DAWN – A decentralized WiFi Controller

I’m Nick. I study Computer Engineering at the TU Berlin. It is my first time participating in Google Summer of Code. I am realizing a decentralized WiFi controller.

DAWN is the first decentralized WiFi controller for OpenWrt. The controller provides access to valuable information, e.g., all connected stations, their capabilities, and information about all participating nodes. Moreover, DAWN provides load balancing to increase the network performance by controlling the clients association.

What’s missing?
An important aspect of the controller is the simple installation. Everybody, even people with limited technical knowledge, should use this controller to increase their network performance at home. Until now, DAWN requires a special patched OpenWrt to run. So a user needs to compile his own image. The first thing I have to do is to bring the last patches upstream. Some of the patches were rejected and that is why I have to rewrite different functionality and create new pull requests. Furthermore, I have to extend the libiwinfo library to get all necessary informations from the OpenWrt system.
After this, the configuration of the nodes should be simplified. So far, the user has to configure all participating nodes individually. I want to implement some bootstrapping to automatically configure the participating routers.
After simplifying the installation and configuration, I want to visualize the information of the participating nodes with a graphical user interface.
The last step is to improve the controller functionality by adding mechanisms like a channel interference detection and other useful features. Moreover, this step contains to improve the load balancing.

In my next blog post, I will write about why some of my OpenWrt patches were rejected, how I have to extend the libiwinfo. However, if this steps are successful everybody will be able to simply install DAWN without the need to patch OpenWrt.

Babel Wireless Mesh hackathon (Paris, 19-20-21 July 2013)

A hackathon dedicated to the Babel wireless mesh routing protocol will be held during three days in Paris, at the LeLoop.org hackerspace. The event primarily aims at testing the new features of Babel (diversity, RTT metric, source-specific routing, etc…) in a real-world environment.


Start: Friday 19 July @ 09:00

End: Sunday 21 July @ 22:00 


  • Setup of a testbed of 20 nodes or more, some of them on batteries
  • Test the new features of Babel in real-world conditions
  • Test interoperability between different implementations and different extensions of the protocol
  • Basic tests inspired by the Wireless Battle Mesh ones
  • Data collection, statistics and reproductibility of the experience
  • Bug hunting (hopefully there aren’t many)
  • Degustation of belgian beers, and probably Attitude Adjustment cocktails too 🙂


Along with the main events, some talks are scheduled on Saturday and Sunday. Feel free to propose a talk, they will be listed on the wiki page of the event: http://wiki.leloop.org/index.php/Babel_hackathon

More information will be available on LeLoop website: http://leloop.org

We provide

  • electricity
  • internet connectivity
  • meeting place
  • coffee and tea
  • toilets
  • if needed, hosting, but get in touch with us before

Do not forget:

* Bring your laptop/computer and european power plug wire (multiprises)

* Bring your compatible router(s) with OpenWRT pre-installed

* Bring your WiFi antenna(s) and connectors

* Bring your sleeping bag, and if you need hosting send an email


Please register as soon as possible on Framadate: http://framadate.org/studs.php?sondage=q4hlhbsehmh37kgm

The entrance is free, both as in “freedom” and as in “free beer” (although the beer won’t actually be free).



La Gare XP

0bis avenue Lucien Descaves

75014 Paris

Tramway: Montsouris, on T3a

Metro: Porte d’OrlĂ©ans on ligne 4

RER: Cité Universitaire on RER B

Google Maps: http://ur1.ca/ej4jb

Open Street Map: http://osm.org/go/0BOc0dK0C–?m


* http://www.pps.univ-paris-diderot.fr/~jch/software/babel/
* http://leloop.org
* http://garexp.org


IRC: #babel on irc.freenode.net

Wiki: http://wiki.leloop.org/index.php/Babel_hackathon

Baptiste Jonglez
Email: baptiste.jonglez at ens-lyon.fr
GSM: (+33) 6 03 72 24 79

Benjamin Henrion
Email: bh at udev.org
GSM: (+32) 484 566109

Freifunk Halle Interview Loop von Tmk

Freifunker aus Halle (Saale) haben einen Film gemacht und erklaeren die Motive und Begeisterung fuer freie Netze.

