Reply to remote unicast DHCP requests

Paúl Ortiz Imedio portizimedio at
Wed May 4 07:53:07 UTC 2011

Glenn Satchell wrote:
>So do you have a definition for net2 in dhcpd.conf?
>There needs to be a minimal definition, even if there are no 
>clients on that subnet. Something like:
>subnet a.b.c.0 netmask { }
>(with whatever the appropriate subnet and netmask is.)
>That should all be fine. The dhcp server is always going to 
>receive requests via the local network interface.
I did not know that was needed, and in my simple scenario is easy
to do it. But in a more general topology, I suppose that this 
implies that dhcpd MUST define (with 'subnet a.b.c.0 ...') every 
local subnet through which the server might receive a DHCP
request. The packets may arrive the server through different
interfaces and so dhcpd MUST have all their corresponding local 
subnets configured in dhcpd.conf, even there are no clients on 
those subnets.
>Are there other clients on net1 that do work? Or do all clients 
>fail to renew? Can you ping the client from the dhcp server? Is 
>the default router set properly on the client via the initial 
>dhcp request? Is there a firewall in there anywhere, either 
>between the subnets or on the device in question?
I have no other clients on net1, but I am pretty sure that the
problem was not having configured local subnets in dhcpd.conf
Alex Bligh wrote:
>Don't do this then. dhcpd in essence needs to know about every
>subnet on which it might ever get any form of IP address.
>(unless you use the hack which should only be used
>between consenting adults in the privacy of their own networks).
I am not using the hack. All I needed was to tell dhcpd
about the local subnet in dhcpd.conf .
Thanks for your help
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