Bits und Bytes im Heizwerk

Jetzt geht's richtig los mit und um Terminal.21. Mit einer guten Portion Glück ist es uns gelungen, ein ausgedientes kleines Heizwerk in Halle zu mieten, mit großer Halle und langem Schornstein. Platz, der mit einer großen Portion Arbeit und kreativen Ideen genutzt werden will. Und dafür brauchen wir euch, eure Unterstützung, eure Projekte und eure Visionen.

Vieles ist denkbar: Kino, Hackspace, Kunstraum, Biblitothek, Seminare und Workshops, Selbsthilfewerkstatt, Medienkunst, Installationen, Ideenschmiede, Projektspace, ... und alles andere, was ihr euch vorstellen könnt.

Los geht es am Sonntag, dem 11.10.2009 ab 15:00 mit einem kleinen Baustartfest. Wir werden euch kurz erzählen, wer wir sind, was uns dazu gebracht hat, dieses Projekt zu starten, was andere Leute auf dieser Welt so treiben, was wir alle miteinander in Zukunft an diesem neuen Platz treiben wollen und was dafür zu tun ist. Ihr findet das Heizwerk in der Hordorfer Straße in Halle, oder hier mit Blick von oben.

Multicast for OLSR mesh networks: Obamp release by Saverio Proto

Saverio Proto (ZioPRoTo) has the released the olsr OBAMP plugin, that was a freifunk project for the Google Summer Of Code. The OBAMP plugin allows multicast traffic to be forwarded in a OLSR mesh network. OBAMP is an overlay protocol. It first makes a mesh network with overlay links (udp tunnels) between the OBAMP nodes, and then it creates a distribution spanning tree over these mesh links.

This version of the OBAMP protocol, implemented as an OLSR plugin, is a simplified one for Wireless Community Networks, where we assume the nodes to be in fixed positions on the roof of the houses. Protocol features regarding mobility have not been implemented (yet).

To explain how the plugin works consider the scenario in the following figure:

There are 7 routers, where only 5 have the OBAMP plugin working. Router 1 2 and 6 also have an attached HNA network with some hosts.

OBAMP nodes generate OLSR OBAMP_ALIVE messages, these OLSR messages are forwarded in the whole network (also by the nodes that do not understand OBAMP thanks to the OLSR design). Because of the flooding mechanism every OBAMP node has a complete list of all the other OBAMP nodes in the mesh network. Every OBAMP node listens on the UDP port 6226 for OBAMP signalling.

When a OBAMP nodes starts it has 5 timers to periodically start operations:

OBAMP_alive_timer: every obamp node sends alive messages to advertise its presence to the other obamp nodes in the network. In the alive message every nodes states its IP address, and if it has already a tree link or not (we will see later this information is important for the outer tree create procedure).
The OBAMP network must have a member called “Core”, that starts the TREE_CREATE procedure. The core is the node with the smallest IP address. When the list of known OBAMP nodes changes, the Core Election procedure is eventually called.

mesh_create_timer: every obamp node every OBAMP_MESH_CREATE_IVAL evaluates how far the other obamp nodes are and selects a subset of nodes to keep mesh links with. Note that to reduce signalling and to increase scalability, the overylay mesh links are setup only with a subset of the nearest OBAMP nodes. To select the overlay neighbor the OBAMP nodes first calculates the ETX distance of the nearest OBAMP nodes, and the creates overlay mesh links to every node that are far in the range (minETX,minETX+1)

tree_create_timer: the core of the network every OBAMP_TREE_CREATE_IVAL sends a message called TREE_CREATE on its mesh links. The creation of the spanning tree is very similar to the spanning tree protocol. When a TREE_CREATE message is received a OBAMP node enables a tree link with its parent and forwards the TREE_CREATE on the other mesh links. TREE_CREATE messages are generated only by the core and are numbered, so TREE_CREATE received over loops can be discarded.

outer_tree_create_timer: The mesh_create algorithm may create cluster of OBAMP nodes within the network that are disconnected between each other. This happens if there are groups OBAMP nodes that are far from each other. If this happens only the cluster where the Core is present will receive the TREE_CREATE and will receive traffic from the distribution tree. To overcome this problem if in a cluster there are not TREE_CREATE every OBAMP_TREE_CREATE_IVAL the node with the smallest IP in the cluster will make a long mesh link with the nearest node that has at least a tree link. All the necessary information to perform this procedure is diffused in the OBAMP_ALIVE messages.

purge_nodes_timer: checks expire time of various variables, and deletes nodes or tree links in a soft state fashion

The OBAMP nodes will capture the multicast udp traffic from the non-OLSR interfaces, and will forward this traffic encapsulated in the UDP tunnels of the distribution tree. The other OBAMP nodes will forward the traffic in the tree and will decapsulate it on their non-OLSR interfaces. To avoid duplicated packets the data is carried into OBAMP_DATA messages, that are identified by a sequence number, and the OBAMP source node where the traffic has been encapsulated.

