DHCPDISCOVER packets being received by host, but not responded to by dhcpd

[David W. Hankins]

On Wed, Jul 01, 2009 at 09:20:14AM -0700, Kyle Dion wrote:
> FYI, we saw with strace that the process *was* receiving the packets, 
> despite no log entries or replies.  In the end, all it took to resolve the 
> problem was restarting the service.  Why dhcpd was dropping the packets, we 
> may never know.

The dhcpd daemon has to use two network interfaces; a raw
(bpf/lpf/dlpi) and a bsd socket.

The BSD socket is only ever used to transmit unicast replies; any
packets received on it are dropped.

If your system call trace is only showing one reception per packet,
then there's something going on with the raw socket.

What, I can't say, we haven't had any bug reports or recent bug
fixes for raw sockets on the linuxes.

-- 
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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