The Ultimate Shodan Search Engine Guide: Mastering ASM in 2026

Google crawls content. Shodan crawls infrastructure.

While traditional search engines index HTML and text to help you find blog posts and Wikipedia articles, Shodan indexes the service banners of every device connected to the internet. If a device has an IP address and a port open to the public, Shodan has likely knocked on its door and written down exactly what it said.

The media loves to call Shodan the “hacker’s playground” for finding open webcams and exposed databases. Unsecured devices are absolutely visible on Shodan (that part is true). But the reality is far more professional than the headlines suggest. In 2026, Shodan has become the gold standard for Attack Surface Management (ASM). Security teams at Fortune 500 companies use it every day to map their digital footprints, identify exposed assets before attackers find them, and close security gaps before they become breach headlines.

This guide moves beyond the scary stories to teach you a professional workflow: Search, Verify, and Monitor.

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Core Concepts: How Shodan Actually Works

Understanding Shodan requires grasping three technical pillars. Shodan does not “hack” systems. It listens to what systems broadcast to anyone who asks.

Banner Grabbing: The Digital Handshake

Technical Definition: Banner grabbing is the process of connecting to a networked device and recording the metadata (known as a “banner”) that the device sends back in response. This banner contains identifying information about the service running on that port, including software names, version numbers, and configuration details. Shodan’s crawlers perform this process billions of times across the entire IPv4 address space.

The Analogy: Think about the difference between Google and Shodan like this: Google is a neighbor who reads the newspaper left on your porch. They see what you’ve chosen to make publicly visible. Shodan is more like a building inspector who knocks on every door in the neighborhood and waits for an answer. The inspector doesn’t force entry (that would be illegal). But when you answer the door and say “Hi, I’m running Apache Server version 2.4.41 on Ubuntu 20.04,” the inspector writes that down verbatim.

Under the Hood:

Component	Function	Technical Detail
Crawler Network	Distributed scanning infrastructure	Global nodes send connection requests to every IP address across common ports
Connection Request	Initial handshake attempt	TCP SYN packet sent to target IP:port combination
Banner Capture	Response recording	Raw text response from service stored with timestamp and metadata
Data Fields	Extracted information	Software name, version, OS, certificates, headers, CVE associations
Index Update	Database storage	Banner data indexed for search with geolocation enrichment

Ports and Services: The Entry Points

Technical Definition: Ports are virtual endpoints where network traffic enters and exits a device. Each port number (0-65535) can host a different service. Common services run on well-known ports: HTTP on port 80, HTTPS on 443, SSH on 22, RDP on 3389. When Shodan scans an IP address, it checks multiple ports to identify which services are actively listening and accepting connections.

The Analogy: If an IP address is a house, ports are the windows and doors. Shodan walks around the neighborhood checking which windows are open, which doors are unlocked, and what’s visible through the glass. It doesn’t climb in through the window, but it does note that the kitchen window is open and there’s a laptop visible on the counter.

Under the Hood:

Port	Service	What Shodan Captures
22	SSH	Protocol version, key fingerprint, authentication methods
80	HTTP	Web server software, response headers, page titles
443	HTTPS	SSL/TLS certificate details, issuer, expiration, SANs
3389	RDP	Windows version indicators, NLA status, certificate info
3306	MySQL	Database version, authentication capabilities
27017	MongoDB	Version, authentication status, database names if exposed
5900	VNC	Authentication requirements, desktop sharing status
1883	MQTT	IoT messaging broker version, authentication status

When a port is “listening,” it signals that an active service is ready to accept connections from the internet. Some services are meant to be public (web servers serving your company website). Others like database management ports or remote desktop services should almost never be exposed without additional protection.

The Snapshot Reality: Point-in-Time Data

Technical Definition: Shodan is a historical index, not a real-time live feed. The data you see represents the state of a device at the moment Shodan’s crawler last visited. The timestamp field shows when that scan occurred. Depending on the IP address’s popularity and the port in question, this data could be hours, days, or weeks old.

The Analogy: Shodan works exactly like Google Street View. You see what the house looked like the day the camera car drove by. If you painted your front door yesterday, the old color shows in the photos until Google’s car returns. If a system administrator patched a vulnerability last week, Shodan might still show the old, vulnerable version until the next scan cycle refreshes that record.

