Re: question about socket with link local addr

>A stack which conforms to the current spec will know to ARP for the LL
>destination and send the packet directly to the destination even if the
>source has a routable address. If there is no response to the ARP the
>packet will be discarded.
>
>However, since this is a draft spec which has been changing recently, it is
>very likely that mainstream stacks such as Mac, Windows or Linux will not
>conform to these rules. To find which rules they do follow, you would have
>to investigate each stack individually. I would expect to find a wide
>variety of behaviours - remember all of these operating systems have been
>through many versions and revisions of TCP/IP stack.

Mac OS 9 has done this correctly for years, as has Mac OS X.

I'm told by Alan Cox that current Linux distributions also know how to 
route to link-local. If yours doesn't, then type the following commands:

  route add -net 169.254.0.0 netmask 255.255.0.0 dev eth0 metric 99 
  route add default dev eth0 metric 99 

No version of Windows to date, AFAIK, knows how to route to link-local 
out-of-the-box, but you can fix yourself this by hand. In place of 
"put_my_address_here" put the Windows machine's own IP address.

  route add 169.254.0.0 mask 255.255.0.0 put_my_address_here

Stuart Cheshire <[email protected]>
 * Wizard Without Portfolio, Apple Computer, Inc.
 * www.stuartcheshire.org