Password Managers…

Posted on by Daniel Kirstenpfad

I am using 1Password for years now. It’s a great tool. So far.

As I am using it locally synced across my own infrastructure I feel like I am getting slowly but surely pushed out of their target-customer group. What does that mean?

The current pricing scheme, if you buy new, for 1Password looks like this:

So it’s always going to be a subscription if you want to start with it and if you want it in a straight line.

It used to be a one-time purchase per platform and you could set-up syncing across other cloud services as you saw fit. If you really start from scratch the 1Password apps still give you the option to create and sync locally but the direction is set and clear: they want you to sign up to a subscription.

I am not going to purchase a subscription. With some searching I found a software which is extremely similar to 1Password and fully featured. And is available as 1-time purchase per platform for all platforms I am using.

Also. This one is the first that could import my 1Password export files straight away without any issues. Even One-Time-Passwords (OTP) worked immediately.

The name is Enpass and it’s available for Mac, Windows, Linux, iOS, Android and basically acts as a step in replacement for 1Password. It directly imports what 1Password is exporting. And its pricing is:

much more reasonable and without subscriptions.

Subscriptions for services as this are a no-go for me. It’s a commodity service which I am willing to pay for trailing updates and maintenance every year or so in a major update.

I am not willing to pay a substantial amount of money per user per month to just keep having access to my Passwords. And having them synced onto some companies infrastructure does not make this deal sweeter.

Enpass on the other hand comes with peace-of-mind that no data leaves your infrastructure and that you can get the data in and out any time.

It can import from these:

As mentioned I’ve migrated from 1Password in the mere of minutes and was able to plug-in-replace it immediately.

an OS in your browser

Posted on by Daniel Kirstenpfad

So I leave this right here:

OS.js is an open-source JavaScript Web Desktop implementation for your browser with a fully-fledged window manager, Application APIs, GUI toolkits and filesystem abstraction.

It really does implement a lot of what an operating system UI and portions of the backends are supposed to be. It looks quite funky and there are applications to this. Of course it’s open source

I want all electron Apps to start existing there so I can call all of them with just a browser from anywhere.

If you want to give it a spin, click here:

Circuit Board Design in your browser

Posted on by Daniel Kirstenpfad

Once every while when you make things you actually need to make things. Things like PCBs – printed circuit boards to hold and wire your chips.

bold claim

Maybe you want to give EasyEDA a try as it’s in-browser experience is better than anything I had come across so far. Granted I am not doing PCBs regularly but nevertheless – whenever I tried with the programs I’ve got recommended it wasn’t as straight forward as it is with this tool.

host GIT repositories painlessly

Posted on by Daniel Kirstenpfad

As people around me discuss what to go for in regards to manage their growing number of private GIT repositories I joined their discussion.

A couple of years ago I assessed how I would want to store my collection of almost 100 GIT private repositories and all those cloned mirrors I want to keep for archival and sentimental reasons.

An option was to pay for GitHub. Another option, which most seemed to prefer, was going for a local Gitlab set-up.

All seemed not desirable. Like chaining my workflows to GitHub as a provider or adopting a new hobby to operate and maintain a private GitLab server. And as it might have become easier to operate a GitLab server with the introduction of container management systems. But I’ve always seemed to have to update to a new version when I actually wanted to use it.

So this was when I had to make the call for my own set-up about 4 years ago. We were using a rather well working GitLab set-up for work back then. But it all seemed overkill to me also back then.

So I found: gogs.io

It runs with one command, the only dependency is two file system directories with (a) the settings of gogs and (b) your repositories.

It’ll deploy as literally a SINGLE BINARY without any other things to consider. With the provided dockerfile you are up and running in seconds.

It has never let me down. It’s running and providing it’s service. And that’s the end of it.

I am using it, as said, for 95 private repositories and a lot of additionally mirrored GIT repositories. Gogs will support you by keeping those mirrors in sync for you in the background. It’s even multi-user multi-organization.

Walk through Tokyo

Posted on by Daniel Kirstenpfad

Let me introduce you to a wonderful concept. We are using these movies as backdrop when on the stepper or spinning, essentially when doing sports or as a screensaver that plays whenever nothing else is playing on the screens around the house.

What is it you ask?

The thing I am talking about is: Walking Videos! Especially from people who walk through Tokyo / Japan. And there are lots of them!

