[Dnsmasq-discuss] same DHCP client on multiple interfaces

[Simon Kelley]

On 08/09/2022 07:08, Hamish Moffatt wrote:

> 
> So, I got the suggestion off-list to set the DHCP client-id uniquely for 
> each connection. This fixed IPv4, even without matching on the client ID 
> in the config, because dnsmasq is tracking both separately in the leases 
> file. Leases (just IPv4) showed:
> 
> 1662658086 38:c9:86:40:86:37 192.168.42.18 potoroo 
> ff:b7:b0:95:87:00:03:00:01:83:6d:06:a5:ef:01
> 1662658067 38:c9:86:40:86:37 192.168.66.18 potoroo-iotlan 
> ff:cc:62:6a:65:00:03:00:01:cb:45:f5:1b:f7:42
> 
> 
> However it did not fix IPv6, where the hostnames ended up being 
> associated with the wrong IP sometimes and even shown that way in the 
> log. 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Just to clarify: it works if you stick to client-ids, but IPv6 breaks if 
you match both MAC and client-id, even when the client-ids are different?


Simon.


The fix for this was to match on client ID, but I couldn't get the
> client ID to match for IPv4 and IPv6, so I ended up with two separate 
> entries for each host:
> 
> dhcp-host=,id:ff:b7:b0:95:87:00:03:00:01:83:6d:06:a5:ef:01,192.168.42.18,potoroo 
> 
> dhcp-host=,id:ff:cc:62:6a:65:00:03:00:01:cb:45:f5:1b:f7:42,192.168.66.18,potoroo-iotlan 
> 
> dhcp-host=,id:00:03:00:01:83:6d:06:a5:ef:01,[::0:18],potoroo
> dhcp-host=,id:00:03:00:01:cb:45:f5:1b:f7:42,[::0:18],potoroo-iotlan
> 
> 
> This seems to work as expected. In NetworkManager I had to set the 
> following on each connection to get distinct client IDs:
> 
> connection.stable-id:                   "${CONNECTION}"
> ipv4.dhcp-client-id:                    ipv6-duid
> ipv6.dhcp-duid:                         stable-ll
> 
> 
> ... although there are many other configurations that would work too.
> 
> 
> Hamish
> 
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