Now that we have discussed why the information gathering phase is so important, let's jump into some of the tools to gain various types of information. The first thing you may notice very quickly is that there are a lot of tools and methods to gain increased intelligence from the environment. The second thing is that there is a lot of overlap of these tools and their respective function and outputs. This is a good thing, as with experience, every penetration tester will come to learn the tools they like to use the most, the ones they find the most beneficial, and the ones they want to avoid.
The following tools are the ones that I have used in my lab environment and in the real world to discover more information about what exactly is on the network I am running the penetration test on.