User Management – Linux Teaching Plan

This 2‑hour module teaches students how to create, modify, delete and audit users and groups on a Linux system. The plan assumes familiarity with the filesystem and basic shell usage.

Learning Objectives

• Understand the relationship between users, groups, and UIDs/GIDs.
• Add, modify, lock and delete user and group accounts.
• Manage user passwords and account aging.
• Configure SSH key‑based authentication.
• Set up sudo privileges for a user or group.
• Use getent, id, passwd and chage for auditing.
• Automate user provisioning with shell scripts.

Schedule & Topics

1. Intro & UID/GID Overview (5 min)
2. Adding Users – useradd (10 min)
3. Modifying Accounts – usermod (10 min)
4. Deleting Accounts – userdel (5 min)
5. Managing Groups – groupadd / groupmod / groupdel (10 min)
6. Password & Account Aging – passwd / chage (10 min)
7. SSH Key‑Based Logins (10 min)
8. Sudo Configuration (10 min)
9. Auditing – getent, id, lastlog (10 min)
10. Automation & Mini‑Project (15 min)
11. Q&A & Wrap‑up (5 min)

Command Topics & Hands‑On Exercises

sudo useradd -m -s /bin/bash newuser
sudo useradd -m -s /bin/bash -G developers alice

sudo usermod -aG sudo bob
sudo usermod -L carol           # lock account
sudo usermod -U carol           # unlock account

sudo userdel -r bob
sudo userdel carol

sudo groupadd developers
sudo groupmod -n devops developers
sudo groupdel devops

sudo passwd bob
sudo passwd -l carol          # lock password
sudo passwd -u carol          # unlock password

sudo chage -l bob
sudo chage -E 2025-12-31 bob
sudo chage -M 90 bob

ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519 -N ""
cat ~/.ssh/id_ed25519.pub | ssh bob@localhost 'mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys && chmod 600 ~/.ssh/authorized_keys'

sudo visudo
# Add line
bob ALL=(ALL) NOPASSWD: /usr/bin/systemctl restart apache2
# Or grant group sudo
%poweradmins ALL=(ALL) ALL

getent passwd bob
getent group poweradmins
getent shadow bob

id
id bob
id -Gn bob

lastlog -u bob
faillog -u bob

sudo usermod -aG poweradmins bob

sudo chfn -f "Bob Builder" -o "42 Main St" -p "(555) 1234" bob

passwd -S bob

sudo useradd -m -s /bin/bash -k /etc/skel newuser

Mini‑Project: “Automated User Onboarding”

Students write a Bash script that takes a CSV file of usernames, groups, and password expiry dates, then:

1. Creates the user with a home directory.
2. Adds the user to the specified group.
3. Sets an initial random password.
4. Configures password expiry based on the CSV field.
5. Writes a one‑time login message to ~/.profile.

They run the script for at least 3 test accounts and demonstrate the results with id, chage -l and lastlog.

Assessment

1. Quick quiz (5 min) – 5 short answer questions.
2. Hands‑on: Add a user, lock the account, unlock, delete, and verify each step (10 min).
3. Script review: peer‑review each other’s onboarding scripts (10 min).

Resources

• man useradd
• man usermod
• man chage
• man passwd
• man ssh_config
• sudo Project

Feel free to adapt the project or add optional commands (e.g., pam modules) if the audience is ready for more advanced user management.