Day 20: User Management in Linux – adduser, passwd, usermod, sudo Explained (Hindi Guide + Practice Lab)
🐧 Day 20: User Management in Linux
(Bug Hunting / Ethical Hacking Course – Day 20)
Aaj hum seekhenge Linux ka User Management System, jo security ka backbone hota hai 🔥
Agar aap ethical hacker banna chahte ho, to ye samajhna bahut zaruri hai:
✔ Linux me users kaise bante hain
✔ Password kaise set hota hai
✔ Admin rights kaise milte hain
✔ Kaun root hai aur kaun normal user
🔥 1️⃣ Linux Me Users Kya Hote Hain?
Linux ek multi-user operating system hai.
Iska matlab:
Ek hi system ko multiple users use kar sakte hain — har user ke apne files, permissions aur settings hote hain.
📌 Important User Types
| User Type | Description |
|---|---|
| Root | Super Admin (Full control) |
| Normal User | Limited access |
| System User | Background services ke liye |
Root user sabse powerful hota hai ⚠️
🔥 2️⃣ Current User Check Karna
whoami
Agar output aata hai:
kali
To aap normal user ho.
Root check karne ke liye:
sudo -i
whoami
Agar output:
root
To aap admin mode me ho.
🔥 3️⃣ New User Create Karna (adduser)
Syntax:
sudo adduser username
Example:
sudo adduser alok
System aapse:
Password
Confirm password
User details puchega
User create ho jayega.
🔥 4️⃣ User Delete Karna (userdel)
sudo userdel username
Example:
sudo userdel alok
Home directory bhi delete karna ho to:
sudo userdel -r alok
🔥 5️⃣ Password Change Karna (passwd)
Current user ka password change:
passwd
Kisi aur user ka password change:
sudo passwd username
Example:
sudo passwd alok
🔥 6️⃣ User Ko Sudo Access Dena (Very Important)
Agar kisi user ko admin rights dene hain:
sudo usermod -aG sudo username
Example:
sudo usermod -aG sudo alok
👉 Ab wo user admin commands run kar sakta hai.
Check karne ke liye:
groups username
🔥 7️⃣ Users List Kaise Dekhe?
System me sab users dekhne ke liye:
cat /etc/passwd
Is file me system ke saare users listed hote hain.
🔥 8️⃣ Important File: /etc/passwd
cat /etc/passwd
Output example:
kali:x:1000:1000:Kali User:/home/kali:/bin/bash
Iska format hota hai:
username:password:UID:GID:info:home:shell
👉 Ethical hacking me ye file important hoti hai.
🧪 Practice Lab (Must Do)
Terminal me ye commands try karo:
whoami
sudo adduser testuser
groups testuser
sudo usermod -aG sudo testuser
groups testuser
sudo passwd testuser
sudo userdel -r testuser
Observe karo kya change ho raha hai.
🔁 Quick Revision (Day 15–20)
🔹 Linux Basics
✔ Linux open-source OS hai
✔ Kali Linux hacking ke liye best
🔹 Commands Part 1
✔ pwd
✔ ls
✔ cd
✔ mkdir
✔ rm
🔹 Commands Part 2
✔ cp
✔ mv
✔ nano
✔ chmod
✔ ip a
🔹 File Permissions
✔ rwx system
✔ 755, 644 important
✔ chmod +x script.sh
🔹 User Management
✔ adduser
✔ passwd
✔ usermod
✔ userdel
✔ sudo concept
🧠 Real Hacker Advice
✔ Kabhi bhi daily kaam root user me mat karo
✔ Sirf jab zarurat ho tab sudo use karo
✔ System security user management se hi start hoti hai
✔ Practice without fear – but legal environment me
🎯 Day 20 Final Summary
✔ User create & delete karna seekha
✔ Password change samjha
✔ Sudo access dena seekha
✔ /etc/passwd file ka role samjha
✔ Full revision complete ki