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Day 10Friday, January 30, 20262 min read

Linux Fundamentals Part 2 (SSH, Filesystem, Permissions)

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🎯 Goal

Deepen Linux fundamentals by working with remote access, filesystem operations, and permissions, focusing on skills directly transferable to real systems.

✅ What I Did

TryHackMe

  • Completed Linux Fundamentals Part 2

Remote Access

  • Connected to a remote Linux machine using SSH

  • Understood SSH as a core skill for administration and pentesting

Command Line Usage

  • Used command flags and switches to extend functionality

  • Consulted man pages and --help for self-documentation

Filesystem Operations

  • Created files and directories (touch, mkdir)

  • Copied and moved files (cp, mv)

  • Deleted files and folders (rm, rm -R)

  • Identified file types using file

Permissions & Users

  • Learned Linux permission model:

    • Read / Write / Execute (rwx)

    • Numeric permissions (755, 644, 700)

  • Explored ownership:

    • User

    • Group

    • Others

  • Switched users with:

    • su

    • su -l

System Directories

  • Reviewed key directories:

    • /etc – configuration and credentials

    • /var – logs and variable data

    • /root – root user home

    • /tmp – writable temporary directory

✅ What Worked

  • SSH usage finally feels practical, not abstract

  • Man pages reduced reliance on copy-pasting commands

  • Numeric permissions started to make sense

  • Filesystem navigation feels more deliberate

❌ What Didn’t

  • grep syntax still causes friction

  • rm -R is powerful enough to be dangerous

  • Permissions require repetition to become instinctive

🧠 Key Takeaways

  • SSH is foundational to almost everything in Linux security

  • Flags + man pages turn basic commands into powerful tools

  • Linux permissions are a security boundary, not just syntax

  • Understanding /etc and /var is critical for real-world analysis

  • /tmp stands out as a frequent point of interest in attacks

❓ Questions

  • When should su be preferred over sudo?

  • What are the most common real-world permission misconfigurations?

  • How often is /tmp abused in actual pentests?

📚 Resources

Personal Objective (Why This Exists)

  • ⬜ Build solid Linux operational confidence

  • ⬜ Reduce reliance on copy-paste commands

  • ⬜ Prepare for real-world lab environments

  • ⬜ Strengthen foundations for privilege escalation later