man SHODAN

Introduction

SHODAN is a search engine that lets you find specific computers (routers, servers, etc.) using a variety of filters. Some have also described it as a public port scan directory or a search engine of banners.
Web search engines, such as Google and Bing, are great for finding websites. But what if you're interested in finding computers running a certain piece of software (such as Apache)? Or if you want to know which version of Microsoft IIS is the most popular? Or you want to see how many anonymous FTP servers there are? Maybe a new vulnerability came out and you want to see how many hosts it could infect? Traditional web search engines don't let you answer those questions.
So what does SHODAN index then? Good question. The bulk of the data is taken from 'banners', which are meta-data the server sends back to the client. This can be information about the server software, what options the service supports, a welcome message or anything else that the client would like to know before interacting with the server. For example, following is a FTP banner:

This tells us a potential name of the server (kcg.cz), the type of FTP server (Solaris ftpd) and its version (6.00LS). For HTTP a banner looks like:

The Basics

Now that you know what a banner is, you can start searching for computers that match your interests. First, lets take a look at the user interface:

1. Search input box: where all the magic happens
2. Country map: click on a country to only see computers from there in the results
3. Service filter: decide which services should be searched
4. Options bar: click on it to see the above filters

The interface should be familiar to anybody who's used search engines before. Onwards to actually using SHODAN!
To get things started, search for computers that contain 'Apache' in their banner: Apache

1. Search input: the query we used for searching, in this case 'apache'.
2. Save: store useful search queries.
3. Export: export up to 1,000 results in XML format.
4. Result info: shows how many total hosts were found for the query.
5. Country breakdown: highlights the countries that had the most matches for your query.
6. Left side of results: contains the IP, operating system, date when it was added and the country the computer is in. If there's domain information available then that is shown as well.
7. Right side of results: shows the banner with the search term(s) highlighted.

Now that you know the basics of searching on SHODAN, it's time to move on and check out the various filters you can use to narrow down your search results.