Older blog entries for LaForge (starting at number 272)

Back in late April, the well-known high-quality SDR hardware company Nuand published a blog post about an Open Source Release of a VHDL ADS-B receiver.

I was quite happy at that time about this, and bookmarked it for further investigation at some later point.

Today I actually looked at the source code, and more by coincidence noticed that the LICENSE file contains a license that is anything but Open Source: The license is a "free for evaluation only" license, and it is only valid if you run the code on an actual Nuand board.

Both of the above are clearly not compatible with any of the well-known and respected definitions of Open Source, particularly not the official Open Source Definition of the Open Source Initiative.

I cannot even start how much this makes me upset. This is once again openwashing, where something that clearly is not Free or Open Source Software is labelled and marketed as such.

I don't mind if an author chooses to license his work under a proprietary license. It is his choice to do so under the law, and it generally makes such software utterly unattractive to me. If others still want to use it, it is their decision. However, if somebody produces or releases non-free or proprietary software, then they should make that very clear and not mis-represent it as something that it clearly isn't!

Open-washing only confuses everyone, and it tries to market the respective company or product in a light that it doesn't deserve. I believe the proper English proverb is to adorn oneself with borrowed plumes.

I strongly believe the community must stand up against such practise and clearly voice that this is not something generally acceptable or tolerated within the Free and Open Source software world. It's sad that this is happening more frequently, like recently with OpenAirInterface (see related blog post).

I will definitely write an e-mail to Nuand management requesting to correct this mis-representation. If you agree with my posting, I'd appreciate if you would contact them, too.

I've been giving a keynote at the Black Duck Korea Open Source Conference yesterday, and I'd like to share some thoughts about it.

In terms of the content, I spoke about the fact that the ultimate goal/wish/intent of free software projects is to receive contributions and for all of the individual and organizational users to join the collaborative development process. However, that's just the intent, and it's not legally required.

Due to GPL enforcement work, a lot of attention has been created over the past ten years in the corporate legal departments on how to comply with FOSS license terms, particularly copyleft-style licenses like GPLv2 and GPLv3. However,

License compliance ensures the absolute bare legal minimum on engaging with the Free Software community. While that is legally sufficient, the community actually wants to have all developers join the collaborative development process, where the resources for development are contributed and shared among all developers.

So I think if we had more contribution and a more fair distribution of the work in developing and maintaining the related software, we would not have to worry so much about legal enforcement of licenses.

However, in the absence of companies being good open source citizens, pulling out the legal baton is all we can do to at least require them to share their modifications at the time they ship their products. That code might not be mergeable, or it might be outdated, so it's value might be less than we would hope for, but it is a beginning.

Now some people might be critical of me speaking at a Black Duck Korea event, where Black Duck is a company selling (expensive!) licenses to proprietary tools for license compliance. Thereby, speaking at such an event might be seen as an endorsement of Black Duck and/or proprietary software in general.

Honestly, I don't think so. If you've ever seen a Black Duck Korea event, then you will notice there is no marketing or sales booth, and that there is no sales pitch on the conference agenda. Rather, you have speakers with hands-on experience in license compliance either from a community point of view, or from a corporate point of view, i.e. how companies are managing license compliance processes internally.

Thus, the event is not a sales show for proprietary software, but an event that brings together various people genuinely interested in license compliance matters. The organizers very clearly understand that they have to keep that kind of separation. So it's actually more like a community event, sponsored by a commercial entity - and that in turn is true for most technology conferences.

So I have no ethical problems with speaking at their event. People who know me, know that I don't like proprietary software at all for ethical reasons, and avoid it personally as far as possible. I certainly don't promote Black Ducks products. I promote license compliance.

Let's look at it like this: If companies building products based on Free Software think they need software tools to help them with license compliance, and they don't want to develop such tools together in a collaborative Free Software project themselves, then that's their decision to take. To state using words of Rosa Luxemburg:

Freedom is always the freedom of those who think different

I may not like that others want to use proprietary software, but if they think it's good for them, it's their decision to take.

Have you ever used mobile data on your phone or using Tethering?

In packet-switched cellular networks (aka mobile data) from GPRS to EDGE, from UMTS to HSPA and all the way into modern LTE networks, there is a tunneling protocol called GTP (GPRS Tunneling Protocol).

This was the first cellular protocol that involved transport over TCP/IP, as opposed to all the ISDN/E1/T1/FrameRelay world with their weird protocol stacks. So it should have been something super easy to implement on and in Linux, and nobody should have had a reason to run a proprietary GGSN, ever.

However, the cellular telecom world lives in a different universe, and to this day you can be safe to assume that all production GGSNs are proprietary hardware and/or software :(

In 2002, Jens Jakobsen at Mondru AB released the initial version of OpenGGSN, a userspace implementation of this tunneling protocol and the GGSN network element. Development however ceased in 2005, and we at the Osmocom project thus adopted OpenGGSN maintenance in 2016.

