Patches for BOOTP/DHCP code to support Windows Server DHCP

John Howie john at
Sun Jun 1 10:22:18 UTC 2014

Hi Steinar,

In short, no, I have no packet traces. Given that the DHCP code in the
FreeBSD boot loader and NFS subsystem does not request those options, but
that ISC-DHCP does provide them, I will go out on a limb and say that it
must be serving them without being asked if they are configured.



On 6/1/14, 1:24 PM, "sthaug at" <sthaug at> wrote:

>> Section 3.5 of RFC 2131 (the DHCP RFC) states that "...Second, in its
>> initial DHCPDISCOVER or DHCPREQUEST message, a client may provide the
>> server with a list of specific parameters the client is interested in"
>> and "...The client can inform the server which configuration parameters
>> the client is interested in by including the 'parameter request list'
>> option."  The data portion of this option explicitly lists the options
>> requested by tag number. A DHCP Server is not required to return any
>> parameter that a client does not ask for. It appears that the ISC-DHCP
>> server, which is recommended by most, will return configured options
>> regardless of whether or not the client asks for them.
>As far as I know this is wrong. ISC DHCP does *not* behave this way.
>Do you have packet sniffer traces to indicate oterwise?
>In any case - yes, the client should absolutely request all the
>parameters it wants.
>Steinar Haug, Nethelp consulting, sthaug at

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