Think of it as a relaxing walk around a neighborhood you might not know. Take in the sounds and sights and enjoy. That’s the idea of it.

If you want the immediate experience, try this:

Of course there are a couple of different such YouTube channels waiting for your subscription. The most prominent ones I know are:

In addition to attract your interest there’s a map with recent such walks in Tokyo. So you can specifically pick a walk you want to see by a map!

don’t forget to zoom out – there is more than just the Tokyo area

code autocomplete with deep learning

Posted on by Daniel Kirstenpfad

When you are writing code the patterns seem to repeat every once in a while. Not only the patterns but also the occasion you are going to apply certain code styles and methods while developing.

To support a developer with this creative work the tedious and repetitious tasks of typing out what is thought can be supported by machine learning.

Chances are your favourite IDE already supports an somehow AI driven code autocomplete feature. And if it does not, read on as there are ways to integrate products like TabNine into any editor you can think of…

Visual Studio IntelliCode is a set of AI-assisted capabilities that improve developer productivity with features like contextual IntelliSense, argument completion, code formatting, and style rule inference.

IntelliCode augments existing developer workflows with machine-learning services that provide an understanding of code and its context. It’s applicable for C#, C++ (in preview), JavaScript/TypeScript (in preview), and XAML code today, and will be updated in the future to support more languages.

Visual Studio IntelliCode

Of course there are some new contenders to the scene, like TabNine:

TL;DR: TabNine is an autocompleter that helps you write code faster. We’re adding a deep learning model which significantly improves suggestion quality. You can see videos below and you can sign up for it here.

TabNine

Deep TabNine requires a lot of computing power: running the model on a laptop would not deliver the low latency that TabNine’s users have come to expect. So we are offering a service that will allow you to use TabNine’s servers for GPU-accelerated autocompletion. It’s called TabNine Cloud, …

TabNine

fiddle with .NET in your browser

Posted on by Daniel Kirstenpfad

There are a lot of different “fiddles”. There’s JSFiddle, SQLFiddle, HTMLFiddle, RegExFiddle, PythonFiddle, R-Fiddle, GoFiddle. There is even a page that curates a list of fiddles.

For .NET there’s one too. It supports C#, F# and VB.NET. For trying something quickly or sharing it online this is a nice way to do it:

Hello World C#
MVC even

electronic fireworks

Posted on by Daniel Kirstenpfad

The firecracker exploded. Apparently after 2 weeks of usage of the Chuwi Hi10 Air the eMMC flash is malfunctioning.

In a totally strange way: Every byte on the eMMC can be read, seemingly. Even Windows 10 boots. But after a while it will hang and blue screen. Apparently because it tries to write to the eMMC and when those writes fail and pile up in the caches at some point the system calls it quits.

Anyhow: It means that no byte that is right now on this eMMC can be deleted / overwritten but only be read.

The great chinese support is really helpful and offered to replace the device free of charge right away. That’s very nice! But I came to the conclusion that I cannot send the device in, because:

It contains a full set of synched private data that I cannot remove by all means because the freaking soldered-on eMMC flash is broken.

The recipient of this broken tablet in china would be able to read all my data and I could not do anything about it.

Only an extremely small fraction of data is on there unencrypted. Only that much I hadn’t yet switched on encryption on during the initial set-up I was still doing on the device. And that little piece of data already is what won’t let me send out the device.

Now, what can we learn from this? We can learn: Never ever ever work with anything, even during set-up, without full encryption.

easily draw text based flowcharts

Posted on by Daniel Kirstenpfad

As I am mainly producing text and markdown notes throughout the day I am always interested in ways to quickly create simple text-based flow-charts.

I did write about a couple of tools to accomplish this previously but I want to take note of the most recent addition to the toolbox: ASCIIFlow Infinity.

You open it in your browser and start drawing with the simple tools provided.

When you are done you export it to plain text and do what you feel like with it.

Here’s a feature overview:

retrofit an old printer to be available on the network

Posted on by Daniel Kirstenpfad

In 2007 I had become proud owner of a Samsung ML-2010 mono laser printer. It’s done a great job ever since and I can recall changing the toner just once so far.

So you can tell: I am not a heavy printer user. Every so often I gotta print out a sheet of paper to put on a package or to fill out a form. A laser printer is the perfect fit for this pattern as it’s toner is not going-bad or evaporating like ink does in ink-printers.

