From: Sean O'Halpin <sean.ohalpin@...>
Date: 2012-02-03T22:47:35+09:00
Subject: Re: Choosing target network for UDP broadcast

On Fri, Feb 3, 2012 at 10:36 AM, Ivo Wever <wever@axini.com> wrote:
> If I send a UDP packet containing 'foo' like this:
>
>  socket = UDPSocket.new
>  socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_BROADCAST, true)
>  socket.send('foo', 0, '<broadcast>', 40001)
>
> then wireshark tells me it gets sent from 192.168.x.y. However, my
> server is listening on localhost:40001. How can I choose the source
> address from which (and the interface via which) the socket will send
> its packet?

Use #bind - http://ruby-doc.org/stdlib-1.9.3/libdoc/socket/rdoc/Socket.html#method-i-bind