DHCP Relay + PPP (your mail)

[David W. Hankins]

On Tue, May 23, 2006 at 08:20:21PM +0100, Simon Hobson wrote:
> Any particular reason ? It is a valid relay configuration and only 
> has to handle unicast packets from the server on the PPP interface.

Largely because it doesn't make sense for a client or server to
operate DHCP on a ppp interface (more to the point, our BPF
interface doesn't understand the link layer...it would look
pretty silly spitting IEEE 802 down a ppp line).

> Pre-empting the answer I expect ... it's never seemed quite right to 
> me for the relay to have to listen in the same way on both 
> interfaces. On the interface(s) that are client facing, then yes, I 
> see the need for special handling to get the broadcast packets. But 
> surely it should be able to just open a normal socket on the server 
> facing interface(s) to handle the unicast packets.

Yeah, we need listen-only behaviour.

Really you want this behaviour reversed for relays - listen only on
the fallback standard BSD socket, and use the BPF etc sockets for
transmit-only.

Some day that ship will come in.

-- 
David W. Hankins		"If you don't do it right the first time,
Software Engineer			you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins