nc does this with the broadcast addresses (read https://en.wikipedia.org/wiki/Broadcast_address for more info):
Recipient listens on 0.0.0.0:
recipient$ nc -l 0.0.0.0 6969 > file
Sender broadcasts to broadcast address: sender$ <file | nc 192.168.0.255 6969
or sender$ <file | nc 255.255.255.255 6969