6mesh project: IPv6 freifunk mesh networks

Alex Morlang and Daniel Paufler had a presentation about the current advancement of the Freifunk 6mesh project for IPv6 routing in wireless mesh networks at a meeting of Freifunk core technologists in Berlin. The presentation is currently only partly available in English, but the German version offers good insights still for people working on wireless mesh networks anywhere. 


* pdf version at freifunk Berlin download site: http://download.berlin.freifunk.net/pdf/vortrag/6mesh/freifunk-ipv6-mesh-siit-praesentation.pdf
* Alexander Morlang http://blogs.k-ita.de/~alx/
* Daniel Paufler http://blog.leo34.net

OLSR-NG Lightning Talk at the 24c3 by Aaron Kaplan

24c3, Chaos Communication Congress: Aaron Kaplan from the OLSR developing team and member of the Austrian funkfeuer community had a short lightning talk on the recent improvements of the OLSR protocol, which they now call OLSR-NG.

The whole lightning talk session can be downloaded via the torrent network (torrents below). 

Wireless Kernel Tweaking or how B.A.T.M.A.N. learned to fly – Presentation at the 24c3 by Marek Lindner and Simon Wunderlich

Marek Lindner and Simon Wunderlich from the Berlin freifunk community gave a talk on Wireless Kernel Tweaking and the B.A.T.M.A.N. routing protocol at the 24c3 Chaos Communication Congress. The video is now available on the torrent network.

Kernel hacking definitely is the queen of coding but in order to bring mesh routing that one vital step further we had to conquer this, for us, unchartered territory. Working in the kernel itself is a tough and difficult task to manage, but the results and effectivity to be gained justify the long and hard road to success. We took on the mission to go down that road and the result is B.A.T.M.A.N. advanced which is a kernel land implementation of the B.A.T.M.A.N. mesh routing protocol specifically designed to manage Wireless MANs.

During the last years the number of deployed mesh networks has increased dramatically and their constant growth drove us around the edge of what we thought was possible. To cope with this rapid development we had to leave the slow and limited track of tweaking existing approaches and take an evolutionary step forward by porting the B.A.T.M.A.N. protocol into the kernel land and going down to layer 2. Using B.A.T.M.A.N. advanced as a showcase we will, in our lecture, deliver a detailed review on how one can go about developing linux kernel modules, give insights in what difficulties to expect and provide practical tips on how to go about this challenge without experiencing a damaging kernel freeze in due process.

We will describe what problems we faced migrating down to layer 2 and how we went about solving them for example how we moved away from the kernel routing and handle the actual routing and data transport in B.A.T.M.A.N. itself. Also moving to layer 2 meant to leave IPs behind and solely rely on MAC-routing enabling features like DHCP, IPX, IPv6, etc which up to now was not possible and therefore comes as a big plus. On the other hand there were little if none diagnostic tools at all for routing on that level so we had to go back one step and develop the tools we needed ourselves.

These and other things we will cover in our presentation and also give an outlook into the future of mesh-routing, which will bring it even closer to the source of wifi – the wireless stack and its drivers and thereby improving the overall performance even more.

Link: www.open-mesh.net


Chaosradio Express mit Elektra zu Freifunk und B.A.T.M.A.N.

Elektra gibt einige Einblicke zu B.A.T.M.A.N., dem Freifunk-Protokoll der Zukunft, im Chaosradio.

Schon in Chaosradio Express
016 hat Elektra einen tiefen Einblick in Wesen und Form des Mesh
Networking geboten. Im Gespräch mit Tim Pritlove werden nun die
neuesten Erkenntnisse der Entwicklung berichtet. Kern der
Neuigkeiten ist der Nachfolger des OLSR-Protokolls namens B.A.T.M.A.N.
Elektra erläutert, wie B.A.T.M.A.N. im Deatil funktioniert, welche
Erfahrungen und Erkenntnisse seinem Design zu Grunde liegen und wie man
sich das alles vorstellen muss. Ein Teil der Diskussion betrifft auch
die geplante Mesh Networking Technologie im OLPC (XO) Laptop. (20.9.2007,


