Next, you will identify whether the host is up and running, or whether it's protected by a firewall. My favorite tool for this phase (and the upcoming phases as well) is Nmap. I strongly suggest that you familiarize yourself with Nmap. The following commands initiate Nmap and another useful host identifier:

• Nmap ping scan:

nmap -sn [IP Address / range]

• Another tool, Netdiscover:

netdiscover -r [IP Address / range]