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Cyber Security Academy · Lesson

Shodan: The Search Engine for Internet Devices

Use Shodan to find exposed services, default credentials, and vulnerable software versions.

Shodan: The Search Engine for Internet Devices is a free Cyber Security Academy lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Cyber Security Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

What is Shodan?

Shodan is a search engine that continuously scans the entire internet and indexes banners from services on open ports. Unlike Google which indexes web content, Shodan indexes service responses — SSH banners, HTTP headers, FTP greetings, and more.

What Shodan Indexes

Shodan captures data from hundreds of protocols:

  • HTTP/HTTPS servers and their headers
  • SSH/Telnet banners including software version
  • FTP/SMTP/RDP/VNC services
  • Industrial control systems (ICS/SCADA)
  • IoT devices: cameras, routers, printers
  • Databases: MongoDB, Elasticsearch, Redis

Basic Shodan Queries

Search operators:

# Find Apache servers in Germany:
apache country:DE
# Find MongoDB with no auth:
mongodb port:27017 -auth
# Find specific product:
product:"nginx" version:"1.14"
# Find by IP range:
net:93.184.216.0/24

Shodan Filters

Useful Shodan filters:

city:"San Francisco"
org:"Amazon"
hostname:example.com
ssl.cert.subject.cn:example.com
http.title:"Dashboard"
before:2024-01-01
after:2023-06-01

Finding Exposed Databases

Shodan frequently reveals unprotected databases:

# Exposed Elasticsearch:
elasticsearch port:9200
# Exposed MongoDB:
mongodb -auth
# Exposed Redis:
redis port:6379
# Exposed CouchDB:
couchdb port:5984

Industrial Control Systems

Shodan indexes thousands of industrial control systems — SCADA, PLCs, HMI interfaces — that control power grids, water treatment, and manufacturing. Many have no authentication. This represents a critical infrastructure security failure.

Shodan Alerts

Shodan provides monitoring alerts: set up notifications when new devices matching your query appear (e.g., your organization's IP ranges appear in results). This is valuable for attack surface monitoring.

Shodan for Defenders

Defenders use Shodan to:

  • Discover what they've unknowingly exposed to the internet
  • Monitor for unauthorized services appearing on company IPs
  • Identify outdated software on exposed endpoints
  • Verify firewall rules are working as expected

Shodan CLI and API

Shodan can be used programmatically:

pip install shodan
shodan init YOUR_API_KEY
shodan search "apache"
shodan host 93.184.216.34
shodan count "product:nginx"

Censys and FOFA: Alternatives

Shodan alternatives:

  • Censys — more certificate-focused, academic origins
  • FOFA — popular in Asia, different indexing
  • ZoomEye — Chinese alternative with different coverage

Using multiple sources gives broader coverage.

Legal and Ethical Use

Shodan queries public data — legal to search. However, using Shodan to identify vulnerable targets and then attacking them is illegal. For authorized penetration tests, Shodan accelerates external recon significantly without touching the target directly.

Quick Check: Shodan

A security team wants to find all devices on their company's IP range that are currently exposed on the internet. Which tool is best suited for this?

Lesson Recap

Shodan indexes internet-facing services across all protocols — not just web pages. It reveals exposed databases, industrial systems, outdated software, and misconfigured services. Defenders use it to audit their attack surface. The Shodan CLI and API enable automation and monitoring alerts. Always use responsibly and within authorized scope.

Frequently asked questions

Is the “Shodan: The Search Engine for Internet Devices” lesson free?

Yes — the full text of “Shodan: The Search Engine for Internet Devices” is free to read here on the web, and the Cyber Security Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Cyber Security Academy course, upgrade to CoddyKit PRO.

What will I learn in “Shodan: The Search Engine for Internet Devices”?

Use Shodan to find exposed services, default credentials, and vulnerable software versions. You practise Cyber Security Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Cyber Security Academy?

No prior experience is required. Cyber Security Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Shodan: The Search Engine for Internet Devices” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Cyber Security Academy lesson?

Yes. Every Cyber Security Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Google Dorking for Information Gathering
  2. WHOIS, DNS Enumeration, and Certificates
  3. Shodan: The Search Engine for Internet Devices
  4. Social Media and People-Search OSINT
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