fidzu : OpenMoko

I've mentioned some of my various retronetworking projects in some past blog posts. One of those projects is Osmocom Community TDM over IP (OCTOI). During the past 5 or so months, we have been using a number of GPS-synchronized open source icE1usb interconnected by a new, efficient but strill transparent TDMoIP protocol in order to run a distributed TDM/PDH network. This network is currently only used to provide ISDN services to retronetworking enthusiasts, but other uses like frame relay have also been validated.

So far, the central hub of this OCTOI network has been operating in the basement of my home, behind a consumer-grade DOCSIS cable modem connection. Given that TDMoIP is relatively sensitive to packet loss, this has been sub-optimal.

Luckily some of my old friends at noris.net have agreed to host a new OCTOI hub free of charge in one of their ultra-reliable co-location data centres. I'm already hosting some other machines there for 20+ years, and noris.net is a good fit given that they were - in their early days as an ISP - the driving force in the early 90s behind one of the Linux kernel ISDN stracks called u-isdn. So after many decades, ISDN returns to them in a very different way.

Side note: In case you're curious, a reconstructed partial release history of the u-isdn code can be found on gitea.osmocom.org

But I digress. So today, there was the installation of this new OCTOI hub setup. It has been prepared for several weeks in advance, and the hub contains two circuit boards designed entirely only for this use case. The most difficult challenge was the fact that this data centre has no existing GPS RF distribution, and the roof is ~ 100m of CAT5 cable (no fiber!) away from the roof. So we faced the challenge of passing the 1PPS (1 pulse per second) signal reliably through several steps of lightning/over-voltage protection into the icE1usb whose internal GPS-DO serves as a grandmaster clock for the TDM network.

The equipment deployed in this installation currently contains:

• a rather beefy Supermicro 2U server with EPYC 7113P CPU and 4x PCIe, two of which are populated with Digium TE820 cards resulting in a total of 16 E1 ports

• an icE1usb with RS422 interface board connected via 100m RS422 to an Ericsson GPS03 receiver. There's two layers of of over-voltage protection on the RS422 (each with gas discharge tubes and TVS) and two stages of over-voltage protection in the coaxial cable between antenna and GPS receiver.

• a Livingston Portmaster3 RAS server

• a Cisco AS5400 RAS server

For more details, see this wiki page and this ticket

Now that the physical deployment has been made, the next steps will be to migrate all the TDMoIP links from the existing user base over to the new hub. We hope the reliability and performance will be much better than behind DOCSIS.

In any case, this new setup for sure has a lot of capacity to connect many more more users to this network. At this point we can still only offer E1 PRI interfaces. I expect that at some point during the coming winter the project for remote TDMoIP BRI (S/T, S0-Bus) connectivity will become available.

18 Sep 2022 10:00pm GMT

I'm happy to announce active participation at the Vintage Computing Festival Berlin 2022 in two ways:

• Running a retronetworking exhibit on Modem and ISDN dial-up

• Giving a talk on the Osmocom Community TDMoIP netwokr

The exhibit will be similar to the exhibit at the retrocomputing village of the last CCC congress (36C3): A digital telephony network with ISDN BRI and POTS lines providing services to a number of laptops with Modems and ISDN terminal adapters.

We plan to demo the following things: * analog modem and ISDN dial-up into BBSs ** text / ANSI interfaces via Telix, Telemate, Terminate ** RIPterm graphical interfaces * analog modem and ISDN dial-up IP/internet * ISDN video telephony

The client computers will be contemporary 486/Pentium machines wit DOS, Windows 3.11 and OS/2.

08 Sep 2022 10:00pm GMT

Almost one year after my post regarding first steps towards a V5 implementation, some friends and I were finally able to visit Wobcom, a small German city carrier and pick up a lot of decommissioned POTS/ISDN/PDH/SDH equipment, primarily V5 access networks.

This means that a number of retronetworking enthusiasts now have a chance to play with Siemens Fastlink, Nokia EKSOS and DeTeWe ALIAN access networks/multiplexers.

My primary interest is in Nokia EKSOS, which looks like an rather easy, low-complexity target. As one of the first steps, I took PCB photographs of the various modules/cards in the shelf, take note of the main chip designations and started to search for the related data sheets.

The results can be found in the Osmocom retronetworking wiki, with https://osmocom.org/projects/retronetworking/wiki/Nokia_EKSOS being the main entry page, and sub-pages about

• Node Control Unit

• 16x BRI Uk0 Line Card

• 32x POTS Line Card

• Line Measurement Unit

• Shelf

In short: Unsurprisingly, a lot of Infineon analog and digital ICs for the POTS and ISDN ports, as well as a number of Motorola M68k based QUICC32 microprocessors and several unknown ASICs.

So with V5 hardware at my disposal, I've slowly re-started my efforts to implement the LE (local exchange) side of the V5 protocol stack, with the goal of eventually being able to interface those V5 AN with the Osmocom Community TDM over IP network. Once that is in place, we should also be able to offer real ISDN Uk0 (BRI) and POTS lines at retrocomputing events or hacker camps in the coming years.

