🔰 Linux Training - Day 6-Linux User Management & Security 🌟

🌟 Yesterday's Wow Moments in Linux User Management & Security 🌟

Diving deeper into Linux fundamentals with user management and security was an incredible experience!

Some Wow Moments:

• 👥 User Management Mastery: Gained control over user creation and password management using useradd, UID assignments, and security protocols.

• 🔒 Security Deep Dive: Explored the shadow file for secure password storage, enhancing system security.

• 🏠 Home Directory Essentials: Understood how the Home and /root directories create structured environments for users.

• 💼 User Profiles: Configured profiles using the skeleton directory and practiced organizing workspaces by hiding/unhiding folders.

Topics Covered:

🔰 Linux Training - Day 6

• 📌 UserAdd Command

• 📌 UID (User ID) Setup

• 📌 Password Management & Shadow File

• 📌 Crypt Command for Encryption

• 📌 Home Directory & /root Directory

• 📌 Absolute Path Navigation

• 📌 /etc Directory

• 📌 Creating Users & Skeleton Directory

• 📌 Folder Management & bashrc File Configuration

This session deepened my skills in Linux management and security—essential tools for any system admin! 🚀

Here's an in-depth summary of the recent topics covered in Linux user management and system security, including a breakdown of essential commands.

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🔰 Linux User Management & Security - In-Depth

1. User Management Fundamentals

• Command: useradd
  The useradd command creates a new user account. When executed, it creates a user directory and assigns a unique user ID (UID).

  • Example: sudo useradd username

  • Flags:

    • -m: Creates a home directory if it doesn’t exist.

    • -d: Defines a custom home directory path.

    • -s: Specifies a login shell for the user.

2. Setting Up UIDs (User IDs)

• Each Linux user has a unique UID. By default, Linux assigns UIDs automatically, but you can manually set them with the -u flag.

  • Example: sudo useradd -u 1050 username

3. Password Management

• Command: passwd
  The passwd command sets or updates a user’s password. Only the root user or an authorized administrator can reset passwords for other users.

  • Example: sudo passwd username

4. The Shadow File

• Located at /etc/shadow, the shadow file securely stores user passwords in an encrypted format. Access to this file is restricted to enhance security.

  • Command: sudo cat /etc/shadow

  • Usage: Only root can view or modify this file, which stores hashed passwords and expiration details.

5. Crypt Command for Encryption

• Command: crypt (available on some systems)
  Encrypts data or strings using various algorithms. However, this command might not be pre-installed on all Linux systems, as it’s specific to some distributions.

  • Example: echo "password" | crypt

6. Home Directory Essentials

• Directory: /home
  Each user has a dedicated directory within /home. For the root user, the default directory is /root.

  • Usage: Provides isolated workspaces and personal storage for each user.

7. Root Directory (/root)

• The root user’s exclusive directory, /root, contains the admin’s files and configurations, accessible only with elevated permissions.

8. Absolute Path Navigation

• Absolute paths start from the root (/) directory and provide full paths for navigating files and directories.

  • Example: /home/username/documents/file.txt

9. /etc Directory

• The /etc directory is where Linux stores all configuration files for system applications and services.

  • Usage: Modify configuration files, such as /etc/passwd or /etc/shadow, for user management.

10. Creating Users with Skeleton Directory

• Command: useradd with -k option
  The skeleton directory (/etc/skel) provides default files (like .bashrc) that are copied to a new user's home directory upon creation.

  • Example: sudo useradd -m -k /etc/skel username

11. Hiding and Unhiding Folders

• Prefixing a folder with a dot (.) hides it. This convention allows users to organize files without cluttering their workspace.

  • Command: mv folder .folder (to hide) and mv .folder folder (to unhide)

12. Configuring the .bashrc File

• File: .bashrc
  This script runs each time a new terminal session opens. Users can customize it to add aliases, set environment variables, and define prompt styles.

  • Command: nano ~/.bashrc

  • Example: Adding alias ll='ls -al' for a quick list-all command.

Additional Commands Overview

• Listing Processes: ps aux (to list all active processes)

• Foreground & Background Tasks:

  • Ctrl + Z: Suspend a task.

  • bg: Move the suspended task to the background.

  • fg: Bring a background task to the foreground.

• Checking Connectivity: ping (e.g., ping google.com to test network status).

• File Creation:

  • mkdir foldername: Create a new directory.

  • touch filename: Create an empty file.