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What Is Shodan? How to Use It & How to Stay Protected [2021]

Shodan is a search engine, like Google, but instead of searching for websites, it searches for internet-connected devices — from routers and servers, to Internet of Things (IoT) devices, such as thermostats and baby monitors, to complex systems that govern a wide range of industries, including energy, power, and transportation.

Shodan can find anything that connects directly to the internet — and if your internet-facing devices aren’t protected, Shodan can tell hackers everything they need to know to break into your network.

But Shodan wasn’t designed by hackers, and hackers aren’t usually the ones using it. Shodan is a crucial resource used by cybersecurity experts to help protect individuals, enterprises, and even public utilities from cyber attacks.

Anyone can search for any internet-connected devices using Shodan, and Shodan will let you see if something is or isn’t publically available. But keep in mind that searching with Shodan is a little more complicated than a basic Google search. 

What Is Shodan?

Shodan is a search engine similar to Google. But while Google searches for websites, Shodan searches for devices that are connected to the internet. Users can perform a search using the Shodan search engine based on an IP address, device name, city, and/or a variety of other technical categories. Users can sign up for free accounts, but they are very limited — Shodan limits its free service to only 50 search results.

Shodan started in 2003 as a pet project for a young computer programmer, John Matherly. Matherly figured out a way to map each device connected to the internet by constantly crawling the web for randomly generated IP addresses, and he eventually developed a search engine to search through his growing database of internet-connected devices. Matherly released Shodan to the public in 2009.

Matherly’s intention was never to create an easy way for hackers to discover devices and infiltrate them, but as soon as Shodan was up and running, it began discovering industrial supervisory control and data acquisition (SCADA) systems, security cameras, traffic lights, and other sensitive devices that shouldn’t have been publicly accessible.

Once Matherly discovered how many devices were exposed online, he began marketing Shodan to IT workers to help them analyze and troubleshoot network vulnerabilities.

How Does Shodan Work?

Shodan works by requesting connections to every imaginable internet protocol (IP) address on the internet and indexing the information that it gets back from those connection requests. Shodan crawls the web for devices using a global network of computers and servers that are running 24/7.

An IP address is your device’s digital signature — it’s what allows Google to tailor searches to your location, and it’s what allows all internet-connected devices to communicate with each other.

Internet-connected devices have specific “ports” that are designed to transmit certain kinds of data. Once you’ve established a device’s IP address, you can establish connections to each of its ports. There are ports for email, ports for browser activity, ports for printers and routers — 65,535 ports in all.

When a port is set to “open”, it’s available for access — this is what allows your printer to establish a connection with your computer, for example. The computer “knocks” at the open port, and the printer sends a packet of information called a “banner” that contains the information your computer needs to interact with the printer.

Shodan works by “knocking” at every imaginable port of every possible IP address, all day, every day. Some of these ports return nothing, but many of them respond with banners that contain important metadata about the devices Shodan is requesting a connection with.

Banners can provide all sorts of identifying information, but here are some of the more common fields you will see in a banner:

  • Device name: What your device calls itself online. For example, Samsung Galaxy S21.
  • IP address: A unique code assigned to each device, which allows the device to be identified by servers.
  • Port #: Which protocol your device uses to connect to the web.
  • Organization: Which business owns your “IP space”. For example, your internet service provider, or the business you work for.
  • Location: Your country, city, county, or a variety of other geographic identifiers.

Some devices even include their default login and password, make and model, and software version, which can all be exploited by hackers.  

What Can You Find on Shodan?

Any device connected to the internet can potentially show up in a Shodan search. Since Shodan went public in 2009, a pretty large community of hackers and researchers have been cataloging the devices they’ve been able to find and connect with on Shodan — things like:

  • Baby monitors
  • Internet routers.
  • Security cameras.
  • Maritime satellites.
  • Water treatment facilities.
  • Traffic light systems.
  • Prison pay phones.
  • Nuclear power plants.

Before you freak out and go hide in a bunker, remember that Shodan merely indexes publicly available information. Yes, it can show users a nuclear power plant’s server banner, but that doesn’t mean that anyone with an internet connection can cause a nuclear meltdown. In the case of industrial computers and old SCADA systems, many of them are protected by passwords, two-factor authentication, firewalls, and strict security protocols.

However, Shodan does reveal just how much of our information is publicly available. If your webcam is internet-facing, and you haven’t changed its default logins, hackers can access it without your knowledge, gaining an easy window into your home. In fact, webcams are one of the most commonly searched terms on Shodan’s “Explore” page.

How to Use Shodan Search Engine

How to Perform a Search on Shodan?

Performing a search on Shodan isn’t as simple as performing a Google search. Google has refined its technology to be as user-friendly as possible, while Shodan is designed with IT professionals in mind.

