This is a companion post to Building an Nmap Short Course from Scratch. Where that post was about the meta - course design, lab infrastructure - this one drills into the actual first-lecture material: how Nmap decides whether a host is up.

Full lecture notes: Nmap/Short Course/Lecture 1.

Why Host Discovery Matters

Before you can scan ports, identify services, or check for vulnerabilities, you have to figure out which IP addresses on the target network actually have a machine behind them. Scanning IPs that aren't responding is a waste of time, generates a lot of unnecessary network noise, and can …

• Introduction

  • What Does Stunnel Do?
  • How Does Stunnel Work?

• Setting Up an Stunnel Server

  • Charlesreid1.com Resources for Stunnel Servers

• Setting Up an Stunnel Client

• Example Protocols

• Stunnel with Docker

• Troubleshooting Stunnel Connections

• References

Introduction

What Does Stunnel Do?

Stunnel is a tool for creating SSL tunnels between a client and a server.

Creating SSL connections is a general task that is very useful. In particular, any packet of any protocol can always be wrapped in an additional SSL layer, with packets embedded within packets, so this means you can wrap arbitrary traffic protocols in SSL using Stunnel.

Stunnel requires …