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Introduction:
Most aspiring cybersecurity professionals waste months jumping between random YouTube tutorials and fragmented blog posts, only to end up confused about where to start. This structured, completely free course takes you from foundational concepts like networking and Linux security all the way to advanced penetration testing and vulnerability assessment—without the noise.
Learning Objectives:
- Build a home lab environment to safely practice reconnaissance, scanning, and exploitation techniques on Linux and Windows.
- Automate security tasks using Python scripting and master command-line tools for log analysis, firewall management, and network monitoring.
- Perform a complete vulnerability assessment lifecycle: from initial OSINT and port scanning to mitigation and hardening.
You Should Know:
- Setting Up Your Isolated Cyber Range (Virtual Lab)
Before touching any real system, you need a safe playground. Use virtualization to create an isolated network where attacking and defending are legal and controlled.
Step‑by‑step guide:
- Install VirtualBox or VMware Workstation Player on your host machine.
- Download a Linux distribution (Kali Linux for attacking, Ubuntu Server or Metasploitable 2 for target).
- Create a NAT Network in VirtualBox: File → Host Network Manager → Create a NAT network named “CyberLab” with DHCP enabled.
- Set both VMs to use this NAT network so they can communicate but remain isolated from your physical LAN.
- Start the target VM, then the Kali VM. Verify connectivity with
ping <target-IP>.
Verification commands (Linux on Kali):
ip a Find your Kali IP nmap -sn 10.0.2.0/24 Discover target IP on the NAT network
For Windows (if you add a Windows target):
Get-NetIPAddress -InterfaceAlias "Ethernet" | Select IPAddress Test-NetConnection <target-IP> -Port 22
2. Linux Hardening and Security Tool Primer
Most security tools run on Linux, but you must also know how to secure a Linux system. This section covers both.
Step‑by‑step guide for hardening an Ubuntu server:
- Update the system: `sudo apt update && sudo apt upgrade -y`
– Remove unnecessary services: `sudo systemctl list-unit-files –type=service | grep enabled` then `sudo systemctl disable`
– Set up a basic firewall with UFW:sudo ufw default deny incoming sudo ufw default allow outgoing sudo ufw allow ssh sudo ufw enable sudo ufw status verbose
- Harden SSH: edit `/etc/ssh/sshd_config` and set
PermitRootLogin no, `PasswordAuthentication no` (after setting up SSH keys),Port 2222. - Install and run `lynis` for an automated security audit: `sudo apt install lynis -y && sudo lynis audit system`
Essential security tools to practice (pre‑installed on Kali):
– `nmap` for network discovery
– `tcpdump` for packet capture
– grep, awk, `sed` for log parsing
– `chkrootkit` or `rkhunter` for rootkit detection
- Python for Security Automation (Scripting for Recon & Log Analysis)
Python is not just for exploits; it’s for automating repetitive defense tasks. Write a script that parses web server logs and flags suspicious IPs.
Step‑by‑step guide:
- On your Kali or any Linux machine, create a file
log_analyzer.py. - Use the following script to extract failed SSH login attempts from `/var/log/auth.log` (or any log file):
import re
from collections import Counter
log_file = "/var/log/auth.log" Change path for Windows Event Logs
failed_pattern = r"Failed password for . from (\d+.\d+.\d+.\d+)"
failed_ips = []
with open(log_file, "r") as f:
for line in f:
match = re.search(failed_pattern, line)
if match:
failed_ips.append(match.group(1))
counter = Counter(failed_ips)
print("IP addresses with failed SSH attempts:")
for ip, count in counter.most_common(5):
print(f"{ip} : {count} attempts")
- Run it with
python3 log_analyzer.py. - Extend the script to automatically add offending IPs to iptables:
import subprocess for ip, count in counter.items(): if count > 5: subprocess.run(["sudo", "iptables", "-A", "INPUT", "-s", ip, "-j", "DROP"])
For Windows log analysis (PowerShell alternative):
Get-WinEvent -LogName Security | Where-Object { $_.Id -eq 4625 } | Select-Object -First 10
4. Reconnaissance and Vulnerability Assessment (The Attacker’s Mindset)
Learn how attackers gather information so you can defend effectively. Use only on systems you own or have written permission to test.
Step‑by‑step guide for passive and active recon:
- Passive OSINT: Use `theHarvester` to find emails and subdomains (demo against a target you own):
theHarvester -d example.com -b google,bing
- Active network scanning with Nmap:
nmap -sV -sC -O -T4 <target-IP> Version, default scripts, OS detection nmap -p- --min-rate 1000 <target-IP> Full port scan
- Vulnerability scanning using OpenVAS (install via `gvm-setup` on Kali):
- Access the Greenbone Security Assistant web interface (https://127.0.0.1:9392)
- Create a target, configure a scan task, and review the generated report.
