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🕶️ Technique Card: Power and Privilege - Different Types of Linux User

Unit 101 – Terminal Tigers 🐯 | Rank: Shadow Recruit

ShadowNet Agency: Recruit Training File – Classified Level 1

🕵️ Mission Prep Briefing

In every secure system, not all users are equal. Some have clearance to view confidential data, others can only access what they need. To succeed in your next mission, you’ll need to understand how Linux handles users, groups, and privileges.

👤 Types of Linux Users

Linux systems have different user roles:

  • root – 👑 The one true superuser. Has complete control. There is only one root user per system.
  • Regular users – Like you. Access is limited to keep the system safe.
  • System users – Used by services and background processes (e.g., daemon, syslog).

To see who you are:

whoami

To see all users:

cat /etc/passwd

🧪 sudo – Power on Demand

Some trusted users are allowed to temporarily act like root using the sudo command:

sudo <command>

This is only possible if you're in a special group – usually called sudo or wheel.

Check if you're in the sudo group:

groups

Note

The original meaning of sudo was super user do as when using sudo a regular user can do as the super user (root) can do

🕸️ Linux Groups: The Network of Trust

Every user can belong to one or more groups. Groups help control who can:

  • Read sensitive logs
  • Access protected directories
  • Run powerful commands

Example groups:

  • adm – Can read log files
  • sudo or wheel – Can use the sudo command
  • www-data – Used by web servers

See which groups you belong to:

groups

Check another user:

groups otherUser

🗂️ /etc/passwd and /etc/group

Two files tell you everything about users and groups:

  • /etc/passwd – Lists all user accounts
  • /etc/group – Lists all groups and who is in them

Note

Passwords are NOT stored in /etc/passwd - they are found in /etc/shadow but this is a restricted file and even then the passwords of users have been hashed so they cannot easily be read

Explore with:

cat /etc/passwd
cat /etc/group

🔍 Want to find all users in the adm group?

grep adm /etc/group

🧠 Clue: Try looking for patterns in these files. Who belongs to what?

🎯 Try This

✅ Who are the users on the system?
✅ What groups exist?
✅ Find all the users in the adm group.

💻 Command Summary

Command Purpose
whoami Shows your current user
groups Lists your groups
groups <user> Lists another user’s groups
cat /etc/passwd View all user accounts
cat /etc/group View all groups
grep <groupname> /etc/group See who’s in a group
sudo <command> Run a command as a privileged user (if allowed)

🧠 Remember:
Not every user is what they seem. In ShadowNet, knowing who has access is just the beginning.
Stay alert. Stay curious.

— ShadowNet Academy: Question. Train. Triumph.

⬅️ Go to Mission 004: Who has the Power?

Watch the video