in reply to Changing Broadcast Interface

You have not specified if you use the same socket for listening and sending. This advice is relevant in case they are different:

You can specify a particular ethernet interface by specifying the IP address (other than INADDR_ANY) in the socket bind command, even for SEND sockets.

     "As you get older three things happen. The first is your memory goes, and I can't remember the other two... " - Sir Norman Wisdom

In Section Seekers of Perl Wisdom