howtos [UWiki XXX]

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====== HOWTOs ======
Instructions for performing tasks that I do often enough to need to know but infrequently enough to never remember the details.

===== Add Linux swap space =====
These commands should all be performed with root permissions. The instructions below assume a destination path of ''/swapfile'' and file size of 1 GiB. 

First, allocate space:

<code bash>
fallocate -l 1G /swapfile
# alternatively
dd if=/dev/zero of=/swapfile bs=1024 count=1048576
</code>

Ensure only root can read the swap file's contents:

<code bash>
chmod 600 /swapfile
</code>

Finally, activate and enable the swap file:

<code bash>
mkswap /swapfile
swapon /swapfile
</code>

To have the swap automount on boot, add the following to ''/etc/fstab'':

<code>
/swapfile swap swap defaults 0 0
</code>

===== Boot an ISO from GRUB =====
Adapted from [[https://forum.manjaro.org/t/howto-boot-manjaro-iso-directly-with-grub/15892]]. Run the following commands from the GRUB2 prompt.

<code>
set isofile="/path/to/isofile.iso"
set dri="free"
set lang="en_US"
set keytable="us"
set timezone="America/Los_Angeles"
search --no-floppy -f --set=root $isofile
probe -u $root --set=abc
set pqr="/dev/disk/by-uuid/$abc"
loopback loop $isofile
linux (loop)/boot/vmlinuz-x86_64 img_dev=$pqr img_loop=$isofile driver=$dri tz=$timezone lang=$lang keytable=$keytable copytoram
initrd (loop)/boot/intel_ucode.img (loop)/boot/initramfs-x86_64.img
</code>

Adjust ''intel_ucode.img'' to ''amd_ucode.img'' for AMD CPUs.

Note that the [[GreatFET]] has Facedancer capabilities, so it should be possible to use it to emulate a mass storage device with the ISO as the source and boot that instead.

===== Make an ethernet loopback connector =====
This trick works with either a socket or a plug. Connect the following pins: 

  * 1 <-> 3
  * 2 <-> 6
  * 4 <-> 7
  * 5 <-> 8

===== Mount an ext4 drive in WSL2 =====
Open a PowerShell window as an administrator, then run the following command to list available disk drives:

<code powershell>
GET-CimInstance -query "SELECT * from Win32_DiskDrive"
</code>

Locate the desired entry, then attach it to the WSL instance: 

<code powershell>
wsl --mount \\.\PHYSICALDRIVE2
</code>

Finally, locate and mount the disk within the WSL instance. 

https://learn.microsoft.com/en-us/windows/wsl/wsl2-mount-disk

===== Fake a document scan =====
===== Create a reverse SSH connection =====