Yep -- This is the root of the problem... With a "weird" netmask, jEmplode would have no idea (that I know of, anyway) to detect it. This is definitely not my bag, though, so if someone knows of a way in Java to do this reliably, I'm all ears.... 1.4 has a much slicker way to enumerate interfaces -- I wonder if it has a getBroadcastAddress() on it? Even if it did, though, I'd have to still have a fallback mechanism for 1.1 VM's. Mike