Technology driven life changes

Last year, when I talked about finally seeing the Apple Watch becoming mildly useful, I had no idea what kind of a ride I was going to be on.

Generally, I’m not really concerned about my health nor fitness, but last September, when my wonderful girlfriend left for a year of study in England, I decided that I finally had enough and I wanted to lose weight.

Having a year of near-zero social obligations would totally allow me to adjust my life-style in a way that’s conducive to weight loss, so here’s what I started doing:

  • During weekdays, I greatly reduced my calorie intake to basically just a salad and a piece of bread every day (you can pry my bread from my cold dead hands – it’s the one food I think I like the most).
  • Every day, no matter the weather, no matter the workload, no matter what, I was going to walk home after my work-day in the office, or on weekends, I would just take an equivalent walk.
  • Every day, I wanted to fill the “Activity” and the “Exercise” rings on my apple watch.

Now walking home sounds like nothing special, but I’m privileged to live in Zürich Switzerland, which means that I have very easy access to forests to walk in.

So commuting home by foot meant that I could walk at least 8 kilometres (4.9 miles), climbing 330m (1082 feet), most of it through the forest.

Every day, no matter whether it was way too hot, way too cold, whether it was raining, hailing or snowing, I would walk home. And every day I would be using my Apple Watch to track what I would generously call a “Workout” (even though it was just walking – but if you go from zero sports to that, I guess it’s ok to call it that).

From September to December I started gradually increasing the distance I walk.

This is the other great thing about Zürich: Once you reach the forest (which you do by walking 20 minutes in practically any direction), you can stay in the forest for hours and hours.

First I extended the 8km walk to 10km, then 12, then 14 and finally 19 (11 miles).

During that time, I kept tracking all the vital signs I could track between the Apple Watch and a Withings scale I bought 1-2 months into this.

My walks got faster and my heart rate at rest got lower and lower, from 80 to now 60.

Every evening after the walk, I would look at the achievements handed out by my Watch which is also why I’ve never updated my movement goals in the Activity app because getting all these badges, honestly, was a lot of fun and very motivational. Every evening I would get notified of increasing my movement streak, of doubling or even tripling my movement goal and of tripling or quadrupling my exercise goal.

screenshot of the activity app

Every morning I would weigh myself and bask in the glory of the ever falling graph painted by the (back then very good) iOS app that came with the scale. I would manage to lose a very consistent 2kg (4.4lbs) per week.

Every walk I would have the chance to experience some of natures beauty.

Crazy sunsets


Beautiful sunrises


Enchanted forests

wintery forest

And frozen creeks

frozen creek

And in spring I could watch trees grow.

When I got home after up to three hours of walk, I was dead tired at around 10pm, meaning that for the first time in ages I would get more than enough sleep and I would still be able to get up between 6 and 7.

By mid of March, after 6 months of a very strict diet and walking home every day, I was done. I had lost 40kg (88.1 lbs).

Now the challenge shifted from losing weight to not gaining weight. I decided to make the diet less strict but also continue with my walks, though I would not do the regular 19km ones any more as they would just take too long (3 hours).

But by June, I really started to notice a change: I wouldn’t feel these walks at all any more. No sweat, no reasonable change in heart rate while on them, no tiredness. The walks really felt like a waste of time.

So I started running.

I never liked running. I was always bad at it. All the way through school where I was the slowest and always felt really bad afterward, through my life until now where I just never did it. Running felt bad and I hated it.

But now things were different.

The first time I changed from walking to running, I did so after reaching the peak altitude, so it was mostly straight and a little bit downhill. But still: I ran 4km (2.48 miles) and when I got home I didn’t feel much more tired.

I was very surprised because running 4km through all of my life would have been completely unthinkable to me, but there I was. I just did.

So next day, I decided to run most of the way, just skipping the steepest parts. Suddenly, there I was, running 8km (4.9 miles), still not feeling particularly tired afterwards.

