In this complete exposition, students will delve into the details about the Linux operating system and its relevance to the world of use in cybersecurity. Basic concepts such as the architecture and the most popular Linux distributions will be introduced as the course begins. This serves as a foundation that promotes the understanding of the critical role Linux plays in cybersecurity.
One particular module under consideration is the Linux shell. A powerful interface enables direct contact with the operating system. This part is designed to teach course participants about the use of the shell and engage them in practical use of the command-line interface (CLI) as a more effective means of communicating with the Linux system. By the end of this module, learners will be well-informed about Linux architecture, distributions, and leveraging the Linux shell as a key entry for many cybersecurity-related purposes.
They will gain theoretical knowledge and practical approaches to realizing their use of Linux in various contexts regarding cybersecurity.
Learning Objectives:
- Discuss why Linux is heavily used in cybersecurity.
- Identify the architecture of the Linux Operating System.
- Identify unique features of popular Linux distributions.
- Describe how the shell provides an interface for user interaction with the operating system.
TEST YOUR KNOWLEDGE: ALL ABOUT LINUX
1. As a security analyst, you might use Linux to review logs when investigating an issue.
- True (CORRECT)
- False
As a security analyst, probably you will be using Linux to peruse system logs while investigating when security incidents have happened as Linux is quite a better tool for log analysis. Commands like grep, less, and cat can help sift-through a whole lot of log files and allow visual identification of suspicious activity. The fact that it has its own logging system, namely syslog and journalctl, keeps important security-related data safe so that they can be referenced later when needed, e.g., during incident response.
2. Which of the following are components of the Linux architecture? Select all that apply.
- Applications
- The kernel (CORRECT)
- The operating system
- The shell (CORRECT)
In a very basic way, we can say that Linux is an operating system composed of these minimal key components: applications, the shell, and the kernel. These also include the user, the Filesystem Hierarchy Standard (FHS), and hardware.
3. Fill in the blank: The Filesystem Hierarchy Standard (FHS) is the component of Linux architecture that _____.
- manages processes and memory
- organizes data (CORRECT)
- enables people to communicate with the system
- consists of the physical components of a computer
The Filesystem Hierarchy Standard (FHS) is a standard that determines the arrangement of data within the Linux operating system through an organized directory structure.
4. Which of the following hardware components are peripheral devices? Select all that apply.
- a printer (CORRECT)
- RAM
- a monitor (CORRECT)
- a CPU
Monitors and printers are known as peripheral devices, which are hardware components connected to and controlled by the computer system. The CPU and RAM, on the other hands are internal hardware components that serve as core for the computer to be able to perform its main function and run natively.
5. How do security analysts use Linux? Select three answers.
- To verify access and authorization in an identity and access management system (CORRECT)
- To use digital forensic tools to investigate what happened following an event (CORRECT)
- To develop new versions of the Linux kernel to increase security in a system
- To examine different types of logs to identify what is going on in a system (CORRECT)
Linux through trained security analysts will be used for validation of access and authorization in an identity and access management system. It will be used for log forensics and incident investigation to help understand and assess what happened and its impact.
6. What is the kernel’s role in the Linux operating system?
- It organizes data.
- It processes commands and outputs the results.
- It manages processes and memory. (CORRECT)
- It helps users perform calculations.
The kernel is the heart of the Linux OS, managing process, memory, hardware, and system resources. It is the middleman between software and hardware, which ensures proper running and allocation of resources.
TEST YOUR KNOWLEDGE: LINUX DISTRIBUTIONS
1. Fill in the blank: Because the _____ is open source, anyone can modify it to build new Linux distributions.
- shell
- application
- kernel (CORRECT)
- hardware
Since the kernel is open source, everyone can modify it and create custom Linux distributions. It is the kernel component under which all other components in the operating systems operate. It manages processes, memory, manages hardware resources, and efficiently coordinates operations between the hardware and software of the components.
2. What is KALI LINUX ™?
(KALI LINUX ™ is a trademark of OffSec.)
- A tool used to guess passwords
- A Debian-derived, open-source distribution of Linux designed for security tasks (CORRECT)
- A tool with a graphical user interface that can be used to analyze live and captured network traffic
- A subscription-based Linux distribution built for enterprise use
Kali Linux is a distribution of Linux that is open-source and is based on Debian, specifically crafted to tackle security-related issues that might be penetrative testing, vulnerability assessments, and digital forensics. Kali comes equipped with a collection of many tools that would help people working in this profession.
3. What is an open-source, user-friendly distribution derived from Debian that is widely used in security and other industries?
- tcpdump
- Ubuntu (CORRECT)
- Red Hat
- Autopsy
Though debian based and open source, ubuntu is a very user friendly distribution which is now popular in security and other industries too. Its popularity has also made it famous and thus there exists a community around it that is very large and active providing many resources and support for users.
