Linux is a Free and Open Source Operating System it is used for making servers like Apache, INGIX, etc.

As a free and open-source operating system, Linux has spawned several distributions over time, spreading its wings to encompass a large community of users. From desktop/home users to Enterprise environments, Linux has ensured that each category has something to be happy about.

Linux Distribution Name’s

  • Red Hat Enterprise Linux
  • Kali Linux
  • Parrot Linux
  • Ubuntu Linux
  • Arch Linux
  • OpenSuse
  • Fedora
  • CentOs

Red Hat Enterprise Linux

Abbreviated as RHELRed Hat Enterprise Linux is a Linux distro designed for Enterprise or commercial purposes. It’s one of the leading open-source alternatives to other proprietary systems such as MicrosoftRed Hat is usually a top choice for server environments given its stability and regular security patches which boost its overall security.

Red Hat Enterprise Linux

You can readily set it up on physical servers, virtual environments such as VMwareHyperV, and also on the cloud. Red Hat has done a perfect job in containerization technology thanks to OpenShift PaaS (platform as a service), a hybrid cloud environment that is built around Docker containers and managed by Kubernetes.

Redhat trains and certifies system administrators through specialist courses such as RHCSA (Red Hat Certified System Administrators) and RHCE (Red Hat Certified Engineer).

Where efficiency, security, and stability are of utmost priority RHEL is the ideal distro to opt for. RHEL is subscription-based and the subscription is renewed annually. You can purchase a license for an array of subscription models such as Linux Developer Workstation, Linux developer suite, and Linux for Virtual Datacenters.

Traditionally, Red Hat and its derivatives such as CentOS have used yum package manager. Things have changed now and the latest release – RHEL 8 (Ootpa) – now uses DNF as its default package manager. RHEL is distributed using 2 main repositories – AppStream repository and the BaseOS.

The AppStream repository (Application Stream) provides all the software applications that you want to install on your system while the BaseOS provides applications only for the core functionality of the system.

Additionally, you can also download and try out RedHat for free by through the Red Hat developer program.

CentOS

The CentOS Project is a community-driven free operating system that aims at delivering a robust and reliable open source ecosystem. Based on RHELCentOS is a perfect alternative to Red Hat Enterprise Linux since it is free to download and install. It gives users the stability and reliability of RHEL while allowing them to enjoy free security and feature updates. CentOS 8 is a favourite among Linux enthusiasts who want to savour the benefits of RHEL.

The latest version is CentOS 8.2 which is the third iteration of CentOS 8. It relies on App stream and BaseOS repositories and ships with the latest software packages such as Python 3.8, GCC 9.1, Maven 3.6, etc.

Fedora

Fedora has enjoyed a reputation for being one of the most user-friendly distros for quite a while now owing to its simplicity and out-of-the-box applications which enable newcomers to easily get started.

It’s a powerful and flexible operating system that’s tailored for desktops & laptops, servers, and even IoT ecosystems. Fedora, just like CentOS, is based on Red Hat and is in fact, a testing environment for Red Hat before transitioning to the Enterprise phase. As such, it’s usually used for development and learning purposes and comes in handy for developers and students.

Fedora has for a while now used the DNF package manager ( and still uses it as its default package manager) and offers the latest and the very best in RPM software packages. The latest Fedora is Fedora 32.

Kali Linux

Developed and maintained by offensive security, Kali Linux is a Debian-based Linux distro designed for penetration testing and conducting digital forensics. It ships with out-of-the-box tools meant for penetration testing such as Nmap, Metasploit Framework, Maltego, and Aircrack-ng to mention a few.

Kali-Linux

Kali Linux is meant for Cybersecurity experts and students who want to venture into penetration testing. In fact, Kali provides industry-standard certifications such as Penetration Testing with Kali and Kali Linux Certified Professional.

Kali uses the APT package manager and the latest version is Kali 2020.2 and here’s a guide on how to install Kali 2020.2.

Download Kali Linux – https://www.kali.org/downloads/.

Creating A Custom Kali ISO

An Introduction to Building Your Own Kali ISO

Building a customized Kali Linux image is not as complex as you may be thinking. It is easy, fun, and rewarding! Kali Linux traditionally, has been a Live Image, but since Kali 2020.1 an Installer Image was introduced. Both these images have different functions, and are also built in different ways.

