really be saved onto the boot-able USB drive with this setup, since we did not use persistence. If you want to save files, use a separate USB drive to plug in while operating Ubuntu.