So I started tracking these runs (using both Runkeeper and Strava for technical reasons – but that’s another post), seeing improvement in my time all the way through July.

And then, on August 1st, I ran half a Marathon climbing 612m (2007 feet)

Screen Shot 2017-08-04 at 11.40.28.png

Considering that this was my first, it’s not even in too bad a time and what’s even more fun to me: I didn’t even feel too tired afterwards and I totally felt like I could run even farther.

So I guess after taking it very slowly and moving from walking a bit to walking more to walking a lot to running a bit to running some more, even I, the most unathletic person possible can push myself into shape.

But what’s the most interesting aspect in all of this is that without technology, the Apple Watch in particular, without the cheesy achievements, none of this would ever have been possible. I hated sports and I’m honestly still not really interested. But the prospect of getting awarded some stupid batches every day is what finally pushed me.

And now, in only a single month, my girlfriend will finally return to Switzerland and I guess she’ll find me in better shape than she’s ever seen me before in our lives. I hope that the prospect of collecting some more batches from my watch will keep me going even when the social pressure might want to tempt me into skipping a workout.

Joining Debian to ActiveDirectory

This blog post is a small list of magic incantations and to be issued and animals to be sacrificed in order to join a Unix machine (Debian in this case) to a (samba-powered) ActiveDirectory domain.

All of these things have to be set up correctly or you will suffer eternal damnation in non-related-error-message hell:

  • Make absolutely sure that DNS works correctly
    • the new member server’s hostname must be in the DNS domain of the AD Domain
    • This absolutely includes reverse lookups.
    • Same goes for the domain controller. Again: Absolutely make sure that you set up a correct PTR record for your domain controller or you will suffer the curse of GSSAPI Error: Unspecified GSS failure. Minor code may provide more information (Server not found in Kerberos database)
  • Disable IPv6 everywhere. I normally always advocate against disabling IPv6 in order to solve problems and instead just solve the problem, but bugs exist. Failing to disable IPv6 on either the server or the client will also cause you to suffer in Server not found in Kerberos database hell.
  • If you made previous attempts to join your member server, even when you later left the domain again, there’s probably a lingering host-name added by a previous dns update attempt. If that exists, your member server will be in ERROR_DNS_UPDATE_FAILED hell even if DNS is configured correctly.
    • In order to check, use samba-tool on the domain controller samba-tool dns query your.dc.ip.address memberservername ALL
    • If there’s a hostname, get rid of it using samba-tool dns delete your.dc.ip.address memberservername A ip.returned.above
  • make sure that the TLS certificate served by your AD server is trusted, either directly or chained to a trusted root. If you’re using a self-signed root (you’re probably doing that), add the root as a PEM-File (but with .crt extension!) to /usr/local/share/ca-certificates/ ad run /usr/sbin/update-ca-certificates. If you fail to do this correctly, you will suffer in ldap_sasl_interactive_bind_s: Can't contact LDAP server (-1) hell (no. Nothing will inform you of a certificate error – all you get is can't connect)
  • In order to check that everything is set up correctly, before even trying realmd or sssd, use ldapsearch: ldapsearch -H ldap:// -Y GSSAPI -N -b "dc=your,dc=base,dc=dn" "(objectClass=user)"
  • Aside of all that, you can follow this guide, but also make sure that you manually install the krb5-user package. The debian package database has a missing dependency, so the package doesn’t get pulled in even though it is required.

All in all, this was a really bad case of XKCD 979 and in case you ask yourself whether I’m bitter, then let me tell you, that yes. I am bitter.

I can totally see that there are a ton of moving parts involved in this and I’m willing to nudge some of these parts in order to get the engine up and running. But it would definitely help if the various tools involved would give me meaningful log output. samba on the domain controller doesn’t log, tcpdump is pointless thanks to SSL everywhere, realmd fails silently while still saying that everything is ok (also, it’s unconditionally removing the config files it feeds into the various moving parts involved, so good luck trying to debug this), sssd emits cryptic error messages (see above) and so on.

