50th Anniversary of Apollo 11 – My Book Recommendations

Project Apollo InsigniaNot long now and we will celebrate the 50th anniversary of the first human landing on the moon! 50 years ago, on the 20th July 1969, humankind’s greatest tech adventure culminated with Neil Armstrong setting foot on the lunar surface. Altough I wasn’t born back then, this has inspired me from early childhood and over the years my fascination grew even more. Even after several trips to the Manned Space Flight center in Huston and Kennedy Space Center in Florida, I still get goosebumps when I pick up a book about a particular aspect of the Apollo program. So in anticipation of the 50th anniversary celebrations, here are the top three books I think one should have read about Project Apollo: Continue reading 50th Anniversary of Apollo 11 – My Book Recommendations

Is There A Way To Clone An Android Installation?

Impact crater on phone displayWhen you accidentally drop your phone and it looks like on the picture on the left when you pick it up, your plans for the rest of the day are pretty much out the window. There are several options after such an accident one of them is to just get another device and start from scratch. This is what I did and spent the next 3 hours installing LineageOS and all apps and data from scratch again. Once done I thought I’d make the best out of the broken phone, which was still working, and see if I could have been faster (next time…) by just cloning the complete Android installation from one device to the other. This works great on the PC with Linux and I regularly do this to make sure I have a backup SSD with a working clone of my installation. After several hours and approaching the issue from several angles, I have to say that I came up empty handed.

Continue reading Is There A Way To Clone An Android Installation?

Book Review: All These Worlds

When I finished the second book of the Bobiverse trilogy by Dennis E. Taylor, I immediately jumped into ‘All These Worlds‘, the third and (so far) final part of this brilliant science fiction series. Short summary of what happened so far without too many spoilers: Geek brain gets frozen today, wakes up as replicant a hundred years later, explores the Galaxy and tries to save mankind with the help of his clones. The second book ended with the clear indication that in the third part, Bob and his ‘descendant’ clones would have to deal with ‘the Others’ and that a peaceful solution was probably not in the cards.

Continue reading Book Review: All These Worlds

My 5G Intro at GPN19 – In German

Thanks to a public holiday in Germany, I just had a 4 day weekend and spent most of it at GPN19 in Karlsruhe learning new things, meeting people and giving back to the community by holding talks as well. I really like that we have lots of community organized hacking events all year around and this one is a particular fun one. It is not as big as the yearly ‘Congress’ in December but still has a lot of diverse topics to get inspired and 1800 people attending.

One of the talks I gave was  a technology introduction to 5G (in German). Probably too high level for most of you visiting this site regularly but being even more overhyped than 4G a decade ago, I thought it was time to talk about technology and reality rather than myths and marketing fluff. A big thank you to the great C3 Video team, it took them less than 2 hours to publish it!

How To Run A Server At Home Without An IPv4 Address

IPv4 tunnelingOnce upon a time the Internet was bidirectional and everyone could run a server at their end. Unfortunately, these days are long gone and many ISPs today, especially cable providers, do not assign a public IPv4 address to their customers. Not even when you ask them nicely. Not even for money, unless you are a business customer who is willing to pay through the nose for the privilege. Fortunately, there is a way to run servers at home and make them accessible to the outside world and an easy one at that. The following text and shell commands are from a talk I gave at GPN19 (in German).

Continue reading How To Run A Server At Home Without An IPv4 Address

5G NR Throughput Calculator

So far I’ve always made a quick and approximate calculation when somebody asked me what the theoretical peak data rate of 5G NR would be for a given bandwidth. But there is a more scientific way to do this as 3GPP has put a formula together to include all relevant factors in the calculation. Using this formula it is then possible to not only calculate the theoretical peak throughput but also what can be achieved in realistic transmission conditions. As the number of parameters that go into the calculation is quite lengthy a number of people have made online calculators available. Here’s a good example.

Continue reading 5G NR Throughput Calculator

Looking Back: The Year I Published My First Website

After trying to remember when I used the Internet for the first time in my previous article on Gopher and the early World Wide Web, and coming to the conclusion that it was in 1994, I’ve then taken the next step and tried to remember when I actually published my first website. So here’s the story.

Continue reading Looking Back: The Year I Published My First Website

LTE RAN Congestion Behavior

Uncongested network througputThings are good in the network when you get downlink and uplink throughput results like in the first screenshot on the left. Downlink speeds are in the 150 Mbit/s range, uplink is in the 50 Mbit/s range and the round trip delay time is around 19 ms. Unfortunately, this is not always the case. I’m a bit disappointed that I sometimes have to discover that in places such as large train stations with thousands of people in close proximity, networks are only on air with a single LTE carrier. No carrier aggregation and no small cell deployment anywhere to be seen.

Continue reading LTE RAN Congestion Behavior

Configuring Prosody for iOS and Chatsecure Push

I’m one of those people who run their own XMPP server because I like my privacy. In my case I use Prosody and by default it communicates directly with the client apps such as ‘Conversations’ or ‘Pix-Art Messenger’ on Android. Unfortunately, iOS is much less cooperative and in the name of power saving, cuts the connection to clients a few minutes after they have gone to the background. Sending messages to these clients then requires the use of Apple’s push service to wake up the client app, e.g. the Chatsecure app, so it can pull the message from the server. So how is that done in practice?

Continue reading Configuring Prosody for iOS and Chatsecure Push