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"

Freifunk Summer of Code – Questions for your application

Eight Questions to answer for your application for the Freifunk Summer of Code. We are interested in your
answers to get an idea, how you would be able to contribute to
Freifunk. Dont worry too much about a correct English. We are more
interested in the content of what you have to say and how you could
join up with us, than about perfect Englich.

1. Please tell us your name and your country or origin or local background.

2. Please list contributions to the Freifunk/OpenWrt and related
projects or any other freely licensed Open Source project below.

3. Please tell us about your proposed project and the relevance to
Freifunk. You can also provide a link where you offer more details here.

4.  What is your expertise and ability to conduct the project you
propose? How do you plan to achieve the goals of the proposed project?

5. How would you describe your knowledge of development of Linux OS and OpenWrt related programming languages such as Lua?

6. How do you think you will participate in the Freifunk/OpenWrt development after the Google Summer of Code?

7. What would you like us to do to ensure that you stick with the project after the program concludes?

8. How do you plan to keep in touch with the Freifunk/OpenWrt community and your mentor during the summer of code?



* Ideas


Freifunk Participation in the Google Summer of Code 2009

I applied for the Google Summer of Code for Freifunk again this year and we got in 🙂 Please check the info page on the summer of code page for Freifunk here: . Applications need to be submitted via the Google Summer of Code website.

Discuss your ideas for development on the IRC channels of Freifunk and OpenWrt here: #freifunk #openwrt 

We have set up a wiki page for ideas. Please add your idea here:

Some frequently asked questions from the Summer of Code FAQ

How does a student apply?
Students can submit their applications via the Google Summer of Code 2009 site from March 23 – April 3, 2009. … make sure to check out each organization’s "Ideas" list to get to know a particular open source organization better.  

What should a student application look like?
Your application should include the following: your project proposal, why you’d like to execute on this particular project, and the reason you’re the best individual to do so. Your proposal should also include details of your academic, industry, and/or open source development experience, and other details as you see fit. An explanation of your development methodology is a good idea, as well. If the organization you want to work with has a specific application template they would like you to use, it will be made available to you to fill in when submitting your proposal via the GSoC web app.   

Can a student submit more than one application?
Yes, each student may submit up to twenty applications. However, only one application will be accepted. We’ve heard from our mentoring organizations that quality is better than quantity.   

Can students already working on an open source project continue to work on it as part of Google Summer of Code?
Yes, as long as they meet all other requirements for program eligibility. Students should be sure to note their previous relationship with the project in their applications. New work will need to be done for the project as part of participation in GSoC.   

Should students begin working on their applications before Google begins accepting program applications?       
That’s up to you. Keep in mind, though, that our mentoring organizations will be publishing a list of proposed project ideas, so you may find that you’ll want to revamp your application later, or create an entirely new one to address one of those ideas.   

Can a student work on more than one project?
No, each participant is only eligible for one stipend.   

Can a group apply for and work on a single proposal?
No, only an individual may work on a given project. Of course, students should feel free to collaborate with others to accomplish their project goals. 



* Ideas