Re: receiving broadcasts from host zero in a subnet?

Andi Kleen (ak@muc.de)
Wed, 20 Oct 1999 15:30:18 +0200

On Wed, Oct 20, 1999 at 03:12:45PM +0200, Jens-Uwe Mager wrote:
> On Wed, Oct 20, 1999 at 04:53:55AM +0200, Andi Kleen wrote:
> > jum@ra.han.de (Jens-Uwe Mager) writes:
> >
> > > I am attempting port a program to linux that listens to broadcast UDP
> > > packets from a particular device while performing a network boot. This
> > > UDP broadcast is received OK if it is from the all zeroes 0.0.0.0 address
> > > to the all ones broadcast address. But if the packet is from for example
> > > 192.168.1.0 to 192.168.1.255 (with subnet mask 255.255.255.0) the packet
> > > does not appear to be received on an UDP socket bound to INADDR_ANY. The
> > > device in questions its subnet but not its IP address so it uses this
> > > peculiar broadcast. Is there any special rule I need to enable to receive
> > > these kind of broadcasts?
> >
> > SO_BROADCAST, as documented in socket(7).
>
> This option is already turned on, otherwise I would not have been able
> to send broadcast packets.

You need correct routing tables so that Linux knows that 192.168.1.255
is a broadcast.

-Andi

-- 
This is like TV. I don't like TV.


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