[Gllug] arp problem?

[Adrian McMenamin]

On Sun, 2006-06-11 at 21:21 +0100, Casper Gasper wrote:
> On 11/06/06, Ian Northeast <ian at house-from-hell.demon.co.uk> wrote:
> > Casper Gasper wrote:
> > > On 11/06/06, Adrian McMenamin <adrian at mcmen.demon.co.uk> wrote:
> > >
> > >> On Sun, 2006-06-11 at 13:12 +0100, Casper Gasper wrote:
> > >> > > But the second box doesn't have an IP address, it just has a MAC
> > >> > > address. The box is booted with a very simple slave program which
> > >> simply
> > >> > > loads loads the kernel into the right memory location and runs the
> > >> > > bootloader.
> > >> >
> > >> >  If it doesn't have an ip address, why are you attempting to ping it?
> > >> >
> > >>
> > >> Because the arp table ought to tell the kernel which MAC address to aim
> > >> for
> > >
> > >
> > >  That won't work, I've thought that in the past but it doesn't.  The
> > > arp table entry will send the packets to the machine, but when say a
> > > ping packet goes through the TCP/IP stack, it will get discarded
> > > because the destination IP address doesn't match the local ip -- or
> > > else, forwarded if ip forwarding is enabled on the machine.
> >
> > It does with *some* devices, it's how we used to get an address onto
> > Axis print servers. These interpret a ping sent to their MAC as an
> > instruction to set the IP address to the one in the packet. This is
> > enough to get onto the box with telnet/HTTP and configure the netmask,
> > gateway etc.
> >
> 
>   Interesting -- never heard of that before!  Technically though, it's
> not quite the same thing; the box is taking the ip address from the
> first ping packet it receives, as opposed to being able to respond
> without an ip address (or an incorrect one), which is what I'm arguing
> won't work.
> 

Well the box (the Dreamcast) does respond. So how does that work?
(Serious question)

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