“Freifunk Halle Interview Loop” von Tmk, Oktober 2009, Creative Commons: by-nc-sa.

Join the Wireless Battle Mesh in Brussels

HackerSpaceBrussels (HSB) announces the second Wireless Battle Mesh, which aims to test 3 popular WiFi routing protocols (OLSR, Batman and Babel), in Brussels on Saturday and Sunday 17-18 October 2009.

Wireless Mesh Battle: OLSR vs. BATMAN vs. Babel


  • Tue 06 Oct @ 21:00: final IRC meeting to prepare the design of the networks (see below)
  • Sat 10 Oct @19:30: IPv6 presentation (Filip P.) + panel on possibilities & pittfalls of IPv6 for free networks
  • Tue 13 Oct – Fri 16 Oct: OpenWRT workshops
    (openwrt installation & configuration, kamikaze build environment,
    ssh keys infrastructure, firmware generation, UCI configuration tool,
    asterisk/ SIP phone)
  • Fri 16 Oct @ 18:00 : Deploy the nodes
  • Sat 17 Oct @ 14:00: Deploy the nodes, setup tests
  • Sat 17 Oct @ 19:00: concert "I’m sitting under an antenna" v.a., org. by OKNO
  • Sun 18 Oct @ 14:00: The battle! 🙂

IRC meetings

We setup some IRC meetings to prepare the configuration: IP’s,
versions, and everything that took too much time at WBM v1. The
meetings will be held on the tuesdays of 15 and 22 September and 06
October at 21:00 CET on irc.freenode.net channel #hsbxl. People from
Brussels and around are invited to join us at the hackerspace.


The event is free. We’ll kindly ask you for a donation to cover some costs.


Quai des Charbonnages 30-34
1080 Brussels


  • Metro: Compte de Flandres / Graaf van Vlaanderen
  • Train: Go to Brussels central station and take metro from there (metro 5 direction Erasmus)
  • Route planner in Brussels


Space is limited, so we ask you to register in advance by registering:

  1. send an email with your name and surname to contact@voidpointer.be AND
  2. register on Doodle


  • Bring your laptop/computer
  • Bring your compatible router(s) with OpenWRT pre-installed
  • Bring your WiFi antenna(s) and connectors


  • Zoobab is offering some free space to sleep (contact him at zoobab@gmail.com)
  • If you have problems finding accomodation, let us know (contact@voidpointer.be) — there always be some couches free at HSB.


Email: contact@voidpointer.be
Tel (ptr_): +32 493 52 50 09
Tel (zoobab): +32 484 56 61 09


[via zoobab]

Juergen Neumann about the Roots of Open Wi-Fi at Open Tech Summit in Taiwan 2008

Xavier Carcelle has put some videos online from the Open Tech Summit in Taiwan at the beginning of 2008. Juergen Neumann of the Freifunk Community talks about the beginnings and history of open Wi-Fi.

Google Video: http://video.google.com/videoplay?docid=4426529986868760558

Build a simple Wi-Fi antenna using household materials – Workshop online at heise UK

The workshop of
Christiane RĂĽtten und Sven Dortmund (German) to build a simple Wi-Fi antenna using household materials is now also available in English at heise uk. As in the German version the authors included an antenna calculator in the article. Thanks also for including a link to the global freifunk newswire!

image 11 [250 x 146 Pixel @ 7,4 KB]

Who’d have thought that a toilet-brush holder, of all things, would turn out to be an excellent Wi-Fi antenna? The lesson is that you can achieve great results for little expense – and half an hour’s work. (15.4.2008, http://www.heise-online.co.uk/networks/Build-a-Wi-Fi-radio…) …

If the access point is three rooms further on, or even in the house on
the other side of the road, you need a directional antenna. If you have
to make a connection to your nearest DSL-equipped acquaintance at the
other end of the village street, or to bridge even longer radio links
to reach the free radio node in the next block but one, you may even require two directional antennas. …

The simply made tin-can antenna, with the dimensions given here, is
suitable for base stations and for clients who transmit on 2.4 GHz in
accordance with the IEEE 802.11b and 802.11g standards. 802.11a uses
the 5-GHz band, requiring different antenna dimensions. The necessary
background for a recalculation is given in an article on building
tin-can radio antenna (Building a Wi-Fi Antenna Out of a Tin Can)