So I still like the printer and it’s in perfect working condition. I’ve just recently filled up the toner for almost no money. But – but this printer needs to be physically connected to the computer that wants to print.

As the usage patterns have significantly changed in the last 12 years this printer needs to be brought into todays networked world.

Replacing it with a new printer is not an option. All printers I could potentially purchase are both more expensive to purchase and the toner is much more expensive to refill. No-can-do.

If only there was an easy way to get the printer network ready. Well, turns out, there is!

First let’s start introducing an opensource project: CUPS

CUPS (formerly an acronym for Common UNIX Printing System) is a modular printing system for Unix-like computer operating systems which allows a computer to act as a print server. A computer running CUPS is a host that can accept print jobs from client computers, process them, and send them to the appropriate printer.

Wikipedia

A good, cheap and energy-efficient way to run a CUPS host is a Raspberry Pi. I do own several first-generation models that have been replaced by much more powerful ones in the previous years.

So I’ve taken one Raspberry Pi and did the set-up steps: Installing the Raspberry Pi Print Server Software.

And now – what did I get?

I got a networked Samsung Laser Printer. No thrills, no problems at all.

the CUPS web interface
the printer shows up on Linux (Ubuntu here)
on iOS and macOS the printer magically appears
on Windows 10.

brain simulators

Posted on by Daniel Kirstenpfad

With recent announcements around human brain and brain-machine interface research like Neuralink the topic is seemingly seeing some more investments now.

As this whole topic is special to my heart I am interested in all things brain simulations. Thus here’s my personal “logbook entry” on the re-appearance of this topic:

This leads to one of the arguments for whole-brain simulation: it’ll help us solve the “biological imitation game,” a Turing test-like assay that pits digitally reconstructed brains against real ones. Iterations of the test help select increasingly more accurate models for a given task, which eventually become the most promising ideas for how specific biological networks operate. And because these models are based on mathematical equations, they could become the heart of next-generation AI.

Singularity Hub

There’s also a paper! – Unfortunately I cannot link directly to the paper as it is behind paywalls. Neuralink on the other side was so kind to publish open-access:

Tool: Partition Recovery and Undelete – Testdisk

Posted on by Daniel Kirstenpfad

Mass storage hardware breaks all the time. Sometimes it’s hardware that breaks, but sometimes it’s the software that breaks. If it’s the software (or own talent) that made the data go boom, TestDisk is a tool you should know about.

DISCLAIMER: If the data you are trying so recover is actually worth anything you might want to reserve to a professional data recovery service rather than trying to train-on-the-job.

Apart from the availability of pre-compiled packages for most operating systems you can also grab a bootable LiveCD when everything seems gone and lost.

The process itself is rather exciting (if you want the data back) and may require a fresh pair of pants upfront, throughout and after.

Thankfully there’s a great wiki and documentation of how to go about the business of data recovery.

TestDisk is powerful free data recovery software! It was primarily designed to help recover lost partitions and/or make non-booting disks bootable again when these symptoms are caused by faulty software: certain types of viruses or human error (such as accidentally deleting a Partition Table). Partition table recovery using TestDisk is really easy.

  • TestDisk can
    • Fix partition table, recover deleted partition
    • Recover FAT32 boot sector from its backup
    • Rebuild FAT12/FAT16/FAT32 boot sector
    • Fix FAT tables
    • Rebuild NTFS boot sector
    • Recover NTFS boot sector from its backup
    • Fix MFT using MFT mirror
    • Locate ext2/ext3/ext4 Backup SuperBlock
    • Undelete files from FAT, exFAT, NTFS and ext2 filesystem
    • Copy files from deleted FAT, exFAT, NTFS and ext2/ext3/ext4 partitions.

TestDisk has features for both novices and experts. For those who know little or nothing about data recovery techniques, TestDisk can be used to collect detailed information about a non-booting drive which can then be sent to a tech for further analysis. Those more familiar with such procedures should find TestDisk a handy tool in performing onsite recovery.

And if you give up, think about writing an article of you actually digging deeper:

my 11 year old blog post about this SD card

Wireless Network Mapping – data source and data sink

Posted on by Daniel Kirstenpfad

When you work with wireless networks and you do programming and mobile app development that works with things like user location you might find this useful.

