Objective Setting up automatic USB drive mounting on a Linux server using systemd mount and automount units Environment OS: Ubuntu Tools: system, USB drive Step 1 - Find Partition UUID Prerequisite: Plugin USB drive blkid /dev/sdb1 Note: UUID and filesystem type Step 2 - Create the Mount Unit sudo nano /etc/systemd/system/mnt-usb.mount Step 3 - Create Automount Unit sudo nano /etc/systemd/system/mnt-usb.automount Step 4 - Enable and Start sudo systemctl enable mnt-usb.automount sudo systemctl start mnt-usb.automount Step 5 - Verify and test Check the automount is active: ...

Objective Build a centralized logging environment where: SERVER receives logs from client1 SERVER receives logs from client2 Logs are stored in separate files: /var/log/client1.log /var/log/client2.log Network Layout Host IP server 192.168.10.10 client1 192.168.10.101 client2 192.168.10.102 Environment OS: Ubuntu Tools: rsyslog Part 1 - Configure the rsyslog Server Verify rsyslog sudo systemctl status rsyslog Enable UDP Syslog reception and restart the rsyslog service sudo nano /etc/rsyslog.conf sudo systemctl restart rsyslog ...

🧪 DNS Lab 📌 Objective Understand DNS from a systems perpective ⚙️ Environment Virtualization: VirtualBox OS: ( 1 DNS Server VM + 1 Client VM) 🛠️ Lab Network Topology 🧩 Phase 1 — Direct DNS (No Cache) Client VM -> dnsmasq (192.168.10.10) Used for: Break #1 (Wrong DNS Server) Break #2 (Wrong DNS Record) 🧩 Phase 2 — Direct DNS (No Cache) Clint VM -> systemd-resolved (127.0.0.53) [CACHE] -> dnsmasq (192.168.10.10) [DNS SERVER] ...

🧪 Inter-Interface Packet Forwarding Failure Investigation 📌 Objective Diagnose why a client cannot reach the internet ⚙️ Environment Virtualization: VirtualBox OS: ( 1 DHCP Server VM + 1 Client VM) 🛠️ Lab Network Topology Server (DHCP) IP: 192.168.10.10 Interfaces: enp0s8 -> LAN enp0s3 -> NAT Client VM IP: 192.168.10.100 Interface: enp0s8 Gateway: 192.168.10.10 🚨 Incident Statement Client cannot access the internet 🔍 PHASE 1 — Verify the Problem Run on Client VM: ...

🧪 Process Management & Resource Control Lab 📌 Objective Simulate and troubleshoot a real-world system slowdown caused by CPU saturation and memory exhaustion. ⚙️ Environment Virtualization: VirtualBox OS: Ubuntu Server 🛠️ Lab Setup Step 1 - Create CPU Load Script nano cpu_hog.sh chmod +x cpu_hog.sh Step 2 - Create Memory Load Script (Python) nano mem_hog.py chmod +x mem_hog.py 🚨 Incident Simulation Step 1 - Check the System Load Baseline uptime ...

🧪 DHCP Lab 📌 Objective Understand how DHCP works in real network environment and how to debug common failure scenarios using a structured top-to-bottom approach. ⚙️ Environment Virtualization: VirtualBox OS: Ubuntu Server (1 DHCP Server VM & 2 Client VMs) Network mode: Internal Network + NAT (enp0s3 ignored for DHCP lab) 🛠️ Network Setup Interfaces DHCP Server enp0s8 -> 192.168.10.10/24 (Lab network) enp0s3 -> NAT Clients enp0s8 -> DHCP assigned IPs enp0s3 -> NAT (not used) ⚙️ Network Configuration (Netplan) Both server and clients are configured using Netplan, which defines interface behavior before DHCP starts. ...

🧪 Basic Network Setup & Connectivity Lab 📌 Objective Understand how IP addressing, subnetting, and basic connectivity work in a controlled virtual environment. ⚙️ Environment Virtualization: VirtualBox OS: Ubuntu Server (2 VMs) Network mode: Internal Network + NAT VMs VM IP Address Role VM1 192.168.10.10/24 Client VM2 192.168.10.20/24 Server 🛠️ Setup Step 1 - Create Virtual Machines Create two Linux virtual machines: server_01 server_02 Recommended specs: 1 CPU 1-2 GB RAM 10+ GB disk Step 2 - Configure Network Both VMs must use the same Internal Network This ensures both machines are on the same isolated Layer 2 network. ...

🧪 Linux Networking and Service Exposure Lab 📌 Objective This lab simulates real-world Linux networking issues and teaches how to troubleshoot: Service availability Port listening Firewall behavior (UFW) Binding (’localhost’ vs external access) Network-layer debugging ⚙️ Environment OS: Ubuntu (VM + Bridged Adapter) Service: Nginx Tools: ss, curl, ufw, systemctl Host machine for external testing (Powershell) 🟢 Stage 1 Verify service: systemctl status nginx Expected outcome: Active (running) Check listening ports: ...

🧪 Log Analysis & System Debugging Lab 📌 Objective Read system logs like real incidents Identify root causes Debug common system failures ⚙️ Environment OS: Ubuntu Tools: journalctl, df, du, dmesg 🚨 Scenario 1: Service Crash Investigation Step 1 - Break the service sudo nano /etc/nginx/nginx.conf Add invalid line: invalid_directive; Restart: sudo systemctl restart nginx Step 2 - Investigate Check status: systemctl status nginx Check logs: sudo journalctl -u nginx -n 50 --no-pager ...

🧪 Linux Permission and Access Control Lab 📌 Objective To test how Linux file permissions and access control mechanisms work in a multi-user environment. ⚙️ Environment OS: Ubuntu Tools: chmod, chown, ls, groups, sudo Users: alice, bob, admin Groups: devs, managers 🛠️ Setup 1. Create Users sudo adduser alice sudo adduser bob sudo adduser admin 2. Create Groups sudo groupadd devs sudo groupadd managers Assign users: sudo usermod -aG devs alice sudo usermod -aG managers bob sudo usermod -aG devs admin sudo usermod -aG managers admin ...