[Dnsmasq-discuss] Lease duration for hosts without names

[Jay Guerette]

My reading of parse_hex in util.c indicates that an octect can be a 
wildcard but can't contain a wildcard with another character.


On 7/19/25 11:20 PM, Jay Guerette wrote:
>
> Thanks Dan, that looks promising. Running "grep -Pi ' \w[26AE][\w:]+ 
> [\d\.]+ ' /var/lib/dnsmasq/dnsmasq.leases" does yield all the leases 
> in scope.
>
> I wasn't able to get a working config just a "bad hex constant" error 
> on that line. It appears to dislike the "*2:*:*:*:*:*" filter.
>
>
> On 7/19/25 1:15 AM, Dan Schaper wrote:
>> You can use --dhcp-host to tag or otherwise dispense with clients 
>> based on mac address. You can also specify mac addresses with a * 
>> wildcard byte, so you might be able to leverage the fact that 
>> randomized mac addresses follow a pattern.
>>
>> Per https://www.rfc-editor.org/rfc/rfc7042.html#section-2.1 the local 
>> bit is set, meaning that the mac addresses will be in the form of 
>> x2:xx:xx:xx:xx:xx, x6:xx:xx:xx:xx:xx, xA:xx:xx:xx:xx:xx, 
>> xE:xx:xx:xx:xx:xx. What I'm not sure of, and would need testing, is 
>> if you can use wildcards for part, like *2:*:*:*:*:*
>>
>> Apple's MAC randomization is _supposed_ to be per WiFi SSID, so each 
>> device _should_ only have one randomized mac address per SSID. I 
>> don't really think it works that way in the real world.
>>
>> Dan
>>
>> ------ Original Message ------
>> From "Jay Guerette" <jayguerette at gmail.com>
>> To donmuller22 at outlook.com; dnsmasq-discuss at lists.thekelleys.org.uk
>> Date 7/18/2025 8:16:21 PM
>> Subject Re: [Dnsmasq-discuss] Lease duration for hosts without names
>>
>>>
>>> I should have been more explicit in my ask. I know how to fix it but 
>>> I want to prevent it in the future. When I'm not around I want my 
>>> network to work without intervention.
>>>
>>> Most people don't know what a MAC is, don't know where the setting 
>>> is, and may not react well to "you have to disable privacy if you 
>>> want to use my wifi". The smaller pool size & longer lease length 
>>> could be considered short-sighted or self-inflicted. I didn't 
>>> anticipate guests requiring 4+ IPs on my network each and constantly 
>>> acquiring new ones without releasing the old ones.
>>>
>>> I think that hosts that don't provide a name are either 
>>> mis-configured, poorly designed, or just privacy focused. We already 
>>> have 'dhcp-generate-names' that identifies these hosts, I'm 
>>> wondering if we could extend the concept to allow you to add a tag 
>>> to such hosts so that specific policies could be applied.
>>>
>>>
>>> On 7/18/25 6:40 PM, Donald Muller wrote:
>>>> Have them turn off MAC randomization or modify your dnsmasq config 
>>>> to increase the pool or set a short lease time while they are guests.
>>>> ________________________________
>>>> From: Dnsmasq-discuss
>>>> <dnsmasq-discuss-bounces at lists.thekelleys.org.uk> 
>>>> <mailto:dnsmasq-discuss-bounces at lists.thekelleys.org.uk> on behalf 
>>>> of Jay Guerette <jayguerette at gmail.com> <mailto:jayguerette at gmail.com>
>>>> Sent: Friday, July 18, 2025 6:01 PM
>>>> To:
>>>> dnsmasq-discuss at lists.thekelleys.org.uk<dnsmasq-discuss at lists.thekelleys.org.uk> 
>>>> <mailto:dnsmasq-discuss at lists.thekelleys.org.uk>
>>>> Subject: [Dnsmasq-discuss] Lease duration for hosts without names
>>>>
>>>>
>>>> I have some house guests who brought devices that randomize their 
>>>> macs and don't provide host names. Due to their usage patterns they 
>>>> quickly exhausted my small DHCP pool.
>>>>
>>>> Is there a way that I can tag hosts that don't provide a name so 
>>>> that I can provide a custom/shorter lease time?
>>>
>>>
>
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