08 Sep 2022 10:00pm GMT

If you have ever worked with Digium (now part of Sangoma) digital telephony interface cards such as the TE110/410/420/820 (single to octal E1/T1/J1 PRI cards), you will probably have seen that they always have a timing connector, where the timing information can be passed from one card to another.

In PDH/ISDN (or even SDH) networks, it is very important to have a synchronized clock across the network. If the clocks are drifting, there will be underruns or overruns, with associated phase jumps that are particularly dangerous when analog modem calls are transported.

In traditional ISDN use cases, the clock is always provided by the network operator, and any customer/user side equipment is expected to synchronize to that clock.

So this Digium timing cable is needed in applications where you have more PRI lines than possible with one card, but only a subset of your lines (spans) are connected to the public operator. The timing cable should make sure that the clock received on one port from the public operator should be used as transmit bit-clock on all of the other ports, no matter on which card.

Unfortunately this decades-old Digium timing cable approach seems to suffer from some problems.

08 Sep 2022 10:00pm GMT

As some of you may know, I've been starting to collect "vintage" telecommunications equipment starting from analog modems to ISDN adapters, but also PBXs and even SDH equipment. The goal is to keep this equipment (and related software) alive for demonstration and practical exploration.

Some [incomplete] information can be found at https://osmocom.org/projects/retro-bbs/wiki/

Working with PBXs to simulate the PSTN (ISDN/POTS) network is fine to some extent, but it's of course not the real deal. You only get S0-buses and no actual Uk0 like actual ISDN lines of the late 80ies and 90ies. You have problems with modems not liking the PBX dialtone, etc.

Hence, I've always wanted to get my hand on some more real-world central-office telephone network equipment, and I finally have a source for so-called V5.1/V5.2 access multiplexers. Those are like remote extension boxes for the central office switch (like EWSD or System 12). They aggregate/multiplex a number of analog or ISDN BRI subscriber lines into E1 lines, while not implementing any of the actual call control or ISDN signalling logic. All of that is provided by the actual telephone switch/exchange.

So in order to integrate such access multiplexers in my retronetworking setup, I will have to implement the LE (local exchange) side of the V5.1 and/or V5.2 protocols, as specified in ITU-T G.964 and G.965.

In the limited spare time I have next to my dayjob and various FOSS projects, progress will likely be slow. Nonetheless I started with an implementation now, and I already had a lot of fun learning about more details of those interfaces and their related protocols.

One of the unresolved questions is to what kind of software I would want to integrate once the V5.x part is resolved.

• lcr would probably be the most ISDN-native approach, but it is mostly unused and quite EOL.

• Asterisk or FreeSWITCH would of course be obvious candidates, but they are all relatively alien to ISDN, and hence not very transparent once you start to do anything but voice calls (e.g. dialup ISDN data calls in various forms).

• yate is another potential candidate. It already supports classic SS7 including ISUP, so it would be a good candidate to build an actual ISDN exchange with V5.2 access multiplexers on the customer-facing side (Q.921+Q.931 on it) and SS7/ISUP towards other exchanges.

For now I think yate would be the most promising approach. Time will tell.

The final goal would then be to have a setup [e.g. at a future CCC congress] where we would have SDH add/drop multiplexers in several halls, and V5.x access multiplexers attached to that, connecting analog and ISDN BRI lines from individual participants to a software-defined central exchange. Ideally actually multiple exchanges, so we can show the signaling on the V5.x side, the Q.921/Q.931 side and the SS7/ISUP between the exchanges.

Given that the next CCC congress is not before December 2022, there is a chance to actually implement this before then ;)

10 Oct 2021 10:00pm GMT

[excuse this German-language post, this is targeted at the current German public discourse]

Ein paar Ergänzungen zu meinem blog-post gestern.

Ich benutzt den generischen Begriff PWS statt SMSCB, weil SMSCB strikt genommen nur im 2G-System existiert, und nur ein Layer ist, der dort für Notfallalarmierung verwendet wird.

19 Jul 2021 10:00pm GMT

18 Jul 2021 10:00pm GMT

[excuse this German-language post, this is targeted at the current German public discourse]

In mehrerern Gegenden Deutschlands gab es verheerende Hochwasser, und die Öffentlichkeit diskutiert deshalb mal wieder die gute alte Frage nach dem adäquaten Mittel der Alarmierung der Bevölkerung.

Es ist einfach nur ein gigantisches Trauerspiel, wie sehr die Deutsche Politik und Verwaltung in diesem Punkt inzwischen seit Jahrzehnten sämtliche relevanten Standards verpennt, und dann immer wieder öffentlich durch fachlich falsche und völlig uninformierte Aussagen auffällt.

Das Thema wurde vor dem aktuellen Hochwasser bereits letztes Jahr im Rahmen des sog. WarnTag öffentlich diskutiert. Auch hier von Seiten der öffentlichen Hand ausschliesslich mit falschen Aussagen, wie z.B. dass es bei Cell Broadcast Datenschutzprobleme gibt. Dabei ist Cell Broadcast die einzige Technologie, wo keine Rückmeldung des einzelnen Netzteilnehmers erfolgt, und das Netz nichtmal weiss, wer die Nachricht empfangen hat, und wo dieser Empfang stattgefunden hat. Ganz wie beim UKW-Radio.