The Fonera Pack Story

This blog entry is mainly in english. Sorry for that, but the original recipient (a belgian guy) is very much better in english. Since beginning of 2007, a startup company called "FON" is distributing very cheap (subventioned) WLAN devices: the la-Fonera wireless LAN router. For these, I've created and published an additional software, called the Freifunk-Fonera-Pack available here: http://download.olsrexperiment.de/fonera/ . The Pack offers Freifunk meshing in parallel to the FON function. Obviously, I've missed to explain the different networking modes and hance a posting on our internal berlin mailing list reaches me with a lot of questions. Mario asked me to publish the anwers here.
Hi Steven,
yes I know. There's not enough info about the networking / mode stuff in the ff-fonera-pack readme. OK – I'll try.
Networking Model
The networking model / how internet is distributed in a Freifunk mesh is very different to the FON business model. The FON model includes a certain amount of hotspots scattered over an arbitrary area. Each FON router should have its own (wired) internet access via DSL, leased line or dialup modem. The idea is – as you hopefully know – to share/sell the unused bandwidth of the payed personal internet access to others. Freifunk is different. We form a wireless intranet, where internet access is a service offered by volunteers. We normally do not pay for internet connectivity. In short: Freifunk forms a network and FON is a hotspot service offer.
To "catch" paying users, a FON hotspot offers it's connectivity in a mode easily understand by typical end-user laptops/notebooks/PCs: the access point wifi mode. A connecting PC should have connectivity and zero-admin config, so it is hopefully really easy to display the"insert-coin-here" page. Freifunk again is different here. To participate as equal with equals in a network, we need to cooperate at least on the techical level. This includes using a specific wifi mode (ad-hoc or IBSS) as well as relaying data of other users and running a certain protocol program to find and configure optimized data paths through the network.
To combine these different networking models, the Freifunk-Fonera-Pack offers different operation "modes". These modes are designed following these simple rules:

  1. The FON and Freifunk stuff should function as designed in parallel
  2. It should not be possible to sell the internet connectivity offered by Freifunk volunteers via FON
  3. It should not be possible to nerve wreck Freifunk users with the FON login page
  4. There should be a benefit for the average FON user to install that stuff

