Linux on Samarthya

Securing Kafka Brokers: A Practical Operations Checklist

Sat, 14 Jun 2025 00:00:00 +0000

I used to think of Kafka security as a client configuration problem. Then I started thinking about the broker host itself: which user owns the process, who can read the configuration, what is exposed on the network, and what happens during an incident.

sed

Tue, 11 Feb 2025 12:00:00 +0000

In the realm of Unix-like operating systems, where command-line prowess reigns supreme, sed stands tall as a versatile and indispensable tool. Born in the early 1970s at the legendary Bell Labs, sed (short for “stream editor”) emerged from the creative mind of Lee E. McMahon. Its creation was inspired by the need for a command-line utility capable of performing substitutions, akin to the functionality found in the grep command but with the added ability to modify the matched text.

Failed to connect to bus: No medium found

Wed, 11 Sep 2024 12:00:00 +0000

If you have ever seen this error, you know the pain of a fellow linux user.

Failed to connect to bus: No medium found

This is message I get when I was trying to install podman.socket

UMASK: What is it?

Wed, 31 Jul 2024 12:00:00 +0000

Introduction
#

In Unix-like operating systems, file permissions play a critical role in ensuring system security and proper access control. One of the key tools for managing file permissions is the umask (user file creation mode mask). This blog post explores the history, purpose, and best practices for using umask.

Target fs?

Wed, 26 Jun 2024 12:00:00 +0000

Linux, as an open-source operating system, has undergone significant transformations over the years. One of the critical components of modern Linux distributions is systemd, a system and service manager introduced to provide a more efficient and unified way of initializing and managing system resources. Central to systemd’s functionality are “targets,” which play a crucial role in orchestrating the boot process and managing system states. In this blog, we’ll explore the history of systemd targets, their usage, and how they function during the Linux boot process.

Containers: A brief take

Fri, 17 May 2024 12:00:00 +0000

The story of Linux containers is a tale of innovation and collaboration, with roots surprisingly deep in the history of the Linux operating system itself.

Ansible Configuration: Make the Defaults Explicit

Sat, 16 Mar 2024 00:00:00 +0000

When I first used Ansible, I was happy that it worked without a configuration file. Later, the same playbook behaved differently depending on which folder I ran it from. That was the point at which I stopped treating the defaults as magic and created a small project-level ansible.cfg.

What about `profile.d`

Thu, 22 Feb 2024 12:00:00 +0000

The /etc/profile.d directory, though seemingly simple, plays a vital role in the smooth operation of your Linux system. But how did this unassuming directory come to be, and how has it evolved over time? Let’s embark on a journey through the history of this essential component.

How a file write happens in Linux?

Wed, 14 Feb 2024 12:00:00 +0000

Writing to a file on a device in Linux involves a fascinating journey through different layers of the system.

💬 When you write to a file on a device, the inode provides context about the file’s location and properties, while the device driver translates that information into instructions for the specific device. The driver then interacts with the hardware to physically write the data to the storage medium. It’s a seamless collaboration between these two crucial elements that enables efficient and reliable data management across diverse devices in Linux.

Writing to a file in Linux deep-dive

Wed, 14 Feb 2024 12:00:00 +0000

Previously I gave a high level flow for how a process of simple file write looks like in a Linux environment here. In this blog, I will add more tech-details. Let’s say I want to write “Hello World” to a file /home/samarthya/myfile.txt – What happens behind the scene?

Getting Started with Ansible: From One Command to a Playbook

Sun, 21 Jan 2024 00:00:00 +0000

I had been writing shell commands for every small infrastructure change. It worked, until I needed to repeat the same change on another machine and could no longer remember which command I had run first. That was my reason for starting with Ansible.

Kernel

Thu, 29 Jun 2023 12:00:00 +0000

Kernel

Introduction
#

The Linux Kernel stands as the backbone of the Linux operating system, serving as a critical component that enables the system to interact with hardware and manage system resources efficiently. Understanding the history and evolution of the Linux Kernel is essential for comprehending the vast ecosystem of this open-source marvel.

Podman Machine: How & Why?

Tue, 07 Mar 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Podman

Python vs Bash

Thu, 02 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Python and bash are both programming languages, but they have different purposes and use cases.

Running QEMu based VM’s on OSX M1

Wed, 24 Aug 2022 12:00:00 +0000

A popular choice in the OSS QEMu is an open source machine emulator (system emulation/usermode emulation) and virtualizer. Since I recently moved to Apple M1 silicone, I had not option of sticking to VirtualBox and was forced to relook at my options.

Bash: Named Reference

Wed, 02 Mar 2022 12:00:00 +0000

Bash is different world. Powerful, simple, elegant and complex all at the same time. Recently while trying to reduce the burden of repetitive code, I was trying to check what can be done to use references in Bash (something like pointers) and it was an interesting problem that I enjoyed solving.

Notes: For self

Wed, 23 Feb 2022 07:27:42 +0000

Bash is a string oriented language
We do not write step=$((step++)) this expression will return a numeric value which the shell will then take as the command to to be executed.
No spaces are allowed around the equal sign for variable assignment.
let "step++" is same as (( step++ ))
Use declare to set variable values and attributes

In bash = and == both mean the same thing

💬 What is the difference between [ and [[?

