https://stackoverflow.com/questions/13669585/how-to-get-a-list-of-all-valid-ip-addresses-in-a-local-network

$ ifconfig
// find local IP address of my machine at en1: section, like inet 172.30.1.5
$ ping 172.30.1.255
// broadcast
$ arp -a
// list of up machines and local IP addresses appear