tuansoibk

1. Introduction
2. Standards
3. Common combinations
4. Conversion
5. Verification/Inspection
6. Tips for recognising

Introduction

It happens that there are many standards for storing cryptography materials (key, certificate, ...) and it isn't always obvious to know which standard is used by just looking at file name extension or file content. There are bunch of questions on stackoverflow asking about how to convert from PEM to PKCS#8 or PKCS#12, while many tried to answer the questions, those answers may not help because the correct answer depends on the content inside the PEM file. That is, a PEM file can contain many different things, such as an X509 certificate, a PKCS#1 or PKCS#8 private key. The worst-case scenario is that someone just store a non-PEM content in "something.pem" file.

protosam

// A small SSH daemon providing bash sessions
//
// Server:
// cd my/new/dir/
// #generate server keypair
// ssh-keygen -t rsa
// go get -v .
// go run sshd.go
//
// Client:

agzam

Zathura on Mac

I want to open PDF files with Zathura on Mac. Problem is - Zathura does not have a proper App Bundle. So you cannot go in Finder to a pdf file, navigate to ‘Get Info’ and set pdf files to be opened with Zathura.

Luckily, you can create a custom App Bundle that wraps up a script that does that

But that is not as straightforward as you think it is, you can’t just execute a shell script. What if the file already opened with one of the instances of zathura process? Since Zathura is not a native OSX app, it will create a new process instance every time you open it.

The following script opens a file in Zathura, and if it was already opened, it would only activate the right window.

How to use it

mkfares

Common zsh Keyboard Shortcuts on macOS

Navigation

CTRL + A : Move the cursor to the beginning of the line
CTRL + E : Move the cursor to the end of the line
OPTION + Left Arrow : Move the cursor one word backward
OPTION + Right arrow : Move the cursor one word forward
Left Arrow : Move the cursor one character backward
Right Arrow : Move the cursor one character forward

katef

#!/usr/bin/awk -f

# This program is a copy of guff, a plot device. https://github.com/silentbicycle/guff
# My copy here is written in awk instead of C, has no compelling benefit.
# Public domain. @thingskatedid

# Run as awk -v x=xyz ... or env variables for stuff?
# Assumptions: the data is evenly spaced along the x-axis

# TODO: moving average

PhilipSchmid

Testing Multicast Traffic on Linux

Prerequisites

By default Linux ignores Broadcast and Multicast ICMP messages. That's why you need to enable it first:

sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=0

Join and Test Multicast Traffic

To join any mutlicast address (e.g. 224.10.10.10/24) just add it to your active interface (e.g. eth0) and append the keyword autojoin at the end:

Hakky54

OpenSSL 🔐

Install

Install the OpenSSL on Debian based systems

sudo apt-get install openssl

brasey

Configure systemd-resolved to use a specific DNS nameserver for a given domain

Use case

Given

• I use a VPN to connect to my work network
• I'm on a Linux computer that uses systemd-resolved
• I have a work domain called example.com
• example.com is hosted by both public and private DNS nameservers

vimtaai

Comparison of syntax extensions in Markdown flavors

I created a crude comparison of the syntax of the various common Markdown extensions to have a better view on what are the most common extensions and what is the most widely accepted syntax for them. The list of Markdown flavors that I looked at was based on the list found on CommonMark's GitHub Wiki.

Flavor	Superscript	Subscript	Deletion* Strikethrough	Insertion*	Highlight*	Footnote	Task list	Table	Abbr	Deflist	Smart typo	TOC	Math	Math Block	Mermaid
GFM

echo-dave

Help my SSH keys are unavailable after restart

I'm still not sure what but on both my systems my keys just don't get loaded back into the ssh-agent on restarts and new login sessions. I got annoyed enough at it that I jumped through the hoops of putting ssh-add into a script and writting a property list file to load as a launchagent to fix it.

Add SSH Keys

If you haven't done so already you can use the well written gub hub instructions for generating ssh keys. Once you get them generated you'll add them with ssh-add -K <sshkey> where sshkey is the file path/name. Keys are stored by default in your ~/.ssh folder

Update

Note that you may need to use ssh-add --apple-use-keychain in Big Sur onward instead of ssh-add -K. I discovered the issue in Montery after skipping Big Sur.

Manual reloading SSH keys

The manual method (assuming your keys were stored into the Mac OS Keychain) is to open up Terminal