Ethical hacking 

is legal hacking conducted by a penetration tester in order to evaluate
the security of an IT infrastructure with the permission of an organization. The concept of
ethical hacking cannot be explained or cannot be performed in a single step; therefore, it has
been divided into several steps. Footprinting is the first step in ethical hacking, where an
attacker tries to gather information about a target. To help you better understand foo tp rin ting ,
it has been distributed into various sections:

Footprinting Concepts

Footprinting Tools

Footprinting Threats

FootPrintng Countermeasures

Footprinting Methodology

Footprinting Penetration Testing


O p e n S o u r c e o r P a s s i v e I n f o r m a t i o n G a t h e r i n g

Open source or passive information gathering is the easiest way to collect information
about the target organization. It refers to the process of gathering information from the open sources, i.e., publicly available sources. This requires no direct contact with the target organization. Open sources may include newspapers, television, social networking sites, blogs, etc.
Using these, you can gather information such as network boundaries, IP address reachable via the Internet, operating systems, web server software used by the target network, TCP and UDP services
n each system, access control mechanisms, system architecture, intrusion detection systems, and so on.