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Back to Taiwan the first time after 5 years

Harald Welte — Tue, 22 Oct 2024 16:00:00 GMT

Some of the readers of this blog know that I have a very special relationship with Taiwan. As a teenager, it was the magical far-away country that built most of the PC components in all my PCs since my first 286-16 I got in 1989. Around 2006-2008 I had the very unexpected opportunity to work in Taiwan for some time (mainly for Openmoko, later some consulting for VIA). During that time I have always felt most welcome in and fascinated by the small island nation who managed to turn themselves into a high-tech development and manufacturing site for ever more complex electronics. And who managed to evolve from decades of military dictatorship and turn into a true democracy - all the while being discriminated by pretty much all of the countries around the world, as everybody wanted to benefit from cheap manufacturing in mainland China and hence expel democratic Taiwan from the united nations in favour of communist mainland Chine.

I have the deepest admiration for Taiwan to manage all of their economic success and progress in terms of democracy and freedom despite the political situation across the Taiwan strait, and despite everything that comes along with it. May they continue to have the chance of continuing their path.

Setting economy, society and politics behind: On a more personal level I've enjoyed their culinary marvels from excellent dumplings around every street corner to niu rou mien (beef noodle soup) to ma la huo guo (spicy hot pot). Plus then the natural beauty, particularly of the rural mountainous regions once you leave the densely populated areas around the coast line and the plains of the north west.

While working in Taiwan in 2006/2007 I decided to buy a motorbike. Using that bike I've first made humble day trips and later (once I was no longer busy with stressful work at Openmoko) multiple week-long road trips around the island, riding on virtually any passable road you can find. My typical routing algorithm is "take the smallest possible road from A to B".

So even after concluding my work in Taiwan, I returned again and again for holidays, each one with more road trips. For some time, Taiwan had literally become my second home. I had my favorite restaurants, shops, as well as some places around the rural parts of the Island I cam back to several times. I even managed to take up some mandarin classes, something I never had the time for while doing [more than] full time work. To my big regret, it's still very humble beginner level; I guess had I not co-started a company (sysmocom) in Berlin in 2011, I'd have spent more time for a more serious story.

In any case, I have nothing but the fondest memory of Taiwan. My frequent visits cam to a forcible halt with the COVID-19 pandemic, Taiwan was in full isolation in 2020/21, and even irrespective of government regulations, I've been very cautious about travel and contact. Plus of course, there's always the bad conscience of frequent intercontinental air travel.

Originally I was planning to finally go on an extended Taiwan holiday in Summer 2024, but then the island was hit by a relatively serious earthquake in April, affecting particularly many of the remote mountain regions that are of main interest to me. There are some roads that I'd have wanted to ride ever since 2008, but which had been closed every successive year when I went there, due to years of reconstructions after [mostly landslides following] earthquakes and typhoons. So I decided to postpone it for another year to 2025.

However, in an unexpected change of faith, the opportunity arose to give the opening Keyonte at the 2024 Open Compliance Summit in Japan, and along with that the opportunity to do a stop-over in Taiwan. It will just be a few days of Taipei this time (no motorbike trips), but I'm very much looking forward to being back in the city I probably know second or third-best on the planet (after Berlin, my home for 23 years, as well as Nuernberg, my place of birth). Let's see what is still the same and what has changed during the past 5 years!

OsmoDevCon 2024: "Introduction to XDP, eBPF and AF_XDP"

Harald Welte — Sat, 04 May 2024 16:00:00 GMT

I've presented a talk Introduction to XDP, eBPF and AF_XDP as part of the OsmoDevCon 2024 conference on Open Source Mobile Communications.

This talk provides a generic introduction to a set of modern Linux kernel technologies:

eBPF (extended Berkeley Packet Filter) is a kind of virtual machine that runs sandboxed programs inside the Linux kernel.
XDP (eXpress Data Path) is a framework for eBPF that enables high-performance programmable packet processing in the Linux kernel
AF_XDP is an address family that is optimized for high-performance packet processing. It allows in-kernel XDP eBPF programs to efficiently pass packets to userspace via memory-mapped ring buffers.

