Footprinting in computer is actually the process of collecting data with regard to a specific network environment, usually for the purpose of finding ways to intrude into the environment. Footprinting can reveal system vulnerabilities and improve the ease with which they can be exploited. Footprinting begins by determining the location and objective of an intrusion. Once this is known, specific information about the organization is gathered using non-intrusive methods. For example, the organization’s own Web page may provide a personnel directory or employee bios, which may prove useful if the hacker needs to use social engineering to reach the objective. Conducting a whois query on the Web provides the domain names and associated networks related to a specific organization. Other information obtained may include learning the Internet technologies being used; the operating system and hardware being used; IP addresses; e-mail addresses and phone numbers; and policies and procedures.

Open Source Footprinting is the easiest and safest way to go about finding information about a company. Information that is available to the public, such as phone numbers, addresses, etc. Performing whois requests, searching through DNS tables, and scanning certain IP addresses for open ports, are other forms of open source footprinting. Most of this information is fairly easy to get, and getting it is legal, legal is always good. Most companies post lots of information about themselves on their website. A lot of this information can be very useful to hackers and the companies don’t even realize it. It may also be helpful to skim through the webpage’s HTML source to look for comments.