Fakt ist, dass alle digitalen Mobilfunkstandards seit GSM/2G, d.h. seit 1991 die Möglichkeit mitbringen, effizient, schnell und datensparsam alle Nutzer (einer bestimmten geographischen Region) mit sogenannten broadcast Nachrichten zu informieren. Diese Technik, in GSM/2G genannt Cell Broacast (oder auch _SMSCB_), unterscheidet sich Grundlegend von allen anderen Kommunikationsformen im Mobilfunknetz, wie Anrufe und herkömmliche SMS (offiziell SMS-PP). Anrufe, SMS und auch mobile Paketdaten (Internet) werden immer für jeden Teilnehmer individuell auf ihm zugewiesenen Funkressourcen übermittelt. Diese Ressourcen sind beschränkt. Es können in keinem Mobilfunknetz der Welt alle Teilnehmer gleichzeitig telefonieren, oder gleichzeitig SMS empfangen.

Stattdessen benutzt Cell Broadcast - wie der Name bereits unmissverständlich klar macht - Einen broadcast, d.h. Rundsendemechanismus. Eine Nachricht wird einmal gesendet, benötigt also nur eine geteilte Ressource auf der Luftschnittstelle, und wird dann von allen Geräten im Empfangsbereich zeitgleich empfangen und dekodiert. Das ist wie UKW-Radio oder klassisches terrestrisches Fernsehen.

Cell Broadcast wurde bereits in den 1990er Jahren von Deutschen Netzbetreibern benutzt. Und zwar nicht für etwas lebensnotwendiges wie die Notfallsignalisierung, sondern für so banale Dinge wie die Liste jener Vorwahlen, zu denen gerade ein vergünstigter "wandernder Ortstarif" Besteht. Ja, sowas gab es mal bei Vodafone. Oder bei O2 wurden über lange Zeit (aus unbekannten Gründen) die GPS-Koordinaten der jeweiligen Basisstation als Cell Broadcast versendet.

In der folgenden (nun fast abgeschalteten) Mobilfunkgeneration 3G wurde Cell Broadcast leicht umbenannt als Service Area Broadcast beibehalten. Schliesslich gibt es ja Länder mit - anders als in Deutschland - funktionierender und kompetenter Regulierung des Telekommunikationsmarktes, und die langjährig bestehenden gesetzlichen Anforderungen solcher Länder zwingen die Netzbetreiber und auch die Ausrüster der Neztbetreiber, neue Mobilfunkstandards so zu entwickeln, dass die gesetzlichen Vorgaben bzgl. der Alarmierung der Bevölkerung im Notfall funktioniert.

Im Rahmen dieser Standardisierung haben eine Reihe von Ländern innerhalb der 3GPP-Standardisierung (zuständig für 2G, 3G, 4G, 5G) sogenannte Public Warning Systems (PWS) standardisiert. Zu diesen gehören z.B. das Japanische ETWAS (Earthquake and Tsunami Warning System), das Koreanische KPAS (Korean Public Alerting System), das US-Amerikanische WEA (Wireless Emergency Alerts, früher bekannt als CMAS) und auch das EU-ALERT mit den nationalen Implementationen NL-ALERT (Niederlande) und UK-ALERT (Großbritannien) sowie RO-ALERT (Rumänien).

Die zahlreichen Studien und Untersuchungen, die zur Gestaltung obiger Systeme und der internationalen Standards im Mobilfunk geführt haben, weisen auch nochmal nach, was sowieso vorher jedem Techniker offensichtlich erscheint: Eine schelle Alarmierung aller Teilnehmer (einer Region) kann nur über einen Broadcast-Mechanismus erfolgen. In Japan war die Zielvorgabe, die Alarmierung in Erdbebenfällen innerhalb von weniger als 4 Sekunden an die gesamte betroffene Bevölkerung zu übertragen. Und das ist mit PWS möglich!

Die relevanten PWS-Standards in 2G/3G/4G/5G bieten jede Menge nützliche Funktionen:

• Benachrichtigung in bestimmten geographischen Regionen

• Interoperable Schnittstellen, so dass Netzwerkelemente unterschiedlicher Hersteller miteinander kommunizieren

• Konfigurierbare Benachrichtigungstexte, nicht nur in der primären Landessprache, sondern auch in mehreren anderen Sprachen, die dann automatisch je nach Spracheinstellung des Telefons wiedergegeben werden

• Unterschiedliche Schweregrade von Alarmierungen

• Übermittlung nicht nur im Broadcast, sondern auch im Unicast an jeden Teilnehmer, der gerade in einem Telefongespräch ist, und dessen Telefon gerade währenddessen aus technischen Gründen den Broadcast nicht empfangen würde

• Unterschied zwischen Wiederholung einer Übertragung ohne Änderung des Inhalts und einer übertragung mit geändertem Inhalt

Es gibt also seit vielen Jahren internationale Standards, wie sämtliche heute eingesetzten Mobilfunktechniken zur schnellen, effizienten und datensparsamen Alarmierung der Bevölkerung eingesetzt werden können.

