Deep Dive Articles

The Best Way to Learn a New Programming Language from Scratch - How I Approach and Learn Any Programming Language Efficiently

Preface: The following article is based on my experiences and opinions on learning programming languages. I have been learning about computers in-depth and find learning languages with specific purposes useful. For example, Python was for beginning, C is for memory management and Rust is for learning to write memory-safe code in my case. This time, I started learning Golang which is known for its simple syntax and powerful performance, and widely known for its awesome concurrency.

Why More is Not Always Good in Terms of Software - Words on Cross Platform Utilities, Bash-ism, and POSIX Compliance.

Preface: This article is about my views on software compliance and cross-platform support, and reflects my opinions and experience with the subject. Your experience and opinions may vary, which I respect. What I am Specifically Talking About? I am going to talk about the issues caused by non-compliant software and why more features are not always good, especially in the case of the upgrade of tools on a single platform.

Why I Shifted From Arch Linux to Debian Linux?

Preface: The following article is based on my personal experience with Arch Linux and Debian Linux. While I appreciate both distributions for their unique strengths and different use cases, the information provided reflects my own opinions and experiences. Your experiences may vary. What was I going for Initially? Bit of my Story as a Beginner Linux User When I started using Linux, I was going through security stuff and learning computer security when I was in my High School.

Tmux is the Ultimate Choice for Power Users - An Awesome Terminal Multiplexer for Managing Persistent Sessions

What is Tmux? Tmux is a Terminal Multiplexer Application for Linux and MacOS for managing terminal sessions and Windows. It is to be mentioned that Tmux is not a terminal emulator, instead, it’s a terminal application, a binary that allows you to stay productive over your terminal. It doesn’t matter which terminal emulator you are using (although I recommend the Suckless Terminal). The functionality of managing Windows and the session doesn’t happen on the desktop GUI side but on the terminal session, you are working with.

The Concept of RSS Feed - A Reliable Way for Publishers and Subscribers Model

Preface: I have been looking for simple solutions in nearly everything related to computing. A lot of software designed these days is not designed per your requirements but as per companies’ profit. Hence, most of these solutions end up sucking your time and energy and need to be replaced by more optimised solutions that would boost your productivity in the right way. RSS Feed is something that I found after searching for solutions related to subscribing to websites or creators without sucking much resources and design that is reliable to the user itself.

Breaking RSA Encryption on Hardware Devices with Side Channel Power Analysis — Leaking the Private Key by Exploiting Square-Multiply Algorithm

Preface: This article is about leaking the private key from hardware devices that implement RSA encryption which is part of hardware hacking. The author is not responsible for any damage caused by the given information. It is recommended to be careful while performing these attacks as they can damage the hardware or even destroy it. All the information provided here is for educational purposes. There are no such prerequisites for understanding the theory, although knowledge about modular arithmetic, basics of encryption mathematics, basic electronics, etc.

Serious Reconnaissance with Unmanned Aerial Vehicles — Mapping Out Devices in an Area with Drones

Introduction: The following content is for educational purposes and for hackers living in basements knowing enough ethics. The author is not responsible for any damage caused by the knowledge provided here and does not support anything like that. It’s essential to check out the rules in the area of reconnaissance about the tactics provided here and the use of materials (unless and until there is any apocalypse and a solid recon is required).

The Fundamentals of Hardware Hacking — Breaking and Reverse Engineering Smart IoT Devices

Disclaimer — This is an introductory article about Hardware Hacking and Security of IoT Devices. None of the mentioned information or techniques are intended for any illegal purposes and the author is not responsible for any damage. It’s advisable to experiment on devices that you own or have explicit permission to do so. Rest of all, hardware hacking is fun! The Beauty of Electronic Devices In the ever-growing world of smart devices and the connectivity of things to the internet, life has become more convenient than ever.