Under the Hood:

Factor	Impact on Data Freshness	Practical Consideration
IP Popularity	High-traffic IPs scanned more frequently	Major hosting providers updated more often
Port Priority	Common ports (80, 443, 22) scanned first	Obscure ports may have stale data
Scan Credits	On-demand scans bypass the cycle	Fresh scans available with paid credits
Geographic Location	Some regions scanned less frequently	Remote networks may have older data
Device Responsiveness	Slow devices may timeout	Incomplete banners for overloaded systems

This snapshot reality has critical implications for security work. You cannot assume that a vulnerability shown in Shodan still exists, nor that a clean record means a device is secure. Verification is always required. Cross-reference Shodan data with real-time reconnaissance.

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The Toolbox: Mastering the Language of Filters

Mastering Shodan means learning its query syntax. Unlike Google, Shodan uses structured filters in a filter:value format. Logic is additive by default. Each additional filter narrows your results further with an implicit AND operator.

The Essential Filter Arsenal

These five filters form the foundation of professional Shodan work. Combine them strategically to isolate exactly the devices you need to find.

Filter	Purpose	Example Query	What It Finds
port:	Target specific services	port:22	All devices with SSH listening
country:	Geographic focus	country:DE	Devices located in Germany
org:	Organization targeting	org:"Amazon"	Assets within Amazon’s IP space
product:	Software identification	product:"nginx"	Servers running Nginx
vuln:	Vulnerability search	vuln:CVE-2021-44228	Devices vulnerable to Log4Shell

Advanced Reconnaissance Filters

Once you’ve mastered the basics, these filters unlock serious reconnaissance power.

Filter	Use Case	Example Query
ssl:	Certificate analysis	ssl:"example.com" finds all servers using certs for that domain
http.title:	Web page identification	http.title:"Dashboard" locates admin panels
os:	Operating system targeting	os:"Windows Server 2012" finds outdated Windows systems
hostname:	Subdomain discovery	hostname:.example.com reveals subdomains
asn:	Network block targeting	asn:AS15169 targets Google’s autonomous system

The Power Filters: Enterprise Intelligence

These specialized filters require paid subscriptions but deliver intelligence that justifies the cost.

Filter	Requirements	What It Unlocks
vuln:	Small Business plan ($299/month)	Direct CVE searches for known vulnerabilities
tag:ics	Corporate plan ($899/month)	Industrial control system discovery
before:/after:	Membership	Historical comparisons to track exposure changes

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The CLI: Automation for Professionals

The web interface is fine for learning. The command-line interface is where professionals work.

Installation and Setup

pip install shodan
shodan init YOUR_API_KEY_HERE

Your API key lives in your Shodan account dashboard.

Essential CLI Commands

Command	Purpose	Example
shodan search	Execute queries from terminal	shodan search "port:22 country:US"
shodan download	Save results to JSON file	shodan download results "apache port:80"
shodan parse	Extract specific fields from JSON	shodan parse --fields ip_str,port results.json.gz
shodan stats	Generate statistical summaries	shodan stats --facets country "nginx"
shodan host	Deep-dive on single IP	shodan host 8.8.8.8
shodan convert	Transform data formats	shodan convert results.json.gz csv

Workflow Example: To audit all MongoDB instances in your organization’s IP space:

shodan download mongo_audit 'org:"Acme Corp" port:27017'
shodan parse --fields ip_str,port,product mongo_audit.json.gz > mongo_ips.txt
shodan convert mongo_audit.json.gz csv

You now have structured data ready for remediation.

Monitoring: Set It and Forget It

The shodan alert system turns Shodan into a continuous monitoring platform. You define network blocks to watch, and Shodan emails you whenever new services appear or existing services change.

shodan alert create "Production Network" 203.0.113.0/24
shodan alert list
shodan alert info ALERT_ID

Why This Matters: Shadow IT is real. Developers spin up test servers, marketing launches campaign microsites, someone configures a database without telling security. With monitoring active, you get notified the moment Shodan’s crawlers detect new exposures.

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Real-World Workflows: From Search to Action

Theory is important. Execution is everything. Here are three complete workflows you can implement immediately.

Workflow 1: Asset Discovery Audit

Goal: Map your organization’s complete internet-facing attack surface.

Steps:

1. Identify IP ranges: Start with org:"Your Company Name". Note every IP address and subnet Shodan returns.
2. Cross-reference with ARIN: Visit ARIN.net (or RIPE for Europe) and verify these IP blocks are actually yours.
3. Port enumeration: For each IP, check which ports are open: shodan host 203.0.113.45
4. Service identification: Note what’s running on each port. Web servers on 80/443 are expected. Databases on 3306 or remote desktop on 3389 are red flags.
5. Documentation: Export to CSV and build a master spreadsheet.