Es gibt zahlreiche Länder, die diese Systeme seit langem einsetzen. Das US-Amerikanische WEA wurde nach eigenen Angaben seit 2012 bereits mehr als 61.000 Mal benutzt, um Menschen vor Unwetter oder anderen Katastrophen zu warnen.

Sogar innerhalb der EU hat man das EU-ALERT System spezifiziert, welches weitgehend mit dem amerikanischen WEA identisch ist, und auf die gleichen Techniken aufbaut.

Und dann gibt es Länder wie Deutschland, die es seit genauso vielen Jahren vermissen lassen, durch Gesetze oder Vorschriften

1. die Netzbetreiber zum Betrieb dieser Broadcast-Technologien in ihrem Netz verpflichtet

2. die Netzbetreiber zur Bereitstellung von standardisierten Schnittstellen gegenüber den Behörden wie Zivilschutz / Katastrophenschutz zu verpflichten, so das diese selbständig über alle Netzbetreiber Warnungen versenden können

3. die Gerätehersteller z.B. über Vorschriften des FTEG (Gesetz über Funkanlagen und Telekommunikationsendeinrichtungen) zu Verpflichten, die PWS-Nachrichten anzuzeigen

In den USA, dem vermeintlich viel mehr dem Freien Markt und dem Kapitalismus anhängenden System ist all dies der Regulierungsbehörde FCC möglich. In Deutschland mit seiner sozialen Marktwirtschaft ist es anscheinend unmöglich, den Markt entsprechend zu regulieren. Eine solche Regulierung schafft man in Deutschland nur für wirklich wichtige Themen wie zur Durchsetzung der Bereitstellung von Schnittstellen für die Telekommunikationsüberwachung. Bei so irrelevanten Themen wie dem Katastrophenschutz und der Alarmierung der Bevölkerung braucht man den Markt nicht zu regulieren. Wenn die Netzbetreiber kein PWS anbieten wollen, dann ist das einfach so Gottgegeben, und man kann da ja nichts machen.

Falls jemand sich SMSCB und PWS technisch näher ansehen will: In 2019 haben wir im Osmocom-Projekt eine Open Source Implementation des kompletten Systems von BTS über BSC bis zum CBC, sowie der dazwischen befindlichen Protokolle wie CBSP vorgenommen. Dies wurde freundlicherweise durch den Prototype Fund mit EUR 35k finanziert. Ja, so günstig kann man die nötige Technik zumindest für eine einzelne Mobilfunkgeneration entwickeln...

Man kann also in einem selbst betriebenen Labor-Mobilfunknetz, welches auf Open Source Software basiert mehr in Punkt standardkonformer Notfallalarmierung, als die Deutsche Politik, Verwaltung und Netzbetreiber zusammen hinbekommen.

Wir haben in Deutschland Leute, die diese Standards in und auswendig kennen, sogar daran mitgearbeitet haben. Wir haben Entwickler, die diese Standards implementiert haben. Aber wir schaffen es nicht, das auch mal selbst praktisch zu benutzen - das überlassen wir lieber den anderen Ländern. Wir lassen lieber zuerst die ganze Katastrophenalarmierung mittels Sirenen vergammeln, machen den Netzbetreibern keine Vorgaben, entwicklen komische Apps, die Anwender extra installieren müssen, die prinzipbedingt nicht skalieren und beim Test (WarnTag) nicht funktionieren.

Was für eine Glanzleistung für den hochentwickelten Techhologie-Standort Deutschland.

18 Jul 2021 10:00pm GMT

Converting an existing Objective-C/Swift framework to Swift Package Manager I'm a big fan of the database library YapDatabase, which is a collection/key/value store for macOS, iOS, tvOS & watchOS. It comes with many high level features and is built atop sqlite. In the last 5 years, I have used this successfully for many of my projects. It is written in Objective-C and comes with a bunch of Swift files for more Swifty use. Since I recently announced to go all-in with Swift, I want to convert all my dependencies to the Swift Package Management system. I have never been a fan of CocoaPods or Carthage as I found them too invasive. As this point of time though, YapDatabase is not Swift Package Manager (SPM) compatible and all approaches to do this using the current source layout did fail. So I had a fresh look at it and decided to do it slightly differently: If you don't have to work with the constraints of an existing tree layout, the process is relatively straightforward. Read on to find out what I did. Prerequisites Use swift package init to create a package named YapDatabase. Edit Package.swift to make the package create two libraries with associated targets ObjCYapDatabase is going to hold the Objective-C part in Sources/ObjCYapDatabase, SwiftYapDatabase is going to hold the Swift parts in Sources/SwiftYapDatabase. I couldn't name the Objective-C library simply YapDatabase, since this would have required to rename the (then umbrella) header file YapDatabase.h, which I didn't want to. Swift vs. Objective-C At the moment, SPM is not capable of handling mixed language targets, i.e., you either have only Swift files or no Swift files at all in your target - therefore I split the repository accordingly and moved Swift files below Sources/SwiftYapDatabase. Source and Header file locations SPM is pretty rigid when it comes to the location of source and header files. This is the reason why I unfortunately could not deliver this work on top of the original source repository. Fortunately though, the source repository was very well structured. To layout the files in a way that makes SPM happy, I Created two header file directory, include for public headers, privateInclude for private headers. Moved all header files from Internal directories and those with private in their name to the privateInclude directory. Moved the remaining header files to the public include directory. Swift The aforementioned steps were enough to make SPM compile the ObjCYapDatabase. To make the Swift part compile, I had to Edit all Swift files to import ObjCYapDatabase instead of Foundation via sed -i -e s,Foundation,ObjCYapDatabase,g *.swift. This made the SwiftYapDatabase compile. What's Next There are some parts missing: I didn't include the example programs, the tests, and the Xcode project. I don't know Robbie Hanson's (creator of YapDatabase) plans. As it stands, this shuffling around was merely a proof-of-concept to find out whether such an approach is sufficient to SPM-ify YapDatabase or whether to there are more problems to consider. I will incorporate this in one of my projects to put it through a real world test. I have published the repository as mickeyl/SwiftYapDatabase and will report this work via the YapDatabase issue tracker. Let's see what happens next.

