Introduction
After gathering information about a target, the next step in ethical hacking and penetration testing is scanning. Scanning helps ethical hackers identify live hosts, open ports, running services, and potential vulnerabilities. In this guide, we’ll explore different types of scanning, the best tools for the job, and how hackers use scanning techniques to detect security weaknesses.
Types of Scanning in Ethical Hacking
1. Network Scanning
Network scanning helps identify active devices, their IP addresses, and the services running on them. It provides a map of the network and helps detect security flaws.
🔹 Common Network Scanning Techniques:
- Ping Sweep: Identifies active hosts in a network.
- Traceroute: Traces the path packets take to reach a destination.
- Live Host Detection: Finds which systems are up and running.
2. Port Scanning
Port scanning is used to discover open ports and services running on a system. Attackers use this method to find entry points into a network.
🔹 Types of Port Scanning:
- TCP Connect Scan: Checks if a connection can be established with a port.
- SYN Scan (Half-Open Scan): Sends SYN packets to test if ports are open without completing a full connection.
- UDP Scan: Scans for open UDP ports, often used for DNS and VoIP services.
- Xmas Scan & FIN Scan: Advanced scans used to bypass firewalls.
3. Vulnerability Scanning
This type of scanning looks for known weaknesses in software, services, and operating systems. Ethical hackers use automated tools to detect vulnerabilities that attackers could exploit.
🔹 Examples of Vulnerabilities Scanned:
- Outdated software versions
- Weak or default credentials
- Misconfigured security settings
- Unpatched system vulnerabilities
Best Tools for Scanning
✅ Nmap (Network Mapper)
A powerful tool used for network discovery and security auditing.
Basic network scan:
nmap -sS -A 192.168.1.1/24
✅ Zenmap
A graphical interface for Nmap, making it easier for beginners to visualize scan results.
✅ Angry IP Scanner
A fast and lightweight scanner to detect live hosts and open ports.
✅ Netcat (nc)
A command-line tool for testing open ports and transferring data between systems.
Example:
nc -zv 192.168.1.100 1-1000
✅ Nessus
A vulnerability scanner that helps identify security flaws in systems and networks.
✅ OpenVAS
An open-source vulnerability scanner used for penetration testing.
✅ Masscan
A high-speed port scanner that can scan the entire internet in minutes.
Scanning in Action: How Hackers Use It
1️⃣ Step 1: Identify Active Hosts
Hackers start by performing a ping sweep or using Nmap to identify which systems are online.
2️⃣ Step 2: Scan for Open Ports
Using tools like Nmap, hackers check for open ports to find services that might have vulnerabilities.
3️⃣ Step 3: Detect Services and Versions
Once ports are found, the next step is to identify which services and software versions are running.
Command to check service versions:
nmap -sV -p 22,80,443 192.168.1.100
4️⃣ Step 4: Look for Vulnerabilities
Hackers use vulnerability scanners like Nessus or OpenVAS to check if the system is running outdated or misconfigured software.
5️⃣ Step 5: Plan an Attack or Fix Security Issues
If vulnerabilities are found, ethical hackers report them to the organization so they can be fixed before malicious hackers exploit them.
How to Protect Against Scanning Attacks
✔ Use a Firewall: Block unauthorized scanning attempts.
✔ Disable Unused Services: Close unnecessary open ports.
✔ Use Intrusion Detection Systems (IDS): Detect and prevent suspicious scanning activities.
✔ Apply Security Patches: Keep all software up to date to prevent known exploits.
✔ Implement Network Segmentation: Restrict access between sensitive and public-facing systems.
Conclusion
Scanning is a crucial phase in ethical hacking that helps identify weaknesses before attackers can exploit them. By understanding how hackers use scanning techniques, organizations can strengthen their security defenses.
💡 Next Blog Post: After scanning, the next step in ethical hacking is exploiting vulnerabilities. Stay tuned for the next guide on how ethical hackers test and exploit weaknesses in systems!
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