Linux Explained: Distributions, Differences, Benefits, Security

Like Windows, iOS, and Mac OS, Linux is an operating system. Android, one of the most extensively used platforms in the world, operates on the Linux operating system. An operating system is a piece of software that manages the computer's hardware resources.

Linux is the most commonly used operating system around the world. Since Linux was first created for personal computers using the Intel x86 architecture, it has been ported to more platforms than any other operating system. As of May 2022, Linux, including Android, had the greatest installed base of any general-purpose operating system due to the dominance of the Linux-based operating system on smartphones. Although only 2.3 percent of desktop computers are running Linux as of May 2022, the Chromebook, which runs Chrome OS on a Linux kernel, dominates the US K-12 education sector and accounts for about 20 percent of sub-$300 laptop sales in the country. It is not only used by endpoint devices, such as phones, tablets, IoT, and servers but also a variety of network devices like firewalls, routers, and switches, and cloud instances are based on Linux. Since November 2017, Linux has been dominating other huge iron systems like mainframe computers and is the only OS used on TOP500 supercomputers (nearly 96.4 percent of the top 1 million web servers run Linux) (having gradually eliminated all competitors). Which explains why Linux is so popular.

Many Linux versions have the word "Linux" in their names. At the same time, the Free Software Foundation prefers to refer to its operating system as "GNU/Linux" to stress the significance of GNU software, which has generated some debate.

Today, there are many Linux distributions developed by communities and businesses. The most well-known Linux distributions are Debian, Fedora, and Ubuntu. Lubuntu and Xubuntu are just two of the many distinctive distributions and customizations that are included in Ubuntu itself. Commercial Linux distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise, for instance. Desktop Linux distributions include a desktop environment, such as GNOME or KDE Plasma, in addition to a windowing system, such as X11 or Wayland. Graphics may be entirely absent from distributions made for servers, or they may be replaced by a LAMP-style solution stack. Anyone may make a distribution for any purpose because Linux is freely distributable.

Throughout this article, we will go over what Linux is, the history of Linux, what Linux is used for, the benefits of using the Linux OS, the most commonly used Linux distros; the basic features of the Linux system, and whether Linux is Open Source or not, how Linux is different from other OSs. We will also review whether Linux is more or less secure than Windows. Lastly, we will explain installing Zenarmor next-generation firewall on Linux distributions.

What is Linux?

Linux is the most popular and well-known open source operating system used to directly handle a system's hardware and resources, such as the CPU, memory, and storage. Linux serves as an operating system (OS) between software and hardware. It connects your applications to the hardware resources that do the task. Linux is widely utilized in the operating systems of modern supercomputers, smart gadgets, and internet infrastructure equipment. The most well-known of them is the operating system developed by Google, called Android.

What does Linux Include?

The Linux operating system consists of the following components:

• Bootloader: The software that controls the computer's launch procedure. For the majority of users, this is merely a welcome screen that appears and disappears as the operating system loads.

• Kernel: The fundamental component of the operating system. Without it, the OS cannot function. The kernel is responsible for managing system resources and communicating with hardware. It is responsible for managing memory, processes, and files. The OS's lowest level is the kernel.

• Init system: This subsystem is responsible for controlling daemons and bootstrapping the user space. systemd, which is one of the most popular init systems, is also one of the most controversial. The init system manages the launch process after the bootloader (such as GRUB or GRand Unified Bootloader) has completed the initial booting.

• Applications: A variety of software that enables the completion of a mission. Apps range from desktop utilities and programming languages to multi-user business suites. Most Linux distributions provide a central repository for searching and downloading additional applications. Linux, like Windows and macOS, offers tens of thousands of high-quality software titles that can be found and installed with relative ease. The vast majority of contemporary Linux distributions include App Store-like utilities that centralize and facilitate application installation. For instance, Ubuntu Linux includes the Ubuntu Software Center (a rebranding of GNOME Software), which enables you to search and install thousands of applications from a central location.

• Daemons: These are secondary services (printing, sound, scheduling, etc.) that start up either during launch or after logging into the desktop.

• Desktop environment: This is the portion with which consumers interact. There are numerous desktop environments (GNOME, Cinnamon, Mate, Pantheon, Enlightenment, KDE, Xfce, etc.) to choose from. Each desktop environment includes pre-installed applications (file managers, configuration tools, web browsers, and games, for example).

• Graphical server: This is the subsystem that displays the graphics on your monitor. It is commonly known as the X server or simply X.

History of Linux

At AT & T's Bell Labs in the United States, the Unix operating system was developed and put into use in 1969 by Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna. As was customary at the time, Unix was fully in assembly code when it was first published in 1971. Except for a few hardware and I/O routines, Dennis Ritchie rewrote them in the C programming language in 1973, a very innovative move. The ability to develop Unix in a high-level language made it simpler to adapt it to many computing platforms.

Due to an earlier antitrust case prohibiting it from joining the computer industry, AT & T licensed the operating system's source code as a trade secret to anybody who inquired. As a result, Unix expanded swiftly and was widely used by corporations and academic institutions. AT & T started selling Unix as a proprietary product in 1984 after AT & T was freed from its requirement to refrain from entering the computer industry. However, users were not permitted to change Unix under this private product model.

In 1980, Onyx Systems started selling early Unix workstations powered by microcomputers. Sun Microsystems later started selling Unix-based desktop workstations in 1982 after being created as a spin-off of a Stanford University student project. Sun workstations constituted the first successful commercial attempt at delivering a predominantly single-user microcomputer that ran a Unix operating system, despite not using common PC hardware like Linux was later created for.