4. Which of the following are distributions of Linux? Select all that apply.
- Red Hat (CORRECT)
- Pen Test
- CentOS (CORRECT)
- Parrot (CORRECT)
Red Hat, CentOS, and Parrot were all distributions based on Linux; each specifies its features and focuses. Red Hat, being enterprise-level, is known to be stable in its business rule, while CentOS is more of a community-focused free version of Red Hat, while on the other side, there’s Parrot which is security oriented and is intended for the purpose of penetration testing and digital forensics.
5. What type of components might be different from one Linux distribution to another? Select three answers.
- Their kernels
- Their user interfaces (CORRECT)
- Their pre-installed programs (CORRECT)
- Their parent distributions (CORRECT)
There are a lot of differences in the Linux distributions as far as the pre-installed softwares, user interfaces of the software, and parent distributions are concerned. Each distribution will have software distinctly installed in its purpose-designed environment, interface, and usage since most distributions are designed for certain purposes, such as secure computing, development, or general use.
6. Which of the following statements accurately describe the KALI LINUX ™ distribution? Select all that apply.
- It contains many pre-installed tools that can be used for cybersecurity tasks. (CORRECT)
- It is derived from Debian. (CORRECT)
- It should be used on a virtual machine. (CORRECT)
- It is a closed-source distribution.
Kali Linux™ is a completely open-source Debian derivative that is specially tailored for digital intelligence. In fact, it boasts a vast number of tools preset for penetration testing, detecting vulnerabilities, and forensics. It is better if you run this on a virtual machine when you want to use it.
TEST YOUR KNOWLEDGE: THE SHELL
1. What is the shell?
- Data consisting of an ordered sequence of characters
- Information received by the operating system (OS) via the command line
- An instruction telling the computer to do something
- The command-line interpreter (CORRECT)
The shell is the command line interpreter in Linux. It takes user commands and processes them and executes the results. This is the interface between an individual user and the system, giving it access and use to the operating system through text commands rather than physically manipulating system components.
2. After a user inputs a command into the shell, what can the shell return to the user? Select two answers.
- A request for user approval
- A request for more input from the user
- An error message (CORRECT)
- Output (CORRECT)
Users get error messages or outputs when using the shell to input commands. The first is the computer’s response to valid input, while the latter occurs if the shell fails to decode or execute the input correctly.
3. What is standard error in Linux?
- Information received by the operating system via the command line
- Information returned by the operating system through the shell
- Error messages returned by the operating system through the shell (CORRECT)
- A Linux command that outputs a specified string of text
- Information received by the operating system via the command line
- Information returned by the operating system through the shell
- Error messages returned by the operating system through the shell (CORRECT)
- A Linux command that outputs a specified string of text
The operating system uses as a stream to return error messages through shell media standard errors (stderr). When a command fails to execute or encounters problems, the error messages are sent to this stream with the purpose of identifying and remediating the issue by the user.
4. What is the difference between standard input and standard output?
- Standard input is sent to the operating system. Standard output is sent from the operating system. (CORRECT)
- Standard input is sent from the operating system. Standard output is sent to the operation system.
- Standard input is sent to the Filesystem Hierarchy Standard (FHS). Standard output is sent from the FHS.
- Standard input is sent from the Filesystem Hierarchy Standard (FHS). Standard output is sent to the FHS.
Standard input indicates the stream from which data is received to the operating system; typically input from the user or other programs. Standard output is the opposite; it’s the stream through which an operating system sends and displays results or information to users against requests.
5. What is the purpose of the shell?
- It activates the Linux operating system.
- It helps humans and computers communicate with each other. (CORRECT)
- It organizes data.
- It instructs the computer to do something.
The shell as an interface enables the communication of a human with a computer. Being a command-line interpreter, it lets the user communicate with the OS that executes the commands key-in through the command line.
6. What can the shell return after a user types a command?
- Standard input or standard error
- Standard output or standard error (CORRECT)
- Standard output only
- Standard output or standard input
When a command has been typed by the user in a shell, either output or error can be returned by the shell. Standard output contains what is being returned by the operating system through the shell, while standard error contains messages that are generated by the operating system in case of errors while executing the command.
MODULE 2 CHALLENGE
1. What is an effect of Linux being open source?
- It allows for collaboration among a community of developers. (CORRECT)
- It requires a yearly subscription.
- It is the easiest OS for beginners to use.
- It is the most simple OS in terms of architecture.
2. Which of the following components are part of the Linux architecture? Select all that apply.
- The Filesystem Hierarchy Standard (FHS) (CORRECT)
- The kernel (CORRECT)
- Standard output Hardware (CORRECT)
3. What are distributions?
- Simulated attacks that help identify vulnerabilities
- The different versions of Linux (CORRECT)
- Data consisting of an ordered sequence of characters
- Programs that perform specific tasks
4. Which of the following statements correctly describe KALI LINUX ™? Select three answers.
(KALI LINUX ™ is a trademark of OffSec.)
