Viktor Svub viktor-svub

ZFS tuning notes

Note: this is mainly meant for Root on ZFS on desktop or server systems, where latency is important.

Goal: keep the machine responsive under heavy writes (especially with compression enabled) by letting ZFS buffer more in RAM, limiting CPU spent in the write pipeline, and sending large I/Os to the SSD.

Note: Zstd compression / blake3 hashing / dnodesize auto require (if you use e.g. grub) to have a dedicated /boot partition.

Set "dirty" buffering to 1-2 GiB, so short bursts of writes don't immediately throttle.
zfs_dirty_data_max=1073741824

.NET: Avoid using Guid.CreateVersion7

TL;DR: Guid.CreateVersion7 in .NET 9+ claims RFC 9562 compliance but violates its big-endian requirement for binary storage. This causes the same database index fragmentation that v7 UUIDs were designed to prevent. Testing with 100K PostgreSQL inserts shows rampant fragmentation (35% larger indexes) versus properly-implemented sequential GUIDs.

Guid.CreateVersion7 method was introduced in .NET 9 and is now included for the first time in a long-term-supported .NET 10. Microsoft docs for Guid.CreateVersion7 state “Creates a new Guid according to RFC 9562, following the Version 7 format.” We will see about that.

RFC 9562

RFC 9562 defines a UUID as a 128-bit/16-byte long structure (which System.Guid is, so far so good). RFC 9562 requires UUIDv7

hi, i'm daniel. i'm a 15-year-old high school junior. in my free time, i hack billion dollar companies and build cool stuff.

3 months ago, I discovered a unique 0-click deanonymization attack that allows an attacker to grab the location of any target within a 250 mile radius. With a vulnerable app installed on a target's phone (or as a background application on their laptop), an attacker can send a malicious payload and deanonymize you within seconds--and you wouldn't even know.

I'm publishing this writeup and research as a warning, especially for journalists, activists, and hackers, about this type of undetectable attack. Hundreds of applications are vulnerable, including some of the most popular apps in the world: Signal, Discord, Twitter/X, and others. Here's how it works:

Cloudflare

By the numbers, Cloudflare is easily the most popular CDN on the market. It beats out competitors such as Sucuri, Amazon CloudFront, Akamai, and Fastly. In 2019, a major Cloudflare outage k

A Short IPv6 Guide for Home IPv4 Admins

This guide is for homelab admins who understand IPv4s well but find setting up IPv6 hard or annoying because things work differently. In some ways, managing an IPv6 network can be simpler than IPv4, one just needs to learn some new concepts and discard some old ones.

Let’s begin.

First of all, there are some concepts that one must unlearn from ipv4:

Concept 1

Overview

How to document a new codebase

Use this template to document a new codebase.

Business Logic

A place to record any important logic that you come across that is worth documenting.

Landmarks

Refers to the different landmarks of a codebase to help you navigate around. Where are the API methods defined? Where are interactions with the database?

Compiling a standalone executable using modern JavaScript/TypeScript runtimes

We have the same code working using node, deno, and bun.

E.g.,

bun run index.js

	#!/usr/bin/dotnet fsi

	open System
	open System.Collections.Generic
	open System.Globalization
	open System.IO
	open System.Net.Http
	open System.Numerics
	open System.Text

	#!/usr/bin/env python3
	# Copyright 2024 Neil Madden.
	# License: https://creativecommons.org/licenses/by-sa/4.0/deed.en.

	# Like this? I do training courses & consultancy:
	# https://illuminated-security.com/

	import hashlib
	import math
	import os

	*.crowdstrikexdr.co.za,crowdstrikexdr.co.za
	japan.crowdstrikebenefits.com
	*.crowdstrikedataprotection.cc,crowdstrikedataprotection.cc
	*.crowdstrikedataprotecton.com,crowdstrikedataprotecton.com
	*.crowdstrike-cspm-reg-test.com,crowdstrike-cspm-reg-test.com
	*.crowdstrikemalware.zip,crowdstrikemalware.zip
	land.crowdstrikebenefits.com,us.crowdstrikebenefits.com
	ww16.crowdstrike.capethemes.com
	*.crowdstrike.1-27.us-east-1.k8s.dev.appian-internal.com
	*.crowdstrike.1-29.us-east-1.k8s.dev.appian-internal.com

	/* Gist: Win32 Message Loop with `node-addon-api`
	* Author: Gage Sorrell <[email protected]>
	* Copyright: (c) 2023 Gage Sorrell
	* License: MIT
	*/

	/* This file demonstrates how to get access to the Windows API (Win32)
	* message loop in your NodeJS application via node-addon-api.
	* This code goes into your node-addon-api package, with no additional
	* build tools necessary.