The talk provides a high-level overview. It should provide some basics before the other/later talks on bpftrace and eUPF.

You can find the video recording at https://media.ccc.de/v/osmodevcon2024-204-introduction-to-xdp-ebpf-and-afxdp

OsmoDevCon 2024: "Using bpftrace to analyze osmocom performance"

Harald Welte — Sat, 04 May 2024 16:00:00 GMT

I've presented a talk Using bpftrace to analyze osmocom performance as part of the OsmoDevCon 2024 conference on Open Source Mobile Communications.

bpftrace is a utility that uses the Linux kernel tracing infrastructure (and eBPF) in order to provide tracing capabilities within the kernel, like uprobe, kprobe, tracepoints, etc.

bpftrace can help us to analyze the performance of [unmodified] Osmocom programs and quickly provide information like, for example:

Histogram of time spent in a specific system call
Histogram of any argument or return value of any system call

You can find the video recording at https://media.ccc.de/v/osmodevcon2024-203-using-bpftrace-to-analyze-osmocom-performance

OsmoDevCon 2024: "Anatomy of the eSIM Profile"

Harald Welte — Fri, 03 May 2024 16:00:00 GMT

I've presented a talk Anatomy of the eSIM Profile as part of the OsmoDevCon 2024 conference on Open Source Mobile Communications.

In the eSIM universe, eSIM profiles are the virtualised content of a classic USIM (possibly with ISIM, CSIM, applets, etc.).

Let's have a look what an eSIM profile is:

how is the data structured / organized?
what data can be represented in it?
how to handle features provided by eUICC, how can the eSIM profile mandate some of them?
how does personalization of eSIM profiles work?

There is also hands-on navigation through profiles, based on the pySim.esim.saip module.

You can find the video recording at https://media.ccc.de/v/osmodevcon2024-174-anatomy-of-the-esim-profile

OsmoDevCon 2024: "Detailed workings of OTA for SIM/USIM/eUICC"

Harald Welte — Fri, 03 May 2024 16:00:00 GMT

I've presented a talk Detailed workings of OTA for SIM/USIM/eUICC as part of the OsmoDevCon 2024 conference on Open Source Mobile Communications.

Everyone knows that OTA (over the air) access to SIM cards exists for decades, and that somehow authenticated APDUs can be sent via SMS.

But let's look at the OTA architecture in more detail:

OTA transport (SCP80) over SMS, USSD, CellBroadcast, CAT-TP, BIP
The new SCP81 transport (HTTPS via TLS-PSK)
how to address individal applications on the card via their TAR
common applications like RFM and RAM
custom applications on the card
OTA in the world of eUICCs
talking to the ECASD
talking to the ISD-R
talking to the ISD-P/MNO-SD or applications therein

You can find the video recording at https://media.ccc.de/v/osmodevcon2024-175-detailed-workings-of-ota-for-sim-usim-euicc

OsmoDevCon 2024: "GlobalPlatform in USIM and eUICC"

Harald Welte — Fri, 03 May 2024 16:00:00 GMT

I've presented a talk GlobalPlatform in USIM and eUICC as part of the OsmoDevCon 2024 conference on Open Source Mobile Communications.

The GlobalPlatform Card Specification and its many amendments play a significant role in most real-world USIM/ISIM, and even more so in eUICC.

The talk will try to provide an overview of what GlobalPlatform does in the telecommunications context.