In the figure black links represent real radio links, and red links represent overlay mesh links (udp tunnels). Router 1 2 3 and will create a OBAMP cluster, with two mesh links. Router 6 and 7 will create a mesh link between them. Because the mesh_create algorithm does not create a mesh link between the two clusters, the router 6 (supposing it has the smallest IP address in the mesh) will create an outer tree link with Router 3.

So please download the code and use it . If you find bugs please report them to Saverio and in the Sourceforge tracker here:

Thanks for this great result of the summer. Special thanks also to Nino from who was the mentor for this projet.



IPv6 and TLS capable network-superserver in Lua and C with HTTP and RPC Slave

The summer of code project of Steven Barth aka Cyrus is about planning and implementing an IPv6 and TLS capable superserver in Lua as well as an HTTP/1.1-Server working on top of it using the LuCI HTTP-Stack. This application will serve LuCI - the Freifunk Firmware web user interface - and replace the currently used slower CGI-solution without IPv6 and encryption support. Additionally an RPC-Server will be built to allow remote administration of one or more OpenWrt devices in a standardized way using JSON-RPC over TCP.

LuCId HttpD

The results of the summer work of Cyrus is pretty overwhelming. There is for example nixio, the new POSIX Lua library which will help us getting rid of the Lua 3rd party library mess. And based on that there is also LuCId - which was described in the GSoC project. It brings us a new efficient HTTP-server. Some people may have discovered that Cyrus already checked in things into trunk ocassionally. Also SSL support is working. Another nice new feature is native support for creating wizards which will be used in the near future. The results of LuCId are already being tested in productive environments. They are performing well. Kernel mode IO and TLS encryption function well. Special thanks for the achievements also go to John Crispin aka BLogic who is the mentor of Steve during the summer.


Freifunk Google Summer of Code Project LXNM (Lightweight Network Manager) current results

Fred Chien from Taiwan has published some results on the LXDE blog about his current work for the LXNetworkManager and I am happy to present some screenshots here. Besides having Fred working on code related to wireless networks, the goal of teaming up with him in the Freifunk Google Summer of Code is to bring him closer in touch with the global free wireless community. For a long time we are looking for an easier to use and faster lightweight network manager, that supports freifunk community networks. Through his previous work Fred has shown that he shares those goals and that he is eager and able to get things done. Also we can be sure, that he will continue working on the code once the summer of code funding is finished. The rewritten LXNM already supports wireless connection settings and we are discussing at the moment different ways to define standards for wireless freifunk networks. So, I am looking forward to an exciting ongoing development. Thanks for a great job this summer, Fred!

Lightweight Network Manager

Detailed description of the current status provided by Fred: LXNM (Lightweight Network Manager) is working now after a long time for development. If you often check the news of SVN, you can notice that the next generation of LXNM has already supported wireless connection setting, also it has many feature as old version of LXNM. The new implementation and protocol defination seems to work well at least there is no bug of old version of LXDE had that no Access Point was scanned always.

As a network manager, wireless is the basic feature, but only the feature is not enough for new internet devices. To be a full function network connection utility, it must provide most popular methods of internet connection service something’s like 3G(HSPDA), PPPoE, dial…etc. And also we can expect WiMAX will be coming soon, so supporting WiMAX maybe important and necessary in the feature as well.

So far most network connections methods need to use PPP(Point-to-Point Protocol) to make connection, so we must try to focus on how’s PPP working and how to integrate PPP stuffs with our program. Fortunately, Most of operating system was using pppd to handle the ppp connections, it seems to be a standard we can consider. If we know how to get pppd immediate status, it will be easy to integrate PPP with our utility for us.

