Ping requires ICMP packets. These packets can only be created via a
socket of the SOCK_RAW type. Currently, Java only allows SOCK_STREAM
(TCP) and SOCK_DGRAM (UDP) sockets. It seems unlikely that this will be
added very soon, since many Unix versions only allow SOCK_RAW sockets
to be created by root, and winsock does not address ICMP packets (win32
includes an unsupported and undocumented ICMP.DLL)