Anyways. I’m just happy I go this working and now for reproducing it one more time, but this time recording everything in Ansible.

Apple Watch starting to be useful

Even after the Time for Coffee app has been updated for WatchOS 2.0 support last year and my Apple Watch has become significantly more useful, the fact that the complication didn’t get a chance to update very often and the fact that launching the app took an eternity kind of detracted from the experience.

Which lead to me not really using the watch most of the time. I’m not a watch person. Never was. And while the temptation of playing with a new gadget lead to me wearing it on and off, I was still waiting for the killer feature to come around.

This summer, this has changed a lot.

I’m in the developer program, so I’m running this summer’s beta versions and Apple has also launched Apple Pay here in Switzerland.

So suddenly, by wearing the watch, I get access to a lot of very nice features that present themselves as huge user experience improvements:

  • While «Time for Coffee»’s complication currently is flaky at best, I can easily attribute this to WatchOSes current Beta state. But that doesn’t matter anyways, because the Watch now keeps apps running, so whenever I need public transport departure information and when the complication is flaky, I can just launch the app which now comes up instantly and loads the information within less than a second.
  • Speaking of leaving apps running: The watch can now be configured to revert to the clock face only after more than 8 minutes have passed since the last use. This is perfect for the Bring shopping list app which now suddenly is useful. No more taking the phone out while shopping.
  • Auto-Unlocking the Mac by the presence of an unlocked and worn watch has gone from not working at all, to working rarely, to working most of the time as the beta releases have progressed (and since Beta 4 we also got the explanation that WiFi needs to be enabled on the to-be-unlocked mac, so now it works on all machines). This is very convenient.
  • While most of the banks here in Switzerland boycott Apple Pay (a topic for another blog entry – both the banks and Apple are in the wrong), I did get a Cornèrcard which does work with Apple Pay. Being able to pay contactless with the watch even for amounts larger than CHF 50 (which is the limit for passive cards) is amazing.

Between all these features, I think there’s finally enough justification for me to actually wear the watch. It still happens that I forget to put it on here and then, but overall, this has totally put new life into this gadget, to the point where I’m inclined to say that it’s a totally new and actually very good experience now.

If you were on the fence before, give it a try come next autumn. It’s really great now.

another fun project: digipass

As a customer of digitec, I often deal with their collection notices which I get via email and which invite me to go to their store and fetch my order (yes. I could have the goods delivered, but I’m impatient and not willing to pay the credit card surcharge).

Ever since Passbook happened on iOS 6, I wished for these collection notices to be iOS Passes as they have a lot of usability benefits:

  • passes are location aware an pop up automatically when you get close to the location
  • Wallet automatically turns the screen brightness all the way up
  • passes could potentially be updated remotely
  • once added to the Wallet, passes don’t clutter your mailbox and you’ll never lose them in the noise of your inbox.

So my latest fun project is digipass.

Next time you get a digitec collection notice, just forward it to

After a few seconds, you will get the same collection notice again, but with the PDF replaced by an iOS Wallet pass that you can add to your Wallet.

I have slightly altered the logo and the name to make it clear that there’s no affiliation to digitec.

The pass will be geo-coded to the correct store, so it will automatically pop up as you get close to the store.

As I don’t want access to your digitec account and because digitec doesn’t have any kind of API, I unfortunately can’t automatically remove the pass when your fetch your order – that’s something only digitec can do.

The source code for the server is available under the MIT license.


