Re: Issues with Netatalk and MACE

[Dennis Ferguson <dennis.c.ferguson%gmail.com@localhost>]

On 9 Jul 2010, at 13:04 , David Riley wrote:
> I never see a copy of the NBP packet go out over the network, because the 
> Appletalk layer throws it out as soon as it's determined that it can't 
> resolve the address with AARP.  In a sense, you're right; my machine is 
> querying to see if the NBP name is in use.  It works fine for finding its own 
> Appletalk address, but the probing for the name is failing.

While NBP might be complicated, AARP is just ARP for Appletalk and is
exceedingly simple.  The only useful function that ARPing for your
own address could have is the side effect of telling others that you
are using that address.  If it isn't doing that, and is really, truly
trying to discover its own MAC address by sending packets, then it is
broken and you need to figure out why it isn't recognizing its own
address, and is instead sending AARP packets for it, in the first place.

Note that the first thing at_aarpinput() does is this

        /* Check to see if from my hardware address */
        if (!memcmp(ea->aarp_sha, CLLADDR(ifp->if_sadl), sizeof(ea->aarp_sha))) 
{
                m_freem(m);
                return;
        }

so getting the ethernet device driver to loop a copy of the packet back
into the box won't help since AARP will drop packets from itself anyway.
Which makes perfect sense: if it knew the answer it wouldn't send the
query in the first place, so if receives its own query that is clearly
something it won't know the answer for.

I think the box inherently needs to be able to recognize its own addresses
to function, which means it shouldn't be sending packets to itself out of
a wire let alone arping for its own MAC address.  What does the routing
table entry for the local address look like?

Dennis Ferguson