David W. Hankins dhankins at isc.org
Wed Jun 10 15:14:31 UTC 2009

On Wed, Jun 10, 2009 at 01:35:22AM -0700, Loren M. Lang wrote:
> nothing in the log file to indicate otherwise.  I tried setting up
> dhcrelay to listen on ppp0 and relay it to the IP of the ethernet card
> on the DHCP server, however dhcrelay complained that it did not support
> device type 512 of ppp0.  We are using ISC DHCP 4.  Is there any way to
> respond to the DHCPINFORM messages generated by Windows on a PPP link?

There are two obstacles.  The first is that ISC DHCP has to use raw
sockets in order to process RFC 2131 conforming broadcast DHCP
messages (both to receive and transmit them).  This means the software
has to understand how to perform the link layer framing, and we have a
limited number of link layers supported currently.  This can be worked
around by compiling the software with USE_SOCKETS, but then your RFC
2131 conformance with regard to those special messages comes under

The second obstacle I think is that dhcrelay will refuse to use an
interface that is non-broadcast.  This may prove more difficult to

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
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