  • I’m not affiliated with digitec aside of being a customer of theirs. If they want me to shut this down, I will.
  • I am not logging the collection notices you’re forwarding me. If you don’t trust me, you can self-host, or redact the notice to contain nothing but the URLs (I need these in order to build the pass).
  • This is a fun project. If it’s down, it’s down. If it doesn’t work, submit a pull request. Don’t expect any support
  • The LMTP daemon powering this is running in my home. I have a very good connection, but I also have not signed an SLA or anything. If it’s down, it’s down (the message will get queued though).
  • The moment I see this being abused, it will be shut down. Just like my previous email based fun project

AV Programs as a Security Risk

Imagine you were logged into your machine as an administrator. Imagine you’re going to double-click every single attachment in every single email you get. Imagine you’re going to launch every single file your browser downloads. Imagine you answer affirmative on every single prompt to install the latest whatever. Imagine you unpack every single archive sent to you and you launch ever single file in those archives.

This is the position that AV programs put themselves on your machine if they want to have any chance at being able to actually detect malware. Just checking whether a file contains a known byte signature has stopped being a reliable method for detecting viruses long ago.

It makes sense. If I’m going to re-distribute some well-known piece of malware, all I have to do is to obfuscate it a little bit or encrypt it with a static key and my piece of malware will naturally not match any signature of any existing malware.

The loader-stub might, but if I’m using any of the existing installer packagers, then I don’t look any different than any other setup utility for any other piece of software. No AV vendor can yet affort to black-list all installers.

So the only reliable way to know whether a piece of software is malware or not, is to start running it in order to at least get it to extract/decrypt itself.

So here we are in a position where a anti malware program either is useless placebo or it has to put itself into the position I have started this article with.

Personally, I think it is impossible to safely run a piece of software in a way that it cannot do any harm to the host machine.

AV vendors could certainly try to make it as hard as possible for malware to take over a host machine, but here we are in 2016 where most of the existing AV programs are based on projects started in the 90ies where software quality and correctness was even less of a focus than it is today.

We see AV programs disabling OS security features, installing and starting VNC servers and providing any malicious web site with full shell access to the local machine. Or allow malware to completely take over a machine if a few bytes are read no matter where from.

This doesn’t cover the privacy issues yet which are caused by more and more price-pressure the various AV vendors are subject to. If you have to sell the software too cheap to pay for its development (or even give it away for free), then you need to open other revenue streams.

Being placed in such a privileged position like AV tools are, it’s no wonder what kinds of revenue streams are now in process of being tapped…

AV programs by definition put themselves into an extremely dangerous spot on your machine: In order to read every file your OS wants to access, it has to run with adminitrative rights and in order to actually protect you it has to understand many, many more file formats than what you have applications for on your machine.

AV software has to support every existing archive format, even long obsolete ones because who knows – you might have some application somewhere that can unpack it; it has to support every possibly existing container format and it has to support all kinds of malformed files.

If you try to open a malformed file with some application, then the application has the freedom to crash. An AV program must keep going and try even harder to see into the file to make sure it’s just corrupt and not somehow malicious.

And as stated above: Once it finally got to some executable payload, it often has no chance but to actually execute it, at least partially.

This must be some of the most difficult thing to get right in all of engineering: Being placed at a highly privileged spot and being tasked to then deal with content that’s malicious per definitionem is an incredibly difficult task and when combined with obviously bad security practices (see above), I come to the conclusion that installing AV programs is actually lowering the overall security of your machines.

Given a fully patched OS, installing an AV tool will greatly widen the attack surface as now you’re putting a piece of software on your machine that will try and make sense of every single byte going in and out of your machine, something your normal OS will not do.

AV tools have the choice of doing nothing against any but the most common threats if they decide to do pure signature matching, or of potentially putting your machine at risk.

AV these days might provide a very small bit of additional security against well-known threats (though against those you’re also protected if you apply the latest OS patches and don’t work as an admin) but they open your installation wide for all kinds of targeted attacks or really nasty 0-day exploits that can bring down your network without any user-interaction what so ever.

If asked what to do these days, I would give the strong recommendation to not install AV tools. Keep all the software you’re running up to date and white-list the applications you want your users to run. Make use of white-listing by code-signatures to, say, allow everything by a specific vendor. Or all OS components.