Setting Up a Remote Git Server — A Simple and Concise Step-by-Step Guide to Host a Private Git Server

Preface: This is a concise and simple guide to hosting a remote git server. I have been researching this topic for a while and came up with the idea of writing an article with a step-by-step guide for hosting a private git server. Covering all the aspects of git is not possible in a single article, so it’s assumed that the reader has prior knowledge of git and version control.

The Nature of Linux Kernel Development — Difference Between Rules of Kernel Level and User-Space Application Level

Preface: This article is intended to explain a clear distinction between the core principles of Linux Kernel Development and User-Application Level Development. The provided information is based on my research on Kernel Development through various sources and I have tried to make it as accurate as possible. Efforts have been made to explain it as simply and concisely as possible. Introduction to the Nature of Linux Kernel Linux Kernel is the abstraction layer between the Operating System and the Hardware in the system.

Linux Process Scheduling — The Reason your Linux System Processes so Efficiently (Kernel Perspective)

Preface: I was going through the book “Linux Kernel Development” by Robert Love, one of the best books I have referred to for low-level stuff and understanding the workings of Linux. I study this book with intensity, simplify the concepts and write it down here so that the readers can get a straightforward description and all they need to know about the topic. Covering the whole Linux Process Scheduling is not possible and is not the goal of this article.

Linux Processes — A Kernel’s Perspective Explained with Clarity and Simplicity

Preface: I have been going through the book “Linux Kernel Development” by Robert Love which I highly recommend for understanding the Linux Kernel in depth. I decided to write this article to explain “Linux Processes” simply and concisely. The topic itself is broad and is not explained into the deepest of it, but essential for Linux Administrators, Developers and even Linux users to appreciate the beauty of the Kernel they make use of every day.

NGINX for Deploying Next.js Application on AWS EC2 with AWS ELB — Control and Stability of Deployments

I was looking for an article like this a few days ago, which I didn’t find at that time, so I did the deployment on my own and came up with this article to prevent other developers from saving those efforts and focusing on development. I am not explaining every single step and have provided links for references. I prefer manual deployment of applications over automated (and even serverless) methods. Although they are convenient and require less effort by the developers, they are bound to the providers and offer less control over the underlying system.

Configuring and Building the Linux Kernel — Absolute Guide to Compiling Your Kernel

Linux Kernel is an Open-Source Software and the user is free to modify and customise it as per the requirements. The modification of the Kernel requires a deep understanding of the working of the Kernel, although patches are available to make the Kernel optimised for specific hardware. Linux Kernel Source Code has various options to configure the drivers, modules, preferences on hardware options, etc. This part can be studied by the user and is pretty much easy to work with.

The Elegance of the Linux Kernel — A Concise History of Unix and the Creation of the Linux Kernel

Introduction and Context I was going through the book “Linux Kernel Development” by Robert Love, an absolute guide to getting started with Linux Kernel Development and a highly recommended book for understanding the core of the Linux Kernel. Linux Kernel has been one of the most important software ever written and is even considered one of the biggest projects ever undertaken by a single person. The idea of the Linux Kernel was initiated by Linus Torvalds, a student from the University of Helsinki and is maintained by him to date (while writing this article).

Linux Shell Scripting — A Suckless and Concise Guide to the Command-line of Linux

Prior Statements: This is a concise guide on the Linux Shell Scripting while consolidating all the facts about the Linux Shell for quick developer’s reference while using Linux. I am referencing the Bash (Bourne-Again Shell) which is the default shell for Linux-based systems. I will also be providing references and external links to dive into depth and not fill the article with too much explanation about a single topic which is not universally required by all the readers.

Suckless Utilities for Arch Linux — The Most Minimal Way Run a Computer

Suckless utilities have been my favourite at this time and kind of essentials for my use of the computer. I have been using Arch Linux for a fair amount of time now and I started using it with XFCE for few weeks. I would appreciate the XFCE desktop environment for it’s smoothness and light-weight nature with works really fine when newly shifting on Arch Linux. But then I learnt the suckless ecosystem and eventually shifted to it as my full-time environment.