Richard Stallman launched the GNU Project in 1983 with the intention of developing a "full Unix-compatible software system" made up completely of free software. Work started in 1984. Stallman founded the Free Software Foundation in 1985 and the GNU General Public License (GNU GPL) in 1989, respectively. Many of the operating system programs (such as libraries, compilers, text editors, a command-line shell, and a windowing system) were finished by the early 1990s, but low-level components like device drivers, daemons, and the kernel, known as GNU Hurd, remained stuck and unfinished.

A simple Unix-like operating system called MINIX was developed by computer science professor Andrew S. Tanenbaum and released in 1987 with the intention of teaching operating system fundamentals to students and others. The licensing conditions kept MINIX from being free software until the licensing changed in April 2000, despite the fact that the whole source code was freely accessible.

NetBSD, OpenBSD, and FreeBSD all came from 386BSD, which was made before Linux, even though it wasn't released until 1992 because of legal issues.

Several times, Linus Torvalds, the main developer of the Linux kernel, has admitted that he probably would not have developed Linux if the GNU kernel or 386BSD had been around in 1991.

In the fall of 1990, Torvalds enrolled in a Unix course as a student at the University of Helsinki. "Operating Systems: Design and Implementation" by Andrew S. Tanenbaum was one of the required texts for the course, which made use of a MicroVAX minicomputer running Ultrix. A copy of Tanenbaum's MINIX operating system was provided in this textbook. Torvalds' introduction to Unix came through this course. He started working on his operating system kernel, which ultimately became the Linux kernel, in 1991 after becoming frustrated with MINIX's license, which at the time restricted it to educational use only.

Applications created for MINIX were also utilized on Linux when Torvalds started working on the Linux kernel. Later, as Linux grew older, more Linux kernel development was done on Linux-based systems. Because it was advantageous to use the freely accessible code from the GNU Project with the developing operating system, GNU applications also replaced all MINIX components. Code covered by the GNU GPL can be reused in other software applications as long as those programs are also released under the same or a similar license. The GNU GPL was introduced at Torvalds' initiative as a replacement for his earlier license, which forbade commercial redistribution. The Linux kernel and GNU components were combined by programmers to create a fully functional and open operating system.

What is Linux used for?

Linux is utilized to manage multiple services, such as process scheduling, application scheduling, fundamental peripheral devices, and file systems. Linux can run any type of program you're used to running on Windows or macOS, from basic calculators to sophisticated graphics editing tools.

Kubernetes, Docker, and Open Daylight (used to accelerate the adoption of SDNs and Network Functions Virtualization) are examples of Linux-based products that have had a significant impact on the IT industry and have become indispensable to the tech stacks of a large number of organizations. In addition, cloud service providers favor Linux-based operating systems due to their free and open-source nature.

Linux can be found in a variety of contexts and has the following use cases:

• Headless Systems: Linux is used for headless server systems that do not need a graphical user interface (GUI) or a terminal and keyboard that are directly linked. Headless systems are often used for remotely operated network servers and other devices.
• Network Devices: Linux is a common network operating system for routers, switches, DNS servers, home networking devices, and more. Cisco, for instance, provides a version of the Cisco Internetwork Operating System (IOS) that employs the Linux kernel.
• Embedded Devices: Linux is used as an embedded operating system for a range of applications, such as home appliances, automobile entertainment systems, and network file system appliances with modest computing needs.
• Cloud: Linux is used as a cloud operating system for cloud instances. Major cloud computing service providers provide Linux-powered cloud instances for cloud servers, desktops, and other services.
• Servers: Server operating system for web servers, database servers, file servers, email servers, and other types of shared servers. Linux is well-suited for all sorts of server applications due to its capacity to run high-volume and multithreading applications.
• Desktops: Operating system for desktop productivity computing. Linux is a free, open-source desktop environment for those who prefer it over proprietary operating systems. Linux OS is used for the following purposes by end users:
• Office Jobs: A full office suite, such as LibreOffice, Apache OpenOffice, or Calligra Suite, is generally included with Linux. On Linux, Microsoft Office won't operate natively (although for the dedicated user, we do have some workarounds). However, one of those alternatives will suffice for the majority of customers' office requirements. The majority of them work without a hitch to open, edit, export, and save files. DOC, DOCX, XLSX, PDF, and other extensions. Some even offer more sophisticated features like tracking changes and macros.
  • Emailing: In addition to using webmail in a browser, there are several Linux email programs you can use to manage your inbox. Thunderbird and Evolution are a couple of the well-liked options. They frequently provide you with an interface that is more sleek and streamlined than Microsoft Outlook.
  • Using a web browser: Web browsers are a necessary component of any modern PC and are always included in Linux desktop packages. Most computers come pre-installed with Firefox or Chromium, but you can also get ordinary Chrome, Microsoft Edge, or Brave.
  • Gaming: Contrary to popular belief, Linux is compatible with gaming. How is that even doable? This is owing in part to the Linux application Wine, also known as PlayOnLinux, which enables the running of Windows programs on Linux. Even though it's true that many well-known games don't have native Linux versions, Wine enables you to work around this issue.
  • Audio and graphic editing: Most distributions will have at least one graphics editing program pre-installed. Unfortunately, without the assistance of the aforementioned Wine tool, you won't be able to install the Adobe Creative Suite on Linux. However, there are several available options, many of which are free, such as GIMP or Inkscape. More sophisticated audio editors and mixers like Cecilia and Mixxx, as well as Audacity, are simple to install on Linux. You can also choose from a wide variety of open-source and free video editors. For more dedicated artists, Linux environments are even available.
  • Multimedia Playback and Streaming: Like any other operating system, Linux is completely capable of playing your favorite audio, video, and podcasts. Numerous additional Linux apps will stream music from other locations or play local music, and Spotify provides a native desktop version for Linux. For video, Celluloid and VLC Player both support this. With the file manager and picture viewer that your Linux distribution contains, you can also browse and organize your photo library.