If your users are more tech-savy (like developers or sys admins), don’t whitelist but also don’t install AV on their machines. They are normally good enough to not accidentally run malware and the risk of them screwing up is much lower than the risk of somebody exploiting the latest flaw in your runs-as-admin-and-launches-every-binary piece of security software.

The new AppleTV

When the 2nd generation of the AppleTV came out and offered AirPlay support, I bought one more or less for curiosity value, but it worked so well in conjunction with AirVideo that it has completely replaced my previous attempts at an in-home media center system.

It was silent, never really required OS or application updates, never crashed and never overheated. And thanks to AirVideo it was able to play everthing I could throw at it (at the cost of a server running in the closet of course).

The only inconvenience was the fact that I needed too many devices. Playing a video involved my TV, the AppleTV and my iOS device. Plus remotes for TV and AppleTV. Personally, I didn’t really mind much, but while I would have loved to give my parents access to my media library (1 Gbit/s upstream FTW), the requirement to use three devices and to correctly switch on AirPlay has made this a complete impossibility due to the complexity.

So I patiently awaited the day when the AppleTV would finally be able to run apps itself. There was no technical reason to prevent that – the AppleTV totally was powerful enough for this and it was already running iOS.

You can imagine how happy I was when finally I got what I wanted and the new 4th generation AppleTV was announced. Finally a solution my parents can use. Finally something to help me to ditch the majority of the devices involved.

So of course I bought the new device the moment it became available.

I even had to go through additional trouble due to the lack of the optical digital port (the old AppleTV was connected to a Sonos playbar), but I found an audio extractor that works well enough.

So now after a few weeks of use, the one thing that actually pushed me to write this post here is the fact that the new AppleTV is probably the most unfinished and unpolished product that I have ever bought from Apple. Does it work? Yes. But the list of small oversights and missing pieces is as big as I have never seen in an Apple product. Ever.

Let me give you a list – quite like what I’ve done 12 years ago for a very different device

  • While the AppleTV provides you with an option to touch it with an iOS device for the configuration of the Wifi and the appleid settings, I still had to type in my appleid password twice: Once for the AppStore and once for the game center. Mind you, my appleid password is 30 characters long, containing uppercase, lowercase digits and symbols. Have fun doing this on the on-screen keyboard
  • The UI is laggy. The reason for having to type in the game center password was because the UI was still loading the system appleid as I was pressing the “Press here to login button”. First nothing happened, then the button turned into a “Press here to sign out button” and then the device reacted to my button press. Thank you
  • The old AppleTV supported either the Remote app on an iPhone or even a bluetooth keyboard for character entry. The new one doesn’t support any of this, so there’s really no way around the crappy on-screen keyboard.
  • While the device allows you to turn off automatic app updates, there is no list of apps with pending updates. There’s only “Recently updated”, but that’s a) limited to 20 apps, b) lists all recently updated apps, c) gives no indication what app is updated yet and what isn’t and finally d) isn’t even sorted by date of the last update. This UI is barely acceptable for enabled automatic updates, but completely unusable if you want them disabled to the point that I decided to just bite the bullet and enable them.
  • The sound settings offer “Automatic”, “Stereo” and “Dolby Surround”. Now, “Dolby Surround” is a technology from the mid-90-ies that encodes one additional back-channel in a stereo signal and is definitely not what you want (which would be “Dolby Digital”). Of course I’ve assumed that there’s some “helpfulnes” at work here, detecting the fact that my TV doesn’t support Dolby Digital (but the playbar does, so it’s perfectly fine to send out AC/3 sinal). Only after quite a bit of debugging I found out that what Apple calls “Dolby Surround” is actually “Dolby Digital”. WHY??
  • The remote is way too sensitive. If you so much as lift it up, you’ll start seeking your video (which works way better than anything I’ve seen before, but still…)
  • Until the first update (provided without changelog or anything the like), the youtube app would start to constantly interrupt playback and reload the stream once you paused a video once.
  • Of course in Switzerland, Siri doesn’t work, even though I would totally be able to use it in english (or german – it’s available in Germany after all) Not that it matters because the Swiss store is devoid of media I’d actually be interested in anyways and there’s no way for third-parties to integrate into the consolidated system-wide interface for media browsing.
  • Home Sharing doesn’t work for me. At. All. Even after typing in my Apple ID password a third time (which, yes, it asked me to).
  • It still doesn’t wake up on network access, nor appear in the list of Airplay-able devices of my phone when it’s in sleep mode. This only happens in one segment of my network, so it might be an issue with a switch though – wouldn’t be the first time :/

