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Export existing private ssh key to OpenPGP card or Yubikey

Before you begin

This will only work with OpenPGP v2.0 or newer or with PIV cards. Your existing ssh key has to be in a format that is supported by your opengpg card. For example my the OpenPGP V2.1 Card from FLOSS Shop supports only 2048 bit RSA keys. RSA exponent should be 65537, Putty and old OpenSSH releases use different expnent that for example Yubikey does not support.

Required software

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This uses Linux kernel dyamic debug features

https://www.kernel.org/doc/html/latest/admin-guide/dynamic-debug-howto.html

This asumes that debugfs is mounted under /sys/kernel/debug

Enable WireGuard debug

echo 'module wireguard +p' | sudo tee /sys/kernel/debug/dynamic_debug/control

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NB: This document describles a 'Old-School' way of using Yubikey with SSH

Modern OpenSSH has native support for FIDO Authentication. Its much simpler and should also be more stable with less moving parts. OpenSSH also now has support for signing arbitary files witch can be used as replacement of gnupg. Git also supports signing commits/tags with ssh keys.

Pros of FIDO

• Simpler stack / less moving parts
• Works directly with ssh, ssh-add and ssh-keygen on most computers
• Simpler
• Private key can never leave the FIDO device

Cons of FIDO

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#!/usr/bin/env python3
""" XInput Game Controller APIs

Pure Python implementation for reading Xbox controller inputs without extra libs

Copyright (C) 2020 by Arti Zirk <arti.zirk@gmail.com>

Permission to use, copy, modify, and/or distribute this software for any purpose
with or without fee is hereby granted.

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# Matrix Synapse workers example config 

# backends
upstream synapse_master {
	server 192.19.18.12:38008;
}

upstream synapse_federation {
	server 192.19.18.12:8083;
}

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Converting openssh private key format to pem

man page says that you can use -e option to convert private and public keys to other formats, that seems to be wrong. Instead you can use -p option to request changing the password but not actually setting the password.

ssh-keygen -p -f id_rsa -m pem

Converting pem to OpenPGP

Monkeysphere project includes a pem2openpgp command that can be used to import ssh private keys to gnupg keyring.

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List COM ports in windows with names

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM
    \Device\Serial0    REG_SZ    COM1
    \Device\Silabser0    REG_SZ    COM6
    \Device\VCP0    REG_SZ    COM3

Press any key to continue . . .

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Restore access to a unifi controller

When you are unable to login to the unifi controller or forgot admin password, you can restore access using SSH and manipulating mongodb directly.

Warning

Do not uninstall unifi controller - most of the data is not stored in mongodb. In case you thought a mongodb backup would be sufficient, you may have fucked up already, just like me. However I managed to write this "tutorial" for anyone to not run into the same trap.

Apparently this guide no longer works with recent unifi controller versions (starting nov/dec 2022). Since I no longer use unifi hardware in my home system, I can not update the guide myself. In case you've gotten here to recover your data, you're likely doomed. But giving it a try won't hurt anyway, therefore: good luck.

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Arch Linux btrfs install

0. Prerequisites

1. Latest Arch Linux install iso because those have newer kernels and more bugfixes in btrfs.
2. Have previous experience with installing Arch (like you can install arch with a blind fold).

1. Parititions

We will ne two of them, one for /boot and the other one will be a btrfs partition with subvolumes.

1. /dev/sda1 - this will be /boot with vfat filesystem because UEFI or syslinux for legacy BIOS boot

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#!/usr/bin/env python3
# This script is useful for setting fallback mtime for isync/mbsync CopyArrivalDate option
# If you use notmuch then you could do something like this to fix mtime on new mail
# notmuch search --output=files tag:new | xargs -P0 -i ~/code/mailutils/fix_maildir_mtime.py {}

import email
import sys
import os
from email.utils import parsedate_tz, mktime_tz