Deliverable: Complete inventory of every internet-facing asset, categorized by risk level.

Workflow 2: Vulnerability Validation

Goal: Confirm whether a newly disclosed CVE affects your infrastructure.

Steps:

1. Check CVE applicability: When a new vulnerability drops, immediately search: vuln:CVE-2024-XXXX org:"Your Company"
2. Version verification: If vuln filter is unavailable, search banner text directly: "nginx/1.20.1" org:"Your Company"
3. Fresh scan: Use scan credits for updated scans: shodan scan submit 203.0.113.45
4. Manual validation: Confirm with targeted Nmap scans: nmap -sV -p 80,443 203.0.113.45

Deliverable: Verified list of vulnerable systems requiring immediate remediation.

Workflow 3: Competitor Intelligence (Ethical Reconnaissance)

Goal: Understand a competitor’s technology stack without breaking any laws.

Steps:

1. Domain certificate search: ssl:"competitor.com" reveals all servers using their SSL certificates, exposing subdomains and infrastructure.
2. Technology fingerprinting: Look for product: patterns. Are they running AWS, Azure, or on-premise?
3. Geographic distribution: org:"Competitor Inc" stats --facets country shows where their infrastructure lives.
4. Historical analysis: before:2024-01-01 org:"Competitor Inc" compared to current state reveals infrastructure changes.

Deliverable: Intelligence report on competitor infrastructure for strategic planning.

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Legal and Ethical Boundaries

Let’s be clear about what is legal and what is not.

Legal Activities:

• Searching Shodan’s database for publicly indexed information
• Analyzing banner data to understand exposed services
• Monitoring your own organization’s IP space
• Researching vulnerabilities in systems you own or have permission to test

Illegal Activities:

• Accessing systems you don’t own based on credentials found in Shodan
• Exploiting vulnerabilities without authorization
• Using Shodan to facilitate unauthorized access or data theft
• Port scanning targets without permission

The Bright Line: Searching is legal. Accessing is (usually) not. Shodan gives you the address and tells you the door is unlocked. Walking through that door without permission is trespassing.

Many countries have laws similar to the U.S. Computer Fraud and Abuse Act (CFAA). Unauthorized access is illegal, even if the system is poorly secured. “The door was unlocked” is not a legal defense.

Best Practice: If you discover a serious security issue affecting a third party through Shodan, practice responsible disclosure. Contact the organization’s security team (security@company.com is standard), give them time to fix the issue, and only publish details after they’ve had reasonable opportunity to remediate.

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Pricing and Access Tiers

Shodan operates on a credit-based system. Understanding this helps you budget for professional work.

Credit Type	Purpose
Query Credits	Bulk data downloads for offline analysis
Scan Credits	On-demand fresh scans bypassing cache
API Credits	Programmatic access for tool integration

The Membership is the foundation. This one-time, lifetime payment (typically $49, occasionally $5 during sales) unlocks full search access, basic API capabilities, and monitoring for limited IPs. No subscription fees. Students with .edu addresses get free upgrades.

Professional API plans: Freelancer ($69/month), Small Business ($299/month), Corporate ($899/month). The vuln filter requires Small Business minimum, tag filter for ICS requires Corporate.

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Problem-Solving Framework

Problem	Root Cause	Solution
“Vulnerability searches return nothing”	Free account or Membership limitation	Upgrade to Small Business plan; alternatively, search banner text for version strings (e.g., "Apache 2.4.49") instead of using vuln: filter
“Worried about using my real IP”	OPSEC concern	Run CLI from a Virtual Private Server (VPS) or trusted commercial VPN; Shodan API calls don’t hit targets directly
“Results are overwhelming”	Missing specificity	Stack additional filters: add city:, org:, or os: to narrow scope systematically
“Data seems outdated”	Normal scan cycle delay	Use scan credits to request fresh scan of specific IPs
“Can’t find my own assets”	Unknown IP ranges	Start with org: filter using your organization name; verify IP ranges with ARIN/RIPE registries
“Too many false positives”	Banner misinterpretation	Verify findings manually; cross-reference with targeted Nmap scans
“Need data in spreadsheet format”	JSON output default	Use shodan convert data.json.gz csv to transform downloaded data

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Attack Surface Management in 2026

Shodan has evolved from a curiosity into critical infrastructure for security programs. As organizations adopt hybrid cloud, IoT proliferates, and shadow IT expands, maintaining visibility into your internet-facing attack surface has become existential.