Very recent base stations that comply with the draft standard
802.11n also use the 2.4 GHz band. But they automatically use a number
of methods to combine their antennas for optimal range and speed.
However, this only works if the antennas have the characteristics
expected by the WiFi chipset. (15.4.2008, http://www.heise-online.co.uk/networks/Build-a-Wi-Fi-radio…)

Locations Based Services in Free Wireless Networks: MagicMap – Kooperative Positionsbestimmung mit Hilfe von WLAN

Eine Idee, die auch in freien Netzen genutzt werden kann: Bereits 2004 haben
Peter K. Ibach, Tobias HĂĽbner und Martin Schweigert
von der HU Berlin auf dem Chaos Communication Congress 2004 ein Paper über kooperative Positionsbestimmung mit Hilfe von WLAN veröffentlicht. Auf dem Gründerkongress in Berlin stellten die Entwickler die neueste Version der Software vor, die aus dieser Idee entstanden ist: MagicMap

magicmapMit Hilfe der "Karte des Rumtreibers" konnte Harry Potter die Positionen aller Personen in und um Schloss Hogwarts überblicken. Wir haben eine solche "magische Karte" zur Positionsbestimmung mobiler Systeme basierend auf WLAN-Signalstärke-Auswertung entwickelt. MagicMap ist eine reine Softwarelösung, die bei den mobilen Systemen außer einer konventionellen WLAN-Ausstattung keine weitere Hardware erfordert. Die WLAN Access Points können beliebig verteilt sein und es sind weder Eingriffe an der AP-Hardware noch an der Software nötig. Unsere Versuche am Uni-Campus Berlin-Adlershof zeigen in typischen Büroumgebungen eine Positionierungsgenauigkeit im einstelligen Meter-Bereich. Die eigene Sichtbarkeit unterliegt dabei der vollen Kontrolle der Peer-Knoten, die den Zugriff auf ihre Positionsinformation individuell festlegen können. Die Software steht zum freien Download zur Verfügung und kann für Experimente oder Anwendungen genutzt werden. (1. Mai 2008, http://www2.informatik.hu-berlin.de/rok/MagicMap/)

Das Projekt wird am Lehrstuhl Rechnerorganisation und Kommunikation des Instituts für Informatik der Humboldt-Universität zu Berlin umgesetzt. Die Software steht unter der GNU General Public License (GPL) und ist bei Sourceforge für Windows und Linux verfügbar. Das Wiki mit vielen weiteren Infos ist hier: http://wiki.informatik.hu-berlin.de/nomads/index.php/MagicMap

Mit der Idee lassen sich Locations Based Services umsetzen. Auch in Räumen, wo die Positionsbestimmung von Personen und Gegenständen sinnvoll ist, kann die Software hilfreich sein, z.B. in Kraftwerken, auf Schiffen oder möglicherweise auf einer Mondbasis :-).

WLAN-Antenne Selbstbauanleitung einer Dosenantenne

Christiane RĂĽtten und Sven Dortmund haben auf heise einen Artikel zum Selbstbau von WLAN-Antennen veröffentlicht: „WLAN-Richtfunk mit Hausmitteln – Worauf es beim Selbstbau einer leistungsfähigen Richtantenne ankommt“

Die einfach nachzubauende Dosenantenne mit den hier angegebenen MaĂźen eignet sich fĂĽr Basisstationen und Clients, die nach den Standards IEEE 802.11b und 802.11g bei 2,4 GHz funken. 802.11a nutzt dagegen das 5-GHz-Band, fĂĽr das andere MaĂźe gelten.

Auch Freifunk wird kurz erwähnt. Leider gibt es keinen Link zu unserer Website. Ein tolles Feature des Beitrags ist der Antennenrechner mit dem man einfach die notwendigen Maße von WLAN-Antennen berechnen kann. In unserem Wiki gibt es weitere Infos zu WLan-Antennen unter: http://wiki.freifunk.net/WLAN-Antennen. Wir freuen uns immer über Ergänzungen und Antennen-Bauanleitungen.