Installing Pacman in Arch Linux — When You Blow it Up

Let me suckless and divide the article into two parts: My story how I blew up Pacman Package Manager How to reinstall the Pacman Package Manager If you only care about the second part, skip the first one. The Scenario — Blow it Up I was trying to install the pacman game from the Internet to get it running on my Arch Linux Terminal (I use Suckless Terminal BTW). When I got it installed and played it, it was super awesome.

Boot Process of Computers — A Learner’s Perspective Of Exploring the Depth of Computers

Prior Clarifications: Here, I will be providing a philosophical explanation about the bootloaders and understanding them in a simple and as minimal way as possible. This is not supposed to be a manual for bootloader or provide any advice for experimenting over your live system. It’s my journey to understand computers (one of the most complex creations of mankind) and I will be stating my thoughts. Take it with a pinch of salt.

Networking Fundamentals for Linux Administrators — A Suckless and Concise Explanation

Statistics are clear on the fact that 96.3% (while writing this article) of the servers use Linux as their Operating System which is no doubt what every other Linux user on this Earth expects. I believe that the Linux Administrator has to take the shot about the configuration of Networking in Linux Based Server. Some of the underlying concepts remain the same for any other distros but it is mainly intended for Linux.

Operating Systems and Low-Level Access to the Hardware — Why should you learn it?

Today, I completed the whole read of the book “Linux Kernel in a Nutshell” by Greg Kroah-Hartman and I highly recommend that you go through it if you want to understand how to build your custom configuration of Linux Kernel and all you need to know about all the nuts and bolts. It’s always great to have such handbooks around the desk. This blog is about why it’s so awesome to look into the operating system you are using with your hardware and why have a grasp on the Low-Level aspects of a computer.

Arch Linux Custom Builds — Freedom of the Operating System

While writing this blog, I was reading the book “Linux Kernel in a Nutshell” by Greg Kroab-Hartman and as far as the pages of the book are concerned, it seems to be a two-day read (this is a handbook so reading it once and having around the desk is super useful). By the way, the author has the book left open for download http://www.kroah.com/lkn/ so check that out if you want to follow up.

Bypassing the Linux Login to access the files (with Physical Access), even the root!

Imagine being away from the computer for a couple of minutes and getting to know that the system has been compromised and a backdoor has been installed into the system. “The system was locked?” doesn’t matter, without the bios security implementation (which most probably would not be implemented), all the files can be recovered without any login made to the Login Screen. This goes with the story of me trying to get my Wi-Fi troubleshooting in Arch Linux where I was trying to upgrade the Kernel of my System to get the Wi-Fi working properly (as mentioned in the previous blog.

Configuring and Building the Linux Kernel — Absolute Guide to Compiling Your Kernel

Planted January 25, 2024

Linux Kernel is an Open-Source Software and the user is free to modify and customise it as per the requirements. The modification of the Kernel requires a deep understanding of the working of the Kernel, although patches are available to make the Kernel optimised for specific hardware. Linux Kernel Source Code has various options to configure the drivers, modules, preferences on hardware options, etc. This part can be studied by the user and is pretty much easy to work with. The confusing part, however, is building the Kernel.

Building the Kernel includes creating user-specific configurations, and modifications as well as building in a way that is most efficient and error-free. It’s comforting for the fact that you can get the default configuration and build the Kernel over it in the simplest manner. But this approach lacks the freedom that you have over the clone of the code you own. For the most efficient build of the Kernel, you need to understand all the nuts and bolds of how to build the finest version of your Kernel. (if you are particularly a computer nerd, then you will be proud of the fact that you have your version of the Kernel).

The idea of building the Kernel is to create the .config file and compile it to the reference of this file. This file instructs the compilation process to build the Kernel as per the configuration in this file. There are various methods to create this file, ranging from the most configurable to the fastest way to get it done.

Configuring from Scratch

The most basic method for configuring the Kernel is to use the make config method. This way, the Kernel will prompt you to set up every single configuration as per your wish and you need to fill in all the prompts to create the configuration file which you would need to build the kernel.