AI-driven risk scoring is now standard. Shodan’s data feeds integrate with platforms that automatically prioritize exposures. Machine learning models correlate Shodan data with threat intelligence to predict which assets attackers target first.

Real-time continuous monitoring has replaced periodic assessments. Organizations deploy Shodan monitoring alerts to detect new exposures within hours instead of months.

Supply chain visibility extends ASM beyond your boundaries. When evaluating a new SaaS provider, checking their Shodan footprint is due diligence.

Shodan is a mirror. If you don’t like what you see, fix your network. Secure those open ports. Patch those vulnerable versions. Configure authentication. Remove default credentials.

Don’t guess. Know. Your attack surface is visible to adversaries right now. The only question is whether you see it too.

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Frequently Asked Questions (FAQ)

What is the Shodan Search Engine?

The Shodan Search Engine is a specialized platform that indexes the service banners of every device connected to the internet, capturing metadata like software versions and configuration details from any device with an IP address and a public open port.

Is Shodan illegal to use?

No, Shodan is completely legal. It indexes publicly accessible data that devices broadcast to anyone who connects. Using Shodan is no different from using Google (you’re searching an index of information that’s already public). The illegal part begins if you access systems without authorization based on what you find.

How do I remove my device from Shodan’s index?

You cannot request deletion from Shodan’s database directly. The solution is to secure the device: close unnecessary ports, configure proper authentication, or place it behind a firewall. Once the device stops responding to Shodan’s crawlers, the record ages out and eventually disappears from search results during subsequent scan cycles.

Is the Membership worth the investment?

For anyone doing professional security work, absolutely. The one-time lifetime payment unlocks full search capabilities, API access, and removes the crippling two-page result limit. Students and academics with .edu addresses get free membership upgrades.

Can Shodan see devices inside my private network?

No. Shodan only indexes devices with ports exposed to the public internet. If your devices are behind a properly configured NAT firewall with no port forwarding, Shodan’s crawlers cannot reach them. Shodan sees what you expose (nothing more).

How often does Shodan scan the internet?

Shodan continuously crawls the IPv4 address space, but scan frequency varies by IP and port. Popular addresses and common ports get scanned more frequently (sometimes daily). Less common ports on obscure IP ranges might not update for weeks. Use scan credits if you need guaranteed fresh data.

What’s the difference between Shodan and Censys?

Both are internet-wide scanning platforms, but they have different architectures and data coverage. Shodan has deeper historical data going back to 2017, specialized IoT device fingerprinting, and a stronger focus on industrial control systems. Censys offers more comprehensive certificate transparency data and TLS/SSL analysis. Many security teams use both for comprehensive coverage.

Can Shodan find ICS/SCADA systems?

Yes, and this is one of Shodan’s most powerful (and sensitive) capabilities. Enterprise subscribers can use the tag:ics filter to find industrial control systems. Common queries include port:502 for Modbus devices and port:47808 for BACnet building automation systems. As of 2024, Shodan indexes approximately 110,000 ICS devices globally.

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Sources & Further Reading

• Shodan Official Help Center: https://help.shodan.io/ – Query syntax documentation, CLI reference, and API documentation for filter construction and programmatic access
• NIST SP 800-115 (Technical Guide to Information Security Testing and Assessment): https://csrc.nist.gov/publications/detail/sp/800-115/final – Foundational methodology for security assessments
• CISA Attack Surface Management Guidance: https://www.cisa.gov/topics/cyber-threats-and-advisories/advanced-persistent-threats/apt-groups – Official U.S. government recommendations for continuous exposure monitoring
• MITRE ATT&CK Framework (T1596 – Search Open Technical Databases): https://attack.mitre.org/techniques/T1596/ – Adversary technique documentation for reconnaissance tradecraft
• CISA/NSA/FBI Joint Advisory on Volt Typhoon: https://www.cisa.gov/news-events/cybersecurity-advisories – Threat actor tradecraft including use of internet scanning platforms
• Forescout Threat Briefing “Better Safe Than Sorry” (2024): https://www.forescout.com/resources/ – Analysis of global ICS/OT exposure trends and mitigation strategies
• Shodan Blog: https://blog.shodan.io/ – Case studies, new feature announcements, and Trends API documentation