Installing Debian Linux on Mac OS

This is a guide to installing Debian on Mac OS as a virtual machine. These instructions assume you will be using it headless (meaning you will only interact with it through ssh and not through a GUI. In essence, you will treat it as a remote server that happens to be running on your local machine.

Here is a screencast that walks through this process. I recommend watching it and following along, using these written instructions as a reference:

• https://www.youtube.com/watch?v=JK8tqowOavg

Download the Debian installer

Start at the Debian website:

• https://debian.org/

From there, find the right installation image:

• Click on “Other downloads”, which is right under the big “Download” button.
• Click on “small installation image” under the “Download an installation image” heading.
• Click on “arm64” under the “Small CDs or USB sticks” heading for Apple Silicon, or choose “amd64” if you have an older Intel-based Mac.

This will download the .iso file, typically to your “Downloads” directory (make note of where you save it).

Install UTM

UTM is a free virtual machine system for Mac OS based on the qemu project. Download it from the main website:

• https://mac.getutm.app/

Click on the “Download” link and install it as you would a normal Mac OS app.

Install Debian

Launch UTM and follow these steps:

Tell UTM to install from your Debian install image

• Click on “Create a New Virtual Machine”
• Click on “Virtualize”
• Choose “Other” as the Operating System
• Click on “Browse” and find the debian install image you downloaded earlier. It should have a name that starts with “debian” and ends with “.iso”.
• Click on “Open” once you have selected it and then “Continue”

Choose the hardware resources to give to the VM

• On the Hardware page, move the slider to 8 GB of RAM and then click on “Continue”
• On the Storage page you can drop the hard drive size down to 8 GB so it will use less space on your SSD and then click on “Continue”
• On the Shared Directory page just click “Continue”
• When it shows the summary, click “Save”

Run the installer

• Click on the big play button to launch the installer
• When the first screen comes up with “Install” selected, hit enter to continue
• For the language hit enter on “English”
• For the location hit enter on “United States”
• For the keyboard hit enter on “American English”

The installer will start by configuring the network. Make sure you have a solid internet connection as it will download most packages directly from the internet to make sure you have the latest versions. This saves you having to upgrade everything right after installing.

• When it asks for a hostname, you can accept the default of “debian” or name it something else

Since this VM will only ever run on your machine and is not accessible to the rest of the world, we can use simple defaults and lax security.

• For the domain just leave it blank and hit enter
• For the root password, pick something simple. Remember that someone would have to have your computer before they can log in to the VM. I used “password”.
• For the full name and username, pick anything you want. I used “Student” as the full name and “student” as the account name.
• For the account password, again it does not really matter. I used “password” here as well.
• Pick your time zone. We are in the Mountain time zone so that would be a good choice.

Next it will ask you to partition the disk:

• Hit enter on “Guided - use entire disk”
• Hit enter on the virtual disk (the only choice)
• Select “All files in one partition” (the default) and hit enter
• Select “Finish partitioning and write changes to disk” (the default) and hit enter
• The next screen is where it actually starts writing to the disk. Since this would destroy anything already on the disk, it forces you to move the cursor over to “Yes” manually before you hit enter

The next section asks you to choose a Debian mirror that it will use to download and install packages

• It will install for a few minutes then ask if you want to scan extra installation media. Hit enter on “No”
• Pick a Debian server to install from:
  • Select “United States”
  • Pick a mirror. “deb.debian.org” is a safe choice.
  • No proxy information required, so hit enter
• For the popularity contest page you can choose what you like. I picked the default of “No”

On the software selection page you will tell it what basic packages to install:

• Pick only “SSH Server” and “standard system utilities”
• Hit tab to move the cursor down to “Continue” and then hit enter

Reboot the VM into the newly-installed system

When the installation is complete, you must eject the install media (UTM is emulating an installion DVD) so that when you reboot it will start the new system and not re-run the installer.

• Switch back to the UTM window, go down to the “CD/DVD” pulldown and select “Clear”
• Switch back to the VM window and select “Continue”

At the GRUB menu you will see “Debian GNU/Linux” as the default option. Either hit enter to continue or let it sit for 5 seconds or so and it will continue automatically.

Configure the system directly through the VM window

There are a few setup steps you will complete directly in the VM window. The VM window is inconvenient because Mac OS essentially sees it as a video window and does not know how to interact with it, so things like copy-and-paste do not always work well.

• At the login prompt, login as “root” with the password you set up earlier (I used “password”).

root is the administrative user and you will rarely use it in practice, but you will use it now to complete enough setup that the main user can take over.

Run this command:

apt install sudo

Next run:

usermod -aG sudo student

If you named your used account something other than “student” you should modify that command to use the appropriate account name.

Now you need to get the IP address of the VM. Type:

hostname -I

and take note of the IP address at the beginning of the output line. It will probably be something like “192.168.64.3” but yours may vary.

Now you can log out as root by typing “exit” or hitting ctrl-d

You are finished interactive directly with the VM window, so you can minimize it to get it out of the way.

Connect to the VM through the terminal

Next launch the Mac OS terminal app and use it to connect to the VM using this command:

ssh student@192.168.64.3

but you should substitute in the account name you created and the IP address you noted earlier.

• The first time you log in you will need to type “yes”
• Enter the account password when prompted

You are now connected to the VM through an ssh connection, similar to how you would normally interact with a server. You can hit ctrl-d to exit back to the Mac OS shell. Note that there are two distinct shells:

• When you open the terminal app, you are in Mac OS and interacting with
• When you ssh to the VM, you are in the same window as before but you are interactive with the Debian VM
• When you log out of the ssh connection, you are back to the Mac OS terminal

Set up ssh for easier connections

Every time you want to use the VM, you will need to make sure it is running (you may need to launch UTM if it is not already running and boot the VM if it is not already started) and then connect to it via ssh. To make that last part simpler we will complete a few additional steps.

Launch a Mac OS terminal and do NOT connect to the VM. Check if you have an ssh keypair already by typing:

cd
ls .ssh

If you see a file called id_rsa then you already have a key and should skip the next step. If you do not see it, or if ls .ssh gives you an error, then you should generate a new keypair by typing:

ssh-keygen

Hit enter to accept the default location for saving it, again to set an empty passphrase, and again to confirm. Now repeat this part:

ls .ssh

You should see files called id_rsa and id_rsa.pub.

Now type:

ssh-copy-id student@192.168.64.3

Substituting your account name and IP address as before. You will need to enter the password again as well.

This tells the VM to trust your account so that you can login without a password in the future (it will confirm your identity using the ssh keys instaed).

Try running the ssh command to login again:

ssh student@192.168.64.3

(substitute your username and IP address as before). It should login without requiring a password.

Hit ctrl-d to get back to Mac OS.

Edit a new file called .ssh/config using vim or your editor of choice. For example:

vim ~/.ssh/config

or

nano ~/.ssh/config

If you have not used vim before, then you will probably have better luck with nano.

In that file, add the following:

Host cs2810
    User student
    HostName 192.168.64.3

(substitute your account name and IP address)

After you save it, you should be able to connect to the VM using just:

ssh cs2810

No password, no username, and no IP address required.

In the future, you can launch the VM, then launch a terminal window and type that one command to connect. If you use vscode, you can also give it that command when using the remote development plugin and it can connect to the VM using your ssh configuration.

Next steps

From here you should go to the “Setting up Linux for CodeGrinder assignments” link on the CS 2810 page and follow the instructions. From this point forward they are the same for Windows with WSL and Mac OS with a VM.