What are the Benefits of Linux OS?

Compared to other operating systems, Linux has the following advantages:

• Open Source: Software that is open-source allows anybody to contribute, edit, and improve the source code. Additionally, it is free to download and use by users.

• Secure: Compared to Windows operating systems, Linux is more secure and less prone to attack. The administrator must enter a password in order to authorize each program in the application. Linux reduces the likelihood that any malware will be executed in this way.

• License expenses: Linux, unlike Microsoft Windows and Apple macOS, does not need explicit license costs. While many Linux companies offer system support for a charge, the OS itself is free to copy and use. Some IT businesses have boosted their savings by migrating from a commercial server operating system to Linux.

• Revive outdated computer systems: - Linux, which makes use of antiquated technologies like firewalls, backup servers, low-end systems, etc., can resurrect old and out-of-date PCs.

• Reliability: Linux is regarded as a trustworthy operating system and is well-supported with security updates. Linux is also regarded stable, indicating that it can function in the majority of situations. Linux also handles software-related failures and unexpected input.

• Easy to update: Linux offers quicker and simpler software updates than Windows does.

• Lightweight: Linux is portable. Linux has far fewer system requirements than other operating systems. Linux has a smaller memory footprint and storage space. In general, the majority of Linux distributions needed 128MB or less of RAM and the equivalent amount of disk space.

• Easy to manage: With customization, users may quickly add or remove features as desired, as well as add icon sets and wallpapers. Unlike Windows, no restart is required after installing and removing apps.

• Backward Compatibility: Linux and other open source software are routinely patched for security and functionality while preserving their fundamental functionality. It is probable that configurations and shell scripts will continue to function normally once software upgrades have been implemented. In contrast to commercial software companies that release new versions of their operating systems along with new modes of operation, Linux and open source programs often do not modify their modes of operation when releasing new versions.

• Easy to Install: The Linux installation procedure is quicker than that of Windows and other operating systems. In addition, its installation procedure is much simpler since it involves less human input. It requires little additional system settings and may be readily installed on older devices with little configuration.

• Rich Distribution Options: Linux comes in a variety of distributions, or distros, including Fedora, Ubuntu, Arch Linux, Debian, Linux Mint, and others. These distributions give consumers more feature options.

• Community Assistance: Linux has huge community support. Linux users obtain help in a variety of places. There are several online forums for customer assistance. Additionally, developers from other open-source communities are willing to assist people.

• Ideal for Programming: Linux is widely used by programmers, so there is a wealth of online assistance for faults or situations.

• Stability: Linux systems rarely experience performance issues or failures.

• Privacy: To protect user privacy, Linux does not gather a lot of information from users.

• Efficiency: Without sacrificing efficiency, many networks and workstations can operate concurrently.

• Executable File Types: Almost all file types are supported by Linux for execution.

• Multitasking: It is a multitasking operating system because it can execute numerous processes concurrently without slowing down the system.

• Multiple Desktop Support: Linux system offers numerous desktop environment support for its increased usage. During installation, the desktop environment option may be chosen. Both GNOME (GNU Network Object Model Environment) and KDE (K Desktop Environment) have their own environment, therefore we may choose any desktop environment.

• Networking: Linux enables networking with robust networking functionality. The client-server systems are readily adaptable to Linux. It includes a variety of command-line utilities, including ssh, IP, mail, and telnet, for connecting to other computers and servers. The backup of a network is much quicker than other tasks.

Figure 1. Benefits of Using Linux

What are the Disadvantages of Linux OS?

Compared to other operating systems, Linux has the following drawbacks:

• System Compatibility: Certain hardware devices receive limited or no support in Linux. This could be due to a number of factors, including the device's lack of an open-source driver or the manufacturer's refusal to provide Linux-compatible drivers.

  To avoid hardware compatibility issues, it is essential to verify that your hardware devices are compatible with Linux before installing the operating system. This may involve visiting the manufacturer's website to determine if Linux drivers are available or browsing online for information regarding the compatibility of particular hardware devices.

  Although hardware compatibility can be an issue with Linux, taking the time to verify compatibility prior to installing the operating system can help you avoid potential problems and ensure that your hardware devices function as intended. This issue with hardware compatibility is one of Linux's disadvantages.

• A Steep Learning Curve: Linux has a harsher learning curve than other operating systems, such as Windows and macOS, which is one of its primary disadvantages. Linux frequently requires command-line interfaces for certain duties, such as software installation and system configuration. This may take some getting used to for users accustomed to graphical user interfaces (GUIs).

  Linux offers advanced customizability and flexibility, which means that users may need to learn how to configure various aspects of the system in order to maximize its capabilities. This may require modifying configuration files or using command-line tools, which some users may find intimidating.

  In addition, Linux can have a steeper learning curve, but there are numerous user-friendly distributions that can mitigate this issue. These distributions typically include graphical user interfaces that resemble those of other operating systems, as well as software that facilitates the completion of common duties.

• Software interoperability: A further potential disadvantage of Linux is that not all software and applications are readily accessible. This is due to the fact that many software developers concentrate on creating applications for Windows and macOS, which have larger user bases. However, users can circumvent this issue in a variety of methods.

  Many open-source and free software applications are available for Linux and can be used in lieu of proprietary software. The LibreOffice suite, for instance, provides equivalent functionality to Microsoft Office, while GIMP can be used as an alternative to Adobe Photoshop.

