Using Physical Key for SSH, Git, Github For More Security

Normally, when using SSH (including SSH with Git), you generate a private and public key.  The public key is what you give to others (e.g. Github).  The private key should be kept secure and not be shared with anyone.  I don't like keeping my private keys on my laptop because mobile devices have a higher chance of being lost, stolen, or unknowingly accessed.  One solution is use a physical security key to store the private key that is plugged in to the laptop when needed.

To set this up requires having a security key such as the Yubikey from Yubico.  Then it is a matter of generating a key pair with SSH:

> ssh-keygen -t ecdsa-sk  # -t ed25519-sk is also an option but not always supported

This will generate the private key on the security key.  The generated id_ecdsa_sk file in the SSH directory is just a reference to the security key instead of the normal private key.  The id_ecdsa_sk.pub is the public key that you would share.  Whenever ssh needs to authenticate, the key will blink and with a tap of the key you'll be good to go!

For each computer that you want to use the key, you'll need to copy the reference key file to the SSH directory.

Installing Windows 11 without WIFI/Network Connection

 When installing Windows 11, it assumes you have a network connection and doesn't let you proceed with the installation.  To bypass this, press Shift+F10 to open a terminal and type:

oobe\bypassnro

The laptop will restart and when it reaches the network connection page there will be a new option for no network that will allow you to continue the installation.

Windows and Linux On a Single Drive and Installing Linux First

I previously posted on how to dual boot between Windows and Linux with each on them on separate disks, but what if you only had one storage device?  This is also possible can be a bit more messy because Windows and Linux must share the same boot partition (the part of the storage with the instructions on how to boot the OS).

The common convention is the install Windows first and then install Linux.  Windows has a "you don't need any other OS" mentality so when it gets installed it doesn't care if you have another OS, it will change the boot sequence to boot itself and you'll need to go into the UEFI menu to boot into Linux.  Linux distributions, on the other hands, comes with a boot loader that offers a menu of all the OS so that you can choose which OS to boot.  So the common convention is to

1. Install Windows
2. Resize the storage partition to make room for Linux to install.
3. Install Linux

What you end up with is that when you boot up, you'll see the Linux boot manager with the options to pick either Linux or Windows.

What happens when you install Linux first and then Windows?  Since Windows doesn't have a boot manager, it will just tell your system to boot directly into Windows.  To restore the Linux boot manager on older systems (BIOS-based), you'll need to use your Linux recovery disk and restore the boot manager (Windows mostly likely did NOT delete your Linux disk unless you installed windows on top of where you installed Linux).  

The general process is pretty similar:

1. Create a partition for Linux and Windows (just like Windows create a new partition from an existing one later)
2. Install Linux
3. Install Windows
4. Change the boot order back to Linux through the UEFI menu or efibootmgr tool (for UEFI systems) or use the Linux recovery disk (for BIOS)

On newer UEFI systems, the boot manager pointing to all the OS is still there in the boot partition but Windows only just changed it to boot its section.   You can generally change this back by going into your motherboard's UEFI menu on or on Linux you can use the efibootmgr tool to make the change.

Changing Fedora's GRUB Menu's Resolution

After installing Fedora on a laptop with a 2256 x 1504 resolution screen, the GRUB boot menu screen became too small to read.  To change the resolution, I needed to edit /etc/default/grub and replace the GRUB_TERMINAL_VALUE and add GRUB_GFXMODE with the desired resolution:

#GRUB_TERMINAL_OUTPUT="console"
GRUB_TERMINAL_OUTPUT="gfxterm"
GRUB_GFXMODE=800x600

Then commit the changes to GRUB with:

> sudo grub2-mkconfig -o /boot/grub2/grub.cfg