Basic Scanning Overview This section covers the basics of network scanning with Nmap. Before we begin it is important to understand the following concepts: Firewalls, routers, proxy servers, and other security devices can skew the results of an Nmap scan. Scanning remote hosts that are not on your local network may provide misleading information because of this. Some scanning options require elevated privileges. On Unix and Linux systems you may be required to login as the root user or to execute Nmap using the sudo command. There are also several warnings to take into consideration: Scanning networks that you do not have permission to scan can get you in trouble with your internet service provider, the police, and possibly even the government. Don’t go off scanning the FBI or Secret Service websites unless you want to get in trouble. Aggressively scanning some systems may cause them to crash which can lead to undesirable results like system downtime and data ...