Re: Proxy ARP

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

Robert Elz <kre%munnari.OZ.AU@localhost> wrote:
>When a host is answering ARP queries for an IP address that is not its
>own, there are two ways (and reasons) for how it does that.
>
>It can send its own MAC address (kind of claiming ownership of the
>IP address, though all it will usually do with the packet is relay it 
>elsewhere.)
>
>Or it can send someone else's MAC address - so that the host that sent
>the query gets told the MAC address of the owner of the IP address (one
>hopes.)  This was used in the ancient times Christos mentioned when some
>hosts existed that did not understand ARP (IP over ethernet existed before
>ARP was invented.)
>
>One of those was known as proxy ARP, the other wasn't - but I'm not sure
>the nomenclature has remained consistent over time.  Any rational need for
>the second form vasnished long long ago, I can't imagine any host still
>running which understands both IP and ethernet, but not ARP.

I have an emulated host that runs on NetBSD that doesn't understand
ARP but will talk BOOTP and TFTP to a tap(4) interface.

I'm fairly sure I only used the 'pub' keyword to arp(8) on the server
to get things to work. Can check this.

Robert Swindells