RE: what's the meaning of the 0.0.0.0?

["David Gillett" <gillettdavid () fhda edu>]

  Just as 255.255.255.255 is interpreted as "the broadcast address
of whatever network I'm on", 0.0.0.0 should usually mean "the network
address of whatever network I'm on".
  Which raises the questions of:

1. If I have more than one interface, which one should I send this to?

2. How do I translate this layer 3 destination (IP address) into a 
layer 2 destination (MAC address)?

  Network addresses are reserved, but their useful implementation has
not really been defined.  So question #1 means that routing this traffic
to the loopback interface is defensible, and question #2 means that 
sending it as a local broadcast is defensible.

  (0.0.0.0 might also be set/reported as the source address in a DHCP
request, because the station does not yet have an assigned IP address.
Note that in this case it is the source, and it's the destination 
address that determines how the questions above get answered.)

David Gillett


> -----Original Message-----
> From: Fernando Gont [mailto:fernando () gont com ar]
> Sent: July 25, 2003 12:35
> To: security-basics () securityfocus com
> Subject: RE: what's the meaning of the 0.0.0.0?
>
>
> At 15:42 24/07/2003 -0400, you wrote:
>
> > In linux machines when you try to connect to 0.0.0.0 it goes to
> > localhost ...
>
> A bug, perhaps?
>
>
> > And in my last email i said that its a broadcast because
> > it is going to "all" ips in this "broadcast domain*"...
>
> The 0.0.0.0 is *not* the broadcast address.
>
> I think this could only be possible on old BSD systems, that 
> used zero's 
> instead of one's for broadcast addresses.
>
>
> --
> Fernando Gont
> e-mail: fernando () gont com ar || fgont () acm org
>
>
>
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