Take thousands of users and you’ve got the worlds wifi networks mapped…

WiGGLE (Wireless Geographic Logging Engine) is a project which takes wireless network data + location and puts it into a big database. On top of storage it’s giving you access to that data.

We consolidate location and information of wireless networks world-wide to a central database, and have user-friendly desktop and web applications that can map, query and update the database via the web.

https://wigle.net/faq

So what’s my use-case? Apart from the obvious I will make use of this by finding out more about those fellow travelers around me. Many people probably to the same as me: Travel with a small wifi / 4g access point. Whenever this accesspoints shows up in scans the path will be traceable.

I am curious to see which access point around me is in the million-mile club yet…

full website screenshots from your commandline

Posted on by Daniel Kirstenpfad

Think of this: You want to capture a whole, multi-scroll-pages, web-page into one image.

This can be difficult without the right tools. It surely will be a lot of work to accomplish a 10th of thousand pixel height screenshot put together from multiple single screenshots…

CutyCapt is there to help! It’s a command line tool encapsulating the very powerful WebKit browser engine to render a full page and then create a single file screenshot of the whole page for you.

By example, this is what it did when told to screenshot this website:

PixelFed – Federated Image Sharing

Posted on by Daniel Kirstenpfad

In search of alternatives to the traditional centralized hosted social networks a lot of smart people have started to put time and thought into what is called “the-federation”.

The Federation refers to a global social network composed of nodes that talk to each other. Each of them is an installation of software which supports one of the federated social web protocols.

What is The Federation?

You may already have heard about projects like Mastodon, Diaspora*, Matrix (Synapse) and others.

The PixelFed project seems to gain some traction as apparently the first documentation and sources are made available.

PixelFed is a federated social image sharing platform, similar to instagram. Federation is done using the ActivityPub protocol, which is used by Mastodon, PeerTube, Pleroma, and more. Through ActivityPub PixelFed can share and interact with these platforms, as well as other instances of PixelFed.

the-federation

I am posting this here as to my personal logbook.

Given that there’s already a Dockerfile I will give it a try as soon as possible.

WiFi QR Code Generator

Posted on by Daniel Kirstenpfad

Whenever we arrive at a place that we have not been before it is important to get properly connected to the internet.

Finding wifi SSIDs and typing passwords is tedious and prone to errors. There is an easier way of course!

The owner of the wireless network can generate a QR code that you can easily take a photo of and your phone will automatically prompt you to log into the wireless network without you having to type anything.

On your phone it looks like this:

To generate these QR codes that contain all information for visitors/new users to connect this simple tool / online generator can be used:

Ever wanted to create a cool QR code for your guests? But never wanted to type in your WiFi credentials into a form that submits them to a remote webserver to render the QR code? QiFi for the rescue! It will render the code in your browser, on your machine, so the WiFi stays as secure as it was before (read the code if you do not trust text on the internet :-))!

Qifi.org

Don’t worry: your access point information is not transferred over the internet. As this is open source at the time of writing the data was held in HTML 5 local storage on the local browser only and not transferred out.

generate web-ready graphs and data visualizations without coding

Posted on by Daniel Kirstenpfad

Plot.ly is both a well known software library of impressive visualizations and a company providing software and know-how around visualizations.

With the libraries requiring a fair amount of know-how and programming to be useful to everyone there is now seemingly a multitude of tools that wraps the powers of the library and provides a great online-/web-browser experience to create impressive visualizations:

The access path to this quite powerful tool does somehow not be very easily found. So I am linking to it for your and my later reference.

electronic firecracker: Chuwi Hi10 AIR Tablet

Posted on by Daniel Kirstenpfad

The Android tablets I am using for my kitchen scale display and for myfitnesspal data-entry are aging quite bad and apart from the near-display death of one of the tablets both are not supported and updated anymore.

Using them therefore poses an increasing risk. After one of them almost died on me I was determined to replace them both. Looking at alternatives at the lowest possible price quickly showed that I am not going to get another Android tablet.

Instead I was ready to give a chinese company a chance:

I ordered it on 24th of June and it was delivered today. All in all I’ve paid 136 Euro for the tablet and 45 Euro for the keyboard attachement.

