Implementing the MU Online login flow in Rust: peeling back three encryption layers (SimpleModulus, XOR32, XOR3), building a domain model with Ports and Adapters, and wiring up a session state machine to take a player from credentials to the game world.

Cracking the Login: Encryption Layers, Domain Modeling, and Sessions in Rust

Dive into "My eBPF Journey," a series that narrates the exploration of eBPF programming, starting from the basics and gradually advancing to more complex applications.

The beginning of my eBPF Journey - Kprobe Adventures with BCC

IPv4 Socket Surveillance - Tracing using kprobe, kretprobe and maps with BCC

Beyond Observability: Modifying Syscall Behavior with eBPF - My Precious Secret Files

Beginner's Guide to XDP: A Journey Through Crafting XDP-Based Firewall with BCC

Harnessing eBPF and XDP for DDoS Mitigation: A Rust Adventure with rust-aya

Uprobes Siblings - Capturing HTTPS Traffic: A Rust and eBPF Odyssey

Fooling Port Scanners: Simulating Open Ports with eBPF and Rust

Embark on a fascinating journey into the realm of eBPF programming through this blog post. We kickstart our exploration with Kprobe, a dynamic tracing tool in the Linux kernel, by delving into a simple 'Hello World' and other experiment using BCC.

Through a simple app, this post illustrates real-time monitoring of network activities triggered by syscalls, utilizing kprobe, kretprobe, and maps. It highlights the synergy between eBPF and these probing tools, showcasing a practical approach to understanding network operations.

This article dives into a subtle application of eBPF, extending beyond its conventional use for observability to demonstrate its capability to modify system call behavior, showcased through a simple application designed to safeguard our precious files.

Step into the world of eBPF/XDP with this beginner's guide. Learn to build a simple SSH firewall, utilizing XDP's capabilities for secure, incoming network traffic management!

DDoS Mitigation with XDP and Rust: Dive into a Rust-based eBPF program for redirecting UDP flood attacks to a honeypot. This hands-on guide demonstrates the potent synergy of XDP and Rust in network security, offering a practical approach to packet manipulation and cybersecurity.

In this engaging blog post, we embark on a journey to create a basic HTTPS sniffer using Rust and eBPF, focusing on the widely used OpenSSL library. Using uprobes for monitoring OpenSSL functions and capturing unencrypted data from SSL/TLS operations. 

Dive into the world of network security with this comprehensive guide on using eBPF and Rust to outsmart port scanners. This article explains the TCP three-way handshake, explores the popular Stealth SYN Scan technique, and demonstrates how to implement an eBPF program that simulates open ports.

My eBPF Journey

Join me on my humble journey of socket discovery in Linux with the "My Socket Learning Adventure" series. Together, we'll explore the world of Unix sockets,

Socket sharding in Linux example with Go

Understanding Unix Domain Sockets in Golang

A simple example of using unix domain socket in Kubernetes

Optimizing Large File Transfers in Linux with Go - An Exploration of TCP and Syscall

Getting Started with Networking and Sockets

Networking and Sockets: Endianness

Networking and Sockets: Syn and Accept queue

Uncover socket sharding in Linux using Go, enabling multiple sockets to bind to the same IP and port for enhanced load balancing. The article provides insights into setting the SO_REUSEPORT socket option, creating a ListenConfig instance in Go.

Delve into the workings of Unix domain sockets in Golang, contrasting them with network sockets. Explore their creation, efficient inter-process communication on the same machine, and practical code examples demonstrating a simple echo server setup​.

Discover using Unix domain sockets in Kubernetes for inter-container communication within a pod, illustrated with Go applications. Gain insights into setup, benefits like faster communication, and testing the deployment​.

Explore efficient large file transfers in Linux using Go, focusing on minimizing data copies and context switches via the sendfile syscall.

This article provides a comprehensive introduction to the fundamentals of socket programming using Rust and the nix crate. It starts with an overview of the OSI model and its practical application through the TCP/IP model, laying the groundwork for understanding network communication.

This article explores the concept of endianness in computer systems, focusing on how different byte orders (little-endian and big-endian) affect data interpretation in network communication. Through practical examples using Rust, we demonstrate the importance of handling endianness correctly when sending and receiving data between clients and servers.

In this article, we delve into the mechanics of TCP connection management, focusing on the SYN queue and the accept queue. We explore backlog configurations, system parameters like net.core.somaxconn and net.ipv4.tcp_abort_on_overflow, and how they affect queue behavior.

My Socket Learning Adventure

Welcome to Rust 101! This series covers my exploration of Rust, from basic concepts to more advanced topics. It's not in any particular order — just a collection of things I find interesting or at least interesting enough to write a post or note about. If you're curious about Rust, feel free to jump into any post that catches your eye.

Rust Raw Pointers

Rust PartialEq, Eq, PartialOrd and Ord

Copy or Move?

Rust's Cell<T>

Understanding Rust's Equality and Ordering Traits

Learn about Rust's copy and move semantics.

Rust 101

A nostalgia fueled deep dive into reverse engineering the MU Online binary protocol, using OpenMU as a reference to build a working game server from scratch in Rust.

From Nostalgia to Code: Building a MU Online Server in Rust

MU Online in Rust: Hardening the Foundation, runtime, Timeouts, and Packet Size Limits

Driven by nostalgia for MU Online, we use OpenMU as a reference to build a server from scratch in Rust. In this first episode, we decode the binary protocol, understand packet framing and encryption, explore the ConnectServer/GameServer architecture, and implement just enough to see the legendary login screen appear.

Before diving into login and encrypted packets, we harden the server foundation. We introduce mu-runtime for generic TCP handling, implement read/write timeouts, and add max packet size enforcement to protect against slowloris and memory exhaustion attacks.

Building a MU Online Server in Rust

Dive into the dynamic world of Kubernetes with our in-depth series, 'Kubernetes in Action: A Journey Through Its Ecosystem'. This series is your gateway to know about the Kubernetes ecosystem, one article at a time.

How to setup simple load balancing with IPVS, demo with docker

Implementing a simple K8s admission controller in Go

CEL for admission controller with ValidatingAdmissionPolicy in K8s 1.26

Explore setting up simple IPVS load balancing on Linux with a hands-on Docker demo, covering tool installation, virtual service creation, and verification.

Dive into implementing a Kubernetes admission controller in Go, governing cluster usage by intercepting API requests pre-persistence. Explore setup, webhook registration, and server creation, alongside simple validation/mutation use cases, for better cluster governance and security​.

Explore enhancing Kubernetes cluster security with the Common Expression Language (CEL) for creating fine-grained admission control policies in K8s 1.26, including setup and policy binding instructions​.

Kubernetes in Action: A Journey Through Its Ecosystem

Delve into a series of insightful articles where we explore common challenges and practices in software engineering. Join us as we navigate the complexities of software development, sharing personal experiences and thoughts.

The Broken Window in Software Projects

Turning Problems into Solutions: Provide Alternatives, Not Excuses

Explore the 'Broken Window' theory in software development and how small, unaddressed issues can lead to significant technical debt.

This article emphasizes the importance of providing solutions instead of excuses in software engineering, promoting a proactive mindset.

Douglas Mendez

Start here

The beginning of my eBPF Journey - Kprobe Adventures with BCC

Beginner's Guide to XDP: A Journey Through Crafting XDP-Based Firewall with BCC

Fooling Port Scanners: Simulating Open Ports with eBPF and Rust

Connected writing

My eBPF Journey