  Users can utilize compatibility layers, such as Wine, to execute select Windows applications on Linux. Wine does not support all Windows applications, but it can provide a solution for users who need to execute a specific program.

• Unsufficient standardization: The lack of standardization in the Linux ecosystem is another drawback. Unlike Windows and macOS, which have a centralized approach to software distribution and standardization, Linux has a decentralized approach with numerous distributions and package formats.

  This fragmentation may result in compatibility issues between different distributions. Some software applications, for instance, may only be available in specific package formats that may not be compatible with all distributions. This results in incompatibility issues when attempting to install software on various distributions, which is extremely aggravating for users.

  With the increasing prevalence of Linux and the community's efforts to standardize aspects of the ecosystem, this concern may diminish in the near future.

• Lack of Commercial Support: Linux lacks the same level of commercial support as competing operating systems. This can make it difficult for users to obtain assistance when operating system problems or issues arise. For instance, a user may be unable to locate a commercial support team that can assist them with Linux troubleshooting.

• Poor Gaming Support: Similarly to software, games do not support Linux natively. Because Linux is not a widely adopted platform, gaming developers have little interest in it. You cannot therefore anticipate your beloved game to function on Linux. In recent years, however, the number of games developed for Linux has increased. Even though you can obtain any game using third-party software, the game will not function as efficiently as it does on a native operating system.

The advantages and disadvantages of Linux are listed in the following table:

Advantages	Disadvantages
Open Source	System Compatibility
Secure & Reliable	A Steep Learning Curve
License expenses	Software interoperability
Backward Compatible	Unsufficient standardization
Easy to install & update & manage	Lack of Commercial Support
Lightweight	Poor Gaming Support
Community Assistance
Rich Distribution Options
Ideal for Programming
Stability
Privacy
Efficiency
Multitasking
Multiple Desktop Support
Robust networking

Table 1. Advantages & Disadvantages of Linux

What Does "Linux Distribution" mean?

A "Linux distribution", often shortened to "distro", is an operating system made from a group of software that includes the Linux kernel and, often, a package management system. Linux users often download one of the Linux distributions, which are available for everything from powerful supercomputers (like OpenWrt) to embedded devices (like Linux Mint) and personal computers (like Ubuntu Desktop).

A typical Linux distribution includes a Linux kernel, GNU tools and libraries, extra software, documentation, a window manager, a desktop environment, and one or more window systems, most often the X Window System or, more recently, Wayland.

Most of the software that is included is free and open source. The source code and generated binaries are available, so the original program can be changed. Usually, Linux distributions have the option to include proprietary software that may not be available in source code form, such as binary blobs needed for some device drivers.

A Linux distribution is a set of tools and utilities, like different GNU tools and libraries, that are packaged with the Linux kernel in a way that lets it meet the needs of many different users.

Most of the time, the people who take care of the distribution change the software for it before compiling it into software packages. The software programs can be found online in repositories, which are storage spaces that are often spread out all over the world. There are very few packages that are actually built by a distribution's maintainers aside from "glue" components like the package management systems and installers (like Debian-Installer and Anaconda).

There are almost a thousand Linux distributions.

Distributions come in a wide range of shapes and sizes because there is so much software out there. There are distributions that can be used on desktops, servers, laptops, netbooks, mobile phones, tablets, and in the minimal environments that are usually found in embedded devices. There are distributions like Fedora Linux (Red Hat), openSUSE (SUSE), and Ubuntu (Canonical, Ltd.), which get money from companies, and distributions like Debian, Slackware, and others, which only get money from the community. Most distributions are already compiled and ready to use for a certain instruction set. However, some, like Gentoo, are mostly distributed as source code and must be compiled locally in order to be installed.

Which are the most popular Linux distros?

With approximately 3-3.5 billion users worldwide, Linux is one of the most popular operating systems. Because it can be changed and is open source, a lot of Linux distributions with strong features have been built on top of it.

These are the top Linux distributions:

• Ubuntu: Ubuntu is a free and open-source Linux distribution that comes in three flavors: Desktop, Server, and Core for IoT. Ubuntu is easy to use. It comes with free software like LibreOffice, Firefox, Thunderbird, and Transmission, as well as games like Sudoku and chess. Aside from its ease of use, the operating system is known to be more secure than Windows. It is not immune to viruses, but it has a much lower risk of exposure. Also, it is easy to change, so you can make your Ubuntu environment fit your needs.

• CentOS: Because its software is simple and light, CentOS runs faster than other Linux distributions. The operating system has a longer upgrade cycle, lasting approximately five years. (Other distributions have shorter cycles.) Because of the more frequent updates, those other distributions may be less reliable at times. As a result, CentOS is regarded as a stable operating system.

• Fedora: Fedora is also known for being a stable and dependable operating system. Fedora has a lot of graphical tools and useful software for office work, virus protection, system management, playing media, learning, and other things. Because of its popularity, it is supported by a large community, which is an important consideration when selecting open-source software.

• Debian: Debian is a stable Linux distribution, but it also lets early adopters try out packages that aren't quite ready yet. In comparison to the alternatives, Debian provides the most packages. The time it takes to upgrade Debian is also long, which means you can keep using the same version for a long time. This keeps you from having to upgrade software often and restart your server to make the changes take effect. People think it's a great distribution for running servers because its software is stable and it comes out less often.

• Red Hat Enterprise Linux: Red Hat Enterprise Linux (RHEL), which calls itself the "world's leading enterprise Linux platform," is used for a lot of different things, such as making software and running hardware. RHEL is well-known for its stability and speed. It works well with third-party software and has a quick security patch cycle. Because this distribution is run by Red Hat, a multinational software company, you will get great support.

