In 2020, we will be seeing the boom in the Internet of Things (IoT) space continue to grow with more explosions in the number and variety of IoT solutions in the market. Additionally, large amounts of funding are being deployed at IoT startups. It also happens to be that industry giants are investing in the IoT space, such as Google Cloud IoT, Microsoft Azure’s IoT Hub, and Amazon’s AWS IoT Core. These come with their own advantages and shortcomings. …

Why Have an SSH Tarpit?

If you have any servers that you access using SSH (Secure Socket Shell) connection, you’ll be familiar with how it can be used my hackers to gain access to your servers. However, you’ll also notice through reviewing your server authentication logs look like something like below:

Docker Certified Associate (DCA)

Continuing where we had previously left off. Here is “Set-2" in our series of DCA Practice Questions. Remember, the more you practice, the better are your chances. 😉

  1. What is a grant made up of in Docker’s Role-Based Access Controls (RBAC)? (select three)

Options are :

  • Certificate
  • Role
  • Resource Collection
  • Subject

Answer: Role Resource Collection Subject

2. Where do you create Docker Role-Based Access Controls (RBAC)?

Options are :

  • Docker Machine
  • Universal Control Plane
  • Docker compose
  • Docker Trusted Registry

Answer: Universal Control Plane

3. What is the docker command to add or update a node label?

Options are:

  • docker node…

Docker Certified Associate (DCA)

Docker is quite the buzz tool nowadays, it is a tool that is making it easier to create, deploy, and run applications by using containers.

In today’s job market having Docker skills proves to be of immense importance and the Docker Certified Associate (DCA) exam is designed to validate that skillset with real-world questions designed by experienced Docker practitioners.

I believe you have stumbled on this post cause you have already begun your journey in becoming a Docker Certified Associate. To aid you in the process, I have compiled a few sample questions and answers below. This will definitely give…

JavaScript Promises: Promise.all vs Promise.allSettled vs Promise.race vs Promise.any

On your way to become a “JavaScript Superstar” and “Promises whizz”, you’ll need to master the concept of handling multiple promises at the same time. There are some methods that are provided by the language to do just that, but before we dwell on those methods let’s begin with understanding some basics of “states” and “fates” of promises.

States and Fates

Promises generally have 3 possible mutually exclusive states, they are:

  • fulfilled — A promise is “fulfilled” if promise.then(f) will call f as soon as possible
  • rejected — A promise is rejected if promise.then(undefined, r) will call r "as soon as possible."
  • pending

Easy PGP Encryption using Node.js

What Is Pretty Good Privacy Encryption?

Pretty Good Privacy (PGP) encryption is an encryption system used for sending and receiving encrypted emails and sensitive files. Over the years, PGP has become the de facto standard for email security.

Essentially, PGP uses a combination of two forms of encryption: symmetric key encryption and public-key encryption. Below is a diagram that illustrates how PGP encryption works:


OpenStreetMaps (OSM) is quoted to be a “free wiki world map”. The OSM tile server is essentially a web server specialized in delivering raster maps. It serves them as static ties and is also able to perform rendering in real-time or providing cached images.

Install Dependencies

we will start by updating our Ubuntu repositories

sudo apt-get update && sudo apt-get upgrade

Once done, we will start install the required base packages

sudo apt-get install postgresql postgresql-contrib postgis postgresql-10-postgis-2.4 postgresql-10-postgis-2.4-scripts osm2pgsql git

Just a brief description of all the above dependencies are mentioned below:

  • Postgres is the default database solution we will use…

What Is Tee?

tee on Linux is a command-line tool, it reads from the standard input and is the capability of writing results to the terminal's standard output and files at the same time. This essentially lets you store and view (both at the same time) the output at any time.

How to Use It?

Let’s illustrate the use of tee with a simple example. We can use a command to ping [](


The output should be displayed only on your screen which is standard output (STDOUT):

Why Screen?

screen is this awesome software tool in Linux that provides you the ability to spring-up and use multiple shell sessions from a single ssh session. Screen essentially acts as a terminal multiplexer emulator that is packed with features (just look at the size of its man page, you'll know 😝)

A few key benefits of screen are:

  • Leverage the use of multiplexer to create multiple shell windows from a single shell SSH session
  • Re-establish access and control of the shell session through network disruptions
  • Ability to disconnect and re-connect to a shell session from any system
  • Ability to daemonize a…

If you haven’t been using VS Code, you have no idea what you have been missing. This editor with its speed, customization, and an immense sea of plugins, has become my go-to for everything I do. But one of the most under-rated features of VS Code is its debugging capability. In this post, we will see how to perform remote debugging on a server running heedlessly leveraging the power of an SSH tunnel.

Without further ado, let’s get going…


First thing first, you’ll need to have VS Code installed, you can do so by clicking here.

Once you have done…

Zubair Ahmed

Chief Technology Officer at RAZRLAB

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