Shodan is a search engine for Internet-connected devices. Web search engines, such as Google and Bing, are great for finding websites. But what if you're interested in measuring which countries are becoming more connected? Or if you want to know which version of Microsoft IIS is the most popular? Or you want to find the control servers for malware? Maybe a new vulnerability came out and you want to see how many hosts it could affect? Traditional web search engines don't let you answer those questions.
Shodan gathers information about all devices directly connected to the Internet. If a device is directly hooked up to the Internet then Shodan queries it for various publicly-available information. The types of devices that are indexed can vary tremendously: ranging from small desktops up to nuclear power plants and everything in between.
So what does Shodan index then? The bulk of the data is taken from banners, which are metadata about a software that's running on a device. 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:
220 kcg.cz FTP server (Version 6.00LS) ready.
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:
HTTP/1.0 200 OK
Date: Tue, 16 Feb 2010 10:03:04 GMT
Server: Apache/1.3.26 (Unix) AuthMySQL/2.20 PHP/4.1.2 mod_gzip/188.8.131.52a mod_ssl/2.8.9 OpenSSL/0.9.6g
Last-Modified: Wed, 01 Jul 1998 08:51:04 GMT
The information gained from these services is applied to many areas:
As you can tell the use cases for the data are varied. We provide the platform that ensures accurate, consistent and up-to-date information on Internet-facing devices - it's up to you to decide what type of information you're most interested in.
The most fundamental difference is that Shodan crawls the Internet whereas Google crawls the World Wide Web. However, the devices powering the World Wide Web only make up a tiny fraction of what's actually connected to the Internet. Shodan's goal is to provide a complete picture of the Internet.
Another difference with Google is that Shodan requires you to understand the search query syntax. For example, you can't simply enter power plant into Shodan and expect to get proper results. We designed Shodan for engineers/ developers and to get the most out of the data you need to understand the search query syntax.Next: Search query fundamentals