Topics include:

security domains
key loading
card and application life cycle
loading and installation of applications
Secure Channel Protocols SCP02, SCP03

You can find the video recording at https://media.ccc.de/v/osmodevcon2024-173-globalplatform-in-usim-and-euicc

OsmoDevCon 2024: "High-performance I/O using io_uring via osmo_io"

Harald Welte — Thu, 02 May 2024 16:00:00 GMT

I've co-presented a talk (together with Andreas Eversberg High-performance I/O using io_uring via osmo_io as part of the OsmoDevCon 2024 conference on Open Source Mobile Communications.

Traditional socket I/O via read/write/recvfrom/sendto/recvmsg/sendmsg and friends creates a very high system call load. A highly-loaded osmo-bsc spends most of its time in syscall entry and syscall exit.

io_uring is a modern Linux kernel mechanism to avoid this syscall overhead. We have introduced the osmo_io`API to libosmocore as a generic back-end for non-blocking/asynchronous I/O and a back-end for our classic `osmo_fd / poll approach as well as a new backend for io_uring.

The talk will cover

a very basic io_uring introduction
a description of the osmo_io API
the difficulties porting from osmo_fd to osmo_io
status of porting various sub-systems over to osmo_io

You can find the video recording at https://media.ccc.de/v/osmodevcon2024-209-high-performance-i-o-using-iouring-via-osmoio

RetroNetCall: "Datex-L, the German CSPDN"

Harald Welte — Tue, 31 Jan 2023 16:00:00 GMT

I've presented about Datex-L, the German CSPDN (Circuit Switched Public Data Network) as part of the RetroNetCall talk series on retro-networking technology.

You can find the video recording at https://media.ccc.de/v/retronetcall-20230201-laforge-datex-l-cspdn

I've always been fascinated by "ancient" data communications - both the kind that I personally consciously witnessed from the late 1980s as well as the kind that I never experienced myself (like Datex-L).

I am not an expert in the subject by all means, as I was never involved in its design, implementation or even used it. However, given that there's very few public information online about Datex-L and/or other CSPDNs, I thought I could improve the situation by presenting about it.

RetroNetCall: "ISDN B-Channel protocols"

Harald Welte — Tue, 06 Dec 2022 16:00:00 GMT

I've presented about ISDN B-Channel protocols (X.75, V.120, V.110, T.70, ...) as part of the RetroNetCall talk series on retro-networking technology.

You can find the video recording at https://media.ccc.de/v/retronetcall-20221207-laforge-isdn-b-channel-protocols

Many people with some kind of telecom background are familiar with D-channel (signalling) protocols of ISDN, and you can find many publications on that topic. Surprisingly, much less publications are talking about the B-channel protocols used for data transmission, like VX.75, V.110, V.120, T.70, ...

RetroNetCall: "OCTOI project status update"

Harald Welte — Tue, 08 Nov 2022 16:00:00 GMT

I've presented an OCTOI project status update (Nov 2022) as part of the RetroNetCall talk series on retro-networking technology.

You can find the video recording at https://media.ccc.de/v/retronetcall-20221109-laforge-octoi-status-update

OsmoDevCall: "Osmocom SIMtrace2 Tutorial"

Harald Welte — Tue, 18 Oct 2022 16:00:00 GMT

I've presented an SIMtrace2 Tutorial - SIM protocol tracing: how and why as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20221019-laforge-simtrace2-tutorial

OsmoDevCall: "Advanced SIM card topics: GlobalPlatform SCP02, OTA, ARA-M, ISIM"

Harald Welte — Thu, 24 Feb 2022 16:00:00 GMT

I've presented on Advanced SIM card topics: GlobalPlatform SCP02, OTA, ARA-M, ISIM as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20220225-laforge-advanced-sim-topics

OsmoDevCall: "Control/User Plane Separation (CUPS) and PFCP"

Harald Welte — Mon, 27 Dec 2021 16:00:00 GMT

I've presented on Control/User Plane Separation (CUPS) and PFCP as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20211125-laforge-cups-pfcp

OsmoDevCall: "Retronetworking: V5 interfaces in ISDN/PSTN"

