Martin – Page 38 – WirelessMoves

My Codium Weekend

Apart from having fun and providing useful software for researchers, my quality time software project I’ve been working on for almost a decade, is to stay up to date with the latest software development methods and tools. Earlier this year, I’ve switched my development environment and deployment method to Docker containers. Once set up, this made my software development routine much easier and users of my Document Research Database software can swiftly install an instance from Gitlab on a server of their choice. While the software is in constant evolution, one thing however has remained the same throughout: The development environment. So far, I’ve been using Eclipse, as once upon a time, that was the standard development environment for PHP. But things have changed over the years and VSCode now seems to be the preferred editor for software developers. And indeed, it looks very nice. Unfortunately, it has one major flaw: It’s maintained by a company that, like no other, stood for fighting against Linux and open source.

Wireguard, OpenWrt and a Linksys Router

One VPN technology I wanted to try out for quite some time now is Wireguard. Everybody I talk to about the topic speaks very highly of it but unfortunately, the stable version was just released a bit too late for proper NetworkManager support to be included in Ubuntu 20.04 last year. While I could live with a couple of scripts to establish and tear down a tunnel to my home network, that’s unfortunately not an option for others I work with. But then I remembered that OpenWrt, the open source Linux operating system for embedded network devices such as Wi-Fi access points, has support for the protocol. And as I just needed to update a Linksys WRT-1200 AC Wi-Fi Router to the latest OpenWrt version anyway, I used the opportunity to gain some experience with the protocol along the way.

My New Thinkpad X13 with 16 CPU Threads – First Impressions

O.k. I admit it, the sheer performance of video calls on current notebook processors made me go for a new instead of a used notebook, as incidentally, a couple of other unforeseen developments required the move anyway. So instead of buying a used Lenovo X270 with a 7th generation Intel processor from 2017 with 2 cores and 4 CPU threads, I went for a new Thinkpad X13 Gen 1 from 2020 with an AMD Ryzen 7 4750U CPU with 8 cores and 16 CPU threads. So here’s the story of how that went.

Booting From /dev/sdb

When installing a new OS, I am quite used to booting a computer from a USB drive. However, from way back in the days I faintly remember that connecting a drive with an installed Linux system with a SATA to USB adapter to a notebook / server would not work. Particularly so when the notebook / server already contains a disk drive that uses the default SATA port (/dev/sda). But I recently discovered that things have become way better these days!

Routing it Your Way Part 3: Socat for OpenVPN Forwarding

O.k., I’m going deeper and deeper down the layer 7 routing rabbit hole. As I like to have a plan B when it comes to my infrastructure at home, I have backup Internet connectivity over a separate Internet connection and a separate router. When main connectivity fails, a script detects that my services are no longer reachable. It then changes the DynDNS entries of all domains I use at home to point to the IP address of the backup connectivity. So far, so good.

But here is the catch: Backup connectivity is routed through a VM on the Internet that terminates ssh reverse port mapping tunnels from my VMs at home. These tunnels do not use the main Internet link so they don’t break when connectivity is lost. Instead, the VMs at home have an entry in the routing table for the IP address of the cloud VM that points to the backup connectivity router. This works great but has one major shortcoming: ssh can only tunnel TCP ports. Unfortunately, OpenVPN and similar products use UDP as transport protocol, and hence, ssh tunneling doesn’t work. But there’s another way!

M.2 Slots – SATA and NVME SSDs

A quick hardware episode today because every now and then I was puzzled about how to identify if an M.2 SSD is a SATA drive or if it supports the faster and today’s more common NVME interface. The same goes for the M.2 connector on the notebook side. Turns out it is quite simple.

Video Calling Performance On New Notebooks

By and large, I am pretty happy with my approach of using a refurbished notebook as my main device for my daily work. Currently, I use a Lenovo X250 from 2015, i.e. it’s around 6 years old. It runs fast enough and I don’t perceive a significant difference when I sit in front of a newer notebook that also runs Linux. Until recently.

Routing it Your Way Part 2: ssh + socat to Simplify Tunneling

In a previous post I’ve described of how ssh reverse tcp forwarding and socat forwarding can be used in combination to make the services of a server without a public IP address and no ssh access available to the outside world. The setup requires two intermediate gateway servers, one on the Internet and one in the local network. On the one hand, this is complicated but on the other hand offers a number of interesting simplifications if you have more than just one server in your local network that you want to expose to the world. Let me explain…

Routing It Your Way Part 1: ssh + socat

Every now and then I get questions that make me think in new directions and the results are often useful far beyond the original intent. Here’s an example: For many years I’ve been using ssh reverse tcp port forwarding to make servers available on the Internet that are behind a NAT, for example in a home network without a public IP address. Here’s my original post from back in 2014 and here’s a post about a talk I gave on the topic in 2019. But what if one can’t initiate an ssh tunnel from the server behind the NAT? Well, I have a solution for that as well now: Combining ssh and socat!

Confidential Computing – Some Thoughts

At the end of 2020, I first came across the term Confidential Computing for the first time over here. This article describes how to encrypt a virtual machine image and then upload and run it on a physical host of a cloud provider without the cloud provider being able to look into the VM and into the virtual disk image. If this was actually offered by a cloud hosting company in the future, it would go a long way to overcome my aversion of processing sensitive personal data in the cloud. Over the next months, however, it turned out that the term ‘Confidential Computing’ is used for quite a number of different things, so one has to be very careful what people mean when they are using this term. So let’s have a look at the different kinds of Confidential Computing.