Querying system tables in Cassandra on RHEL 8

How to install cassandra on RHEL 8

Apache Cassandra is an open-source NoSQL database. One of it’s main features is it’s decentralized nature that gives unique fault tolerance. Having our data replicated across datacenters means our production will not suffer from the loss of one of our sites, something all sysadmins dream of (or really happy to have such setup).

In this tutorial we will install Cassandra on Red Hat Enterprise Linux 8 by adding the Cassandra repository, install the software, and set up all else needed to have our service up and running and easy to manage.

In this tutorial you will learn:

  • How to add Cassandra repository
  • How to install needed packages
  • How to repair systemd unit file
  • How to test Cassandra with cqlsh

Read more

Stepping trough a for loop with gdb.

How to install gdb in RHEL 8

Gdb or GNU Project Debugger is a great tool when you need to debug a program. You can set breakpoints, watch for value change of a variable, or even change a value for the program while it is halted at a point of it’s state, then continue, just to pick some of the features of gdb.

In this tutorial we will install gdb on RHEL 8, and test how it is working with a simple C application.

In this tutorial you will learn:

  • How to install gdb
  • How to compile a simple C application with debug symbols
  • How to set breakpoints in the running application with gdb
  • How to print actual values of given variables within the application

Read more

Consuming messages on Kafka topic from the command line.

How to install kafka on RHEL 8

Apache Kafka is a distributed streaming platform. With it’s rich API (Application Programming Interface) set, we can connect mostly anything to Kafka as source of data, and on the other end, we can set up a large number of consumers that will receive the steam of records for processing. Kafka is highly scaleable, and stores the streams of data in a reliable and fault-tolerant way. From the connectivity perspective, Kafka can serve as a bridge between many heterogeneous systems, which in turn can rely on it’s capabilities to transfer and persist the data provided.

In this tutorial we will install Apache Kafka on a Red Hat Enterprise Linux 8, create the systemd unit files for ease of management, and test the functionality with the shipped command line tools.

In this tutorial you will learn:

  • How to install Apache Kafka
  • How to create systemd services for Kafka and Zookeeper
  • How to test Kafka with command line clients

Read more

Installed Matomo (Piwik) on Red Hat Enterprise Linux 8 Server/Workstation.

How to Install Matomo (Piwik) on RHEL 8 Linux

This article covers an installation of Matomo (Piwik), an all-in-one premium web analytics platform, on RHEL 8 Linux Server. In this instance the installation is based on the well-know LAMP stack comprising the RHEL 8, MariaDB, PHP and Apache webserver.

In this tutorial you will learn:

  • How to Install LAMP Stack on RHEL 8.
  • How to configure MariaDB database.
  • How to install Matomo (Piwik) on RHEL 8.
  • How to open HTTP and HTTPS firewall ports.

Read more

Nmap command on RHEL 8 Linux Server/Workstation

Install nmap on RHEL 8 / CentOS 8

The nmap command is an invaluable tool for any system or network administrator. This command is not available on RHEL 8 / CentOS 8 default installation. However, it can be installed with a single dnf command.

In this tutorial you will learn:

  • How to install Nmap command on RHEL 8 / CentOS 8.
  • How to to check Nmap version on RHEL 8 / CentOS 8.

Read more

LAMP stack server installation on RHEL 8 / CentOS 8

How to install LAMP Server on RHEL 8 / CentOS 8 Linux

The LAMP server is the foundation of Linux web hosting. If you’re looking to set up a LAMP stack to host your website, this guide will provide you with the necessary information on how to get start with LAMP on RHEL 8 / CentOS 8 Linux server.

In this tutorial you will learn:

  • How to install all LAMP prerequisite packages on RHEL 8 / CentOS 8.
  • How to secure MariaDB database.
  • How to start httpd and MariaDB services.
  • How to open HTTP and HTTPS firewall ports.

Read more

Enabled IPv6 on RHEL 8 Linux system.

RHEL 8 / CentOS 8 enable/disable IPv6

An Internet Protocol Version 6 (IPv6) address is an identifier of a network interface of a computer or a network node involved in an IPv6 computer network. This article will guide the user via simple steps on how to disable or re-enable IPv6 network addresses on RHEL 8 / CentOS 8. To temporarily enable/disable the IPv6 address on RHEL 8 / CentOS 8 we will use the sysctl command. Additionally, to permanently disable the IPv6 address we will modify the GRUB boot options.

In this tutorial you will learn:

  • How to temporarily disable the IPv6 address.
  • How to permanently disable IPv6 by modifying the GRUB boot options.

Read more

Active SSH service and firewall SSH port 22 open on RHEL 8

RHEL 8 / CentOS 8 enable ssh service

The following article will explain how to install and start SSH service on RHEL 8 / CentOS 8 system. SSH is a client-server service providing secure encrypted connections over the network connection.

In this tutorial you will learn:

  • How to Install SSH service.
  • How to start SSH service.
  • How to enable SSH to start after reboot.
  • How to open SSH port 22 for incoming traffic.

Read more

How to check Linux version

How to check Linux Version

The common scenario is that you have been given an access to a Linux system physically or via remote login and you have no idea what Linux version is installed on this particular system. Given that many of the today’s Linux Distributions have implemented systemd as part of their core design, to check for a Linux version is in many cases relatively simple procedure.

The simplest way to check Linux version is by using the hostnamectl command without any arguments. For example the below hostnamectl command will return the Linux distribution name, version and codename in use along with the currently loaded Linux kernel version:

$ hostnamectl 
   Static hostname: x220
         Icon name: computer-laptop
           Chassis: laptop
        Machine ID: 2d4efda5efb0430faeb2087d0a335c6b
           Boot ID: f8c4a3a776a74d42878347efc2c00634
  Operating System: Debian GNU/Linux 10 (buster)
            Kernel: Linux 4.9.0-9-amd64
      Architecture: x86-64
DID YOU KNOW?

It is a common mistake to refer to the entire GNU/Linux operating system simply as Linux. The important note here is that the so called Linux is actually only the Kernel part of the system whereas GNU is the actual system as in collection of pre-compiled binaries, libraries and system tools. Both GNU and Linux kernel must function in tandem in order for the operating system to actually work.

Hence, one cannot exists without the other, so next time when you talk about your operating system and you wish to be technically correct, refer to it as GNU/Linux or simply as Lignux.

In this tutorial you will learn:

  • Basic introduction to Linux package
  • How to check system architecture and Linux kernel version
  • How to check CPU architecture
  • How to check CentOS, Redhat, Debian, Ubuntu, Mint, Arch, Fedora Linux system version

Read more

Ansible Architecture

How to install and configure Ansible on Redhat Enterprise Linux 8

This tutorial covers step by step installation and configuration of Ansible on Redhat Enterprise Linux 8.
Ansible is the leading Open Source configuration management system. It makes it easy for administrators and operations teams to control thousands of servers from central machine without installing agents on them.

In this tutorial you will learn:

  • Ansible Overview
  • Install and Configure Python
  • Set Password-less SSH
  • Install Ansible
  • Testing and Managing the Ansible

Read more