18 Oct 2020 12:00pm GMT

Why unfair?

Well when I obtained the iCE40HX8K-EVB it had already existed for quite some time the ULX3S I had just received the unit from the Crowd Supply campaign.
And Olimex therefore had lots of time to "perfect" the documentation Radiona on the other hand has not yet had the luxury of time yet.

Hardware

Well I'm not really going to… The FPGA on the ULX3S is quite powerful and the board itself has more features as well, lets just call them different classes of products.

Software

Well both FPGAs are supported by the open source command line friendly toolchains.
Xilinx years ago sort of cured me of any desire for using huge closed source applications for programmable logic.
Many thanks to the developers of yosys, icestorm, nextpnr, prjtrellis, writers of programmer software and GNU / libre-software in general.

Getting started documentation

I must admit that I'm not that impressed with the getting started experience.

The Radiona wiki links to what they call the ULX3S official site.
And at the time of writing this I find it somewhat lacking in getting started information.
Things I miss:

• How to power the board (without frying it or having to look closely at the schematic).
• Precompiled "hello world" bit streams for the different variants of the FPGA on there boards.
• A simple guide on flashing said bit stream using the build in programmer on the board.

Eventually one does find the https://github.com/emard/ulx3s-examples, and gets around to compiling the toolchain for ECP5 (I previously only compiled it for ICE40)
However when trying to flash the bitstream (after changing the makefile to suit the 85F variant that I got)
The pre build binary of ujprog that comes with the example code fails with the message

ULX2S / ULX3S JTAG programmer v 3.0.92 (built Oct 3 2020 19:32:10)
Cannot find JTAG cable.

I have try to specify the port using -P and it does get a LED flashing but no blinking LEDs.
I also try to build ujprog from the sources, but I get the same massage including the version number.

Longer down the road I stumble across https://github.com/q3k/ulx3s-foss-blinky.git which from the get go targets my variant of FPGA (let doubt that I just compile the bitcode the wrong way)
It uses OpenOCD to do the flashing and best of all it WORKS

The OpenOCD flashing does seem to be a bit slow though… So I keep looking and finds a manual of sorts it has a list of programming options and even a description of how to power the board.
The list contains a different programmer openFPGALoader that seems to have more resent updates than ujprog, and the schematic does have a note about them changing the wiring of the programmer in a revision of the board.
Compiles the code, fingers crossed that they have updated it to match the production PCB…

Success 2: openFPGALoader -board=ulx3s bitstream.bit also works

Conclusiuon

Is the current documentation a bit rough around the edges? Probably yes.
Is the board amassing?
Probably also yes…
I mean the FPGA is large enough to hold an entire Amiga "implementation".
The quality of the hardware looks nice too.
And the board contains an integrated programmer and a selection of peripherals to keep me busy for a while.

Would I recommend the board… Well I haven't spend enough time with it just yet, but it does seem likely.

If you do get the 85F I would recommend the ulx3s-foss-blinky as a hello world.
And if you have a production PCB i would recommend checking out openFPGALoader for flashing the bit stream.