  • Live Image – allows you to try Kali, without altering the system (making it create for USB). It is created using live-build
  • Installer Image – allows for you to customize Kali by picking packaging during installation, such as picking the desktop environment as well as what metapackages get installed. This image is powered by simple-cdd (which uses debian-cd to make Debian-Installer).

You can configure virtually any aspect of your Kali ISO build, such as adding packages from outside of Kali network repositories, unattended installations to changing the default wallpaper. Our build-scripts provides a framework that uses a configuration set to automate and customize all aspects of building the images. The Kali Linux development team use the same build-scripts to produce the official Kali ISO releases.

Where Should You Build Your ISO?

Ideally, you should build your custom Kali ISO from within a pre-existing Kali environment, as there is less chance of items going wrong. However, it is possible to generate the images on a Non-Kali but still a Debian-Based system.

Kali Environment

Getting Ready — Setting Up The build-script Kali System

We first need to prepare the Kali ISO build environment by installing and setting up the required packages with the following commands:

kali@kali:~$ sudo apt update
kali@kali:~$ sudo apt install -y git live-build simple-cdd cdebootstrap curl
kali@kali:~$
kali@kali:~$ git clone https://gitlab.com/kalilinux/build-scripts/live-build-config.git

Building an Updated Live Image

Now you can simply build an updated Kali ISO (with our default configuration) by entering the live-build-config/ directory and running our build.sh wrapper script, as follows:

kali@kali:~$ cd live-build-config/
kali@kali:~/live-build-config$ ./build.sh --verbose

The build.sh script will take a while to complete, as it downloads all of the required packages needed to create your ISO. Good time for a drink.

Building an Updated Installer Image

By default, it will generate a Live Image. If you want an Installer Image, add --installer:

kali@kali:~/live-build-config$ ./build.sh --verbose --installer

We are using the --verbose to output more on the screen rather than it being captured in just the build.log output. If you want even more output, you can use --debug instead, which will then give more information.


Non-Kali Debian-Based Environment

Setting Up The build-script Non-Kali Debian-Based System

You can build an Kali ISO on a Debian-based systems other than Kali Linux. The instructions below have been tested to work with both Debian and Ubuntu.

First, we prepare the system by ensuring it is fully updated, then proceed to download the Kali archive keyring and packages:

$ sudo apt update
$ sudo apt full-upgrade -y
$
$ wget https://http.kali.org/pool/main/k/kali-archive-keyring/kali-archive-keyring_2020.2_all.deb
$ wget https://http.kali.org/kali/pool/main/l/live-build/live-build_20210407_all.deb

Note: You may need to check thatkali-archive-keyring_20YY.X_all.deb & live-build_20YYMMDD_all.deb are the latest files.

With that completed, we install some additional dependencies and the previously downloaded files:

$ sudo apt install -y git live-build simple-cdd cdebootstrap curl
$
$ sudo dpkg -i kali-archive-keyring_2020.2_all.deb
$ sudo dpkg -i live-build_20210407_all.deb

With the environment all prepared, we start the process by setting up the build-script profile and clone out the build config:

$ cd /usr/share/debootstrap/scripts/
$ (echo "default_mirror http://http.kali.org/kali"; sed -e "s/debian-archive-keyring.gpg/kali-archive-keyring.gpg/g" sid) > /tmp/kali
$ sudo mv /tmp/kali .
$ sudo ln -s kali kali-rolling
$
$ cd ~/
$ git clone https://gitlab.com/kalilinux/build-scripts/live-build-config.git
$
$ cd live-build-config/

At this point, depending on the host OS and its version, we may need to edit build.sh to bypass a version check for debootstrap. We do this by commenting out the exit 1 below:

$ cat build.sh
...
		ver_debootstrap=$(dpkg-query -f '${Version}' -W debootstrap)
		if dpkg --compare-versions "$ver_debootstrap" lt "1.0.97"; then
			echo "ERROR: You need debootstrap (>= 1.0.97), you have $ver_debootstrap" >&2
			exit 1
		fi
...
$

With the above change made, build.sh should look similar:

$ cat build.sh
...
		ver_debootstrap=$(dpkg-query -f '${Version}' -W debootstrap)
		if dpkg --compare-versions "$ver_debootstrap" lt "1.0.97"; then
			echo "ERROR: You need debootstrap (>= 1.0.97), you have $ver_debootstrap" >&2
			#exit 1
		fi
...
$

At this point, we can build our ISO as normal

$ ./build.sh --verbose

Configuring The Kali ISO Build (Optional)

If you want to customize your Kali Linux ISO, this section will explain some of the details. Through the kali-config/ directory, there are a wide range of customization options, which are well-documented for live-build page. Simple-CD is a little more limited with options. For the impatient, here are some of the highlights.