Despite the ridiculously low price this thing is quite impressive. It’s sporting a fast-enough Intel Atom processor with 1.4 ghz and 4 Gbyte of RAM. The 64 Gb of solid-state storage where quickly upgraded by an additional 400 Gb MicroSD card for local data storage.

As of writing this it’s still installing and updating the Windows 10 to 1903 but so far I am beyond impressed.

I’ll write more about the device when I’ve had more time to use it. One word for the keyboard attachement: the keyboard is good-enough. Not great but better than for example that on the Pinebook. The touchpad is very small but works – the thing has a Touchscreen anyway.

I don’t like the long-tail Windows 10 default cursor

Posted on by Daniel Kirstenpfad

The first device in my household recently has updated itself to the newest Windows 10 1903 build.

On the very first moment of the login screen appearing and logging in I could tell that I hate one specific change that has made it into this latest update.

And it’s the default mouse cursor.

Back in the Pre-Windows Vista days, when I used to work for Microsoft, I was using the latest internal build of Windows and just around the first RTM (release-to-manufacture) build they touched up on the final designs.

I remember vividly when the mouse cursor had changed from the one we new and used since Windows 3 to a shorter tailed more “high-def” looking one.

Since then there were a couple of changes on the cursor but the general design was kept.

Now apparently with the latest Windows 10 update from 1803 to 1903 I got a new – old default mouse cursor.

left: like!
right: booh!

By reflex I changed it back to the one I love and stored safely in a backup. I cannot stand the long tail and the weird pixel-ness of the cursor. It just looks kinda weird to my eyes.

the “new” cursor in 1903
the beloved cursor.

Which one do you like better?

terminates the calling process if buffer is not a valid userspace pointer.

Posted on by Daniel Kirstenpfad

How to build security into your software? It’s always simple to find examples where things gone wrong. Where security was compromised and things did not work out as the software authors envisioned.

As always there are new concepts and operating systems being implemented.

A particularly interesting example of security software design can be observed here:

Fuchsia is an open source capability-based operating system currently being developed by Google.

In contrast to prior Google-developed operating systems such as Chrome OS and Android, which are based on the Linux kernel, Fuchsia is based on a new microkernel called Zircon. The name Zircon refers to the mineral of the same name.

Google Fuchsia

So you now know what Fuchsia is. Now on to the actual example. For this we have to take a look into the developer documentation of Zircon:

zx_cprng_draw

So this describes a method to get random numbers from the systems cryptocraphically-secure-random-number-generator (CPRNG). It takes a pointer to a memory location as a parameter.

Now. What’s secure about that? It’s the behaviour of the method when it is encountering an unsecure situation:

It’ll kill the calling process when the pointer is not valid.

automated downloads

Posted on by Daniel Kirstenpfad

Hmm… I’ve set-up a script to automatically download a TV show about a year ago and just remembered it…

Apparently 1 year of this show is 167 Gbyte…

For completeness the download script – ignore my bad scripting:

#!/bin/bash

# parameter 1: month
# parameter 2: from day
# parameter 3: to day
# parameter 4: year

# data -dmonday +%d

next_monday=$(date -dmonday +%d)
next_monday_month=$(date -dmonday +%m)
next_monday_year=$(date -dmonday +%y)

previous_monday=$(date -d'monday-7 days' +%d)
previous_monday_month=$(date -d'monday-7 days' +%m)
previous_monday_year=$(date -d'monday-7 days' +%y)

next_friday=$(date -dfriday +%d)
next_friday_month=$(date -dfriday +%m)
next_friday_year=$(date -dfriday +%y)

previous_friday=$(date -d'friday-7 days' +%d)
previous_friday_month=$(date -d'friday-7 days' +%m)
previous_friday_year=$(date -d'friday-7 days' +%y)

for i in `seq 1 7`;
do
        day=$(date -d'today+'$i' days' +%d)
        month=$(date -d'today+'$i' days' +%m)
        year=$(date -d'today+'$i' days' +%y)
        wget -c "https://rodlzdf-a.akamaihd.net/none/zdf/"$year"/"$month"/"$year$month$day"_sendung_dku/1/"$year$month$day"_sendung_dku_3328k_p36v14.mp4"
done

IP-over-DNS

Posted on by Daniel Kirstenpfad

Picture yourself in this situation. You connect to a network and nothing works. Except for this:

It is quite common to have DNS working in networks while everything else is not. Sometimes the network requires a log-in to give you access to a small portion of the internet.

