Imprint | Privacy Policy

Let’s Communicate

(Usage hints for this presentation)

Neuland im Internet 2019
Dr. Jens Lechtenbörger (License Information)

DBIS Group
Prof. Dr. Gottfried Vossen
Chair for Computer Science
Dept. of Information Systems
WWU Münster, Germany


Bob, a Browser

  • Process on some Internet host

  • Host with one network card
    • IP address
    • MAC address 0:0:0:0:0:42
    • Default router with IP address
    • Name server with IP address

Routers: Rolf and Rosie

  • Each with lots of network cards, two relevant here

    Switch with cable nest

    Switch with cable nest” by Justin Smith under CC BY-SA 2.5; from Wikimedia Commons

    • Rolf, first network card
      • IP address
      • MAC address 0:0:0:0:0:1
    • Rolf, second network card
      • IP address
      • MAC address 0:0:0:0:42:1
    • Rosie, first network card
      • IP address
      • MAC address 0:0:0:0:42:2
    • Rosie, second network card
      • IP address
      • MAC address 0:0:0:0:6:1

Sarah, the Web Server

  • DNS name, listening on TCP port 80

  • One network card
    • IP address
    • MAC address 0:0:0:0:6:250

Eve, a curious Eavesdropper

  • One network card

    • IP address
    • MAC address 0:0:0:0:0:5

Mallory, the Malicious Attacker

Supporting Roles

  • Dave, DNS server at IP address
  • TCP/IP interfaces as necessary
    • E.g., with Socket(IPAddressOrHostName, Port)
  • More characters as necessary


  • Send request from browser Bob to Web server Sarah
    • Use HTTP request GET /exam-solutions.html HTTP/1.1
      • More on HTTP in separate presentation
      • Maybe tell a story involving all personas/roles
        • You may want to change the name of the Web server and choose a suggestive name for the requested resource …

Persona Summary

  • Endpoints
    • Sarah, server,, 0:0:0:0:6:250
    • Bob, browser,, 0:0:0:0:0:42
    • Dave, DNS server, 0:0:0:0:0:2
  • Routers
    • Rolf
      • with 0:0:0:0:0:1 and with 0:0:0:0:42:1
    • Rosie
      • with 0:0:0:0:42:2 and with 0:0:0:0:6:1
  • Eve, eavesdropper,, 0:0:0:0:0:5
  • Mallory, malicious attacker,, 0:0:0:6:6:6

License Information

This document is part of a larger course. Source code and source files are available on GitLab under free licenses.

Except where otherwise noted, this work, “Let’s Communicate”, is © 2019 by Jens Lechtenbörger, published under the Creative Commons license CC BY-SA 4.0.

No warranties are given. The license may not give you all of the permissions necessary for your intended use.

In particular, trademark rights are not licensed under this license. Thus, rights concerning third party logos (e.g., on the title slide) and other (trade-) marks (e.g., “Creative Commons” itself) remain with their respective holders.