Regarding pppd implementation, it uses a tdb(samba database) to store current connection information(IP, interface, deivce, gateway, dns…etc) in system folder as root. Thus we need to read the file to get network status and the relationship between modem(eg, 3G modem, general modem) and network interface(eg, ppp0, ppp1…). Because of pppd is a user-space implementation as well as it doesn’t have library to provide serial APIs to let us be easy to operate its own stuffs, LXNM must direct open the tdb file. The problem is that pppd will update the tdb file anytime, it is possible that database be modified when LXNM is just reading the file. When it is happened, LXNM will get incorrect information or access failed to cause crazy crash. For solving this bug, we do some to check more information details which is from tdb. After some hard works, right now the issue was solved already.

Besides, the 3G support which is most important feature people concern. LXNM will try to use AT command to control 3G(HSDPA) modem to implement the connection handler, it can provide more information(ISP, Service Location, current area…etc) for your SIM Card with AT command. Some developers suggest us to research the implementation of Modem Manager Project for helping development.

Now we are working on this part which is that dialing with 3G modem, but there were also some weird problems we got. More details about those issues will be explained at blog next time.

List of Access Points on LXNM

Scanning for Access Points on LXNM


* Source code:
* Fred Chien:


Status of Service Discovery for Freimap development

An update on one of our Google summer of code projects: Service Discovery for Freimap. Stefano Pilla from is working on the project. We have widened the project a bit. He is now also working on porting freimap to IDE like Netbeans. This will make it easier in the future to implement new graphic map views.

Service Discovery works fine and at the moment Stefano is testing a prototype and working already on documentation. During the project he got in touch with the creator of JmDNS, Rick Blair. JmDNS is an implementation of mdns for Java. He also started an exchange with the creator of JXMapKit (SwingLabs - Josh) that is the new kind of map for freimap that we want to use with Openstreetmap.

screenshot of the "new freimap"

An important mentor for this project is Alx Morlang from Freifunk in Berlin. Thank you! And our friends from Ninux namely - Saverio, Claudio and all of the team. Service Discovery will be tested first in the freifunk ninux network in Rome during the upcoming weeks with mdns.

screenshot of the "new freimap"

Rundfreifunk vom WCW 2009

Zum Wireless Community Weekend wird am Samstag, den 23.5.2009 zwischen 19-21 Uhr Live on air auf Radio Blau (UKW in Leipzig und Internetstream weltweit) eine Rundfreifunk-Sendung direkt aus dem Herzen Berlins aus gesendet. So stehen uns drei Stunden freier Radioraum auch auf ganz anderen Frequenzbändern zur Verfügung, der nur darauf wartet von uns mit Leben gefüllt zu werden. Wer Radio Blau nicht kennt, hier noch eine kurze Erklärung: Radio Blau ist ein Freies Leipziger Bürgerradio und ist im Großraum Leipzig mit jedem Radio empfangbar. 

Wer möchte, kann hierzu in Vorbereitung schon Audiobeiträge bzw. Interviews vorbereiten, die im Rahmen dieser Sendung ausgestrahlt werden können. Bitte meldet euch hierzu bei Ufo.

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:
* Alexander Morlang
* Daniel Paufler

OpenWrt team announces OpenWrt Kamikaze 808 Release with Luci Interface

The OpenWrt team (Cph) has announced a new version of its Linux distribution for embedded wireless devices named "OpenWrt Kamikaze 808 Release". I talked to Felix Fietkau already at the WCW. Unfortunately we did not have the time to do an interview at the end. But Cyrus from freifunk Halle gave a short showcase of his interface (in German). The OpenWrt team was also impressed by it and they now announce the enclosure of the Luci interface officially. Congratulations Cyrus!

It has been quite a while since OpenWrt had a new Kamikaze release. The developer team has decided that it is time to get things straight and focus on a new release. This release have the official name: OpenWrt Kamikaze 808 Release.

The schedule will look like this:
*Last day in July - final release candidate: 808 RC-1 808 RC-1 will be a feature freeze, and all changes after this point will be bug fixes.
*Last day in August - final release: OpenWrt Kamikaze 808 Release.

OpenWrt Kamikaze 808 Release will focus on bringing the following:
- Firewall rewrite
- Broadcom 47xx running reliably with the new Kernel, not including wifi
- IMQ and Traffic shaping tested with newer kernels, especially 2.6.25
- Sysupgrade for more platforms (x86 is tested again)
- The new web interface (LuCI, Lua Configuration Interface)
- Attention towards the integration of security updates
- Package maintaining and updates between releases
- Testing, testing and lots of testing...

The 808 Release will also include support for several new platforms/targets. ( )

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