Harald Welte — Mon, 27 Dec 2021 16:00:00 GMT

I've presented on Retronetworking: V5 interfaces in ISDN/PSTN as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20211228-laforge-retro-isdn-v5

OsmoDevCall: "E1, TDM, PDH, SDH, Basics"

Harald Welte — Thu, 11 Nov 2021 16:00:00 GMT

I've presented on E1, TDM, PDH, SDH, Basics as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20211112-laforge-tdm

OsmoDevCall: "SIM card profile creation, personalization, production"

Harald Welte — Thu, 11 Nov 2021 16:00:00 GMT

I've presented on SIM card profile creation, personalization, production as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20211022-laforge-sim

OsmoDevCall: "osmo-remsim in practice"

Harald Welte — Thu, 26 Aug 2021 16:00:00 GMT

I've presented on osmo-remsim in practice as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20210827-laforge-osmo-remsim

OsmoDevCall: "GSM-R and how it differs from GSM"

Harald Welte — Thu, 12 Aug 2021 16:00:00 GMT

I've presented on GSM-R and how it differs from GSM as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20210813-laforge-gsm-r

OsmoDevCall: "High-Level intro to IMS, VoLTE & VoWiFi"

Harald Welte — Thu, 22 Jul 2021 16:00:00 GMT

I've presented a talk High-Level intro to IMS, VoLTE & VoWiFi as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20210723-laforge-ims-volte-vowifi

OsmoDevCall: "SS7 and SIGTRAN in 2G/3G networks"

Harald Welte — Sun, 23 May 2021 16:00:00 GMT

I've presented a talk SS7 and SIGTRAN in 2G/3G networks as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20210514-laforge-ss7-sigtran

OsmoDevCall: "pySim-shell - next generation SIM configuration tool"

Harald Welte — Thu, 08 Apr 2021 16:00:00 GMT

I've presented a talk SS7 and SIGTRAN in 2G/3G networks as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20210409-laforge-pysim-shell

OsmoDevCall: "Osmocom 2020 review"

Harald Welte — Thu, 11 Mar 2021 16:00:00 GMT

I've presented a talk Osmocom 2020 review as part of the OsmoDevCall talk series on Osmocom and related technology.

You can find the video recording at https://media.ccc.de/v/osmodevcall-20210312-laforge-overview-of-2020

36C3 Talks on SIM card technology / Mitel DECT

Harald Welte — Sat, 04 Jan 2020 16:00:00 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.

Going to attend Electromagnetic Field 2016

Harald Welte — Sat, 23 Jul 2016 08:00:00 GMT

Based on some encouragement from friends as well as my desire to find more time again to hang out at community events, I decided to attend Electromagnetic Field 2016 held in Guildford, UK from August 5th through 7th.

As I typically don't like just attending an event without contributing to it in some form, I submitted a couple of talks / workshops, all of which were accepted:

An overview talk about the Osmocom project
A Workshop on running your own cellular network using OpenBSC and related Osmocom software
A Workshop on tracing (U)SIM card communication using Osmocom SIMtrace

I believe the detailed schedule is still in the works, as I haven't yet been able to find any on the event website.

Looking forward to having a great time at EMF 2016. After attending Dutch and German hacker camps for almost 20 years, let's see how the Brits go about it!

TelcoSecDay 2016: Open Source Network Elements for Security Analysis of Mobile Networks

Harald Welte — Mon, 14 Mar 2016 16:00:00 GMT

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 https://gitea.osmocom.org/laforge/laforge-slides/src/branch/master/2016/telcosecday

Linaro Connect BKK16 Keynote on GPL Compliance

Harald Welte — Tue, 08 Mar 2016 16:00:00 GMT

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 https://gitea.osmocom.org/laforge/laforge-slides/src/branch/master/2016/linaroconnect

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

netdevconf 1.1: Osmocom kernel-level GTP implementation

Harald Welte — Wed, 10 Feb 2016 16:00:00 GMT

Today I had the pleasure of co-presenting with Andreas Schultz at netdevconf 1.1 about the Osmocom kernel-level GTP implementation.

