Adventures in (Dyn)DNS

So, I made the silly move to rely on my hardware supplier to provide me with a dynamic DNS service. Naturally, this offer expired, and I could no longer reach my home server. Because of Murphy, this naturally took place when I was away from home with no access to anything.

So – how does one find the way back home?

Luckily, I have a VPS that I log in to now and then. After a quick duck-ing (duckduckgo is my friend), I found the last command which was the first piece of the puzzle. Now I had a list of potential IPs.

Did I mention that I travel a lot?

There were quite a few IPs there. Pre-COVID-19, it would have been worse. Still, I found a few likely candidates based on frequency of use. Then I found this handy list of IP blocks in Sweden. Now I could tell my mobile data provider (Telenor) from my fibre data provider (Bahnhof).

Quickly adding my home domain and the suspected IP to /etc/hosts on my laptop allowed me to confirm my suspicions. Once in, I could setup duckdns for dynamic DNS, change the CNAME record of my domain, and now all is operational again.

I learned two things from this:

  1. Don’t rely on the time limited offers of hardware vendors for even the most trivial service. They are all trying to convert you into a as-a-Service deal and make you pay an annual fee. (i.e. read the fine print).
  2. I was really happy to use a CNAME record to redirect a subdomain of mine to my home server, so even when using a dynamic DNS service, I could switch to another dynamic DNS service. (this was pure luck – no foresight from my side was involved).

Also, while on the the topics of experiences. If you have the possibility, you should use bahnhof as your ISP. They have a track record of opposing surveilance laws and work to protect the privacy of their customers. Also – I’ve had zero issues with them since switching some 15 years ago, so I can recommend them from that perspective as well ;-)

Posted in Linux, Personal | 2 Responses

It finally arrived

After waiting a bit over a month, followed by an agonizing week when the new gizmo was at my DHL pickup point and I was some 2h by car away in our summer house.

What gizmo? A Pinebook Pro!

The Pinebook comes in many layers. Like, properly many. I guess this means that it is safe during transport. At least mine arrived without any bruising despite a long journey from Hongkong to Alingsås.

After powering the system on it took quite a long time for the system to reach the Manjaro logo, but once up and running, things move along at a decent pace.

Initial impressions are positive. I had to crank up the backlight a bit, but I’m sitting outdoors (it is overcast). Right now I’m installing the initial set of software updates (some 400+MB to download) while I type this. I also set the keyboard layout to Swedish. I have an ISO keyboard model, so all the keys are there and I don’t mind that the keycaps say something else than what they type.

On the topic of the keyboard. I was warned about the keyboard feel. I was also told that the Pro-model is better than the original Pinebook (which I’ve only used for ~5s at fosdem). To be honest, the keyboard is decent, but not on par with my Dell XPS13, nor my Sculpt Egonomic keyboard.

I still have the night time hacking test to perform – will my wife accept this keyboard clicking in the early morning hours? She preferred the MacBook Pro over the XPS13, so let’s see how this fares ;-).

I also have to see if I can adopt to Manjaro Linux, or if I’ll go to Debian, which I run on all my other machines. It has been years since I tried any alternative distro, so I’ll give it a few days at least to see how much I will miss apt-get – at least it runs KDE Plasma ;-)

Posted in KDE | Comments closed

foss-north kdenlive workflow

As some of you might already have noticed, we’ve complemented foss-north with a new pod / vod / vlog – I’m not sure what to call it. Basically, it is a video based pod cast (making it available as a audio only pod-cast is high on the todo). Our main focus right now is a series on licenses and copyright, but there is more to come.

As a part of this, I’ve started editing videos in kdenlive on a weekly basis, and I’m very happy with it so far.

In this blog, I want to share my workflow. It is probably far from ideal, but it does the work for me.

I usually start with a set of presentation slides that we’ve used to direct the discussions. These are exported as pdf, which is then converted to 1920×1080 pngs for consumtion in kdenlive.

