Before the dawn of computer systems and networks, in the Art of War, Sun Tzu taught, > [!Quote] If you know the enemy and know yourself, your victory will not stand in doubt. If you are playing the role of an attacker, you need to gather information about your target systems. If you are playing the role of a defender, you need to know what your adversary will discover about your systems and networks. Reconnaissance (recon) can be defined as a preliminary survey to gather information about a target. It is the first step in The [Unified Kill Chain](https://www.unifiedkillchain.com) to gain an initial foothold on a system. We divide reconnaissance into: - [[Passive Reconnaissance]] - Active Reconnaissance