  1. y: Build directly into the Kernel
  2. m: Leave entirely out of the Kernel
  3. m: Build as a module, to be loaded if needed
  4. ?: Print a brief descriptive message and repeat the prompt

The fact that the Kernel has over 2000 options makes this process tedious. For users who need the most basic configuration and also have it quite a bit stable can use the default configuration file.

Default Configuration Options

Linux Kernel also ships with a default configuration which is loosely based on the defaults that the Kernel Maintainer has. For the i386 architecture, this configuration matches close to what Linus Torvalds uses on his main development machine. This is a quick way to create a config file and get the Linux Kernel Build in the least time possible (and the fact that maintainers use them makes the config relatively stable for most of the users).

cd linux-<kernel_version>
make defconfig

Now this is a recommended build option even if you want to create your custom Kernel. This method creates a base configuration file that you can modify to add or remove features as per the requirements. This way, you don’t need to worry about each option and have the freedom to skip any section that you want to be the default. So consider it to be the first step of Kernel customisation.

Modifying the Kernel Configuration

The Kernel Configuration can be done in various ways, all resulting in the creation of the config file for building the Kernel itself. There are three ways of configuring the Kernel:

  1. A Terminal-based one called menuconfig: make menuconfig
  2. A GTK+ based graphical one called gconfig: make gconfig
  3. A QT-based graphical one called xconfig: make xconfig

All of them do the same job and it’s the user’s preference to choose one method that is the most comfortable and create the config file. All the options would create a visual way of modifying the options which is comfortable and sorted logically. This way, every option can be found easily and modified as per the requirements.

Building the Kernel Now building the Kernel in the most basic way is to just enter a one-word command: make

This will build the whole Linux Kernel with the provided configurations This will create the Kernel Image once the build is completed. Note that this image needs to be configured with the Linux Distro you are using before trying to boot from it.

Advanced Building Options for the Kernel

The Kernel Source Code is a big file and needs resources to be compiled. Using the full potential of your system to build the Kernel will boost up the compiling process. To use all the cores of your system, you can provide the -j tag with the make command.

make -j<number_of_cpu_cores>

For example, if you have 6 cores CPU, then use the command make -j6 to use all the 6 cores to compile the Kernel.

To find out the number of CPU cores in Linux, use the command: nproc.

So overall, to make use of all CPU cores, you can use the command:

make -j$(nproc)

Building only a Portion of the Kernel

If you only want to build a portion of the Kernel, for example for drivers/usb/serial, you can use the command:

make drivers/usb/serial (but this will not build the final module images)

To build the final module images, use the command:

make M=drivers/usb/serial

To link the module image to the built Kernel, you have to use the make command again to add it to the final Kernel Image.

Output to Another Folder

To output the contents of compiled files to another location, use the command: make O=<location_of_output>. This can be useful when installation is done via CD/ROM and is read-only for any purposes where the compiled image needs to be placed in some other location.

Building for Different Architectures

Linux Kernel allows you to compile the image of other architectures. This is useful for embedded devices as well as to use powerful computers to compile Kernels for small devices. To do this, use the command:

make ARCH=x86_64 defconfig This will create configurations for an x86–64 architecture.

You can use CROSS_COMPILE options to use other architectures toolchain. For example, the ARM toolchain located in /usr/local/bin:

make ARCH=arm CROSS_COMPILE=/usr/local/bin/arm-linux-

To use programs like distcc or ccache (to change the build system used by the compiler), which helps to reduce the compile time significantly, use the CC option.

make CC="ccache gcc"

To use distcc and ccache together:

make CC="ccache distcc"

Conclusion

Building your own Linux Kernel gives you the freedom to configure the system to the roots. Optimisation of Kernel can result in improved performance as well as help you understand the depths of computers. For learning more in-depth, I can recommend a few books:

Linux Kernel in a Nutshell — Greg Kroah-Hartman Linux Kernel Development — Robert Love