Date: Mon, 20 Oct 2003 20:42:50 -0400 From: Barney Wolff <barney@databus.com> To: Wes Peters <wes@softweyr.com> Cc: julian@elischer.org Subject: Re: Help Broadcasting a UDP packet on the LAN:URGENT Message-ID: <20031021004250.GA68072@pit.databus.com> In-Reply-To: <200310201521.26705.wes@softweyr.com> References: <20031020174751.60464.qmail@web20805.mail.yahoo.com> <20031020190019.GD8721@saboteur.dek.spc.org> <20031020194959.GA64879@pit.databus.com> <200310201521.26705.wes@softweyr.com>
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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.
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