Having a userspace implementation of any tunneling protocol of course only works for relatively low bandwidth, due to the scheduling and memory-copying overhead between kernel, userspace, and kernel again.

So OpenGGSN might have been useful for early GPRS networks where the maximum data rate per subscriber is in the hundreds of kilobits, but it certainly is not possible for any real operator, particularly not at today's data rates.

That's why for decades, all commonly used IP tunneling protocols have been implemented inside the Linux kernel, which has some tunneling infrastructure used with tunnels like IP-IP, SIT, GRE, PPTP, L2TP and others.

But then again, the cellular world lives in a universe where Free and Open Source Software didn't exit until OpenBTS and OpenBSC changed all o that from 2008 onwards. So nobody ever bothered to add GTP support to the in-kernel tunneling framework.

In 2012, I started an in-kernel implementation of GTP-U (the user plane with actual user IP data) as part of my work at sysmocom. My former netfilter colleague and current netfilter core team leader Pablo Neira was contracted to bring it further along, but unfortunately the customer project funding the effort was discontinued, and we didn't have time to complete it.

Luckily, in 2015 Andreas Schultz of Travelping came around and has forward-ported the old code to a more modern kernel, fixed the numerous bugs and started to test and use it. He also kept pushing Pablo and me for review and submission, thanks for that!

Finally, in May 2016, the code was merged into the mainline kernel, and now every upcoming version of the Linux kernel will have a fast and efficient in-kernel implementation of GTP-U. It is configured via netlink from userspace, where you are expected to run a corresponding daemon for the control plane, such as either OpenGGSN, or the new GGSN + PDN-GW implementation in Erlang called erGW.

You can find the kernel code at drivers/net/gtp.c, and the userspace netlink library code (libgtpnl) at git.osmocom.org.

I haven't done actual benchmarking of the performance that you can get on modern x86 hardware with this, but I would expect it to be the same of what you can also get from other similar in-kernel tunneling implementations.

Now that the cellular industry has failed for decades to realize how easy and little effort would have been needed to have a fast and inexpensive GGSN around, let's see if now that other people did it for them, there will be some adoption.

If you're interested in testing or running a GGSN or PDN-GW and become an early adopter, feel free to reach out to Andreas, Pablo and/or me. The osmocom-net-gprs mailing list might be a good way to discuss further development and/or testing.

According to some news report, including this report at softpedia, a 26 year old student at the Faculty of Criminal Justice and Security in Maribor, Slovenia has received a suspended prison sentence for finding flaws in Slovenian police and army TETRA network using OsmocomTETRA

As the Osmocom project leader and main author of OsmocomTETRA, this is highly disturbing news to me. OsmocomTETRA was precisely developed to enable people to perform research and analysis in TETRA networks, and to audit their safe and secure configuration.

If a TETRA network (like any other network) is configured with broken security, then the people responsible for configuring and operating that network are to be blamed, and not the researcher who invests his personal time and effort into demonstrating that police radio communications safety is broken. On the outside, the court sentence really sounds like "shoot the messenger". They should instead have jailed the people responsible for deploying such an insecure network in the first place, as well as those responsible for not doing the most basic air-interface interception tests before putting such a network into production.

According to all reports, the student had shared the results of his research with the authorities and there are public detailed reports from 2015, like the report (in Slovenian) at https://podcrto.si/vdor-v-komunikacijo-policije-razkril-hude-varnostne-ranljivosti-sistema-tetra/.

The statement that he should have asked the authorities for permission before starting his research is moot. I've seen many such cases and you would normally never get permission to do this, or you would most likely get no response from the (in)competent authorities in the first place.

From my point of view, they should give the student a medal of honor, instead of sentencing him. He has provided a significant service to the security of the public sector communications in his country.

To be fair, the news report also indicates that there were other charges involved, like impersonating a police officer. I can of course not comment on those.

Please note that I do not know the student or his research first-hand, nor did I know any of his actions or was involved in them. OsmocomTETRA is a Free / Open Source Software project available to anyone in source code form. It is a vital tool in demonstrating the lack of security in many TETRA networks, whether networks for public safety or private networks.

Right now I'm feeling sad. I really shouldn't, but I still do.

Many years ago I started OpenBSC and Osmocom in order to bring Free Software into an area where it barely existed before: Cellular Infrastructure. For the first few years, it was "just for fun", without any professional users. A FOSS project by enthusiasts. Then we got some commercial / professional users, and with them funding, paying for e.g. Holger and my freelance work. Still, implementing all protocol stacks, interfaces and functional elements of GSM and GPRS from the radio network to the core network is something that large corporations typically spend hundreds of man-years on. So funding for Osmocom GSM implementations was always short, and we always tried to make the best out of it.

