Month: May 2018

I’m from the generation that grew up just after punch cards, punched tape and mainframe computers went out of fashion and gave way to interactive programming in front of a terminal or, in my case, a computer at home. So while I was generally aware of the principle of feeding programs and data to mainframes and minis this way, I only had a hazy idea of how programs were encoded on the cards. Recently, a friend gave me a book about Assembler programming written in 1973 which did not only explain in some detail some of the machine instructions of a 1960/70 mainframe but also how Assembly language programs ended up on punch cards and finally in the memory of the computer.

Continue reading A Book About Assembler Programming from 1973 and Punch Cards

If it is not the first time you come across this blog you are probably aware that I host most of the cloud services I use on (now virtual) servers at home. To make sure my Nextcloud and other services are always available when my main connectivity over DSL fails, I have backup LTE connectivity that can take over automatically. There is one major issue with that however: I can’t access my servers from the mobile network. Continue reading Moving from Amazon to Hetzner

Today lets have a look at how the 5G Core (5GC) does Connection-, Registration- and Session-Management for 5G devices. As in the previous posts, the procedures are described in 3GPP TS 23.501 which is the 5G analog to the 4G LTE core network description in 3GPP TS 23.401. I guess the similar number is no coincidence.

Continue reading The 5G Core – Part 6 – Connection-, Registration- And Session Management

A quick observation today about people coming to meetings with their tablets rather than their Windows based notebooks. So far my crude analysis was that those are the people in companies that mostly need a screen to access and consume information. To them, a keyboard for typing in longer texts quickly and efficiently is a rather optional thing, especially in meetings. But there is one more thing Windows notebooks like to do, especially if they are centrally administered: Not do what you want, especially when you use them to present something during a meeting.

Continue reading Windows Notebooks No Longer Fit For Their Purpose In Meetings

After telling my story about upgrading and virtualizing my cloud at home in a previous post, I thought I’d follow-up on the story with some technical details on my new implementation. After deciding to migrate the services I host at home such as Nextcloud, Selfoss, OpenVPN, etc., into virtual machines, the big question was which virtualization environment to use.

Continue reading KVM/Qemu vs Virtualbox for my Cloud at Home

For years I have wondered why accessing my Fritzbox DSL router at home via my LTE backup connectivity doesn’t work reliably. While web pages load at first, things quickly get stuck. After 4 years I finally found the answer and a fix for it.

Continue reading The Fritzbox and Devices With Multiple IP Addresses

As I store quite a lot of data on my Nextcloud at home, it was clear to me when setting-up my new virtualized system at home that I did not want to store the data in the virtual disk image that holds the system partition. If I ever need to migrate the VM or need to extend the storage space, the last thing I want to do is to fiddle with the system partition. KVM/Qemu offers a number of different ways to map additional storage into a virtual machine and surprisingly, the performance of the different options differ quite significantly!

Continue reading A Fast Filesystem For My Cloud at Home: Mapped vs. VirtIO

One of slowest topics in networking is probably the take-up of IPv6 on the client side. Despite this, I’ve been evolving the IPv6 connectivity of my servers at home over the years and with my recent evolution to virtual machines and a new DynDNS hoster, things are now even smoother and a lot simpler.

Continue reading Evolving My IPv6 Setup at Home

One thing that astounded me when reading the 4G specs for the first time many years ago was that there was no separation anymore between attaching (registering) with the network after power-on and activation of a default bearer (getting an IP address). It looks like this will change again in the 5G core network.

Continue reading The 5G Core – Part 5 – The Divorce of Registration and Session Management?

In spring, there are a few weeks in Germany with public holidays sprinkled over weekdays. In many cases, taking an additional day off results in a very long weekend that can, of course, be used to learn new stuff. This time around I particularly had a look tmux which, after the expected steep learning curve, makes working in the shell so much easier.

Continue reading I Finally had My TMUX Moment