I do this in two steps using ImageMagick, as the results seems nicer by first rendering too large images and scaling them down.

convert -verbose -density 300 ../open\ projects-1.pdf -quality 100 -sharpen 0x1.0 11.png

mogrify -resize 1920x1080 *.png

The session is recorded using OBS from our Jitsi instance, but we also encourage each participant to record their audio separately, as it makes it easier to fix things afterwards. (foss-north now self-hosts a Jitsi instance – check out https://github.com/e8johan/virtual-conf-resources to learn about how to setup virtual conferences).

You would be surprised over how many times we’ve run into issues with one or more sound recordings. We’ve had:

  • Too low volume (inaudible)
  • Too high gain (noisy)
  • Local echo of the rest of the participants in one recording (no use of headphones)
  • No recording (forgot to press record)

I’m sure the list will grow longer as we record more episodes :-)

Before I start cutting the recording, I use one of my favorite features in kdenlive. First I set the Jitsi recording as the audio reference as shown below.

Then for each audio track, I tell kdenlive to align it to the reference. This will position it correctly in relation to the Jitsi recording, meaning that I can fade in and out of individual recordings without having to worry about any time shifts.

Finally, I select all the audio recordings and group them. This means that all editing I do (cuts, movements, etc) is applied to all channels.

Now it is just a matter of listening for trouble (you can spot awkward silence in the visualization of the audio tracks), press i to mark the beginning of a section, press o to mark the end, and then shift+X to cut it out.

In general, I try to edit as little as possible, but tightening some parts by removing silence, and sometimes remove failed parts when we’ve decided to start over a section.

Finally I add the pngs as a video stream, our pre-recorded intro sequence, and a YouTube friendly end-screen and click render and go to bed :-)

Posted in foss-north, KDE | Comments closed

foss-north: Enablement Talks

During foss-north 2020 we had a group of talks related to using free and open source in various settings. I call them enablement talks. Someone with a more salesy mind might have said success stories.

This year we had tree such talks. One from about SVT’s (the Swedish public TV broadcaster) video streaming platform by Gustav Grusell and Olof Lindman, one from arbetsförmedlingen (the Swedish public employment service) by Johan Linåker and Jonas Södergren, and about Screenly OSE by Viktor Petersson, a digital signage solution.

We’ve also decided to experiment with a series of shorter videos, and we started by explaining licenses.

Posted in foss-gbg, foss-north, Licensing | Comments closed

Photoframe Hack

Sometimes you just want to get something done. Something for yourself.

You do not intend it to be reused, or even pretty.

You build a tool.

My tool was a photoframe with some basic overlays. I wanted the family calendar, some weather information (current temperature + forecast), time, and the next bus heading for the train station.

To make this acceptable in a home environment, I built it as a photoframe. You can find the sources in the hassframe-ui repository on my github.

A hidden feature is that if you tap the screen, a home automation control panel slides up. That way you can control all the lights, as well as heat in the garage and an AC in the bedroom. Very convenient.

All this is built using QML. Three somewhat useful models are available:

  • IcalModel, taking a URL and parsing whatever it gets back as ICAL data. It is a very naive parser and does not care about things such as time zones and other details.
  • YrWeatherModel, uses yr.no‘s public APIs to pull out a weather forecast for a given location.
  • ButStopModel, uses the APIs from resrobot to look for departures to the train station from two bus stops close to my home and then merge the results into a model.

I also have a bunch of REST calls to my local home assistant server. Most of these reside in the HassButton class, but I also get the current temperature from there. These are hardcoded for my local network, so needs refactoring to be used outside of my LAN.

All of these interfaces require API keys of one kind or another – be it a proper key, or a secret URL. These are pulled from environment variables in main.cpp and then exposed to QML. That way, you can reuse the components without having to share your secrets.

All in all the code is quite hacky. Especially main.qml. I refactor out parts from there now and then, but the photoframe works, so its not anything that I prioritize.

Currently it runs on a Raspberry Pi on top of Raspbian. I want to build an optimized Yocto image making it less hacky and more pre-packaged. Perhaps there will be a rainy day this summer and I’ll get around to it. Burkhard has prepared the instructions needed over at embedded use.

Posted in Embedded, Linux, Qt, RaspberryPi, Yocto | Comments closed

The Cost of no Architecture

Like many others, I enjoy various reverse engineering and tear-down stories. Personally, I mean things like iFixit tear-downs and Ken Shirriff’s blog, so I started following this tweet thread by foone.

