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@maykonchagas
maykonchagas / arch-linux-install
Last active February 15, 2022 19:58 — forked from mattiaslundberg/arch-linux-install
Minimal instructions for installing arch linux on an UEFI system with full system encryption using dm-crypt and luks
# Install ARCH Linux with encrypted file-system and UEFI
# The official installation guide (https://wiki.archlinux.org/index.php/Installation_Guide) contains a more verbose description.
## Download the archiso image from https://www.archlinux.org/
## Copy to a usb-drive
$ dd if=archlinux.img of=/dev/sdX bs=16M && sync # on linux
# Boot from the usb. If the usb fails to boot, make sure that secure boot is disabled in the BIOS configuration.
## Set brazilian portuguese keymap
@cb372
cb372 / riscv.md
Last active April 2, 2024 06:41
Writing an OS in Rust to run on RISC-V

(This is a translation of the original article in Japanese by moratorium08.)

(UPDATE (22/3/2019): Added some corrections provided by the original author.)

Writing your own OS to run on a handmade CPU is a pretty ambitious project, but I've managed to get it working pretty well so I'm going to write some notes about how I did it.

@NikaTsanka
NikaTsanka / rgb-sobel.py
Created July 2, 2017 18:33
RGB Sobel Operator
import numpy as np
from PIL import Image
import matplotlib.pyplot as plt
# Open the image
img = np.array(Image.open('dancing-spider.jpg')).astype(np.uint8)
# Sobel Operator
h, w, d = img.shape

WannaCry|WannaDecrypt0r NSA-Cyberweapon-Powered Ransomware Worm

  • Virus Name: WannaCrypt, WannaCry, WanaCrypt0r, WCrypt, WCRY
  • Vector: All Windows versions before Windows 10 are vulnerable if not patched for MS-17-010. It uses EternalBlue MS17-010 to propagate.
  • Ransom: between $300 to $600. There is code to 'rm' (delete) files in the virus. Seems to reset if the virus crashes.
  • Backdooring: The worm loops through every RDP session on a system to run the ransomware as that user. It also installs the DOUBLEPULSAR backdoor. It corrupts shadow volumes to make recovery harder. (source: malwarebytes)
  • Kill switch: If the website www.iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea.com is up the virus exits instead of infecting the host. (source: malwarebytes). This domain has been sinkholed, stopping the spread of the worm. Will not work if proxied (source).

update: A minor variant of the viru

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.


Effective Engineer - Notes

What's an Effective Engineer?

@rygorous
rygorous / gist:e0f055bfb74e3d5f0af20690759de5a7
Created May 8, 2016 06:54
A bit of background on compilers exploiting signed overflow
Why do compilers even bother with exploiting undefinedness signed overflow? And what are those
mysterious cases where it helps?
A lot of people (myself included) are against transforms that aggressively exploit undefined behavior, but
I think it's useful to know what compiler writers are accomplishing by this.
TL;DR: C doesn't work very well if int!=register width, but (for backwards compat) int is 32-bit on all
major 64-bit targets, and this causes quite hairy problems for code generation and optimization in some
fairly common cases. The signed overflow UB exploitation is an attempt to work around this.
@spaze
spaze / opera-vpn.md
Last active April 20, 2024 02:14
Opera VPN behind the curtains is just a proxy, here's how it works

2023 update

ℹ️ Please note this research is from 2016 when Opera has first added their browser "VPN", even before the "Chinese deal" was closed. They have since introduced some real VPN apps but this below is not about them.

🕵️ Some folks also like to use this article to show a proof that the Opera browser is a spyware or that Opera sells all your data to 3rd parties or something like that. This article here doesn't say anything like that.


When setting up (that's immediately when user enables it in settings) Opera VPN sends few API requests to https://api.surfeasy.com to obtain credentials and proxy IPs, see below, also see The Oprah Proxy.

The browser then talks to a proxy de0.opera-proxy.net (when VPN location is set to Germany), it's IP address can only be resolved from within Opera when VPN is on, it's 185.108.219.42 (or similar, see below). It's an HTTP/S proxy which requires auth.

@bearfrieze
bearfrieze / comprehensions.md
Last active December 23, 2023 22:49
Comprehensions in Python the Jedi way

Comprehensions in Python the Jedi way

by Bjørn Friese

Beautiful is better than ugly. Explicit is better than implicit.

-- The Zen of Python

I frequently deal with collections of things in the programs I write. Collections of droids, jedis, planets, lightsabers, starfighters, etc. When programming in Python, these collections of things are usually represented as lists, sets and dictionaries. Oftentimes, what I want to do with collections is to transform them in various ways. Comprehensions is a powerful syntax for doing just that. I use them extensively, and it's one of the things that keep me coming back to Python. Let me show you a few examples of the incredible usefulness of comprehensions.

@rekyuu
rekyuu / ifttt.py
Last active March 27, 2021 04:37
weechat ifttt script
import weechat, requests
weechat.register("ifttt", "rekyuu", "1.0", "MIT", "IFTTT: Send push notifications to IFTTT.", "", "")
settings = {
"trigger": "",
"token": ""
}
@fasterthanlime
fasterthanlime / state-of-emergency-in-france.md
Last active March 26, 2021 21:29
What the state of emergency means in France, where it's been declared following the Paris attacks