To use Nmap to perform ARP discovery, you will need to have at least one system on the LAN that will respond to ARP requests. In the examples provided, a combination of Linux and Windows systems are used. For more information on setting up systems in a local lab environment, refer to the Installing Metasploitable2 and Installing Windows Server recipes in Chapter 1, Getting Started.

Using Nmap to perform layer 3 and layer 4 discovery does not require a lab environment, as many systems on the Internet will reply to ICMP echo requests, as well as both TCP and UDP traffic. However, it is highly recommended that you perform any type of network scanning exclusively in your own lab unless you are thoroughly familiar with the legal regulations imposed by any governing authorities to whom you are subject. If you wish to perform this technique within your lab, you will need to have at least one system that will respond to ICMP, TCP, and UDP requests. In the examples provided, a combination of Linux and Windows systems are used. For more information on setting up systems in a local lab environment, refer to the the Installing Metasploitable2 and Installing Windows Server recipes in Chapter 1, Getting Started. Additionally, this section will require a script to be written to the filesystem, using a text editor such as Vim or GNU nano. For more information on writing scripts, refer to the Using text editors (VIM and GNU nano) recipe in Chapter 1, Getting Started.