This continues with another tweet sequence about getting software running on the remote control. Having enjoyed these tweets, I started thinking.

The Harmony remotes are quite expensive in my mind. I can’t find any exact numbers for the number of sold devices, but I found this 2018 Q4 earnings report. Looking at the net sales, I guess the remotes are either “Tablets & Other Accessories” or “Smart Home”. They represent sales net sales of ~107 and ~89 MUSD over 12 months. Let’s pick the lower number and just look at magnitudes. The Harmony 900 seems to have retailed for ~350 USD back when it was new. So, if all the Smart Home stuff was harmonies, we’re looking at 250k units over a year. So I’m guessing the magnitude is around 10k – 100k units annually – but the Harmony 900 is from 2013, so I assume that it sold closer to the lower number, if not below. The market was new and so on.

Then we look at the tweets again. What have we got? Let’s put aside security issues, unencrypted communications, and other clear mistakes and just look at how the device is built.

Flash to drive the UI, double web servers on-board, Lua, QNX and what not. A 233 MHz CPU and ~64MB of FLASH – for a remote control. From an engineering perspective, this sounds like a fun system to work on – from an architecture perspective, it looks like a ball of mud.

Back in 2013, QNX might have been a good choice compared to Linux. Today, with Yocto and similar tools for developing embedded Linux systems, it feels like an odd choice to add a license cost to such a device. But no biggie. Back in the day this was not an unreasonable choice (and still isn’t for certain applications).

The Flash stuff. There were alternatives back in 2013, but sure, there were plenty of developers at hand and things like Qt QML was still probably a bit clunky (I can’t recall the state of it back then – it required OpenGL ES, which I guess was a big ask back then).

But the mix of techniques and tools. The on-board web servers. The complexity of a small system and the costs it brings to maintenance and testability. If this is the foundation for Harmony remotes and a platform that has been used for the better past of the past decade, I wonder if the added engineering costs for architecture the platform to be more optimized early on would not have paid off in lower maintenance costs, as well as lower hardware costs.

I know how it is when you’re in a project. The deadline is there in big writing on one of the walls. You can get something working by stringing what you have together with duktape and glue. The question I’m asking myself is more along the lines of how do we run embedded systems engineering projects? Where did we go wrong? Why don’t we prioritize the thinking and refactoring over the just-get-this-thing-out-of-the-door?

The answer is time to market and such, but over a decade of building on a ball of mud, the economical numbers start adding up in favour for the better engineered product. For continuous improvement. For spending time thinking about how to improve the system as a whole.

Posted in Embedded, Linux, Qt, Yocto | Comments closed

The Internet Talks

I’ve previously written about the licensing and embedded talks of foss-north 2020. This time around, I’d like to share the recordings of the Internet related talks.

Internet is a very broad topic, so it is hard to classify talks as not being Internet related these days, but the following three talks stand out.

The first speaker is an old time speaker at foss-north, Daniel Stenberg. He has spoken at foss-north several times, but never about his main claim to fame: curl. This time he righted this by delivering a talks about how to Curl better.

Maintaining privacy on the Internet is a big topic. This is a field where it is hard to deliver black or white answers. Elisabet Lobo-Vesga presents DPella, a query language for differential privacy. Using this technology, it is possible to make the tradeoff between how private the user is vs how detailed the data returned is.

The Internet talks end with Patrik Fältström. One of the people who has been around the Swedish Internet scene the longest. He talks about Keeping Time. It is a journey into leap seconds, atomic clocks, the speed of light and other hassles when keeping clocks in sync over a large network.

The talks are already available on conf.tube, and the presentation material can be found by following the links to each speaker. For those of you who prefer YouTube, the talks will be made available shortly on the foss-north channel. Subscribe to get notified when they are.

Posted in foss-north | Comments closed

The Embedded Talks

The foss-north conference strives to have an assortment of various talks. The point is that visitors should see something unexpected and that the conference should attract all types of visitors to ensure that we as a community can meet across various industries and problem spaces.

