Security for anything you connect to the internet is important. Think of these devices as doorways. They either allow access to services or provides services for someone else. Doorways need to be secure — you wouldn’t leave your door unlocked if you lived in the bad part of a busy city, would you? Every internet connection is the bad part of a busy city. The thing is, building hardware that is connected to the internet is the new hotness these days. So let’s walk through the basics you need to know to start thinking security with your projects.
If you have ever run a server and checked your logs you have probably noticed that there is a lot of automated traffic trying to gain access to your server on a nearly constant basis. An insecure device on a network doesn’t just compromise itself, it presents a risk to all other networked devices too.
The easiest way to secure a device is to turn it off, but lets presume you want it on. There are many things you can do to protect your IoT device. It may seem daunting to begin with but as you start becoming more security conscious things begin to click together a bit like a jigsaw and it becomes a lot easier.
When you think about which of the many technological advances of the 20th century had the most impact on the global economy, which one would you rank as the most important? Would it be the space program, which gave rise to advances in everything from communications satellites to advanced composite materials? Or would it be the related aerospace industry, which stitched the world together so tightly that you can be almost anywhere on the planet within 24 hours? Or perhaps it’s the Internet, the global platform for buying almost anything from almost anyone.
Those are all important, but for the most economically impactful technology of the 20th century, I’d posit that the lowly shipping container and the containerized cargo industry that grew around it win, hands down.
In the last episode, I advocated a little bit for Forth on microcontrollers being a still-viable development platform, not just for industry where it’s usually seen these days, but also for hackers. I maybe even tricked you into buying a couple pieces of cheap hardware. This time around, we’re going to get the Forth system set up on that hardware, and run the compulsory “hello world” and LED blinky. But then we’ll also take a dip into one of the features that make Forth very neat on microcontrollers: easy multitasking.
Mecrisp-Stellaris Forth runs on a great number of ARM microcontrollers, but I’ll focus here on the STM32F103 chips that are available for incredibly little money in the form of a generic copy of the Maple Mini, often called a “STM32F103 Minimum System Board” or “Blue Pill” because of the form-factor, and the fact that there used to be red ones for sale. The microcontroller on board can run at 72 MHz, has 20 kB of RAM and either 64 or 128 kB of flash. It has plenty of pins, the digital-only ones are 5 V tolerant, and it has all the usual microcontroller peripherals. It’s not the most power-efficient, and it doesn’t have a floating-point unit or a DAC, but it’s a rugged old design that’s available for much less money than it should be.
Similar wonders of mass production work for the programmer that you’ll need to initially flash the chip. Any of the clones of the ST-Link v2 will work just fine. (Ironically enough, the hardware inside the programmer is almost identical to the target.) Finally, since Forth runs as in interactive shell, you’re going to need a serial connection to the STM32 board. That probably means a USB/serial adapter.
This whole setup isn’t going to cost much more than a fast food meal, and the programmer and USB/serial adapter are things that you’ll want to have in your kit anyway, if you don’t already.
You can power the board directly through the various 3.3 and GND pins scattered around the board, or through the micro USB port or the 5V pins on the target board. The latter two options pass through a 3.3 V regulator before joining up with the 3.3 pins. All of the pins are interconnected, so it’s best if you only use one power supply at a time.
There are very few things that are so far reaching across many different disciplines, ranging from biology to engineering, as is the relation of the surface area to the volume of a body. This is not a law, as Newton’s second one, or a theory as Darwin’s evolution theory. But it has consequences in a diverse set of situations. It explains why cells are the size they are, why some animals have a strange morphology, why flour explodes while wheat grains don’t and many other phenomena that we will explore in this article.
You find them everywhere from 3D printers to jet airliners. They’re the little switches that detect paper jams in your printer, or the big armored switches that sense when the elevator car is on the right floor. They’re microswitches, or more properly miniature snap-action switches, and they’re so common you may never have wondered what’s going on inside them. But the story behind how these switches were invented and the principle of physics at work in the guts of these tiny and useful switches are both pretty interesting.
It was a dark and stormy afternoon, the kind you get on the east side of the country. I was drinking a coffee, sitting in a camping chair in front of my door, and watching like a hawk for the treacherous cable man to show up. This day there would be no escape. There would be no gently rapping the door with a supple sheepskin leather glove before scurrying away for another union mandated coffee break. I was waiting, I was kind of grumpy, and by God today would be the day. Today would be the day that after hours on hold, after three missed appointments, after they lost my records twice; I would get an answer on whether or not they could actually service internet to my apartment. If I was lucky, and the answer was yes, then approximately two to three thousand years later they would run a cable from the telephone pole to my house and I could stop commandeering WiFi from the pizza shop across from me.
It’s important to note that I was in the middle of the city. I wasn’t out in the boonies. Every house on the block but mine had cable. While this is dumb, it begins to make more sense when you dive into the history. Louisville, Kentucky is a strange place. It used to be the gateway to the west. Ships would crawl up its river until they reached the falls. Then porters would charge an exorbitant fee to carry all those goods down to the bottom of the falls where they would be loaded on a ship and be sent ever westward. Resulting in every rich merchant, captain, and manufacturer in the region having a nice house there. Ever wonder why the Derby is in Louisville and the Queen comes to visit sometimes? It probably has something to do with it having the highest concentration of Victorian buildings and mansions outside of New York City.
There’s a lot to be said in favor of getting kids involved in hacking as young as possible, but there is one thing about working in electronics that I believe is best left as a mystery until at least the teenage years — hide the shrink tube. Teach them to breadboard, have them learn resistor color codes and Ohm’s Law, and even teach them to solder. But don’t you dare let them near the heat shrink tubing. Foolishly reveal that magical stuff to kids, and if there’s a heat source anywhere nearby I guarantee they’ll blow through your entire stock of the expensive stuff the minute you turn your back. Ask me how I know.
I jest, but only partly. There really is something fun about applying heat shrink tubing, and there’s no denying how satisfying a termination can be when it’s hermetically sealed inside that little piece of inexplicably expensive tubing. But how does the stuff even work in the first place?