To test Shodan, I wanted to find all Cisco devices in New York City. I started off with a simple search of: [Cisco]. But I didn’t really feel like sorting through the millions of results myself.

How to Use Shodan Search Engine

So I went a step further and used a simple search for [“Cisco” AND “New York City”].

How to Use Shodan Search Engine

As you can see, I didn’t find what I was looking for — the reason for this is that Shodan didn’t translate my query to mean, “Cisco servers in New York City”, like Google would have done. In order to search for specific keywords in specific locations, you need to use Shodan’s search filters.

With Shodan, users have to type their search filters out in the search bar in order to customize their queries.

Here are some basic search filters you can use:

  • city: find devices in a particular city.
  • country: find devices in a particular country.
  • geo: search for specific GPS coordinates.
  • hostname: find values that match the hostname.
  • product: search the name of the software or product identified in the banner.
  • os: search based on operating system.
  • port: find particular ports that are open.
  • before/after: find results within a timeframe.

So when I finally searched: [Cisco city:“New York”], Shodan returned the following results:

How to Use Shodan Search Engine

Using search filters is the best way to search on Shodan quickly and efficiently, but you have to register for an account with Shodan in order to use search filters. Shodan accounts are available for several different uses, with hugely different pricing tiers — including:

  • Free member. Two pages of search results, limited filters.
  • Basic membership. One-time fee for lifetime use, gives access to map and photo search options, limited filters.
  • Freelance subscription. Under $100/month, scanning and network monitoring for up to 5,120 IP addresses.
  • Small business subscription. Around $300/month, scanning and network monitoring for up to 65,536 IP addresses, plus a vulnerability scanning tool.
  • Corporate subscription. Almost $1,000/month, scanning and network monitoring for up to 327,680 IP addresses, advanced search filters, and premium customer support.

What Is Shodan Used For?

Shodan is most commonly used to help users identify potential security issues with their devices. Businesses and consumers both use more and more internet-connected devices every day — this is especially true due to the rise in remote working in recent years. As we become more plugged in, our chances of falling victim to a malicious attack get higher.

By identifying all of the devices connected to the internet, displaying what information those devices are sharing with the public, and making it clear how easy that information is to access, Shodan can help users to reinforce their security in a variety of ways:

  • Home Security. Discover how many devices in your home are publicly accessible (chances are your printer and your baby monitor don’t need to connect with the entire internet!).
  • Enterprise Security. Shodan can serve as an incredibly helpful tool for a company’s IT team by identifying every endpoint in the enterprise’s system and ensuring all of the banners are as secure as possible.
  • Infrastructure Management. By using Shodan, government and private sector professionals can ensure that all of their systems, from traffic systems to power grids, are secure and that all backdoors have been closed. Shodan can also be useful for finding legacy computer systems that are redundant or unnecessary.
  • Market Research. Businesses can track the distribution of their devices or software using Shodan, whether that’s Google tracking how many internet connected devices are running Android or a thermostat company trying to figure out how many of its smart thermostats are still running.
  • Academic Research. Academics and cybersecurity professionals can use Shodan to analyze what kind of devices are connecting to the internet, what kind of software they’re using, and identify trends in security, device usage, and the overall makeup of the internet.

IT professionals frequently use Shodan to monitor networks for vulnerabilities — Shodan can be set up to alert users whenever a new device pops up in their network, giving security staff the opportunity to analyze and close vulnerabilities before hackers can access them. One such instance occurred at a school in Oregon, where an administrator put a server online with no security protections. Shodan pinged the school district’s IT staff, who were able to quickly reset the security specs on the server.

Shodan is also extremely useful when it comes to patching vulnerabilities — when Microsoft’s Exchange servers were hacked by zero-day threats in March of 2021, experts were able to quickly put out a patch and close the server vulnerabilities. Using Shodan, security experts were able to determine how many Exchange servers had updated their software and patched the vulnerability, and they could also see how many servers were out-of-date and still vulnerable to the exploit.

Can Shodan Expose Your Private Data?

Yes, absolutely. But it’s not likely. Shodan has made identifying IoT devices accessible to anyone with an internet connection and a web browser. And because a shocking number of devices connecting to the internet are unprotected, the potential for your webcam and other devices to be hacked without your knowledge is high.

Unfortunately, there are many individuals out there who will use Shodan with malicious intent. They will attempt to hack baby monitors, webcams, and security systems — and once they have access to a device in your network, they can violate your privacy, install malware on your system, and steal your identity.

But the good news is that Shodan can only discover devices that have open ports — most home routers don’t need to have open ports, so your computer and router probably won’t appear on Shodan. It’s very important to check for your IoT devices, which are often set up to automatically provide communications with the greater internet.

Shodan has been repeatedly used by researchers to demonstrate vulnerabilities at the professional and home level. A quick search reveals Shodan users gaining access to webcams, automated greenhouse watering systems, baby monitors, smart fridges, and more. In my short time with Shodan, I was able to find webcam feeds of adults undergoing home medical care, baby monitoring cams, and even my local school district’s servers (fortunately their banners didn’t reveal any important information!).