The video recording is available from https://www.youtube.com/watch?v=puCMipd8fck

Slides are available at https://gitea.osmocom.org/laforge/laforge-slides/src/branch/master/2016/netdevconf-gtp

netdevconf 1.1: Running cellular infrastructure on Linux

Harald Welte — Tue, 09 Feb 2016 16:00:00 GMT

Today I had the pleasure of presenting at netdevconf 1.1 a tutorial about Running cellular infrastructure on Linux. The tutorial is intended to guide you through the process of setting up + configuring yur own minimal private GSM+GPRS network.

The video recording is available from https://www.youtube.com/watch?v=I4i2Gy4JhDo

Slides are available at https://gitea.osmocom.org/laforge/laforge-slides/src/branch/master/2016/netdevconf-osmocom

32C3: Running your own 3G/3.5G cellular network

Harald Welte — Sat, 26 Dec 2015 16:00:00 GMT

Today I had the pleasure of presenting at 32C3 about Running your own 3G/3.5G cellular network. The tutorial covers the ongoing effort of creating a HNB-GW and Iuh/IuCS/IuPS support as part of the Osmocom project.

The video recording is available from https://media.ccc.de/v/32c3-7412-running_your_own_3g_3_5g_network

Slides are available at https://gitea.osmocom.org/laforge/laforge-slides/raw/branch/master/2015/osmo_iuh/osmo_iuh.pdf

hardwear.io 2015 keynote: Running cellular infrastructure on Linux

Harald Welte — Thu, 01 Oct 2015 16:00:00 GMT

Today I had the pleasure of presenting at hardwear.io 2015 a keynote about Telecom Security - leassons learned... or not?.

Slides are available at https://gitea.osmocom.org/laforge/laforge-slides/raw/branch/master/2015/hardwear_io/keynote.pdf

OpenFest 2014: SIM card protocol tracing using Osmocom SIMtrace

Harald Welte — Sat, 01 Nov 2014 16:00:00 GMT

Today I had the pleasure of presenting at OpenFest 2014 a talk about Running cellular infrastructure on Linux.

The video recording is available from https://www.youtube.com/watch?v=n2GSn9HrEQs

Slides are available at https://gitea.osmocom.org/laforge/laforge-slides/raw/branch/master/2014/simtrace-openfest2014/simtrace.pdf

OpenFest 2014: Software Defined Radio using rtl-sdr

Harald Welte — Sat, 01 Nov 2014 16:00:00 GMT

Today I had the pleasure of presenting at OpenFest 2014 a talk about Software Defined Radio using rtl-sdr.

The video recording is available from https://www.youtube.com/watch?v=3LmAm9kRtgw

Slides are available at https://gitea.osmocom.org/laforge/laforge-slides/raw/branch/master/2014/rtlsdr-openfest2014/rtl-sdr.pdf

DORS/CLUC 2014: Keynote about Open Source Mobile Communications

Harald Welte — Sun, 15 Jun 2014 16:00:00 GMT

Today I had the pleasure of presenting at DORS/CLUC 2014 a keynote about Osmocom.org - Open Source Mobile Communications.

Slides are available at https://gitea.osmocom.org/laforge/laforge-slides/raw/branch/master/2014/osmocom-dorscluc2014/osmocom-overview.pdf

DORS/CLUC 2014: Keynote about OpenBSC - running your own GSM network

Harald Welte — Sun, 15 Jun 2014 16:00:00 GMT

Today I had the pleasure of presenting at DORS/CLUC 2014 a talk about OpenBSC - running your own GSM network.

Slides are available at https://gitea.osmocom.org/laforge/laforge-slides/raw/branch/master/2014/openbsc-dorscluc2014/gsm.pdf