This is an introduction to computer networks, with an emphasis on practically useful knowledge and on wi-fi technology.

Where possible, it includes references to existing material.

[Work in progress. At the moment, just the outline without links to existing material.]


  1. packet switching theory (incl. multiplexing)
  2. network speeds (gross and net data rate, MBit/s and kbyte/s)
  3. OSI reference model
    1. network protocols in general (tasks and examples)
    2. physical layer protocols (MAC addresses)
    3. upper layer protocols (examples)
  4. TCP/IP
    1. services of the TCP/IP suite, and ideas behind
    2. IPs in local networks (dynamic / static, internal / external)
    3. the DNS, DNS updating, BIND9, advantage of DNS in local networks, DDNS
    4. IPv4, classes of addresses, private IP addresses, netmasks
    5. IPv6
    6. DHCP
  5. network device types
  6. routing
    1. local area network to Internet routing
    2. local area network internal routing
    3. quality of service, traffic shaping (example: VoIP)
    4. hackable routers
  7. network security
    1. firewalls, application firewalls
    2. port forwarding (TCP, UDP, …)
    3. wi-fi encryption
    4. VPNs
    5. DNS filtering and workarounds
    6. geolocation filtering and workarounds
  8. wi-fi
    1. concepts and standards for wi-fi (ordering this chaos …)
      1. WEP, WPA, WPA2, CCMP, AES, RSN, 802.11i
      2. 802.11a/b/g/n
      3. 802.1x
      4. channel
      5. SSID, ESSID, hidden networks, beacons, geolocation by SSID
      6. WPS
      7. WDS
      8. WiMAX
    2. wireless spectrum and spectrum sensing
    3. the idea of wireless channels
    4. physical signalling (the shared medium, collisions, …)
    5. wireless antennas
    6. influences on connection quality (channel interference, channel congestion / excessive collisions, mirrors, walls, distance, antenna position, antenna gain, WDS)
    7. timing issues for long-range connections
  9. Ethernet
    1. Ethernet and switched Ethernet
    2. cable quality standards (incl. using Cat3 for 10MBit Ethernet)
    3. cable color standards
    4. connecting cables (incl. improvised RJ45 crimping, soldering with a lighter)
    5. auto-negotiation issues
    6. the uplink port
    7. the three-device rule
  10. VDSL over Twisted Pair
    1. commercial devices
    2. power modem hack
  11. troubleshooting
    1. cable testing with a multimeter
    2. wi-fi connection quality testing (iwconfig)
    3. scanning for wi-fi networks
    4. the route command
    5. the ping command
    6. address space issues (DHCP cache times etc.)


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