Locate systems on the network

When a hacker tries to penetrate a company's information system, the first thing he encounters is its network. The hacker's first task, once he has managed to get past any barriers such as firewalls, application relays (proxies), etc., is to identify the computer systems - whether network equipment, servers, etc. - that are also present on the network. To do this, it uses a range of techniques offering several levels of discretion . It can thus consult tables containing references to objects present on the network, or scan the network by interrogating each IP address to find out whether a machine is active at that particular address. This interrogation can be direct (targeting the machine directly) or indirect (by broadcasting to a multicast or broadcast address), or even innocuous by imitating the behavior of an operating system, for example.