Last minute: Presenting at LinuxTag

As apparently there was a last-minute drop-out in the Security track of LinuxTag 2008, I have been invited to present. It is great that I could convince them to do a talk about my current favorite subject: Enabling more security research in communications protocols outside the TCP/IP/Ethernet based Internet.

I don't want to spoil it by providing too much information upfront. I'm sure there will be recordings available afterwards. For now, you can get the main points from the abstract

Bought another motorbike: Yamaha FZ6 Fazer

During the last week or so, I spent a lot of time test riding a number of various motorbikes. Both real sports / supersports bikes, as well as 'sportive touring bikes'. I wasn't really sure if I should go for a true/real sports bike like the Suzuki GSX-R (750/1000) or start with something less 'extreme' first. One thing I learned, though, is if I went for a sports/supersports bike, I'd definitely have to keep my BMW F650ST around. Those racing bikes are just not useful for casual riding in city traffic. But I want both, fun at the motorway, as well as a useful bike for local travel inside Berlin.

Then I got a really irresistible offer for a two-year-old FZ6 Fazer (with ABS), and I had to buy it. So for now, it is this. It's probably reasonable to first go from the familiar 48bhp to 98bhp before reaching to the 160bhp range of the Suzuki GSX-R. So in the end, I can even claim that I'm being rational and reasonable here, going "only" to an (already-ridiculous) amount of power, than a beyond-ridiculous amount ;)

And please don't worry too much. I'm not suicidal, and I've been riding quite safely for more than 11 years now ;) This is not going to change!

Chaosradio on Software Defined Radio

I've had the pleasure of being invited to Chaosradio Express maker Tim Pritlove to talk about Software Defined Radio in general, and gnuradio plus USRP specifically. You can listen to the resulting 2+ hours of podcast (in German).

It's been a great experience, and I have a good feeling that it was possible for us to explain this fairly detailed subject to our already at least moderately technical audience.

SDR is really hard since it combines aspects of traditional radio, i.e. physics of electric waves, electrical engineering both analog and digital, digital signal processing and software. The biggest part is really advanced mathematics, and at least from all the subjects that I've seen, it's probably the most direct and close-to-theory incarnation of applied math.

Luckily, a fairly high-level understanding of the algorithms and principles involved are already sufficient to do a lot, since most of the deep-down mathematical details of many algorithms have already been implemented as building blocks for gnuradio. Still, I assume the number of developers who are actually able to use gnuradio is far too low. If you're looking for an interesting field of software right now, I suggest going for digital signal processing. It's in every area of communications, ranging from analog modems over ISDN, DSL, WiFi, USB2, Bluetooth, GSM, UMTS, DECT, ZigBee, Ethernet, VoIP and probably any other communication technology that we use today.

Motorbike troubles again

It seems like I lost all my luck. Only a three weeks ago, the Yamaha TW-225 in Taipei had problems after my arrival. Now that I'm back to Berlin, my BMW F-650 had some serious trouble, too.

Starting the engine turned out to be really hard (started only on something like the 10th attempt, even though usually the first one is sufficient). Furthermore, pulling the gas handle only the tiniest little bit kills off the engine completely, independent of how far the choke is asserted.

So today I spent some five hours in disassembling almost the entire bike, removing the twin-carburetor, disassembling and cleaning it and putting the entire bike back together again. The engine is running fine again. I just wonder why I have this kind of carburetor problem already the second time in the last couple of years.

There's almost no visible dirt inside the carburetor, and all the fittings are fine, no signs of any leakage, no signs of any significant wear of any of the involved parts. Still, cleaning and re-assembling it clearly removes the problem.

Back from WGT

There are two fixed dates every year that I never miss: The annual Chaos Communication Congress in Berlin between Christmas and new years eve, and the Wave Gotik Treffen music festival in Leipzig.

This year I was camping at the event campsite again, following two lazy years in a hotel. I enjoyed it a lot, especially since the weather was perfect. Only sunshine, not a single drop of rain for the entire four days.

The festival itself was like always. Great. :) I think my personal favorites this year was the industrial (probably better: rhythmic noise) act NULLVEKTOR as well as INADE.

Victory: Skype withdraws appeals case, judgement from lower court accepted

The court hearing in the "Welte vs. Skype Technologies SA" case went pretty well. Initially the court again suggested that the two parties might reach some form of amicable agreement. We indicated that this has been discussed before and we're not interested in settling for anything less than full GPL compliance.

The various arguments by Skype supporting their claim that the GPL is violating German anti-trust legislation as well as further claims aiming at the GPL being invalid or incompatible with German legislation were not further analyzed by the court. The court stated that there was not enough arguments and material brought forward by Skype to support such a claim. And even if there was some truth to that, then Skype would not be able to still claim usage rights under that very same license.

The lawyer representing Skype still continued to argue for a bit into that direction, which resulted one of the judges making up an interesting analogy of something like: "If a publisher wants to publish a book of an author that wants his book only to be published in a green envelope, then that might seem odd to you, but still you will have to do it as long as you want to publish the book and have no other agreement in place".

In the end, the court hinted twice that if it was to judge about the case, Skype would not have very high chances. After a short break, Skype decided to revoke their appeals case and accept the previous judgement of the lower court (Landgericht Muenchen I, the decision was in my favor) as the final judgement. This means that the previous court decision is legally binding to Skype, and we have successfully won what has probably been the most lengthy and time consuming case so far.

Back from the trip to Taiwan

It's been some time since my last blog post, mainly because I've been quite busy in Taiwan. First there was the conference, then there were a number of meetings with various companies to educate them about GPL licensing and how to interoperate with the FOSS community for better hardware/driver support.

The other part was actual spare time. I spent many months in Taipei during my work for OpenMoko, but I never really had much time to explore the city, or even other parts of the country.

This time I explored quite a bit of the Taipei nightlife, visiting places like Luxy, Lava, Room18, Barcode, ageha, and even the so-called "meat market" of Carnegies and Tavern.

I've also had time to try one of the many hot spa's of Taipei in Beitou, as well as a really great motorbike trip to the national forest in the Wulai mountain region.

Unfortunately the weather wasn't that great, so I had to postpone my plans to visit the northeastern and the eastern coast to some future trip.

And the most interesting part is: I actually made contact to Taiwanese people who are not at all in any way related to work :)

Further Taipei exploration brought me to the Wufenpu fashion wholesale area, as well as Ximending. Most impressive is also the "Taipei underworld", i.e. the various underground shopping malls near Taipei Main Station, such as the Taipei City Mall, Station Front Mall and ZhongShen Mall I and II. You can literally walk for many kilometers underground...

Now I am one day in Frankfurt, and tomorrow one day in Munich, Friday one half day at home, and then there will be four days of music festival at WGT 2008.

Tomorrow: Court hearing in Welte vs. Skype GPL case

Tomorrow at 10:30am at the Oberlandesgericht Muenchen (higher regional court of Munich) there will be an oral hearing in the "Welte vs. Skype Technologies SA" case. The hearing is to be held in room E.06.

This case is about a GPL violation of Skype, related to their sales of Wifi Skype phones based on the Linux operating system kernel.

I'm fighting as part of the gpl-violations.org project in enforcing the GPL against Skype since February 2007. Initially Skype didn't respond, we then applied for a preliminary injunction. That injunction was granted by the court in June 2007, but Skype chose to file an appeals case against it.

The court hearing tomorrow is exactly to debate about this appeal.

Interestingly, Skype is arguing against the validity of the GPL as a whole, asserting that it is violating anti-trust regulation and similarly strange claims.