As per OWASP Testing Guide v4 , the first phase in security assessment is focused on collecting as much information as possible about a target application. Information Gathering is the most critical step of an application security test. The security test should endeavour to test as much of the code base as possible. Thus mapping all possible paths through the code to facilitate thorough testing is paramount. This task can be carried out in many different ways. By using public tools (search engines), scanners, sending simple HTTP requests, or specially crafted requests, it is possible to force the application to leak information, e.g., disclosing error messages or revealing the versions and technologies used. Below are the list of tools, are used to gather information. acccheck ace-voip Amap Automater bing-ip2hosts braa CaseFile CDPSnarf cisco-torch Cookie Cadger copy-router-config DMitry dnmap dnsenum dnsmap DNSRecon dnstracer dnswalk DotDotPwn enum4linux enumIAX exploitdb Fierce Fire