After Holger and I started sysmocom in 2011, we had a chance to use funds from BTS sales to hire more developers, and we were growing our team of developers. We finally could pay some developers other than ourselves from working on Free Software cellular network infrastructure.

In 2014 and 2015, sysmocom got side-tracked with some projects where Osmocom and the cellular network was only one small part of a much larger scope. In Q4/2015 and in 2016, we are back on track with focussing 100% at Osmocom projects, which you can probably see by a lot more associated commits to the respective project repositories.

By now, we are in the lucky situation that the work we've done in the Osmocom project on providing Free Software implementations of cellular technologies like GSM, GPRS, EDGE and now also UMTS is receiving a lot of attention. This attention translates into companies approaching us (particularly at sysmocom) regarding funding for implementing new features, fixing existing bugs and short-comings, etc. As part of that, we can even work on much needed infrastructural changes in the software.

So now we are in the opposite situation: There's a lot of interest in funding Osmocom work, but there are few people in the Osmocom community interested and/or capable to follow-up to that. Some of the early contributors have moved into other areas, and are now working on proprietary cellular stacks at large multi-national corporations. Some others think of GSM as a fun hobby and want to keep it that way.

At sysmocom, we are trying hard to do what we can to keep up with the demand. We've been looking to add people to our staff, but right now we are struggling only to compensate for the regular fluctuation of employees (i.e. keep the team size as is), let alone actually adding new members to our team to help to move free software cellular networks ahead.

I am struggling to understand why that is. I think Free Software in cellular communications is one of the most interesting and challenging frontiers for Free Software to work on. And there are many FOSS developers who love nothing more than to conquer new areas of technology.

At sysmocom, we can now offer what would have been my personal dream job for many years:

• paid work on Free Software that is available to the general public, rather than something only of value to the employer
• interesting technical challenges in an area of technology where you will not find the answer to all your problems on stackoverflow or the like
• work in a small company consisting almost entirely only of die-hard engineers, without corporate managers, marketing departments, etc.
• work in an environment free of Microsoft and Apple software or cloud services; use exclusively Free Software to get your work done

I would hope that more developers would appreciate such an environment. If you're interested in helping FOSS cellular networks ahead, feel free to have a look at http://sysmocom.de/jobs or contact us at jobs@sysmocom.de. Together, we can try to move Free Software for mobile communications to the next level!

This is great news: You can now install a GSM network using apt-get!

Thanks to the efforts of Debian developer Ruben Undheim, there's now an OpenBSC (with all its flavors like OsmoBSC, OsmoNITB, OsmoSGSN, ...) package in the official Debian repository.

Here is the link to the e-mail indicating acceptance into Debian: https://tracker.debian.org/news/755641

I think for the past many years into the OpenBSC (and wider Osmocom) projects I always assumed that distribution packaging is not really something all that important, as all the people using OpenBSC surely would be technical enough to build it from the source. And in fact, I believe that building from source brings you one step closer to actually modifying the code, and thus contribution.

Nevertheless, the project has matured to a point where it is not used only by developers anymore, and particularly also (god beware) by people with limited experience with Linux in general. That such people still exist is surprisingly hard to realize for somebody like myself who has spent more than 20 years in Linux land by now.

So all in all, today I think that having packages in a Distribution like Debian actually is important for the further adoption of the project - pretty much like I believe that more and better public documentation is.

Looking forward to seeing the first bug reports reported through bugs.debian.org rather than https://projects.osmocom.org/ . Once that happens, we know that people are actually using the official Debian packages.

As an unrelated side note, the Osmocom project now also has nightly builds available for Debian 7.0, Debian 8.0 and Ubunut 14.04 on both i586 and x86_64 architecture from https://build.opensuse.org/project/show/network:osmocom:nightly. The nightly builds are for people who want to stay on the bleeding edge of the code, but who don't want to go through building everything from scratch. See Holgers post on the openbsc mailing list for more information.

While preparing my presentation for the Troopers 2016 TelcoSecDay I was thinking once again about the importance of having FOSS implementations of cellular protocol stacks, interfaces and network elements in order to enable security researches (aka Hackers) to work on improving security in mobile communications.

From the very beginning, this was the motivation of creating OpenBSC and OsmocomBB: To enable more research in this area, to make it at least in some ways easier to work in this field. To close a little bit of the massive gap on how easy it is to do applied security research (aka hacking) in the TCP/IP/Internet world vs. the cellular world.

We have definitely succeeded in that. Many people have successfully the various Osmocom projects in order to do cellular security research, and I'm very happy about that.

However, there is a back-side to that, which I'm less happy about. In those past eight years, we have not managed to attract significant amount of contributions to the Osmocom projects from those people that benefit most from it: Neither from those very security researchers that use it in the first place, nor from the Telecom industry as a whole.