• Linux Mint: Mint has become one of the most popular Linux distributions since it first came out in beta in 2006. If you use Windows, you will be familiar with its user interface. When switching to a new Linux distribution, there may be a learning curve, but Mint's simple UI and ease of use can help to reduce that. Furthermore, it includes many useful apps by default, such as Firefox, LibreOffice, and others. It has an effective app management tool. You can search for and install software visually using an internal software manager that works like the App Store.

• OpenSUSE: OpenSUSE gives its users a stable environment and works well with almost all of the best Linux desktop apps. The distribution is simple in software management. You can search for tools on software.opensuse.org and install them directly from there. OpenSUSE is a great choice for both home and business use because it has so many benefits. If you don't want to, you don't have to keep updating your operating system after installing the distro. You can just install it and use it.

• Manjaro: Manjaro, which was released in 2011, has quickly become one of the most popular Linux distributions. Manjaro has distinct advantages over other distributions. Manjaro, in particular, excels at hardware support. Some Linux distributions require you to take extra steps to make your hardware work, such as manually installing drivers and packages, which can be time-consuming. Manjaro, on the other hand, makes this process much easier. It scans your hardware and installs the necessary drivers and packages automatically. Unlike other distros, you don't have to deal with a broken Personal Package Archive (PPA) when you want to install software that isn't supported by the repository.

• Elementary: Elementary OS, which was released in 2011, distinguishes itself from other distributions by including its own desktop environment called Pantheon. It has its own user interface and apps as well. Elementary OS has a minimalist design that focuses on simplicity, making it simple to learn. This minimalist design allows users to focus on what is important and increases productivity.

• OS Zorin: For those new to Linux distributions, Zorin OS is a good place to start. Its user interface looks like Windows, and in Zorin's premium editions of OS 9, you can change the user interface to look like Apple's Mac OS. One of Zorin's strengths is its speed, and its operating system supports over 55 languages.

• Kali Linux: Kali Linux is the best distribution for ethical hacking objectives. Frankly, no other distribution can compete with Kali Linux. The release includes a variety of tools that may be used for ethical hacking. Device categories include wireless assaults, stress testing, online applications, vulnerability analysis, and exploration instruments, among others.

  Because Kali Linux is derived from the Debian Testing branch, the majority of packages are imported from the Debian repository. In prior versions, updates were not sent in an unreliable manner. In the most recent version, however, it has worked with Offensive Security and Cloudflare to ensure that all upgrades are successfully transmitted.

  Kali Linux is installed on a variety of platforms, including Chromebook, Raspberry Pi, BeagleBone, and others. This is one of its major features. In addition, with the introduction of Kali NeHunter, Android cellphones are now supported. Regular rolling updates, tried-and-true hacking tools, vast learning materials, and a solid Debian foundation are some of the advantages of adopting Kali Linux.

  Kali Linux has always been available for free and in numerous languages. It is extremely configurable and comes with over 600 penetration and security testing tools.

  It is the most extensively used distribution for penetration testing on a global scale. The quantity of built-in penetration tools makes ethical hackers' lives easier. In addition to providing a sophisticated platform for penetration testing, it also provides learning opportunities for budding ethical hackers. Additionally, it has an active community and adequate documentation.

• IPFire: IPFire is a fortified open-source Linux distribution whose main role is as a firewall and router. A web-based administrative interface is used for configuration. IPFire Linux Firewall is one of the finest and most effective open-source firewalls for any individual or business network.

  IPFire's primary objective is your safety. Simple to configure, the firewall engine and intrusion detection system prevent attackers from accessing your network. In the default configuration, the network is split into different zones with independent security rules, such as a LAN and a DMZ, in order to limit hazards inside the network and provide customized configurations for the specific requirements of each network segment.

  IPFire employs a Stateful Packet Inspection (SPI) firewall that is based on Netfilter, the Linux packet filtering framework. It swiftly filters packets and has throughputs of tens of gigabits per second.

  Pakfire, IPFire's proprietary package management system, may be used to install add-ons that enhance the capabilities of the firewall. Administrators may utilize add-ons as command-line tools or to expand the capabilities of the system.

  IPFire's Intrusion Detection System (IDS) examines network traffic for exploits, data breaches, and other suspicious activity. When an attacker is found, alerts are generated and the offender is immediately blocked.

What are the Basic Features of Linux?

The following are some of the most important features of the Linux operating system:

• Portable means that software can run on different types of hardware in the same way. The Linux kernel and application programs can be installed on any hardware platform.

• The source code for Open Source Linux is freely available, and it is a community-based development project. Multiple teams collaborate to improve the capability of the Linux operating system, which is constantly evolving.

• Linux is a multiuser system, which means that multiple users can access system resources such as memory/ram/application programs at the same time.

• Linux is a multiprogramming system, which means that multiple applications can run at the same time.

• The Hierarchical File System (HLFS) provides a standard file structure for arranging system and user files.

• Linux Shell includes a special interpreter program that can be used to execute operating system commands. It can be used to perform various operations, such as calling application programs.

• Linux provides user security through authentication features such as password protection, controlled access to specific files, and data encryption.

Is Linux Open Source?

Yes. One of the most well-known instances of open-source, free software is Linux. As long as they follow the rules of the licenses, like the GNU General Public License (GPL), anyone can use, change, and share the source code for commercial or non-commercial purposes. For example, the Linux kernel is licensed under the GPLv2, but system calls are an exception. Otherwise, any software that uses the kernel would be considered a derivative, and the GPL would have to apply to that application.

