The longstanding prohibition against using 0.0.0.0/8 dates back to two issues with the early internet. There was an interoperability problem with BSD 4.2 in 1984, fixed in BSD 4.3 in 1986. BSD 4.2 has long since been retired. Secondly, addresses of the form 0.x.y.z were initially defined only as a source address in an ICMP datagram, indicating "node number x.y.z on this IPv4 network", by nodes tha