You can use the "Open" mode, if you want to share your own internet uplink with the community. Every Freifunk user connecting via Ad-Hoc and running the OLSR routing program can use your internet gateway. It's announced per "HNA" which basically says "Internet here". The OLSR program will search and configure a data path ("route") to the nearest HNA internet gateway available. Without the FON login page of course.
You can use the "Ego" mode, if you do not want the FON stuff / FON login page at all. To keep fair play, the FON callback is stopped and there is no "FON_AP" signal then. If you want to offer internet to the community, simply configure internet as usual. If you want to use a Freifunk gateway, simply do not connect any internet uplink.
If you want to relay data via WLAN/radio from other Freifunk users, but you want your own internet uplink for yourself (and the FON users loggin in), you can use the "Stealth" mode. All the Freifunk mesh routing happens in a background routing table. You do not announce your internet gateway via HNA and an Ad-Hoc connected Freifunk node / PC / laptop uses a different default route (not your standard internet default route).
As a benefit for the FON offering user, you can tunnel your own internet gatway via Freifunk and offer a FON uplink elsewhere in the Freifunk mesh. For this, the different Master-Modes (Open-Master, Ego-Master, Ego-Slave) are offered. You can configure a second / third / forth Fonera as "Slave" and set up a tunnel via Freifunk-meshing to use and sell your own internet gateway via FON. You'll find a sample configuration on the "Freifunk-Advanced" web page installed as part of the Freifunk-Fonera-Pack. Besides that, the Freifunk-Fonera-Pack adds a bit more security currently, provided that you do not use 192.168.x.x as meshing IP – but that's another story.
Q: Why there are no "Open-Slave", "Ego-Slave" nor "Stealth-Slave" modes?
A: Well, if you re-think it and maybe read the above once more you will understand. "Open-Slave" is contraprodutive. A device should not announce internet which it does not have. "Ego-Slave" is not necessary. Simply use "Ego". "Ego" will configure/use the next HNA / Freifunk gateway, possibly your Fonera in "Open" mode. "Stealth-Slave": This is offered as "Slave" mode.
// Sven-Ola
At the next day, a posting with more questions dropped in. I don't want to cite that here, mainly because I have not asked Steven to do so. To summarize: He has not tried the tunnel stuff and wanted to have an easy configuration for a couple of other guys, e.g. "publish the FON password" and "we are all in Linus mode". I may be wrong, but those points are the main questions asked IMO.
uuh! Lots of questions 🙁 OK – to sort that out, here are some more statements.
Tunneling Internet
Our understanding of a mesh network includes using those cheap devices, to form a network. You can – of course – use the precious laptops to join in. But in the long run, a mesh only functions, if the nodes (the laptops, PCs, the routing boxes running OLSR) are switched on for a longer period. I talk about months not minutes. Also, you normally do not want to place the laptop on the roof of your house. For example: we do not have OLSR for Vista currently – and only a very small number of whiners. We all use those boxes to connect (e.g. via DHCP and NAT). You plug in your laptop into the box (either by ethernet or by a second Access Point) and go. That's the main use case.
You wote, that you (and your friends) don't want to break your "FON promise". The ff-fonera-pack is open source, and because of that you are free to do anything you like. Some expertize required. Especially the "Chillispot needs to fiddle with the default route thing" will be the hurdle to master here. Also I expect some dirty policy routing tricks are required. I personally do not want to make that, because of the reasons I wrote in my last post.
Lets form an example. You have internet access via DSL. You have a fonera connected to the DSL line, configured all, and switched to "Open". You have two friends who also bought a Fonera. One has his own DSL line and one not. Your own fonera uses as meshing IP, channel 3 and 02:ca:ff:ee:ba:be as meshing BSSID.
Friend1 with DSL line: That's easy. Just proceed as usual. He can use "Open" or "Stealth" modes, which depends on "does he want to share for free" or not. He switches to channel 3, configures an arbitrary ESSID (say IZEFON, but I would prefer a more sexy name) for meshing and the FON_Friend1 and MyPlace_Friend1 as usual. He configures as meshing IP. The critical thing is the BSSID (the hex number). The meshing ESSID is not really used – the BSSID for meshing and the channel needs to be the same on all meshing Foneras. Ah – and you need a Wiki page stating: "Friend1 uses" as well as "Steven uses".
Friend2 without DSL line: To keep the "Fon promise", he normally needs to buy a DSL line. The FON promise is based on that. But: that friend can use for example the Steven-DSL via the tunnel setup. Setting up tunnels is easy, and the standad Fonera should be able to run ~ 8 tunnels concurrently (depends on memory consumption). The tunnel stuff should also be able to handle ~500kbyte/sec, which in most cases matches your DSL line speed. You will be happy if you reach that speed via meshing with some kilometres distance which also requires a very good antenna setup.
The first thing to do is adding "Friend2 uses" to the wiki page. Friend2 configures BSSID, MeshingIP and Channel3. Friend2 also switches to "Slave" which basically means: The device has internet via tunnel and does not interfere with the OLSR-HNA-search-best-gateway algorithm. He also changes the private MyPlace_Friend2 IP range from the default to (more on this later).
Now Steven switches to Open-Master to let Friend2 in. It needs to be a good friend, since he sells your DSL line to FON and he has access to your private IP range (the used for your own MyPlace_Steven domain). To let his friend in, Steven needs to browse to the Advanced/Freifunk-Advanced page of his Fonera and enter this in the "Private IP" input field: "". Steven also enters a tunnel password there, any arbitrary string will do.
Friend2 now also browse to the Freifunk-Advanced page, and enter the same tunnel password as well as this to the "Private IP" input: "". You may note that those settings are symmetrical. Friend2 needs to define, which Master tunnel endpoint to use. So he enters this to the "Master IP" input: "". Which basically says: On Stevens fonera, there is an open tunnel endpoint on port 4711.
After restarting both Foneras, you should notice the "FON_xxx" on the Fonera of Friend2. This proves: Setup is working. Ah – you may enter the Foners command line or connect to MyPlace_Friend2. Then send "ping". This proves, that both private IP ranges (the and are linked by routing and theres no firewalling in between.
Phew. Much blabla. I hope this will help you a bit.
// Sven-Ola
To write down some final words: It is obvious, that setting up a Freifunk network is not too easy. To teach and inform, it needs much more text than (for example) attracting FON users with a Plug-and-Play promise. I'm sure, that we never reach that Plug-and-Play state, but of course things can be made more easy with good documentation and good Web-UI-Design. I hope that Steven finds his way through the competing network models. It should be clear that a company needs to make a profit, while Freifunk is created by volunteers. But we also want something from others of course – e.g. World domination (cited from Linus). TANSTAAFL!