04 Oct 2020 9:23am GMT

While I never got much into natural languages (beyond my native tounge, a halfway solid english, and some bits and pieces of french), I have always been fascinated by (some) programming languages - I even wrote books about some of them. I (literally) grew up with BASIC and 6502/6510 ASSEMBLER - on the VC20 and the C64. Later on, learned to hate C and love 680x0 ASSEMBLER - on the AMIGA. During the 90s, I enjoyed PASCAL and MODULA II, and then found a preliminary home in Python. The 2000s were largely affected by C++ (which I always found much more interesting than JAVA) until I got acquainted with Objective-C - which later rised to the 2nd place in my top list - shared with Vala, which I still have a sweet spot for, since it liberated me from having to use C. As I grew older (and suddenly realized that my lifetime is actually limited, imagine my surprise…), I learned to embrace higher abstractions and being able to formulate algorithms clear and concise. While Python allowed me to do that, its reliance on runtime errors as opposed to compile-time always bugged me. During the 2010s, I settled on using Python on the server, and Objective-C on the client - still dreaming about a language I could use for both. Fast-forward to 2020. I have been a vocal critic of Apple's new language, Swift, since its debut - for reasons which I'm not going to repeat. Three months have passed since I started learning Swift and I think it's time for a first preliminary report. TLDR: I like it - a lot more than I have ever thought - and will from now on try to use it pretty much everywhere. Before moving on with some details, let me also confess that I'm pretty glad having waited for so long. Judging from the outside, the road to Swift 5 was a very rocky ride. Were I to begin with an earlier version, I might have given up or wasted many hours following a language that was such a moving target - changing every year in more ways than I would have been willing to participate. Syntax, Semantics, and Idioms Swift is very expressive and rich in syntax, semantics, and idioms - and it has a tough learning curve. As someone who has written Objective-C for almost a decade now, let me tell you that whoever told you that Swift is more accessible than Objective-C is a downright lier. Objective-C is a very simple language, as it adds one (yes, just one) construct (and some decorators) on top of another simple language - C. Once I was beyond my reluctance to look into it, I finally see the beauty. Swift has almost everything I have ever wanted in a programming language. Among many other features, it has type safety, generics, multiple inheritance (in the disguise of protocols with default implementation), closures, type inference, namespaces (ok, not first class, but think enums without cases), rich enums, … On top of that it has a REPL (Read-Eval-Print-Loop), which can't be praised enough - it is the #1 missing feature in most compiled languages - and syntax for building DSLs (Domain Specific Languages). And: It is Open Source - which is the #1 feature that has always irritated me with Objective-C. Interoperability I hate repeating myself. I love generic solutions. Over the last decade, I created a number of reusable frameworks that powered all the apps I wrote. It has accumulated quite a bit of stuff, as you can see here (generated using David A Wheeler's SLOCCount): SLOC Directory SLOC-by-Language (Sorted) 2110719 LTSupportCore objc=2063905,ansic=31423,java=5914,cs=3822,cpp=2772, python=2397,sh=486 106939 LTSupportDB objc=106108,sh=831 35669 LTSupportTracking objc=17443,ansic=12219,cpp=4922,java=902,sh=128, python=55 30331 LTSupportUI objc=30053,sh=278 27116 LTSupportDRM objc=27116 9499 LTSupportBluetooth objc=9365,python=134 6143 LTSupportAutomotive objc=6143 5141 LTSupportAudio objc=5141 4510 LTSupportVideo objc=4510 3324 LTSupportCommonControls objc=3324 679 LTSupportDBUI objc=679 340 LTSupportMidi objc=340 271 LTSupportDiagnostics objc=271 One of the things contributing to scare me before switching to Swift was that I may had to rewrite all that again. But it ain't necessarily so. Calling Objective-C from Swift Being probably the company that has the largest Objective-C codebase in the world, Apple worked hard on interoperability. Calling Objective-C from Swift is a breeze - they'll even convert method names for you. Not much to complain here. Almost every Objective-C construct is visible to Swift. Calling Swift from Objective-C Calling Swift from Objective-C is a tad bit harder. Apart from having to including (generated) extra headers, the whole plane of types with value semantics is more or less invisible to Objective-C. There are ways to bridge (AnyObject), but it's cumbersome and sometimes very for generic code (__SwiftValue__). Beyond Apple In a surprising move, Apple released Swift as an open source project. And although the struggle of combining a product oriented software release cycle with a community oriented evolution process is sometimes obvious (you can follow the tension if you read some of the evolution threads on the Swift forums), they manage it quite well. What catched my attention in particular was the invention of Server-side Swift and the Swift Package Manager, since these two projects have the power to replace my use of Python forever. Foreign Platforms My new set of swift-frameworks will be open source and also support UNIX-like platforms (to a certain degree, since Apple still has their crown jewels like UIKit and AppKit closed), hence finally I can use my reusable solutions both on the client and the server. Unfortunately Google backed somewhat out of using Swift. For quite some time it looked like they would embrace it as another first-class language for their forthcoming Android successor. This would have been the icing on the cake, but let's see - Kotlin is pretty similar Swift, but not it. Conclusion I'm now familiar enough with Swift that I made the decision to go all-in, helping to improve the server-side ecosystem as I go. Speaking about which - I still miss a bunch of features, in particular first-class coroutines for asynchronous algorithms, a proper database abstraction, and a cross-platform logging solution. But what I enjoy the most is to be a part of a vibrant (language) community again. People are way more excited when it comes to Swift as they ever were with Objective-C. And this is great!

03 Oct 2020 12:00pm GMT

I assume you already have a working virtual machine that uses pci passthrough and that it works just fine with other games.

BUT very time you start up MS Flight Simulator 2020 Windows crashes with a blue screen of death.
It took me some time to figure out, so I'm writing this in the hope that it saves some other poor souls time.

The fix is quite simple you need to give the option "ignore_msrs=1" to the kvm kernel module.
Create the file "/etc/modprobe.d/kvm.conf"
Containing the line "options kvm ignore_msrs=1"
And reboot the host.

See: https://wiki.archlinux.org/index.php/QEMU#Certain_Windows_games/applications_crashing/causing_a_bluescreen for a slightly more in depth explanation of this.

