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Calculating algorithm complexity from Go code

Sun, 03 May 2026 00:00:00 +0000

What is algorithmic complexity?

Algorithmic complexity describes how the runtime and memory usage of an algorithm grows as the input size increases. Instead of measuring execution time which can vary depending on environment and the underlying hardware, complexity focuses on growth behavior. This allows us to compare algorithms independantly of the machines they run on.

An example

Consider two functions that process an input of the size

One loops over the data once → this means that the work grows linearly with
Another compares every element with every other element in the input → its work grows quadratically with

Even if both are fast for a small inputsize , their behavior diverges significantly as increases.

Configuring DHCPv4 in Packet Tracer

Sun, 03 May 2026 00:00:00 +0000

This article will demonstrate how to configure a Cisco DHCPv4 server and clients in Packet Tracer. You can skip the introduction and go straight to the demonstration here.

What is DHCP?

DHCP (Dynamic Host Configuration Protocol) assigns or “leases” IPv4 addresses from a pool of addresses for a limited time period to clients. When a lease expires and the client still exists within the network, the client is typically reassigned the same address. This ensures that addresses are made available when they are no longer needed by their previous owner.

Handling cybersecurity incidents in Switzerland

Sun, 03 May 2026 00:00:00 +0000

Source: NCSC Homepage

Cyberattacks are no longer a rare event, they are part of everyday business risk. For companies in Switzerland, this means one thing: a data breach is not a question of if, but when.

Yet many organizations still focus primarily on prevention. While technical defenses are essential, they are only half the equation. When a breach occurs, the way you respond, especially how you communicate, determines whether the situation remains manageable or escalates into legal, financial, and reputational damage.

Inter-VLAN Routing in Packet Tracer

Sat, 02 May 2026 00:00:00 +0000

This article will demonstrate how to configure Inter-VLAN routing between two or more VLANs on a network using 802.1Q trunks. At first we will brush up on the fundamentals of VLANs and trunks. You can jump to the demonstration in packet tracer here.

What is a VLAN?

A virtual LAN (VLAN) provides segmentation and organisational flexibility within a switched network. Devices connected to the same VLAN behave as if they were on the same physical network segment. Unlike traditional LANs, VLANs are based on logical rather than physical connections and operate as independant networks, even when sharing the same underlying infrastructure. Any switch port can be assigned to a VLAN.

MITM attack using Ettercap

Fri, 17 Apr 2026 00:00:00 +0000

Ettercap is a MITM (Man-in-the-Middle) attack suite with a wide range of plugins supporting different attack techniques. This article focuses on a simple ARP poisoning and DNS hijacking attack. For this to work, the involved devices must share Layer 2 connectivity.

Credit: The Ettercap Project

Warning

This article is for educational purposes only. Performing MITM attacks on networks without explicit authorization is illegal and unethical. Only practice these techniques in controlled lab environments that you own or have permission to test.

The Man-in-the-Middle attack

The principle of a MITM attack is to insert an attacker into a network or communication path and make the targets believe that it is part of the regular communication relay. There are several different methods to achieve this “trusted imposter” status, many of which are available as plugins in ettercap. This article focuses on two such methods: ARP poisoning and DNS highjacking.

Working with ConfigMaps and Secrets

Sun, 05 Apr 2026 00:00:00 +0000

ConfigMaps and Secrets are essential Kubernetes resources for separating configuration from container images. This guide covers how to create, use, and manage them effectively.

ConfigMaps

ConfigMaps store non-sensitive configuration data as key-value pairs.

Creating ConfigMaps

From literal values:

kubectl create configmap app-config \
 --from-literal=DATABASE_HOST=postgres \
 --from-literal=LOG_LEVEL=info

From a file:

kubectl create configmap nginx-config --from-file=nginx.conf

From YAML:

apiVersion: v1
kind: ConfigMap
metadata:
 name: app-config
data:
 DATABASE_HOST: postgres
 LOG_LEVEL: info
 config.yaml: |
 server:
 port: 8080
 features:
 cache: true

Using ConfigMaps

As environment variables:

Introduction to Helm

Fri, 03 Apr 2026 00:00:00 +0000

Helm is the package manager for Kubernetes. It simplifies deploying and managing complex applications by using charts - packages of pre-configured Kubernetes resources.

Installing Helm

# macOS
brew install helm

# Linux
curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

# Verify installation
helm version

Helm Concepts

Charts

A chart is a collection of files that describe a set of Kubernetes resources. Charts are stored in repositories.

Releases

When you install a chart, Helm creates a release - a specific instance of that chart running in your cluster.

Getting Started with Kubernetes

Wed, 01 Apr 2026 00:00:00 +0000

Welcome to Kubernetes! This guide will walk you through setting up a local Kubernetes cluster and deploying your first application.

Installing Kubernetes Locally

For learning purposes, we recommend using minikube or kind to run Kubernetes locally.

Option 1: minikube

# Install minikube (macOS with Homebrew)
brew install minikube

# Start your cluster
minikube start

# Verify it's running
kubectl cluster-info

Option 2: kind (Kubernetes in Docker)

# Install kind
brew install kind

# Create a cluster
kind create cluster

# Verify it's running
kubectl cluster-info

Understanding kubectl

kubectl is the command-line tool for interacting with Kubernetes clusters.

About kubelize

Mon, 01 Jan 0001 00:00:00 +0000

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