Basic Terms you should know about Linux

A command in Linux is a program or utility that runs from the command line. A command line is an interface that turns lines of text into instructions for the computer.

Any graphical user interface (GUI) is simply a graphical representation of command-line programs. For example, when you close a window by clicking the "X," command is executed behind the scenes.

Moving from Windows to Linux is like entering a completely new world. When you cross the line, you have to learn about new kinds of software, management tools, and security rules. Even the lingo is quite different from what a Windows user is used to. The terminology factor only adds to what is already a fairly complex subject. By breaking down this mini-glossary of basic terms, we hope to make some Linux terms easier to understand.

• The crontab command in Linux: Crontab is a command that allows editing of the cron table on Unix-like operating systems. The list of jobs that are set up on the system to run at regular intervals is contained in the cron table.

  Cron is the name of the daemon that reads the crontab and runs the commands at the appropriate times. It has the name of the Greek deity of time, Kronos.

  To edit your crontab you can run the following command:

  crontab -e

  To display ("list") the contents of your crontab run the next command:

  crontab -l

• The grep command in Linux: A quick and straightforward approach to searching or filtering Linux files for particular strings is to use the grep tool. This Linux program follows a standard syntax and accepts a wide range of search criteria. Global regular expression printing is referred to as "grep". There is no need to install the program because it is part of the Ubuntu essential package. To find strings and patterns, use the grep command. Thus, it enables you to, for instance, filter out the data you're looking for from huge protocol files. However, keep in mind that using grep on device files is never a good idea because it can cause issues. When used correctly, the Linux grep command can assist you in searching through large files. There are numerous parameters you can use to narrow down your search so that it only returns the characters or lines you require. These parameters are denoted by a dash -. Here are some of the most useful grep examples:

  • -c: Rather than returning each line, -c or -count will tell you how many lines the search term appears in. For example, the grep command 'grep -c 'test' example.txt' will tell you how many lines contain the word 'test.'
  • -l: Use the '-l' option to find out which files a specific search term was found in (lowercase L). The grep command 'grep -l 'test' *.text' will return all files containing the word 'test.'
  • -i: This option makes your search case insensitive. 'grep -i' test 'example.txt' will return every line containing the words' or 'Test'.

• The chmod command in Linux: One of the most important Linux security commands is chmod, which sets read, write, and execute permissions. Every object on your Linux system has a permission mode that specifies what actions a user can take with it. Permissions are classified into three types: read (r), write (w), and execute (x). Reading a file means viewing its contents. For example, for someone to read the text contained within a text file, read permission must be granted. If the user wishes to add a sentence to that file, he or she must have written permission. Someone with execute permission can run a file, such as a shell script or a binary program file. The permissions associated with a file are displayed by the ls -l command.

  ls -l
  -rw-rw-r-- 1 bruce bruce 0 Jul 10 16:25 schedule10.txt

  Some permissions (rw) are repeated because they apply to distinct users, groups, and other entities. The user is the same as the owner, and the group is the user's main group, and both are bruised. "Other" includes all additional users.

  The object's kind is indicated by its first position: - for files, d for directories, and l for symbolic links. The authorization mode is described by the following nine slots, which are arranged in threes. The groups are arranged by user, group, and other, while the positions are arranged by r, w, and x.

  rwx rwx rwx
  uuu ggg ooo
  u=user, g=group, o=other

• The ssh key command in Linux: In essence, Secure Shell (SSH) keys are an authentication method employed by the SSH protocol. The largest Infrastructure-as-a-Service (IaaS) systems available today, like Google Cloud and AWS, depend on them. SSH keys come in a variety of sizes, but RSA 2048-bit encryption, equivalent to a 617-character long password, is a common option. You can create your own SSH key pair on Windows PCs by downloading and running an SSH client like PuTTY.

  For Linux:

  1. Update or install OpenSSH as recommended.

     sudo apt-get update

  2. Install openssh-server:

     sudo apt-get openssh-server

  3. Open a command-line terminal and type the following command to begin:

     ssh-keygen -t rsa
     Your key files will then be created as usual in the /HOME/.ssh/directory (including the private key). However, if you want to generate them somewhere else, you can select another place.
     Important: Don't ever divulge your private key to anyone.
     $HOME/.ssh/id rsa1.pub (public key)
     $HOME/.ssh/id rsa1 (private net)

     You'll have the choice to generate a passphrase to aid in preventing unauthorized people from accessing your accounts and preserve the privacy of your keypairs. You'll upload your public key to your server so that SSH key authentication can be used for access control. To automate the transfer process, use the ssh-copy-id command from the OpenSSH package with the syntax shown below:

     ssh-copy-id username@host

  The public SSH key can also be manually placed on the distant server and added to your account.

• The ifconfig command in Linux: A tool for managing networks is called ifconfig (interface configuration). In Linux operating systems, it is used to configure and view the status of the network interfaces. You can adjust the ARP cache, routes, enable or disable interfaces, assign IP addresses, and more with ifconfig.

  Use the -s option to display a short list instead of all the details.