Building Kali Live With Different Desktop Environments

Since Kali 2.0, we now support built in configurations for various desktop environments, including Xfce (default), Gnome, KDE, E17, I3WM, LXDE, MATE. To build any of these, you would use syntax similar to the following:

kali@kali:~/live-build-config$ # These are the different Desktop Environment build options:
kali@kali:~/live-build-config$ #./build.sh --variant {xfce,gnome,kde,mate,e17,lxde,i3wm} --verbose
kali@kali:~/live-build-config$
kali@kali:~/live-build-config$ # To build a Gnome ISO:
kali@kali:~/live-build-config$ ./build.sh --variant gnome --verbose
kali@kali:~/live-build-config$
kali@kali:~/live-build-config$ # To build a KDE ISO:
kali@kali:~/live-build-config$ ./build.sh --variant kde --verbose

This is not required with the installer images, as it includes Xfce, Gnome and KDE by default. You can add others by including their packages as explained in the section below.

Controlling The Packages Included In Your Build

The list of packages included in your build will be present in the the respective kali-config/ directory. For example, if you’re wanting to edit:

  • The default Installer ISO, you would use the following package lists file – kali-config/installer-default/packages
  • The default Live ISO, you would use the following package lists file – kali-config/variant-default/package-lists/kali.list.chroot
  • A non-default Live ISO desktop environment, such as Gnome – kali-config/variant-gnome/package-lists/kali.list.chroot (You can replace Gnome with any supported desktop environments)

By default, these lists will includes the kali-linux-default metapackage, as well as some others. These can be commented out and replaced with a manual list of packages to include in the ISO for greater granularity.

Overlaying Files In Your Build

With Live images, you have the option to include additional files or scripts in your build by overlaying them on the existing file-system, inside the includes.{chroot,binary,installer} directories, respectively.

For example, if we wanted to include our own custom script into the /root/ directory of the ISO (this would correspond to the chroot stage), then we would drop this script file in the kali-config/common/includes.chroot/ directory before building the ISO.

For more information see the live-build documentation.

Build Hooks, Binary and Chroot

For live images, live-build supports hooks allows us to “hook scripts” in various stages of the Kali ISO live image. For more detailed information about hooks and how to use them, refer to the live-build manual.

As an example, we recommend you check out the existing hooks in kali-config/common/hooks/.


Building a Kali Linux ISO for Different Architectures (Optional)

By default, the build-script will generate the Kali image based on the architectures of the current operating system. If you wish to alter this:

  • x64: ./build.sh --verbose --arch amd64
  • x86: ./build.sh --verbose --arch i386

Building a Kali Linux ISO for Older i386 Architectures

The Kali Linux i386 ISO has PAE enabled. If you require a default kernel for older hardware with PAE disabled, you will need to rebuild a Kali Linux ISO. The rebuilding process is much the same as described above, except that the 686-pae parameter needs to be changed to 686 in auto/config before building:

kali@kali:~/live-build-config$ sed -i 's/686-pae/686/g' auto/config
kali@kali:~/live-build-config$
kali@kali:~/live-build-config$ ./build.sh --verbose --arch i386

Using A Custom Network Mirror For Building (Optional)

If you build multiple images, you will find you are often waiting on build.sh to finish. There are a few ways to speed up the build process, such as:

  • Building Installer images as they often build quicker than Live images
  • Have less packages included (such as switching kali-linux-default to kali-linux-top10)
  • Improve access to packages

You often find that you are waiting on packages to be pulled down. You can either setup a local proxy on the same machine (such as apt-cacher or apt-cacher-ng). Alternatively, you can setup a local network mirror.

We can instruct the build-script to use a different mirror, by doing the following (assuming our network mirror is located at http://192.168.0.101/kali):

kali@kali:~/live-build-config$ echo "http://192.168.0.101/kali/" > .mirror
kali@kali:~/live-build-config$ ./build.sh --verbose

Testing Built Image

After producing the issue, you can treat it like any Kali base image, so you can install it (either on bare metal or virtually), or copy to a CD/DVD/USB.