13 Sep 2020 6:56am GMT

For some years now, I have been feeling like Don Quixote fighting against windmills. This is a multidimensional feeling that has its roots in both personal and professional circumstances. With regards to personal issues, I won't go into details as I want to keep this blog free from politics, society, and economics. With regards to professional circumstances, something that bugs me a lot is that I seem to engage in fighting wars that can't be won. Free software lost a lot of wars, most notably though in the mobile sector. As I have complained more than once before, over the last decade, the phone and tablet world has become much less free. Even big companies struggle these days and it looks like we're stuck with a duopoly for a long long time. Today though I want to complain about one of these two players, namely the Apple development platforms. By 2013, software development for Apple devices was a lot of fun. We had a great mature language, nice frameworks, and a big market to try out all kinds of ideas and ways to make a living. For some reason though this changed, when Apple introduced the Swift programming language. It split the developer world and alienated a lot of the veterans. The claims of better readability, performance, and what not could not be achieved. In fact, I (and a lot of people not wearing rose-colored glasses agree with me) think, what has been proposed as a way to flatten the learning curve is actually harder to learn and less readable. For the major part of the last years I ignored everything Swift, hoping that for the remainder of my professional career (lets say 20 more years, if all goes well) Objective-C would be at least well enough supported that I could continue writing programs -- even without a vibrant open source community (since most folks have switched to Swift immediately and despite popular belief mix and match is not a thing) and proper API docs. Last year though the first swift-only frameworks and a whole new approach for semi-declarative UIs appeared. SwiftUI -- they even named it like the programming language sigh. This year they are "moving forward" by deprecating more Objective-C frameworks and introducing SwiftUI as the one and only way in some places. It's now clear to me: It's either I leave the platform or I stop trying to achieve perfection with a certain -- restricted -- set of tools but rather walking their rocky road. And I must confess, I still love the Apple platform so much that I give up fighting aginst the windmills and start from scratch. Learning SwiftUI. Learning Swift. On a slightly related note: For a new contract, I have to revisit the successful build system I co-founded 20 years ago: OpenEmbedded. Though being quite rusty (left the project 11 years ago), I'm looking forward to finding out what the community made out of it. Stay safe and healthy.

25 Jun 2020 12:00pm GMT

Here's the new decade. 2019 went by as an important year where I regained some of my health, discipline, and motivation. Next to the inevitable iOS development, the most important milestones were the release of the 2nd edition of my Vala book and my first music album after more than two decades of inactiveness. I'm looking forward to this decade. The best is yet to come.

10 Feb 2020 12:00pm GMT

After many years of being involved in various projects at the annual Chaos Communication Congress (starting from the audio/vidoe recording team at 15C3), I've finally also departed the GSM team, i.e. the people who operate (Osmocom based) cellular networks at CCC events.

The CCC Camp in August 2019 was slightly different: Instead of helping an Osmocom based 2G/3G network, I decided to put up a nextepc-based LTE network and make that use the 2G/3G HLR (osmo-hlr) via a newly-written DIAMETER-to-GSUP proxy. After lots of hacking on that proxy and fixing various bugs in nextepc (see my laforge/cccamp2019 branch here) this was working rather fine.

For 36C3 in December 2019 I had something different in mind: It was supposed to be the first actual demo of the retronetworking / bbs-revival setup I've been working on during past months. This setup in turn is sort-of a continuation of my talk at 34C3 two years ago: BBSs and early Intenet access in the 1990ies.

Rather than just talking about it, I wanted to be able to show people the real thing: Actual client PCs running (mainly) DOS, dialling over analog modems and phone lines as well as ISDN-TAs and ISDN lines into BBSs, together with early Interent access using SLIP and PPP over the same dial-up lines.

The actual setup can be seen at the Dialup Network In A Box wiki page, together with the 36C3 specific wiki page.

What took most of the time was - interestingly - mainly two topics:

1. A 1U rack-mount system with four E1 ports. I had lots of old Sangoma Quad-E1 cards in PCI form-factor available, but wanted to use a PC with a more modern/faster CPU than those old first-generation Atom boxes that still had actual PCI slots. Those new mainboards don't have PCI but PCIe. There are plenty of PCIe to PCI bridges and associated products on the market, which worked fine with virtually any PCI card I could find, but not with the Sangoma AFT PCI cards I wanted to use. Seconds to minutes after boot, the PCI-PCIe bridges would always forget their secondary bus number. I suspected excessive power consumption or glitches, but couldn't find anything wrong when looking at the power rails with a scope. Adding additional capacitors on every rail also didn't change it. The !RESET line is also clean. It remains a mystery. I then finally decided to but a new (expensive) DAHDI 4-port E1 PCIe card to move ahead. What a waste of money if you have tons of other E1 cards around.

2. Various trouble with FreeSWITCH. All I wanted/needed was some simple emulation of a PSTN/ISDN switch, operating in NT mode towards both the Livingston Portmaster 3 RAS and the Auerswald PBX. I would have used lcr, but it supports neither DAHDI nor Sangoma, but only mISDN - and there are no mISDN cards with four E1 ports :( So I decided to go for FreeSWITCH, knowing it has had a long history of ISDN/PRI/E1 support. However, it was a big disappointment. First, there were some segfaults due to a classic pointer deref before NULL-check. Next, libpri and FreeSWITCH have a different idea how channel (timeslot) numbers are structured, rendering any call attempt to fail. Finally, FreeSWITCH decided to blindly overwrite any bearer capabilities IE with 'speech', even if an ISDN dialup call (unrestricted digital information) was being handled. The FreeSWITCH documentation contains tons of references on channel input/output variables related to that - but it turns out their libpri integration doesn't set any of those, nor use any of them on the outbound side.