  $ ifconfig -s

• The bash command in Linux: Bash is an interpreter for the sh command language that can run scripts that are read from files or the standard input. Additionally, bash integrates helpful elements from the Korn and C shells (ksh and csh). Bash is meant to be a conformant implementation of the IEEE POSIX specification's Shell and Utilities section (IEEE Standard 1003.1). Bash can be set up to be by default POSIX-compliant. You can invoke bash with any of the single-character shell parameters listed in the explanation of the set built-in command. There are also the following choices:

  • -c : The -c option causes commands to be read from a string if it is available. If there are arguments after the string, they are assigned to the positional parameters, starting with $0.
  • -i: The shell is interactive if the -i option is specified. See invocation, below, for further details on interactive shells.
  • -r: The shell is made limited if the -r option is used; for more information, see the "Restricted Shell" section below.
  • -s: Commands are read from standard input if the -s option is available or if no arguments are left after option processing. When launching an interactive shell, this option enables the positional parameters to be set.
  • -D: On the standard output, a list of all double-quoted strings with a $ prefix is displayed. When the current locale is not C or POSIX, these strings may be translated into another language. The -n option is implied by this; no commands are run.

• The apt command in Linux: On Ubuntu, Debian, and related Linux distributions, apt is a command-line tool for installing, updating, removing, and managing deb packages in general. It combines the most popular apt-get and apt-cache tool commands with various default settings for several options. Apt is made to be used interactively. Use apt-get and apt-cache instead of other packages in your shell scripts because they are backward compatible and offer additional functionality. Let's look at how to install new packages or security updates on an Ubuntu or Debian Linux server using the apt command. Enter the following to download package data from all preset sources:

  sudo apt update

How is Linux different from other OSs?

It's crucial to comprehend how Linux differs from other operating systems, including Windows 95/98, Windows NT, OS/2, and other personal computer implementations of Unix. First and foremost, it should be made clear that Linux can coexist peacefully with different operating systems on the same platform. For example, Linux may run side by side with Windows NT and OS/2 without encountering any issues. You'll find that there are even techniques to communicate between different operating systems.

Linux is a great option for home Unix computing. Why use Windows at home if you produce Unix software? You may create and test Unix software on your PC with Linux, including databases and X programs. There's a good probability that Unix is used by your university's computing system if you're a student. You can manage and configure your own Unix system using Linux. If you don't have access to other Unix workstations, installing and running Linux is a great way to learn Unix.

But let's keep our bearings. Linux isn't simply for home users of Unix. It is flexible and strong enough to handle demanding distributed computing requirements as well as large tasks. Many companies are switching from other Unix-based workstation systems to Linux. One of the most reliable and powerful operating systems currently available, Linux offers a fantastic price-performance ratio and is totally adaptable to your needs thanks to its open-source nature. Linux is proving to be the ideal platform for teaching operating systems design courses in universities.

Finally, the fact that the Linux kernel and other key components are free and open-source software is the main distinction between Linux and many other widely used modern operating systems.

What is the difference between Linux and Windows OS?

Linux is a free and open-source operating system that complies with industry standards. It offers a wide range of applications. Linux operating system includes a number of independently developed components, resulting in a system that is entirely interoperable and free of proprietary code.

Windows is a commercial operating system that is intended for corporate and alternative industrial users as well as individuals without any programming knowledge. It is quite basic and easy to use.

The key difference between the Linux and Windows packages is that the former is entirely free, while the latter is a commercial product and is pricey. Linux is an open-source operating system where users can view and modify the system's code. On the other hand, even if Windows is an authorized operating system, users cannot access system files. Let's see how Linux and Windows vary from one another:

Linux	Windows
open-source	not open-source
Cost-free	Expensive
Case-sensitive	regardless of the case
monolithic kernel	microkernel
Better Efficiency	Less effective
forward slash is used to separate folders	the backslash is used to separate directories
offers greater security	offers less security
frequently utilized in purpose-based system hacking	does not offer very good hacking efficiency
3 sorts of user accounts: - Regular - Root - Service	4 different types of user accounts: - Administrator - Standard - Child - Visitors
the root user is the super user and has full administrative rights	All administrative rights on Windows PCs are available to the administrator user

What is the Difference Between Linux and FreeBSD?

Like Linux, FreeBSD is a Berkeley Software Distribution, or BSD, an operating system that is based on the Unix operating system. It is free, open-source, and secure. One of the most widely used BSD operating system distributions is FreeBSD. Despite having numerous similarities with Linux variants, FreeBSD differs significantly from them in a number of crucial areas. In contrast to FreeBSD, Linux is a far more widely used operating system. The original Bell Unix, which was created by the University of California, Berkeley, was later upgraded and altered in several ways, evolving into the modern BSD. One of the full-featured open-source BSD operating systems is FreeBSD.

Below are the top differences between Linux and FreeBSD.

• Linux is more like a kernel, but FreeBSD is a complete operating system.

• Linux is licensed under the GNU General Public License, but FreeBSD is licensed under its own license, which is the BSD license.

• Linux has excellent support for SMP but FreeBSD has good support for SMP.

• Package management in Linux depends heavily on its distribution. Debian has excellent package management capabilities, but package management in FreeBSD is excellent, especially in ports and binary areas.

• Linux supports all types of Oracle or ERP applications, but FreeBSD does not support any of these Oracle or ERP applications.

• Linux shows good performance but FreeBSD has excellent performance.

• Linux has good security, but FreeBSD has better security than Linux.

• Linux has good reliability but is fast as FreeBSD has to use only a few rules.

• Linux has excellent support for all Dell, HP, and IBM servers, but FreeBSD does not have support for any of these servers.

What is the Difference Between Linux and macOS?

Linux is an open-source operating system that can be used on any device. In contrast, Mac is an operating system that can only be used on Mac devices. Linux serves as a server, an operating system, and a platform for other system applications. Mac OS is an operating system that does not permit the use of other system programs.

Despite sharing many characteristics with different Linux distributions, MacOS is very different from them in a number of critical respects.