- Manual verification: After a scan reports a vulnerability (e.g., outdated Apache), manually check:
curl -I http://<target-IP> | grep Server nc -nv <target-IP> 80 HEAD / HTTP/1.0
- Mitigation and Hardening – From Scan to Fix
Finding vulnerabilities is useless unless you can fix them. This section pairs each finding with a mitigation command.
Step‑by‑step guide for common vulnerabilities:
- Open SSH port with weak ciphers: Audit your SSH config:
ssh -Q cipher | grep -v "[email protected]" List weak ciphers
Mitigation: Edit `/etc/ssh/sshd_config` add `Ciphers [email protected],[email protected]`
- SMB share exposed (Windows/Linux): Disable SMBv1 and restrict shares.
On Windows (PowerShell as admin):
Set-SmbServerConfiguration -EnableSMB1Protocol $false Get-SmbShare | Revoke-SmbShareAccess -AccountName "Everyone"
On Linux (remove samba or restrict in `/etc/samba/smb.conf`):
[bash] server min protocol = SMB2 hosts deny = 0.0.0.0/0 hosts allow = 192.168.1.0/24
– Unpatched software: Automate patch management.
– Debian/Ubuntu: `sudo unattended-upgrades –dry-run`
– Windows: `Get-WUInstall -AcceptAll -AutoReboot` (requires PSWindowsUpdate module)
– Weak firewall rules: Use `iptables` or `nftables` to log and drop suspicious packets.
sudo iptables -A INPUT -m state --state INVALID -j DROP sudo iptables -A INPUT -p tcp --dport 22 -m recent --update --seconds 60 --hitcount 4 -j DROP
6. Web Application Security API Hardening
APIs are the backbone of modern apps. Learn to test and secure REST APIs.
Step‑by‑step guide:
- Use `curl` to test for excessive data exposure:
curl -X GET "https://api.example.com/users/1" -H "Authorization: Bearer <token>"
If you get back the user’s password hash or internal IDs, that’s a vulnerability.
- Rate limiting test with a simple bash loop:
for i in {1..100}; do curl -s -o /dev/null -w "%{http_code}\n" "https://api.example.com/login" -d "user=admin&pass=wrong"; doneA 200 or 429? Too many 200s means no rate limiting.
- Mitigation (on a Linux API gateway using Nginx):
limit_req_zone $binary_remote_addr zone=mylimit:10m rate=5r/s; server { location /api/ { limit_req zone=mylimit burst=10 nodelay; proxy_pass http://backend; } } - For cloud APIs (AWS), enable AWS WAF with rate‑based rules and inspect CloudTrail logs for anomalous patterns.
- Using the Free Course Resources (Your Structured Path)
The two LinkedIn links provide a complete video/lab course that mirrors this practical approach. Access them immediately:
- Course Link 1: https://lnkd.in/d8t5b-qp
- Course Link 2: https://lnkd.in/dz-HuKQ3
These materials cover every topic above with hands-on exercises. Additionally, if you’re considering an accredited online degree in cybersecurity, compare 100+ UGC‑approved universities, fees, and admission support at: https://cvadm.com/brAZVF
What Undercode Say:
- Key Takeaway 1: Random tutorials create knowledge gaps; a structured, lab‑driven path from Linux basics to API hardening builds real defensive and offensive skills.
- Key Takeaway 2: Free resources like Dharamveer prasad’s course eliminate financial barriers—but you must actively practice with commands, scripts, and scans to retain the material.
- The combination of Python automation, Nmap reconnaissance, and iptables hardening represents the core “detect‑respond‑harden” loop every junior analyst needs.
- Many professionals skip log analysis and manual verification, yet those skills separate script kiddies from true defenders.
- Windows and Linux commands are equally critical; note the PowerShell examples for log collection and SMB hardening.
- The degree comparison portal offers a legitimate next step for formal education, but the free course alone can prepare you for certifications like Security+ or eJPT.
- Always stay within legal boundaries: use your own lab or authorized targets only.
- The most underrated skill shown here is mitigation—closing the loop from vulnerability discovery to patching.
- Future job roles will demand API security knowledge; the rate‑limiting and WAF sections are increasingly relevant.
- Bookmark both course links and revisit the commands weekly until they become muscle memory.
Prediction:
As AI‑generated code and automated penetration testing tools become mainstream, the industry will shift from “knowing the tool” to “validating tool output and fixing root causes.” The structured free course highlighted here addresses that shift by teaching fundamentals (networking, Linux, Python) rather than just tool‑specific clicks. Within two years, hands‑on lab experience like the one outlined will be a minimum requirement for entry‑level SOC roles, and traditional degree programs will adopt identical practical modules. Professionals who rely solely on automated scanners without understanding the underlying commands (nmap, iptables, curl) will be replaced by those who can script, analyze logs, and harden systems manually. The future belongs to hybrid defenders who blend free, community‑driven learning with formal accreditation—exactly the path these resources enable.
▶️ Related Video (84% Match):
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Reported By: Dharamveer Prasad – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
