Did you know that commercial search engines like Google, Yahoo! Or Bing only index 5% or 10% of all Internet content?
The restis what is known as the deep web, the deep web that does not come out insearch engine results.

What is there?
An increasingly importantpart of this deep web are the objects of the Internet of Things: security cameras, refrigerators, wearables, alarms, and other devices that their owners connect to the Internet, sometimes without the necessary security, and become a treat too tasty for the hackers who dedicate themselves to spy or steal personal data.

Shodan is a search engine created by security expert John Matherly, who defines it as “the most terrifying search engine in the world”.
It takes the name of the artificial intelligence evil that appeared in the mythical video game System Shock.

Shodan is, in simple words, a search engine for HTTP addresses connected to the Internet, many of which belong to the deep web and do not go out in Google searches or similar.
Locate any device that is visible on the Net, so we can also define it as a searcher of the Internet of Things because it finds refrigerators, alarms, security cameras, webcams, wearables, andany other connected device.

The search engine authors themselves have been surprised to locate nuclear power plants, computers that control city power grids, traffic lights, and other public hardware accessible from an HTTP address. Ofcourse, all these devices appear in the browser.Shodan does nothing illegal because it only collects links to devices that are visible on the Internet.

But it is easy to deduce what a malicious hacker can do if he locates the IP address of a webcam, a traffic light or a power plant computer. Especially when many of these devices work with the default passwords, or have a low-security level.