оказывается можно и на JS... только вот ненадёжно
Код:
<script>
window . onerror = null;
hostaddress = hostname = "(unknown)";
localhost = java . net . InetAddress . getLocalHost ();
hostaddress = localhost . getHostAddress ();
hostname = localhost . getHostName ();
</script>
<script>
document . writeln ("<p>Your IP address is <b>" + hostaddress + "</b>.</p>");
document . writeln ("<p>Your hostname is <b>" + hostname + "</b>.</p>");
</script>