My Notes Hub
  • 📍Introduction Page
  • ⭐Learning Process
    • 🧠Learning Mindset
    • 🖇️Learning Dependencies
    • 🧮Learning Process
  • 🔠Fundamentals
    • 🛜Networking Fundamentals
    • 🐧Linux Fundamentals
      • Introduction
    • 🪟Windows Fundamentals
    • 🕵️Active Directory
    • 🕸️Introduction to Web Applications
  • 🧰Tools
    • Nmap
    • Nessus
    • Ffuf
    • Hydra
    • John The Ripper
  • ✍️Write Ups
    • 🗃️Hack The Box Machines
      • Irked
      • Nibbles
      • Brainfuck
      • Lame (Check)
  • 📋Cheat Sheets
    • Penetration Testing Cheat Sheet
  • 🪪Certificates
    • Penetration Tester (HTB CPTS)
      • Penetration Testing Process
      • Reconnaissance, Enumeration & Attack Planning
        • Network Enumeration with Nmap (Continue Here)
        • Footprinting (Just Do Formatting)
        • Vulnerability Scanning (Check)
        • File Transfers (Continue Here)
        • Using the Metasploit Framework
        • Web Information Gathering
      • Exploitation & Lateral Movement
        • Attacking Common Services (Just Do Formatting)
      • Web Exploitation
        • Using Web Proxies (Check)
        • Attacking Web Applications With Ffuf (Check)
        • Login Bruteforcing
        • Cross-Site Scripting (XSS)
        • Command Injection
        • SQL Injection
        • File Upload Attacks
        • File Inclusion
        • Web Attacks (Check)
      • Post-Exploitation
        • Linux Privilege Escalation
  • 🗄️Archive/Backup/Bin
    • Sysmon Usecases (IBM)
    • 🐧Linux Fundamentals (TryHackMe)
      • Introduction
      • Basic Commands
      • Wildcards & Operators
      • Permissions
      • Common Directories
      • Terminal Text Editors
      • General/Useful Utilities
    • 🪟Windows Fundamentals (TryHackMe)
      • Introduction
      • The File System
      • User Accounts
      • Settings & Control Panel & Task Manager
      • System Configuration
    • Active Directory (TryHackMe)
      • Breaching Active Directory
    • FOR508: Advanced Incident Response, Threat Hunting, and Digital Forensics
      • Book 2 - Intrusion Analysis
        • Credential Theft
        • Event Log Analysis for Responders and Hunters
    • Certified Threat Hunting Professional (eCTHPv2)
      • Threat Hunting: Hunting the Endpoint & Endpoint Analysis
        • Event IDs, Logging, & SIEMs
    • OSCP
      • Report Writing
      • ✅Passive Information Gathering
      • ✅Active Information Gathering
      • ✅Vulnerability Scanning
      • Introduction to Web Application Attacks
      • Common Web Application Attacks
        • ✅Cross-Site Scripting (XSS)
        • ✅Directory Traversal
        • ✅File Inclusion
        • ✅File Upload Vulnerabilities
        • Command Injection
        • SQL Injection Attacks
        • Client Side Attacks
      • ✅Locating Public Exploits
      • ✅Exploiting Walkthrough
      • Fixing Exploits
      • ✅Antivirus Evasion
      • Password Attacks
      • Windows Privilege Escalation
      • Linux Privilege Escalation
      • Port Redirection and SSH Tunneling
      • Tunneling Through Deep Packet Inspection
      • The Metasploit Framework
      • Active Directory Introduction & Enumeration
      • Attacking Active Directory Authentication
      • Lateral Movement in Active Directory
      • Assembling the Pieces
      • Other General Information
    • ⚡Port Swigger (Web Penetration Testing)
      • ✅Information Disclosure
      • ✅Path Traversal (Directory Traversal)
      • ✅OS Command Injection
      • Business Logic Vulnerabilities
      • ✅Authentication
      • ✅Access Control
    • Certified Bug Bounty Hunter (CBBH)
      • Web Requests
        • HTTP Fundamentals
    • Getting Started
      • Introduction
      • Pentesting Basics
    • Certified Penetration Testing Specialist (CPTS)
      • Introduction
        • ✅Penetration Testing Process
          • Penetration Testing Overview
          • Laws & Regulations
          • Penetration Testing Process
          • Pre-Engagement
          • Information Gathering
          • Vulnerability Assessment
          • Exploitation
          • Post-Exploitation
          • Lateral Movement
          • Proof-of-Concept
          • Post-Engagement
          • Practice
          • Academy Module Layout
        • Getting Started with Hack The Box (HTB)
      • Reconnaissance, Enumeration & Attack Planning
        • ✅Network Enumeration with Nmap
          • Enumeration & Introduction to Nmap
          • Host Discovery
          • Host and Port Scanning
          • Saving The Results
          • Service Enumeration
          • Nmap Scripting Engine
          • Scanning Performance
          • Firewall and IDS/IPS Evasion
        • Footprinting
        • ✅Information Gathering - Web Edition
          • Introduction
          • Passive Information Gathering
          • Active Information Gathering
        • Vulnerability Assessment
        • File Transfers
        • Shells & Payloads
        • Using the Metasploit Framework
      • Exploitation & Lateral Movement
        • Password Attacks
        • Attacking Common Services
        • Pivoting, Tunneling, and Port Forwarding
        • Active Directory Enumeration & Attacks
      • Web Exploitation
        • Using Web Proxies
        • ✅Attacking Web Applications with Ffuf
        • ✅Login Brute Forcing
        • SQL Injection Fundamentals
        • SQLMap Essentials
        • Cross-Site Scripting (XSS)
        • File Inclusion
        • File Upload Attacks
        • Command Injections
        • Web Attacks
        • Attacking Common Applications
      • Post-Exploitation
        • Linux Privilege Escalation
        • Windows Privilege Escalation
      • Reporting & Capstone
        • Documentation & Reporting
        • Attacking Enterprise Networks
Powered by GitBook
On this page
  1. Fundamentals
  2. Linux Fundamentals