This time I’ve selected three talks about embedded systems from foss-north 2020. The talks touch on building embedded systems around Linux. If your reader does not show you the embedded videos, make sure to follow the actual page or go to our conf.tube channel to see all the contents.

First out was Ron Munitz talk on understanding and building minimal Linux systems. This talk proved to be a real deep dive into the Linux kernel – including setting up a debugger to the kernel itself.

The next embedded speaker on the program was Chris Simmonds. He discussed if going with Yocto or Debian is best for your embedded Linux project. This an interesting topic – how much is customization worth compared to other aspect such as build-time.

The embedded set of talks ended with Drew Fustini talking about running Linux on the RISC-V. This talk dives deep into the hardware part of embedded systems, but also Linux. By being able to run Linux on RISC-V, which is open hardware, we are very close to an completely open eco-system.

The three talks are already available on conf.tube, and the presentation material can be found by following the links to each speaker. For those of you who prefer YouTube, the talks will be made available shortly on the foss-north channel. Subscribe to get notified when they are.

Posted in Embedded, foss-gbg, foss-north, Miscellaneous, Yocto | Comments closed

What a License Track!

The foss-north 2020 videos are rolling out. This year we’re doing a small experiment, so everything is available at once over at conf.tube, while we roll the videos out gradually at YouTube in an attempt to feed the algorithm (like and subscribe!).

This year we had a great set of licensing related talks, and I’d like to discuss them all in this post.

Monday morning started with Frank Karlitschek and his talk Why the GPL is great for business. This a great overview of how you can build an free and open source business – pros and cons and pitfalls to avoid.

Next up is Gabriel Ku Wei Bin from FSFE who talked about REUSE. The REUSE project is about helping creators choose and apply free and open source licenses.

This is followed by Pavel Kopylov and his talk Hacking the legal code of an open source license. This talk is about understanding how licenses works and how to use them.

This is followed by Jason Hammond from Whitesource talking about their compliance tooling and why compliance is important.

The final talk in this track is by Adriaan de Groot talking about the KDE Free Qt Foundation. This is an interesting aspect, as it is about protecting the customers by offering a more liberal license at a given point of time.

Historically we’ve always split talks on a specific topic during the conference to ensure that people move about in the hallways and that most visitors get to see something unexpected. Since we record everything, we can now do both – clustering by topic and a linear playlist.

Posted in foss-north, KDE, Licensing, Qt | Comments closed

foss-north – or doing many things at once

When placing this year’s foss-north event over a quarter break I knew that I would be busy both at work and at the conference. Little did I know what was beyond the horizon ;-)

As a consequence of the COVID-19 situation, the event has to be converted from a physical meeting to a virtual event. This means many things to an organizer: renegotiating all sponsorship contracts, renegotiating with the physical venue, setting up the infrastructure for a virtual event, rescheduling all speakers, and so on.

We at foss-north are lucky. All sponsors continue to stay with us and the venue was very cooperative when it came to rescheduling the event.

I have started to document our virtual conference setup so that other conferences in the same situation can learn. Pull requests are welcome!

This Sunday we decided to stress test the infrastructure by running the lightning talks. This is a good test case, as it involves a maximum number of speaker transitions, as well as more frequent QA sessions. From an organizer perspective, this is really like running a full day of the conference in 90 minutes.

I’m happy to tell you that the talks went well! You find them below. Following the links you find slides as well as recordings of the sessions.

Develop better software with usability testing by Andreas Nilsson
Running Android on the Raspberry Pi by Chris Simmonds
The Yocto Project 10 minute quick-start guide by Ron Munitz
Getting started with your smart, connected, vehicle project by Dimitris Platis
Seven years in Tibet^W^Wat Home by Kristoffer Grönlund
Linux on RISC-V by Drew Fustini
Singularity container platform by Anders Björklund

We’ve also been able to get most of the conference schedule in place and just have a few rough edges to fix before the big event. I am extremely pleased with how this has turned out. We still have a stellar speaker setup and I hope that you will all join in and watch the streams. The event is free for all and open to all and runs from March 29 – April 1.

Posted in foss-north, Miscellaneous | Comments closed
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