•
if cd $dir; then
In this case the command cd $dir will be executed and based on success or failure of the command executed the if or else part will be executed respectively.
if [$dir]; then
```
<span
 class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none">
 <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#if-dir-then" aria-label="Anchor">#</a>
</span>
```
Single bracket is equivalent to test command evaluate conditional expression
1. •
  < & >
  - Within [ compare using simple ASCII ordering & within [[ comparison is lexicographic.
  - Within [ you have to escape \> to avoid redirection.

💬 BC is a language?

 <span></span>
</span>
<span class="accordion-chevron ms-auto flex h-5 w-5 items-center justify-center print:hidden">
 <span class="relative block icon"><svg

xmlns=“http://www.w3.org/2000/svg" viewBox=“0 0 20 20” fill=“currentColor” aria-hidden=“true”

💬 Supports arbitrary precision numbers with interactive execution of statements. (Command line)

awk provides filtering capabilities

> printf 'gate\napple\nwhat\nkite\n' | awk '/at/'

gate
what

printf 'gate\napple\nwhat\nkite\n' | awk '!/e/'

what

awk is primarily used for field based processing

One liner structure awk 'cond1{action1} cond2{action2} … condN{actionN}'

Spinnaker: docker-registry

Fri, 04 Feb 2022 12:00:00 +0000

You will need a valid docker registry before you add any trigger in the pipeline in Spinnaker

Official documentation is a good resource to seek more clarifications — Spinnaker

In my case I have already added an account my-docker-registry as under (The final result after you successfully configure Docker.

Zabbix Agent

Wed, 10 Nov 2021 06:06:09 +0000

In this blog I will walk you through basic steps needed to deploy a Zabbix 5 Agent on a Centos Machine. The Zabbix Release is available here.

Machine
#

root@node4>cat /etc/redhat-release 
CentOS Linux release 7.9.2009 (Core)

Download and install the RPM

PS: Process Status

Tue, 20 Oct 2020 11:13:18 +0000

MAN Pages are one source of truth for all curious queries.

man ps

Name
 ps - report a snapshot of the current processes.

It is used to display instant information about the active processes in the system.

Kernel Mode

Sat, 17 Oct 2020 14:58:39 +0000

The CPU operates in two modes in Linux

User mode (non privileged mode)
Kernel mode (System mode)

When operating in Kernel mode it has un-restricted access to resources like memory and input output devices.

journalctl - Query the systemd journal

Sat, 17 Oct 2020 00:00:00 +0000

journald is used to query the systemd journal contents.

Example 1
#

Lets try and see the kubelet service logs in the systemd journal

Linux Utils

Tue, 13 Oct 2020 08:29:43 +0000

Ping
#

I have used ping often but never to an extend that I could understand the complete range of options and power available at hand.

SYSTEMD: Mother of all processes

Wed, 30 Sep 2020 14:33:47 +0000

systemd is the replacement system for System V and with the primary goal of starting services in parallel.

Remember init levels?

GRUB: Grand Unified Boot Loader — /boot/grub/grub.conf

Some key points

Docker

Sat, 11 Jul 2020 12:00:00 +0000

Usually I use Centos, but this time I wanted to try out docker swarm and ubuntu was the preferred option due to the options and supporting blogs available.

Do read – https://docs.docker.com/get-started/#containers-and-virtual-machines

docker.com

Metric Beat

Fri, 24 Jan 2020 12:00:00 +0000

All right, its been a busy week and finally some time at hand to write about something I have been doing.

Mostly I am working on ELK stack these days, securing, validating, data analytics etc. Today, had the opportunity to go the Secure Elastic way, by enabling the TLS for secure communication within Nodes (Elastic cluster) and finally setup a Metric beat to get the status of the node.

Locale

Fri, 05 Apr 2019 12:00:00 +0000

Did you ever see a warning printed on your console the moment you log into your Linux machine and did that warning ever complaned to you about the benign locale?

Linux on Samarthya

Securing Kafka Brokers: A Practical Operations Checklist

sed

Failed to connect to bus: No medium found

UMASK: What is it?

Introduction #

Target fs?

Containers: A brief take

Ansible Configuration: Make the Defaults Explicit

What about `profile.d`

How a file write happens in Linux?

Writing to a file in Linux deep-dive

Getting Started with Ansible: From One Command to a Playbook

Kernel

Introduction #

Podman Machine: How & Why?

Python vs Bash

Running QEMu based VM’s on OSX M1

Bash: Named Reference

Notes: For self

if cd $dir; then

if [$dir]; then <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#if-dir-then" aria-label="Anchor">#</a> </span>

< & >

Spinnaker: docker-registry

Zabbix Agent

Machine #

PS: Process Status

Kernel Mode

journalctl - Query the systemd journal

Example 1 #

Linux Utils

Ping #

SYSTEMD: Mother of all processes

Docker

Metric Beat

Locale

Introduction
#

Introduction
#

`if [$dir]; then`

`<span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#if-dir-then" aria-label="Anchor">#</a> </span>`

Machine
#

Example 1
#

Ping
#