From: Sean O'Halpin <sean.ohalpin@...>
Date: 2012-02-03T22:49:03+09:00
Subject: Re: Choosing target network for UDP broadcast

On Fri, Feb 3, 2012 at 1:47 PM, Sean O'Halpin <sean.ohalpin@gmail.com> wrote:
> 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

Oops. Wrong link. This is the right one:
http://ruby-doc.org/stdlib-1.9.3/libdoc/socket/rdoc/UDPSocket.html#method-i-bind