Netdiscover is an active/passive address reconnaissance tool, mainly developed
for those wireless networks without dhcp server, when you are wardriving. It
can be also used on hub/switched networks.

Built on top of libnet and libpcap, it can passively detect online hosts, or
search for them, by actively sending arp requests, it can also be used to
inspect your network arp traffic, and find network addresses using auto scan
mode, which will scan for common local networks.