-- How to host both a web server and VPN on port 80
Figure 1. Pictogram of a server responding differently on the same port depending on IP address
Recently, I had to configure one of my servers to handle requests coming from a specific IP differently from the rest of the Internet. Specifically, I wanted port 80 to usually return my website, but for one specific client (based on the IP address), I wanted it to instead forward to request to another server running SSH. (Yes, that's kind of stupid, but drastic firewalls require drastic measures.)
In the following, I will show how to configure iptables to change the backend service handling a connection based on the source IP address. I'll give a quick example using a simple HTTP server using Python and one socat TCP endpoint serving the current date and time over raw TCP. I am intentionally choosing two incompatible protocols here to show that this method allows this.
Leddie is a 6-sided die with nine RGB LEDs on each side. This first prototype is powered by an Atmega8 and an accelerometer, and can run off the wall for about two hours thanks to the built-in 400 mA li-polymer battery.
Two years ago [1], I wrote about running your TrueNAS VMs from the boot pool by manually updating the virsh configuration. The problem here, however, was that you had to repeat these steps each time you rebooted the VM as TrueNAS would reset the configuration. Also, it wasn't 100% reliable and the commands might need a few attempts to work.
Since then, two of my readers, John and Michael, reached out to me to tell me about a better solution they both (independently) discovered: Editing the TrueNAS database instead of manipulating the virsh service configuration.
WARNING! Just as last time, this guide is definitely not how TrueNAS is intended to be used. It may be better than my last approach, but it's still dirty. You may brick your installation (even if you followed this guide perfectly), or even worse, lose your VMs and data. Only do this if you can live with losing everything and having to reconfigure your entire system.
Please note that, by enabling this video, data is transferred to YouTube LLC, and is subject to their privacy policy.
Writing good code is hard. Testing it is arguably even harder. And with the advance of modern technologies, the demand for good verification only keeps growing along with it. However, especially the FPGA world appears to commonly use obsolete and inappropriate verification tools and methodologies. But it doesn’t have to be this way! This post outlines, guided by a real-world example, how to use modern verification languages and tools to create high-quality test benches in less time.
-- I'll probably regret this when I finally lose my data
Figure 1. TrueNAS VM configuration panel
I've been meaning to transfer my Raspberry Pi based services into a virtual machine on my main server running TrueNAS for a while now, but I've always delayed as I didn't know where to store the VM's disk. I have 7 disks in my main server: 2x 128 GB SSDs as the boot array, 4x 4 TB HDDs as the main array, and another single 4 TB HDD for less important data.
Basically, I don't care where I store the VM, but I want my HDDs to spin down during the night and low load periods. Since a VM will definitely keep the drives up, the mechanical drives are out, leaving me only with the boot pool. It has enough storage for what I need, but, and here comes the problem, TrueNAS does not allow me to keep custom datasets on the boot pool.
But, under the hood, TrueNAS is just FreeBSD. So as I had some time over the holidays, I set out to find a solution to do it nonetheless.
→ UPDATE: There is an updated, much more reliable version of this guide based on editing the database [1]. I strongly recommend to use that instead. ←
WARNING! This guide is definitely not how TrueNAS is intended to be used. It's dirty and terrible. If you brick your installation (even if you followed this guide perfectly), or even worse, lose your VMs and data, don't tell me I didn't warn you. Only do this if you can live with losing everything and having to reconfigure your entire system.
-- Based on an AVR and a Raspberry Pi 0W running MPD
Figure 1. DIY Web Radio
Last year, a friend gave me a dead DAB+ radio, whose only function that still worked was the heater-function -- Oh, it wasn't supposed to do that? OK... Then it was 100% dead. --
Either way, I've been meaning to get myself an Internet radio for a while now, but all on the market were missing some feature I wanted, plus building one myself didn't sound too hard.
This post describes the radio that I built in the end, based around only the original case and speaker from the DAB+ radio.
-- Now that's my definition of building a computer!
Figure 1. The finished LW-35
Do you still remember the old electronic typewriters from the nineties? Many of the later machines were already pretty much full-fledged computers, just with a word processor as the operating system. One of these typewriters is the Brother LW-35 released in Europe. I still had one of these lying around; Great keyboard, a fun daisy wheel printer, and a 14 line display for distraction free writing. It even had a floppy drive for data exchange. So in summary, a pretty cool device.
But there were a few problems with it. First of all, the floppy drive stopped working reliably. And secondly, on the days the floppy drive decided to work, it was still a floppy drive. Not exactly the most convenient way to store and transfer data these days, although I'm sure some of you will disagree. Also, the typewriter used its own file format, which needed to be converted on the device itself before it could be read in a DOS or UNIX environment. This may be OK if you're writing a longer document, and only write it on that machine. But as someone who constantly changes the machine they type on, it's not practical.
Yet, even with these problems, I just didn't have the heart to throw it out.
So what can we do about it? Upgrade it!
In this post, I will show you how I converted my old LW-35 typewriter into a modern computer while keeping all the good features of the old machine.
