[Dnsmasq-discuss] Unable to get a reserved address when dhcp-range not specified

[john doe]

On 1/8/23 06:56, Donald Muller wrote:
> I recently added a 2.5GB switch to my network. All devices, which are NAS devices, plugged into the switch have a reservation for their IP4 address except of course the NAS running dnsmasq which has a fixed address. I updated dnsmasq to include the reservations and the following dhcp options.
>
> dhcp-option=tag:eth4,option:netmask,255.255.255.0                                                                                                      # set net mask (1)
> dhcp-option=tag:eth4,option:router,0.0.0.0                                                                                                                                         # set router address (3)
>
> No address range is specified for eth4. When one of the NAS devices attempts to get an IP address I receive the following error message.
>
> no address range available for DHCP request via eth4
>
> Even though I have reservations for the devices they never receive their reserved address. If I add the range option then the devices receive their reserved address.
>
> dhcp-range=tag:eth4,192.168.122.100,192.168.122.199,255.255.255.0,3d
>
> Why do I need to specify a dhcp range when the devices have reservations? I don't want a device that does not have a reservation on this subnet to be able to plug into the switch and get an address. Is this a bug in dnsmasq? If not is there a way to >
 >

Looks like you want the 'DHCP service' with 'static' leases.
If I'm correct,  [1] says The optional <mode> keyword may be static
which tells dnsmasq to enable DHCP for the network specified, but not to
dynamically allocate IP addresses: only hosts which have static
addresses given via --dhcp-host or from /etc/ethers will be served."

[1] https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html

--
John Doe