André Gaul, @andrenarchy, Freifunk Berlin

• free and non-commercial network where everyone can participate
• free as in freedom
• DIY-extension of the internet
• a mesh network
• wifi routers (primarily)
• operated and owned by individuals
• accessible to everyone (commons!)
• communities all over Germany: Hamburg, Leipzig, Berlin, Rheinland, Franken, Augsburg, München, ...
• freifunk.net
• @freifunk

• your router at home doesn't want to be alone
• it's not only about internet access
• Freifunk continues to work when the internet is down
• hard time for fans of censorship
• self-healing: one router goes down -> another one can fill the gap

• use the network for day-to-day internet access
• extend the Freifunk network by setting up your own wifi router
• provide content: websites, owncloud, chat, phone, radio/video streaming, minecraft, ...
• spread the idea of Freifunk

Freifunk @ Rathaus Kreuzberg

Freifunk @ Rathaus Kreuzberg

• electro-magnetic wave: light, radio, satellites, mobile phones, wifi, bluetooth, ...
• currently 2 frequency bands for wifi:
  • 2.4GHz (channels 1-13)
  • 5GHz (channels 36-140)
• two important wifi modes:
  • adhoc (all participants can communicate directly if in range)
  • access point with clients (AP coordinates everything)
• for applications, wifi looks like a cable network (ethernet)
• but: wifi often has severe packet loss due to bad signals!

• Antennas differ
  • Dipole (see your home router)
  • Dish
  • Panel
  • ...

• data is transmitted in packets/frames between devices
• packets/frames have a source and a destination address
• OSI model layers:
  1. physical layer: wifi, twisted pair, fiber, ...
  2. data link layer: usually local area, exchange of frames, MAC addresses (ethernet), example MAC address: 0e:d9:63:1a:a5:83
  3. network layer: internet, exchange of packets, IP-addresses, routing between subnets, example IP address: 10.230.42.42
  4. ...

• get to know your neighbors!
• 2 major routing protocols are used
  • batman advanced
    • layer 2
    • deals with MAC-addresses
    • a batman network works like a huge LAN
  • OLSR
    • layer 3
    • deals with IP-addresses
    • an OLSR network works like the internet at its core

• steps:
  1. get a router
  2. get the Freifunk firmware for your router and community
  3. flash the Freifunk firmware on your router
  4. configure your router
  5. ???
  6. profit!
• steps 2 and 4 depend on the community
• where do you want to use your router?