Mastering Shodan: The Search Engine for Internet-Connected Devices
Introduction
Shodan is often called the “Google for hackers”, but unlike Google, it doesn’t index websites—it scans and catalogs Internet-connected devices. From webcams and routers to industrial control systems (ICS) and databases, Shodan reveals devices exposed online, making it a powerful tool for cybersecurity professionals, ethical hackers, and researchers.
In this guide, we’ll explore:
✔ What Shodan is and how it works
✔ Key Shodan search filters (HTTP, NTP, SSL, Telnet, etc.)
✔ Real-world Shodan search examples
✔ Ethical and legal considerations
1. What is Shodan?
Shodan (https://www.shodan.io) is a search engine for IoT (Internet of Things) devices. Instead of crawling websites, it scans:
- IP addresses
- Open ports
- Banners (metadata from services)
- Vulnerable devices
Why is Shodan Important?
- Security researchers use it to find exposed systems before hackers do.
- Penetration testers use it for passive reconnaissance.
- Companies monitor their own exposed assets.
⚠ Warning: Unauthorized scanning can be illegal. Always get permission before probing networks.
2. How Shodan Works
Shodan constantly scans the internet, collecting:
- Banner information (e.g., server type, software version)
- Open ports (e.g., HTTP, FTP, SSH)
- Geolocation data
- Vulnerability indicators
Example: Finding Exposed Webcams
A simple Shodan search like:
webcam
…can reveal thousands of unsecured cameras worldwide.
3. Shodan Search Filters
Shodan’s real power comes from search filters. Below are the most useful ones.
🔹 General Filters
| Filter | Example | What It Finds |
|---|---|---|
city: | city:"New York" | Devices in a specific city |
country: | country:"US" | Devices in a country |
hostname: | hostname:"google.com" | Devices with a specific hostname |
os: | os:"Windows" | Devices running a specific OS |
port: | port:22 | Devices with SSH (port 22) open |
net: | net:"192.168.1.0/24" | Devices in a specific IP range |
🔹 HTTP Filters (Web Servers)
| Filter | Example | What It Finds |
|---|---|---|
http.title: | http.title:"Admin Panel" | Web pages with “Admin Panel” in the title |
http.status: | http.status:200 | Websites returning HTTP 200 (OK) |
http.html: | http.html:"password" | Pages containing “password” |
ssl: | ssl:"expired:true" | Websites with expired SSL certificates |
🔹 NTP (Network Time Protocol) Filters
| Filter | Example | What It Finds |
|---|---|---|
ntp.version: | ntp.version:4 | NTP servers running version 4 |
ntp.ip: | ntp.ip:"8.8.8.8" | NTP servers at a specific IP |
🔹 SSL/TLS Filters
| Filter | Example | What It Finds |
|---|---|---|
ssl.cert.issuer: | ssl.cert.issuer:"Let's Encrypt" | Sites using Let’s Encrypt SSL |
ssl.version: | ssl.version:"TLSv1.2" | Servers using TLS 1.2 |
ssl.cipher: | ssl.cipher:"RC4" | Weak RC4 cipher usage |
🔹 Telnet Filters
| Filter | Example | What It Finds |
|---|---|---|
telnet.option: | telnet.option:"negotiation" | Telnet servers with negotiation enabled |
telnet.banner: | telnet.banner:"Cisco" | Cisco devices with Telnet open |
4. Real-World Shodan Search Examples
🔍 Finding Exposed Databases
product:"MongoDB" port:27017
→ Finds open MongoDB databases (often without authentication).
🔍 Discovering Industrial Control Systems (ICS)
"Modbus" port:502
→ Finds industrial devices using Modbus protocol (used in factories, power plants).
🔍 Locating Vulnerable Web Servers
http.title:"Apache Tomcat" port:8080
→ Finds Apache Tomcat servers (often misconfigured).
🔍 Finding Unsecured Cameras
"webcamXP" http.component:"webcam"
→ Finds WebcamXP cameras with default credentials.
🔍 Detecting Outdated SSL Certificates
ssl:"expired:true"
→ Finds websites with expired SSL certificates (security risk).
5. Ethical & Legal Considerations
⚠ Shodan should be used responsibly:
✅ For security research (with permission).
✅ To identify and fix vulnerabilities in your own network.
❌ Never scan or exploit systems without authorization (illegal under laws like the Computer Fraud and Abuse Act).
6. Conclusion
Shodan is an incredibly powerful tool for cybersecurity professionals, but with great power comes great responsibility. By using smart search filters, you can:
✔ Discover exposed devices before attackers do.
✔ Monitor your own network for vulnerabilities.
✔ Enhance penetration testing with passive reconnaissance.
🔹 Want to dive deeper? Try Shodan at https://www.shodan.io and explore its API for automation.
Stay curious, stay ethical 🚀