If you're stepping into cybersecurity, chances are you've already heard the name Nessus floating around in Discord groups, YouTube labs, or cybersecurity forums. And there's a good reason for that — Nessus is one of the most trusted and widely used vulnerability scanners in the world, loved by both beginners and professionals.
Whether you're a student practicing on virtual machines or someone starting a career in penetration testing, Nessus is a tool you must get comfortable with. Today, let's take a friendly walkthrough of what it is, how it works, and perform a simple first scan.
What Is Nessus and Why Does It Matter?
Nessus is a vulnerability assessment tool that scans systems, networks, and applications for security weaknesses. Think of it as your personal "doctor" for identifying:
- Misconfigurations
- Weak passwords
- Missing patches
- Outdated services
- Default credentials
- Dangerous open ports
The best part? Nessus doesn't attack systems — it analyzes them and reports back with clear, actionable findings.
How Nessus Works (Simplified Explanation)
Here's a beginner-friendly breakdown:
- You create a scan
- Nessus connects to the target
- It checks for known vulnerabilities using its huge library
- It analyzes risks and assigns severity levels (Critical/High/Medium/Low)
- It generates a detailed report you can download
That's it — scanning made simple.
Setting Up a Basic Scan (Essentials Only)
Before diving into complex policies or credentialed scans, let's perform the simplest version: a Basic Network Scan.
Step 1 — Log into Nessus Dashboard
Step 2 — Click "New Scan" → "Basic Network Scan"
Step 3 — Add Target IP
Example target: 192.168.1.10
Step 4 — Save and Start Scan
That's it — Nessus begins scanning automatically.
Beginner-Friendly Example Scan
Let's run a simple scan on a test machine (like Metasploitable2 or DVWA). After the scan completes, Nessus may show something like:
- Outdated Apache Web Server
- FTP allowing anonymous login
- Weak SSH algorithms
- Open vulnerable ports: 21, 22, 23, 80
Each finding has:
- Description
- Risk level
- CVE IDs
- Steps to fix
Perfect for beginners learning how vulnerabilities are structured.
Wrapping It Up:
Learning Nessus is the easiest way to understand the real-world vulnerability assessment cycle. This first scan is just the beginning — once you're comfortable, you can move into credentialed scans, malware detection, compliance checks, and more.
You're already one step closer to becoming a real security analyst. Keep going! 🔥
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Credits : Dilip Atchuth Kumar Pulamarasetty