Now, with the help of a tool called iodine, you can get access to the full internet with only DNS working in your current network:

iodine lets you tunnel IPv4 data through a DNS server. This can be usable in different situations where internet access is firewalled, but DNS queries are allowed. 

It runs on Linux, Mac OS X, FreeBSD, NetBSD, OpenBSD and Windows and needs a TUN/TAP device. The bandwidth is asymmetrical with limited upstream and up to 1 Mbit/s downstream. 

iodine

Setting it up is a bit of work but given that you are anyway having access to a well connected server on the free portion of the internet it can be easily done.

Of course the source is on github.

making ICs at home

Posted on by Daniel Kirstenpfad

Try to wrap your head around this: There are people out there that take the term “Maker” to new levels. People Like Sam Zeloof. He went out and created his very own integrated circuit designs and then he built them. Like the actual silicon, the die, the bonded chip, the IC. The real thing.

Be inspired:

I am very excited to announce the details of my first integrated circuit and share the journey that this project has taken me on over the past year. I hope that my success will inspire others and help start a revolution in home chip fabrication. When I set out on this project I had no idea of what I had gotten myself into, but in the end I learned more than I ever thought I would about physics, chemistry, optics, electronics, and so many other fields. Furthermore, my efforts have only been matched with the most positive feedback and support from the world; I owe a sincere thanks to everyone who has helped me, given me advice, and inspired me on this project. Especially my amazing parents, who not only support and encourage me in any way they can but also give me a space to work in and put up with the electricity costs… Thank you!

Sam Zeloof
Sam Zeloof

Decoding history, the hard way (and with machine learning)

Posted on by Daniel Kirstenpfad

Imagine you’ve got this ancient piece of technology in front of you. You clearly understand how the hardware works and you are even able to emulate the hardware on your modern-world computer.

Unfortunately hardware is only one half of the story. Software is the other half. And software at this time of the past was burned into chips which do not easily give their secret software away.

But let’s start with the hardware:

The IBM 5100 Portable Computer is a portable computer (one of the first) introduced in September 1975, six years before the IBM Personal Computer. It was the evolution of a prototype called the SCAMP (Special Computer APL Machine Portable) that was developed at the IBM Palo Alto Scientific Center in 1973. In January 1978, IBM announced the IBM 5110, its larger cousin, and in February 1980 IBM announced the IBM 5120. The 5100 was withdrawn in March 1982.

When the IBM PC was introduced in 1981, it was originally designated as the IBM 5150, putting it in the “5100” series, though its architecture was not directly descended from the IBM 5100.

By Sandstein – Own work, CC BY-SA 3.0,

And now on to the software:

The IBM 5100 portable computer came with some of its built-in programs stored in a read-only memory called the “non-executable ROS”. (ROS = “read-only storage”.) In contrast with the “executable ROS”, which supplies instructions to the 5100’s processor directly, the non-executable ROS is accessed using sequential I/O operations, a bit like a tape.

Most notably, the non-executable ROS holds the interactive interpreters for the APL and BASIC programming languages. These are not “native” 5100 programs but were expressed instead in System/370 mainframe and System/3 minicomputer machine code respectively. The 5100 runs emulator programs for those computers in order to host the interpreters, so perhaps it’s just as well that the non-executable ROS is non-executable.

DATA

So this write-up is all about how the bits where pushed to the screen and recorded as pictures of the said screen. The characters in these pictures then where analyzed and with the help of machine learning the data could be successfully extracted. It is mind-boggling. And it is all on Github.

useful CSS Grid Generator

Posted on by Daniel Kirstenpfad

This project is a way for people to use CSS Grid features quickly to create dynamic layouts.

You can set the numbers, and units of your columns and rows, and I’ll generate a CSS grid for you! Drag within the boxes to create divs placed within the grid.

I noticed a lot of people weren’t using Grid because they felt it was too complicated and they couldn’t understand it. Grid is capable of so much, and this small generator only touches on a fraction of the features. The purpose of this is so people get up and running quickly, and create more interesting layouts.

Once you work with this a bit, I suggest checking out resources by Rachel Andrew, Jen Simmons, and Dave Geddes to dive deeper. There is also a CSS Grid Guide on CSS-Tricks, and a fun little game called Grid Garden to help you learn more!

Source