- KALI LINUX ™ should be used on a virtual machine. (CORRECT)
- KALI LINUX ™ was created specifically to be used with penetration testing and digital forensics. (CORRECT)
- KALI LINUX ™ was created as an enterprise distribution of Linux.
- KALI LINUX ™ is an open-source Linux distribution that is widely used in security. (CORRECT)
5. Which of these are common Linux distributions? Select all that apply.
- Bash
- Red Hat (CORRECT)
- Parrot (CORRECT)
- CentOS (CORRECT)
6. Fill in the blank: The _____ communicates with the kernel to execute commands.
- interface
- hardware
- shell (CORRECT)
- Filesystem Hierarchy Standard (FHS)
7. Fill in the blank: When you communicate with the shell, the commands in the shell can ___. Select all that apply.
- give error messages (CORRECT)
- take output
- give output (CORRECT)
- take input (CORRECT)
8. Fill in the blank: Package managers are used to distribute Linux _____.
- commands
- applications (CORRECT)
- shells
- kernels
9. What is standard input?
- A Linux command that outputs a specified string of text
- Information returned by the OS through the shell
- Data consisting of an ordered sequence of characters
- Information received by the OS via the command line (CORRECT)
10. Which of the following components are part of the Linux architecture? Select all that apply.
- Applications (CORRECT)
- The shell (CORRECT)
- The kernel (CORRECT)
- Standard input
11. Which of the following are examples of Linux distributions? Select all that apply.
- Debian (CORRECT)
- tcpdump
- Wireshark
- Ubuntu (CORRECT)
12. What is KALI LINUX ™?
(KALI LINUX ™ is a trademark of OffSec.)
- A subscription-based enterprise distribution of Linux
- A component of the Linux architecture that is responsible for processing commands and outputting results
- A component of the Linux OS that manages processes and memory
- An open-source Linux distribution that is widely used in security (CORRECT)
13. Which of these Linux distributions come with pre-installed tools related to penetration testing and digital forensics? Select two answers.
- CentOS
- Wireshark
- KALI LINUX ™ (CORRECT)
- Parrot (CORRECT)
14. If you enter echo cybersecurity into the command line, what is the output?
- cybersecurity.txt
- cybersecurity (CORRECT)
- echo
- echo cybersecurity
15. Which aspect of Linux makes it available to everyone?
- Its use in cybersecurity
- Its open-source design (CORRECT)
- Its multiple distributions
- Its kernel
16. What is an example of a Linux distribution that comes pre-installed with many security-related tools?
- SUSE
- KALI LINUX ™ (KALI LINUX ™ is a trademark of OffSec.) (CORRECT)
- Kernel
- Wireshark
17. What is the Linux shell used for?
- It manages processes and memory.
- It allows you to communicate with the operating system. (CORRECT)
- It ensures the system allocates resources efficiently.
- It organizes the data stored in the computer so it can be found easily.
18. Which of the following are communication methods with the shell? Select all that apply.
- Standard input (CORRECT)
- Standard error (CORRECT)
- Standard output (CORRECT)
- Standard command
19. Which of the following is an example of hardware?
- CPU (CORRECT)
- Applications
- Shell
- Kernel
20. When the system doesn’t know how to respond to a command, what is the result?
- Standard input
- A request for additional resources
- An error message (CORRECT)
- Standard output
21. Which of the following is an example of an application?
- CentOS
- nano (CORRECT)
- Parrot
- The kernel
22. What is one reason why there are multiple distributions of Linux?
- The Linux kernel is open source, which means anyone can use the kernel and modify it. (CORRECT)
- Linux distributions are closed source, which means users must create a new distribution if they want to use Linux.
- Linux distributions expire after a period of time, which means new distributions must be created.
- The Linux kernel is updated yearly, which means community developers create new distributions to stay updated.
23. What is the shell in Linux?
- The information received by the OS via the command line
- The command-line interpreter (CORRECT)
- An instruction telling the computer to do something
- A Linux command that outputs a specified string of text
24. What does standard error contain?
- Error messages sent as standard input to an application
- Error messages returned by the OS through the shell (CORRECT)
- Error messages sent to an application as string data
- Error messages sent to the OS from the shell
CONCLUSION – The Linux Operating System
At a very high level, this entire exploration is really about Linux, though it probes quite deeply into the true importance of Linux in cybersecurity. This module makes a fundamental clear introduction to Linux concepts, including its architecture and a highlight of the most used distributions of Linux. This sets the stage for an in-depth understanding of how Linux is utilized in various cyber scenarios.
Going to remain an important aspect in the shell, which is the interactive terminal through which one communicates directly with the operating system. The students get familiarized with navigations through the command-line interface improving skills for efficacy as well as accuracy while working with Linux. At the end of the module, students will confidently understand the underpinnings of the architecture and distributions of Linux while at the same time grasping the use of the Linux shell as a weapon within any arsenal of cybersecurity. The comprehensive module covers both theory and application to ensure that participants have what it takes to integrate Linux into any cybersecurity environment successfully.