dhcpd sending on the same IP it receives on
dhcp1 at thehobsons.co.uk
Wed Dec 12 17:41:58 UTC 2007
Phil Mayers wrote:
>I have tried to use dhcpd in various policy-routed ways in the past,
>and it is hard. It would be nice if dhcpd behaved in a similar
>manner to bind/named and ntpd, and bound a file descriptor to each
>IP (re-discovering the IPs every N minutes) and always replied via
>the same file descriptor the request came in on.
Can it always do that ?
bind and ntpd have the luxury of only ever dealing with unicast
packets, dhcpd must deal with broadcast packets.
Also, back to the original problem, I would suggest that the devices
being fussy are broken ! It is valid and legal to set the server
address to a broadcast address and hence have the packets 'delivered'
to multiple servers. Since it is (in the general case) not possible*
to determine whether an address is a broadcast address they should
not assume or expect replies to return from the address they sent the
* Well you can infer that a zero lsb of the address means that it
can't be a broadcast. And you can infer that if the next bit is zero
then it's highly unlikely that it's a broadcast address. But that's
More information about the dhcp-users