Introduction

  • Linux is an operating system like Windows, iOS, Android, or macOS.

  • An OS is software that manages all of the hardware resources associated with a computer.

Philosophy

  • Linux follows these 5 principles:

Principle
Description

Everything is a file

All configuration files for the various services running on the Linux operating system are stored in one or more text files.

Small, single-purpose programs

Linux offers many different tools which can be combined to work together.

Ability to chain programs together to perform complex tasks

The integration and combination of different tools enable us to carry out many large and complex tasks.

Avoid captive user interfaces

Linux is designed to work mainly with the shell (or terminal), which gives the user greater control over the operating system.

Configuration data stored in a text file

An example of such a file is the /etc/passwd file, which stores all users registered on the system.

Components

Component
Description

Bootloader

A piece of code that runs to guide the booting process to start the operating system.

OS Kernel

The kernel is the main component of an operating system. It manages the resources for system's I/O devices at the hardware level.

Daemons

Background services are called "daemons" in Linux. Their purpose is to ensure that key functions are working correctly. These small programs load after we booted or log into the computer.

OS Shell

The operating system shell or the command language interpreter (also known as the command line) is the interface between the OS and the user.

Graphics Server

This provides a graphical sub-system (server) called "X" or "X-server" that allows graphical programs to run locally or remotely on the X-windowing system.

Window Manager (GUI)

It controls the placement and apperance of windows that are created by the graphics server.

Utilities

Applications or utilities are programs that perform particular functions for the user or another program.

There are many different operating systems that are built on the Linux's kernel, these are called distributions (distro).

Path
Description

/

The top-level directory is the root filesystem and contains all of the files required to boot the operating system before other filesystems are mounted, as well as the files required to boot the other filesystems. After boot, all of the other filesystems are mounted at standard mount points as subdirectories of the root.

/bin

Contains essential command binaries.

/boot

Consists of the static bootloader, kernel executable, and files required to boot the Linux OS.

/dev

Contains device files to facilitate access to every hardware device attached to the system.

/etc

Local system configuration files. Configuration files for installed applications may be saved here as well.

/home

Each user on the system has a subdirectory here for storage.

/lib

Shared library files that are required for system boot.

/media

External removable media devices such as USB drives are mounted here.

/mnt

Temporary mount point for regular filesystems.

/opt

Optional files such as third-party tools can be saved here.

/root

The home directory for the root user.

/bin

This directory contains executables used for system administration (binary system files).

/tmp

The operating system and many programs use this directory to store temporary files. This directory is generally cleared upon system boot and may be deleted at other times without any warning.

/usr

Contains executables, libraries, man files, etc.

/var

This directory contains variable data files such as log files, email in-boxes, web application related files, cron files, and more.

Linux Distributions

  • Linux distributions (distros) are operating systems based on the Linux kernel. They are used for various purposes, from servers and embedded devices to desktop computers and mobile phones. Each Linux distribution is different, with its own set of features, packages, and tools.

  • Examples of distros and their usages:

    • Fedora/Ubuntu: Used as a desktop linux that's suitable for beginners and everyday users.

    • Kali Linux/ ParrotOS: Used by cybersecurity specialists.

Debian

  • Debian is a widely used and well-respected Linux distribution known for its stability and reliability. It is used for various purposes, including desktop computing, servers, and embedded systems.

  • Other operating systems are based on Debian, including but not limited to Kali Linux and Ubuntu.

PreviousLinux FundamentalsNextWindows Fundamentals

Last updated 4 months ago

🔠
🐧
  • Philosophy
  • Components
  • Linux Distributions
  • Debian