It’s important to note that the banner grabbing technology that Shodan uses is publicly available, and Shodan performs the most minimal data grabbing possible. Hackers use botnets to crawl networks for vulnerabilities in the exact same way that Shodan does. But hackers search exclusively for software vulnerabilities that will allow them to invade your networks, while Shodan’s vulnerability scan is hidden behind an expensive paywall.

Shodan is simply a publicly available tool that shows us what hackers have been able to find out about our devices for years.

Best Ways to Remove Your IoT Devices from Shodan

You’d have to disconnect your devices from the internet to completely remove them from Shodan’s searches — but it’s pretty easy to limit the amount of information that Shodan can get from your devices. Here are some techniques you can use to remove as much of your information from Shodan’s databases as possible:

  • Limit the number of devices connected to the internet. While it may seem that every device needs to have an internet connection today, many of them can actually be given local-only access to your network with no change in functionality. Printers, thermostats, baby monitors, and many other devices will work just fine connecting with your devices on your home network.
  • Change your login details. Many IoT products ship with generic passwords that are easily hacked. Make sure all of your internet-facing devices are protected with complex and unique passwords, and consider using a password manager to keep your data well protected and organized.
  • Minimize service banner information. Service banners can provide tons of information about your device, and most devices include basic software that allows you to customize the information these devices share with the internet. By removing unnecessary information from your banner, you limit the amount of information Shodan receives.
  • Use a network firewall. Make sure that your network has a properly configured firewall. This will prevent unauthorized requests from being able to access any of the devices located behind the firewall. If you don’t currently have a firewall, I’d recommend the one that comes with Norton 360.
  • Use Shodan. Sign up for a free account and run a search against your household or company. You can find your IP address under your Wi-Fi network properties and then run the search: [net:IP Address]. However, if your router’s ports are closed (which they probably are), then Shodan won’t have any information. By paying for a membership, you can get access to on-demand scanning, where Shodan tells you exactly what information it gets from a specific IP address.

What is Shodan?

Shodan is a search engine scanning the entirety of the internet for connected devices. Shodan is similar to more well-known search engines like Google, but instead of indexing websites, Shodan indexes each publicly available device connected to the internet.

Shodan can discover a ton of devices, from home baby monitors to the SCADA systems that are used to run a variety of industrial processes, from water treatment facilities to power plants. Academics, governments, and cybersecurity professionals use Shodan for a variety of reasons, including network security analysis and market research. Shodan can show developers how many users have installed the latest patch, and it can ping subscribers when a new device is added to their enterprise’s network.

What can Shodan be used for?

Shodan can be used to find vulnerabilities in your devices’ security. Paying users can use on-demand scanning to search for specific IP addresses in order to keep up-to-date on what information their devices are sharing with the web. This is particularly helpful for governments and city planners, but individuals can also disconnect any devices in the home that don’t actually require connection to the internet.

Shodan can also be a useful resource for data scientists, law enforcement officials, and cybersecurity professionals researching about the dispersal of internet of things (IoT) products, operating systems, and server technology.

And, of course, Shodan can be used by hackers to  break into your webcam, install a backdoor in your network, or hijack and sabotage your smart appliances. That said, hackers are more likely to use botnets to crawl the internet for user vulnerabilities — Shodan is rarely used by hackers for this reason, although there are some internet pranksters out there that enjoy finding strange and unsettling devices through Shodan.

How do I use Shodan?

Without an account, users are able to search for free on Shodan.io, but some filters and functions are unavailable for free users. Shodan has 4 accounts available, from more affordable personal plans to costly enterprise plans with a large catalogue of advanced benefits.

The most basic Shodan searches will give you results by country, network, ports, and operating systems. You can also use filters in your queries to narrow your search: for example, if you want to see how many Cisco devices there are in Miami, you would search “Cisco city:Miami”. Your search can be as simple as this, or if you are more technically inclined, you can employ a more sophisticated search method like SafetyDetectives did to uncover a major security breach found in hospital and supermarket refrigeration systems.

Yes! Shodan merely gathers information that’s already publicly available for reference purposes. Shodan doesn’t secretly gather information it isn’t allowed to have.Instead, it collects information already available on the internet.

Although news outlets were quick to label Shodan as a part of the “dark web”, Shodan is a perfectly legitimate website that has many benefits — there are hacker tools similar to Shodan that aren’t publicly available, so Shodan actually helps to “even the playing field” between hackers and IT professionals.

About the Author

Rachel Ho
Rachel Ho
Contributor

About the Author

Rachel Ho is a privacy and technology consultant with an interest in data protection and public policy. In her spare time, she can be found watching movies and pretending to be a coffee connoisseur.