[Dnsmasq-discuss] [PATCH] Nack requests for unknown leases.

[wkitty42 at gmail.com]

On 04/24/2017 05:16 AM, Alin Năstac wrote:
> On Sun, Apr 23, 2017 at 5:46 PM, Simon Kelley <simon at thekelleys.org.uk> wrote:
>> When the client sends the discovery packet, dnsmasq will notice that the
>> requested address is in use by another client, and offer a different
>> address instead.
>
> You did not understood the scenario. The host that already use the requested
> IP address is statically configured to use it (in other words dnsmasq does
> not have a lease for the given IP address).
>
> While at it, you might consider fixing the scenario in which a client fills a
> DHCP discovery message with an option-50 containing an IP address that is
> already used by another statically configured host.

in the above two paragraphs, you use the phrase "statically configured"... do 
you mean "pseudo-statically configured"?

"pseudo-static" where the DHCP gives the same IP to the same MAC all the time

versus

"static" where the machine is configured locally to use a specific IP address

in the first case, the system will be configured for DHCP and will have to ask 
for its address... in the second case, the system will never talk to the DHCP 
server...

something we found in a firewall product was that one must configure their 
dynamically assigned pool to exclude their static and pseudo-static IP address 
ranges otherwise there is the very real possibility that the DHCP server will 
hand out addresses already in use by other systems...


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