Help Broadcasting a UDP packet on the LAN:URGENT

[Barney Wolff]

On Mon, Oct 20, 2003 at 03:21:26PM -0700, Wes Peters wrote:
> 
> But does it send the packet to all attached interfaces on a multi-homed 
> host?  This is the type of bug that has typically bitten such hackish 
> solutions in the past.  One real solution is worth much more than the 
> sum of the sort-of but not really working hacks we have flying about 
> now.

Bughood is in the eye of the beholder.  RFC1122 has this to say, in
section 3.3.6:  (255.255.255.255 is the "Limited Broadcast" address)

               There has been discussion on whether a datagram addressed
               to the Limited Broadcast address ought to be sent from all
               the interfaces of a multihomed host.  This specification
               takes no stand on the issue.
                                                                                
And of course any application that actually needs to send such a packet
on every interface can loop through the interfaces, using the technique
on each one, getting the reply, removing the 255.0.0.0/8 alias, and
moving on to the next interface.  If it were up to me (as of course it
is not) I'd leave it at that and not clutter up the kernel.

-- 
Barney Wolff         http://www.databus.com/bwresume.pdf
I'm available by contract or FT, in the NYC metro area or via the 'Net.