Anyway, after a lot more time than expected the setup was operational, and we could establish modem calls as well as ISDN dialup calls between the clients and the Portmaster3. The PM3 in turn then was configured to forward the dialup sessions via telnet to a variety of BBSs around the internet. Some exist still (or again) on the public internet. Some others were explicitly (re)created by 36C3 participants for this very BBS-Revival setup.

My personal favorite was finding ACiD Underworld 2.0, one of the few BBSs out there today who support RIPscrip, a protocol used to render vector graphics, text and even mouse-clickable UI via modem connection to a DOS/EGA client program called RIPterm. So we had one RIPterm installation on Novell DOS7 that was just used for dialling into ACiD Underworld 2.0.

Among other things we also tested interoperability between the 1980ies CCC DIY accoustic coupler "Datenklo" and the Portmaster, and confirmed that Windows 2000 could establish multilink-PPP not only over two B-channels (128 kbps) but also over 3 B-Channels (192).

Running this setup for four days meant 36C3 was a quite different experience than many previous CCC congresses:

• I was less stressed as I wasn't involved in operating a service that many people would want to use (GSM).

• I got engaged with many more people with whom I would normally not have entered a conversation, as they were watching the exhibits/demos and we got to chat about the technology involved and the 'good old days'.

So all in all, despite the last minute FreeSWITCH-patching, it was a much more relaxing and rewarding experience for me.

Special thanks to

• Sylvain "tnt" Munaut for spending a lot of time with me at the retronetworking assembly. The fact that I had an E1 interface around was a good way for him to continue development on his ICE40 based bi-directional E1 wiretap. He also helped with setup and teardown.

• miaoski and evanslify for reviving two of their old BBSs from Taiwan so we could use them at this event

The retronetworking setup is intended to operate at many other future events, whether CCC related, Vintage Computing or otherwise. It's relatively small and portable.

I'm very much looking forward to the next incarnations. Until then, I will hopefully have more software configured and operational, including a variety of local BBSs (running in VMs/containers), together with the respective networking (FTN, ZConnect, ...) and point software like CrossPoint.

If you are interested in helping out with this project: I'm very much looking for help. It doesn't matter if you're old and have had BBS experience back in the day, or if you're a younger person who wants to learn about communications history. Any help is appreciated. Please reach out to the bbs-revival@lists.osmocom.org mailing list, or directly to me via e-mail.

04 Jan 2020 11:00pm GMT

At 36C3 in December 2019 I had the pleasure of presenting: One full talk about SIM card technology from A to Z and another talk where I presented together with eventphone team members about Security issues in the Mitel SIP-DECT system.

The SIM card talk was surprisingly successful, both in terms of a full audience on-site, as well as in terms of the number of viewers of the recordings on media.ccc.de. SIM cards are a rather niche topic in the wider IT industry, and my talk was not covering any vulnerabilities or the like. Also, there was nothing novel in the talk: SIM cards have been around for decades, and not much has changed (except maybe eSIM and TLS) in recent years.

In any case, I'm of course happy that it was well received. So far I've received lots of positive feedback.

As I'm working [more than] full time in cellular technology for almost 15 years now, it's sometimes hard to imagine what kind of topics people might be interested in. If you have some kind of suggestion on what kind of subject within my area of expertise you'd like me to talk about, please don't hesitate to reach out.

The Mitel DECT talk also went quite well. I covered about 10 minutes of technical details regarding the reverse engineering of the firmware and the communication protocols of the device. Thanks again to Dieter Spaar for helping with that. He is and remains the best reverse engineer I have met, and it's always a privilege to collaborate on any project. It was of course also nice to see what kind of useful (and/or fun) things the eventphone team have built on top of the knowledge that was gained by protocol-level reverse engineering.

If you want to know more low-level technical detail than the 36C3 talk, I recommend my earlier talk at the OsmoDevCon 2019 about Aastra/Mitel DET base station dissection.

If only I had more time, I would love to work on improving the lack of Free / Open Source Software realted to the DECT protocol family. There's the abandoned deDECTed.org, and the equally abandoned dect.osmocom.org project. The former only deals with the loewst levels of DECT (PHY/MAC). The latter is to a large extent implemented as part of an ancient version of the Linux kernel (I would say this should all run in userspace, like we run all of GSM/UMTS/LTE in userspace today).

If anyone wants to help out, I still think working on the DECT DLC and NWK dissectors for wireshark is the best way to start. It will create a tool that's important for anyone working with the DECT protocols, and it will be more or less a requirement for development and debugging should anyone ever go further in terms of implementing those protocols on either the PP or FP side. You can find my humble beginnings of the related dissectors in the laforge/dect branch of osmocom.org/wireshark.git.

04 Jan 2020 11:00pm GMT