I’m sure as time goes on we’ll see updates to fix this mess, but I cannot for the life of me understand why Apple thought that the time was ready to release this.

Again: It works fine and I will be brining one to my mother next Friday because I know she’ll be able to use it just fine (especially using the Plex app). But this kind of lack of polish we’re used to on Android and Windows. How can Apple produce something like this?

SNI progressive enhancment

Today marks another big milestone in the availabilibty of ubuquitous SSL encryption: The «Let’s Encrypt» project got their cross-signature, so come a few more weeks, they will be ready for the public to use.

However, with an unlimited amount of available free SSL certificates, we get another problem: Because back in the day nobody thought about name based virtual hosting, the initial implementation of SSL didn’t support the client telling the server what host it’s trying to connect to. This means that the server didn’t know what certificate to present when multiple host names were to be used for the same address.

This meant that for every site you wanted to offer over SSL, you needed an IP address, which are harder to get as time moves on and we’re running out of them.

«SNI» is a protocol extension that allows the client to tell the server the host-name it’s connecting to, so the server can chose the correct certificate to serve. This fixes above issue and finally allows virtual hosting based on the host name even over SSL.

Unfortunately, SNI isn’t as widely supported as we’d like: Older Android devices and all IEs under Windows XP (which still is a sizeable portion of our users) dont’ support SNI.

What’s also tricky is that you don’t know a client doesn’t support SNI until it’s too late: They connect to your port 443, don’t send a host name and now the server needs to a) answer and b) send a server certificate. So unless the client accidentally hit the correct host name, the client will get a certificate mismatch and it will thus display the usual SSL error message.

This is of course not very good UX as you don’t even get to tell the user what’s wrong before they see the browser-specific error message.

However, I still want to support SSL for all my sites wherever I can. If I could have non-SNI-supporting clients on an unencrypted site and then adding encryption only if they support SNI, then encryption would become a progressive enhancement. The sites I’m dealing with aren’t that far in the «needs encryption» territory, so offering encryption only for good (read: non-outdated) browsers is a viable option, especially as I want to offer this for free for the sites I’m hosting and I only have so many IP addresses at my disposal right now.

Generally, the advice to do that is to do user agent sniffing but that’s error-prone. I’d much rather feature detect.

So after a bit of thinking, I came up with this (it requires JS though):

  • Over port 80, serve the normal site unencrypted instead of just redirecting to https.
  • On that regular site do a jsonp request for some beacon file on your site over https.
  • If that beacon loads properly, then your client is obviously SNI compliant, so redirect to the https version of your site using JS.
  • If the beacon doesn’t load, then the browser probably doesn’t support SNI, so keep them on the unencrypted page. If you want to, you can set a cookie to prevent further probing on subsequent requests.
  • On port 443, serve a HSTS header, so next time the browser visits, they’ll use HTTPS from the start.

IE8 will still show the page correctly but also show a warning that it has blocked content for your own security, so you might want to immediately redirect again (with the cookie set) in order to get rid of the warning.

Contrary to the normal immediate redirect to HTTPS, this means that the first page-view even of compliant browsers will be unencrypted, so absolutely make sure that you serve all your cookies with the secure flag. This also means that in order to get to the encrypted version of the page, you need JavaScript enabled – at least for the first time.

Maybe you can come up with some crazy hack using frames, but this method seems to be the cleanest.