Re: Sending ARP request to unicast MAC instead of broadcast MAC address?

[James Hess <mysidia () gmail com>]

On Wed, Jun 16, 2010 at 5:57 PM, Chris Woodfield <rekoil () semihuman com> wrote:
> OK, this sounds Really Wacky (or, Really Hacky if you're into puns) but there's a reason for it, I swear...

> Will typical OSS UNIX kernels (Linux, BSD, MacOS X, etc) reply to a crafted ARP request that, instead of having 
> FF:FF:FF:FF:FF:FF as its destination MAC address, is instead sent to the already-known unicast MAC address of the 
> host?

In general, hosts respond to these in just the same way as they would
respond to a broadcast arp request.

> Next, what would be your utility of choice for crafting such a packet? Or is this something one would need to code up 
> by hand in a lower-level language?


arping  from the iputils  package will switch to unicast requests
after the first unicast ARP response is received,  and send the rest
of the pings using unicast arp,  assuming you don't use the  -b
option

--
-JH