Freifunkblog

Our mailing list is here: http://freifunk.net/mailman/listinfo/wlanware

You can also use the OpenWrt mailing list for discussing Freifunk specific plugins and tools with OpenWrt devevlopers: https://lists.openwrt.org/mailman/listinfo/openwrt-devel

Every application is welcome. We are not only looking for experienced students, but for anyone wishing to contribute to LXDE also after the summer.

The application period starts on March 29, 2010. Please use the time to discuss your ideas beforehand already.

Timeline: http://socghop.appspot.com/document/show/gsoc_program/google/gsoc2010/timeline

• March 29th 2010: Application period for students begins.
• April 9th 2010: Student application deadline. The earlier you start the more probable it is that you will be accepted! There is two way feedback during the application process which really helps you improve and clarify your application before this final deadline.
• April 26th 2010: Accepted student proposals are announced.
• May 24th 2010: Coding begins!
• July 12-16th: Mid-term evaluation.
• August 9th: Pencils down!

Links

* Idea Page: http://wiki.freifunk.net/Ideas

* Student Check List: http://wiki.freifunk.net/Student_Check_List

* Mailing List http://freifunk.net/mailman/listinfo/wlanware

* Freifunk GSoC Page http://socghop.appspot.com/org/show/google/gsoc2010/freifunk

* Google Open Source Programs: http://socghop.appspot.com

Freifunk is again applying as a project for the Google Summer of Code 2010. For students it is a good way to get deeper involved into Free and Open Source Software and freifunk specifically. During the summer students have the chance to code on freifunk and get paid by Google.

Some other projects also offer freifunk related work. Check out the GSoC site after March 18 when the info on participating projects is released.

We are already gathering project ideas, as a way to start for applicants here. If you are interested to join freifunk at the summer of code and would like to discuss project ideas, please join us on IRC at #freenode on irc://irc.freenode.org and on the mailing list: http://freifunk.net/mailman/listinfo/wlanware

If you have already an idea about a project you would like to do, please also leave your idea here as well: http://wiki.freifunk.net/Ideas

Background info on Google Summer of Code

The most common question we get from students is “How do I prepare for Google Summer of Code?” The simple answer is not to wait for the program to get involved in open source. Start checking out projects now: take a look at documentation, check out their source code and idle in some IRC channels to see what interests you. The projects who have been past participants in Google Summer of Code are a great place to start; use the categorized list of mentoring organizations (e.g. projects listed by programming languages) from 2009 to help you get started.

About Google Summer of Code

Google Summer of Code (GSoC) is a global program that offers student developers stipends to write code for various open source software projects. We have worked with several open source, free software, and technology-related groups to identify and fund several projects over a three month period. Since its inception in 2005, the program has brought together nearly 3,400 students and more than more than 3,000 mentors & co-mentors from nearly 100 countries worldwide, all for the love of code. Through Google Summer of Code, accepted student applicants are paired with a mentor or mentors from the participating projects, thus gaining exposure to real-world software development scenarios and the opportunity for employment in areas related to their academic pursuits. In turn, the participating projects are able to more easily identify and bring in new developers. Best of all, more source code is created and released for the use and benefit of all.

* Frequently asked questions: http://socghop.appspot.com/document/show/gsoc_program/google/gsoc2010/faqs

* Freifunk Project Ideas: http://wiki.freifunk.net/Ideas

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: 

http://sourceforge.net/tracker/?atid=681702&group_id=117612&func=browse

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

Links

* http://zioproto.ninux.org/wordpress/2009/08/31/olsrd-obamp-plugin/
* http://gredler.at/hg/olsrd/rev/8e7887c1247f
* http://olsr.org
* http://blog.freifunk.net
* http://ninux.org

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.

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.

Links

• Project-Homepage: luci.freifunk-halle.net
• Translation Portal: i18n.luci.subsignal.org
• API-Documentation: Luci-Doc
• Development Progress: Trac-Timeline
• Bugs and Features: Tickets
• John Crispin aka BLogic (mentor)

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!

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

Links

* Source code: http://sourceforge.net/project/showfiles.php?group_id=180858&package_id=...
* LXDE: http://lxde.org
* Fred Chien: http://fred-zone.blogspot.com/search/label/LXDE