If you are wanting to quickly test the image before putting it “in production”, we can use qemu (and ovmf for UEFI). First we install the packages:

kali@kali:$ sudo apt update
kali@kali:$ sudo apt install -y qemu qemu-system-x86 ovmf

Next we produce a hard disk to use:

kali@kali:$ qemu-img create \
  -f qcow2 \
  /tmp/kali-test.hdd.img \
  4G

Afterwards, to boot from the image produced (we will be using the Live image on x64):

kali@kali:$ qemu-system-x86_64 \
  -enable-kvm \
  -drive if=virtio,aio=threads,cache=unsafe,file=/tmp/kali-test.hdd.img \
  -cdrom /home/kali/live-build-config/images/kali-linux-rolling-live-amd64.iso \
  -boot once=d

The above will be a “BIOS” boot. For a “UEFI” boot:

kali@kali:$ qemu-system-x86_64 \
  -enable-kvm \
  -drive if=virtio,aio=threads,cache=unsafe,file=/tmp/kali-test.hdd.img \
  -drive if=pflash,format=raw,readonly,file=/usr/share/OVMF/OVMF_CODE.fd \
  -drive if=pflash,format=raw,readonly,file=/usr/share/OVMF/OVMF_VARS.fd \
  -cdrom /home/kali/live-build-config/images/kali-linux-rolling-live-amd64.iso \
  -boot once=d

Note: We have set UEFI configuration file to be read only

Arch Linux

Arch Linux is a lightweight and flexible geeky Linux distro designed for advanced users or Linux experts who care much about what is installed and the services running. It gives users the freedom to custom or configures the system, to their preference. In a nutshell, Arch is meant for users who really know the ins and outs of working with Linux.

Arch-Linux

Arch is a rolling release implying that it is constantly updated to the latest version and all you need is to update the packages on the terminal. It uses Pacman as the default package manager and leverages the AUR (Arch User Repository) which is a community to install software packages and the latest version is 2020.09.01.

Download Arch Linux – https://www.archlinux.org/download/.

OpenSUSE

The OpenSUSE project is a modern and comprehensive community project that provides 2 main SUSE branches: SUSE Leap which is a point release that targets desktop users as well as enterprise development and for testing purposes. This makes it a perfect choice for open source developers and System administrators.

Suse

On the other hand, it has SUSE Tumbleweed, a rolling release that packs the latest software stacks and IDEs and is the closest you’ll get to a bleeding-edge distro. TumbleWeed is any power user’s or software developer’s piece of cake thanks to the availability of up-to-date packages such as office applications, GCC compiler, and the kernel.

OpenSUSE relies on the Yast package manager for managing software packages and is recommended for developers and system administrators.

Download OpenSUSE Linux – https://www.opensuse.org/.

Ubuntu

Created and maintained by Canonical, Ubuntu is one of the most popular Linux distros enjoyed across the globe by beginners, intermediate users, and professionals alike. Ubuntu was specifically designed for beginners in Linux or those transitioning from mac and Windows.

Ubuntu-Linux

By default, Ubuntu ships with GNOME desktop environment with everyday out-of-the-box applications such as Firefox, LibreOffice, and image editing applications such as GIMP, music players, and video players such as Audacious and Rhythmbox.

The latest version is Ubuntu 20.04 LTS codenamed Focal Fossa. It provides numerous improvements and new features such as the new Yaru theme, new look and polished icons, great support for Snap packages, and the fractional scaling functionality that provides support for high-resolution displays.

Ubuntu forms the basis of several other Linux distributions. Some of the distributions based on Ubuntu 20.04 include Lubuntu 20.04 LTS, Kubuntu 20.04, and Linux Mint 20.04 LTS (Ulyana).

Due to its user-friendliness and elegant UI, Ubuntu is ideal for desktop users and newcomers who are trying to wrap their heads around Linux. They can readily get started with default Apps as stated earlier on as they work their way towards getting a better understanding of Linux.

It’s worth mentioning Ubuntu Studio which is geared towards multimedia production. It targets creatives who are looking to make a career in graphics, photography, audio, and video production.

Download Ubuntu ISO image: https://ubuntu.com/download/desktop.

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