The differences between Linux and macOS are listed in the following table:

Linux	macOS
Linus Torvalds is the creator of Linux	Apple Incorporation created macOS
In 1991, Linux was introduced.Embedded systems, mobile devices, personal computers, servers, mainframe computers, and supercomputers are among the system types Linux is intended to run on.	macOS was launched in 2001. Workstations, laptops, and embedded systems are the system types that macOS is intended to run on.
Linux supports the IA-32, x86-64, ARM, PowerPC, and SPARC computer architectures.	The computer architectures that macOS supports include Ax86-64 (10.4.7 and higher), IA-32 (10.4.4 through 10.6.6), and PowerPC (10.0-10.5.8).
Linux uses a monolithic kernel.	"Hybrid with modules" is the kernel type used by macOS.
LINUX/POSIX is the native APIs for Linux.	The native APIs for macOS are BSD-POSIX, Java, Cocoa, and Carbon.
The GNU GPLv2 is the Linux kernel's recommended license.	The preferred licenses for macOS are GNU GPL, APSL, and proprietary.
Linux distribution-specific package management is dependent.	The macOS installer handles package management for macOS.
Linux's subsystems support the non-native APIs Mono, Java, Win16, and Win32.	The subsystems of macOS support Toolbox, Win16, and Win32 as non-native APIs.
Linux distribution-specific factors affect how updates are managed.	Software Update is used to manage updates for the Mac OS.
The ext2, ext3, ext4, btrfs, ReiserFS, FAT, ISO 9660, UDF, and NFS file systems are supported by Linux.	HFS+, APFS, HFS, UFS, AFP, ISO 9660, FAT, UDF, NFS, SMBFS, NTFS, FTP, WebDAV, and ZFS are among the file systems supported by macOS.

Table 2. Linux vs macOS

Is Linux More Secure than Windows?

Yes. In terms of security, while Linux is open source, it is extremely difficult to breach, making it a highly secure operating system when compared to other operating systems. One of the main reasons for Linux's popularity and widespread use is its high-tech security.

Meanwhile, Linux is open source and has a large user community. Because the entire user base has access to the source code, they can monitor for issues, and any vulnerabilities are likely to be discovered before hackers target them.

Furthermore, because Linux is open source, users will investigate and resolve the issue immediately. As a result, Linux receives a high level of support from its developer community.

Windows users, on the other hand, are unable to resolve the issue because they lack access to the source code. If they discover a vulnerability in the system, they must notify Microsoft and wait for it to be fixed.

Users on Windows have full administrative access to their accounts. As a result, when a virus enters the system, it quickly corrupts the entire system. So, in the case of Windows, everything is at risk.

On the other hand, Linux has the advantage of accounts that give users limited access, so that if a virus attacks, only a portion of the system is damaged. Because Linux does not run as root by default, the virus will not be able to infect the entire system.

There is UAC (user account control) mechanism in Windows to control access privileges, though it is not as robust as Linux.

To improve system security, Linux employs IP tables. Iptables aid in network traffic control by configuring specific rules that are enforced via the Linux kernel firewall. This contributes to a more secure environment for running commands or gaining network access.

Linux has segmented working environments that protect it from virus attacks. However, because the Windows OS is not well segmented, it is more vulnerable to threats.

Linux has fewer users. Linux accounts for nearly 3% of the market, while Windows accounts for more than 80%. As a result, hackers are always more interested in targeting Windows because the virus or malicious software they create affects a large number of users. As a result, Linux users are safer.

To summarize, Linux has some security features that make it more secure than Windows and other operating systems.

Does Linux have a Firewall built in?

Yes. Because the Linux kernel includes a built-in firewall, and technically all Linux distributions include one that is not configured or activated. This is due to the fact that using a firewall necessitates some knowledge.

Even without an active firewall, Linux remains secure. Most distributions, including Ubuntu and Linux Mint, have no open ports by default, ensuring that intruders cannot access your computer.

Nonetheless, you must enable a firewall. A firewall consumes few resources but adds an extra layer of security. An inexperienced user may unknowingly open some ports by installing samba, ssh, or apache, for example.The firewall will still protect the system from unauthorized access in this case.

In Linux, you can configure and run a firewall using a variety of programs listed below:

• UFW is the most user-friendly firewall available for Linux. Use UFW if you are a complete newbie or simply want to use your Linux without delving too deeply into its settings.

• iptables which is a more advanced but likely correct way to configure the Linux firewall. If you truly want to learn Linux and become a Linux expert, you must first learn iptables.

Using Zenarmor on Linux Distributions

Whether you have a small home network or a multi-device business environment, Zenarmor can be installed and secured in a matter of seconds.

Zenarmor adds next-generation firewalling features like Application Filtering & Control, TLS Inspection, Advanced Network Analytics, and many more to your BSD/Linux-based packet-filtering firewall.

Zenarmor can be deployed as a gateway or per-server in any cloud environment.

Before installing Zenarmor, make sure you have the minimum system requirements to run Zenarmor and have the best user experience.

You can try Zenarmor Free Edition forever by installing it on Linux or other platforms. These Linux platforms are supported:

• Ubuntu Linux

• RedHat EL

• CentOS Linux

• Debian

• Alma Linux

• Amazon Linux

warning

To use all of Zenarmor's filtering features, you must have either the netmap framework or the nfqueue framework installed on your system. Netmap is not installed by default in Ubuntu, CentOS, or Debian. On Linux distributions, you can use the default NFQ framework or install netmap manually.

To install Zenarmor on supported Linux distributions, simply run the one-liner below, which will install the package repository as well as the main package:

curl https://updates.sunnyvalley.io/getzenarmor | sh

Get Started with Zenarmor Today For Free