I can understand that the large telecom equipment suppliers may think that FOSS implementations are somewhat a competition and thus might not be particularly enthusiastic about contributing. However, the story for the cellular operators and the IT security crowd is definitely quite different. They should have no good reason not to contribute.

So as a result of that, we still have a relatively small amount of people contributing to Osmocom projects, which is a pity. They can currently be divided into two groups:

• the enthusiasts: People contributing because they are enthusiastic about cellular protocols and technologies.
• the commercial users, who operate 2G/2.5G networks based on the Osmocom protocol stack and who either contribute directly or fund development work at sysmocom. They typically operate small/private networks, so if they want data, they simply use Wifi. There's thus not a big interest or need in 3G or 4G technologies.

On the other hand, the security folks would love to have 3G and 4G implementations that they could use to talk to either mobile devices over a radio interface, or towards the wired infrastructure components in the radio access and core networks. But we don't see significant contributions from that sphere, and I wonder why that is.

At least that part of the IT security industry that I know typically works with very comfortable budgets and profit rates, and investing in better infrastructure/tools is not charity anyway, but an actual investment into working more efficiently and/or extending the possible scope of related pen-testing or audits.

So it seems we might want to think what we could do in order to motivate such interested potential users of FOSS 3G/4G to contribute to it by either writing code or funding associated developments...

If you have any thoughts on that, feel free to share them with me by e-mail to laforge@gnumonks.org.

Today I had the pleasure of presenting about Open Source Network Elements for Security Analysis of Mobile Networks at the Troopers 2016 TelcoSecDay.

The main topics addressed by this presentation are:

• Importance of Free and Open Source Software implementations of cellular network protocol stacks / interfaces / network elements for applied telecom security research
• The progress we've made at Osmocom over the last eight years.
• An overview about our current efforts to implement at 3G Network similar to the existing 2G/2.5G/2.75G implementations.

There are no audio or video recordings of this session.

Slides are available at http://git.gnumonks.org/index.html/laforge-slides/plain/2016/telcosecday/foss-gsm.html

Today I had the pleasure of co-presenting with Shane Coughlan the Linaro Connect BKK16 Keynote on GPL compliance about GPL compliance.

The main topics addressed by this presentation are:

• Brief history about GPL enforcement and how it has impacted the industry
• Ultimate Goal of GPL enforcement is compliance
• The license is not an end in itself, but rather to facilitate collaborative development
• GPL compliance should be more engineering and business driven, not so much legal (compliance) driven.

The video recording is available at https://www.youtube.com/watch?v=b4Bli8h0V-Q

Slides are available at http://git.gnumonks.org/index.html/laforge-slides/plain/2016/linaroconnect/compliance.html

The video of a corresponding interview is available from https://www.youtube.com/watch?v=I6IgjCyO-iQ

Today, I took some time off to attend the court hearing in the GPL violation/infringement case that Christoph Hellwig has brought against VMware.

I am not in any way legally involved in the lawsuit. However, as a fellow (former) Linux kernel developer myself, and a long-term Free Software community member who strongly believes in the copyleft model, I of course am very interested in this case - and of course in an outcome in favor of the plaintiff. Nevertheless, the below report tries to provide an un-biased account of what happened at the hearing today, and does not contain my own opinions on the matter. I can always write another blog post about that :)

I blogged about this case before briefly, and there is a lot of information publicly discussed about the case, including the information published by the Software Freedom Conservancy (see the link above, the announcement and the associated FAQ.

Still, let's quickly summarize the facts:

• VMware is using parts of the Linux kernel in their proprietary ESXi product, including the entire SCSI mid-layer, USB support, radix tree and many, many device drivers.
• as is generally known, Linux is licensed under GNU GPLv2, a copyleft-style license.
• VMware has modified all the code they took from the Linux kernel and integrated them into something they call vmklinux.
• VMware has modified their proprietary virtualization OS kernel vmkernel with specific API/symbol to interact with vmklinux
• at least in earlier versions of ESXi, virtually any block device access has to go through vmklinux and thus the portions of Linux they took
• vmklinux and vmkernel are dynamically linked object files that are linked together at run-time
• the Linux code they took runs in the same execution context (address space, stack, control flow) like the vmkernel.

Ok, now enter the court hearing of today.

Christoph Hellwig was represented by his two German Lawyers, Dr. Till Jaeger and Dr. Miriam Ballhausen. VMware was represented by three German lawyers lead by Matthias Koch, as well as a US attorney, Michael Jacobs (by means of two simultaneous interpreters). There were also several members of the in-house US legal team of VMware present, but not formally representing the defendant in court.

As is unusual for copyright disputes, there was quite some audience following the court. Next to the VMware entourage, there were also a couple of fellow Linux kernel developers as well as some German IT press representatives following the hearing.