[Dnsmasq-discuss] VLANs and multiple IP addresses for one mac address

[David Joslin]

I have a wireless network split into several vlans, each with its own
subnet, with dnsmasq serving all vlans. The wireless network is a Ubiquti
Unifi system and the access points all have static IP addresses on the
management vlan. Additionally, the access points each request IP addresses
via DHCP for the other vlans and dnsmasq correctly allocates the IP
addresses for the relevant vlans.

I noticed in dnsmasq's logs recently a bunch of 'lease not found' messages
whenever the access points attempted to renew the leases for these
addresses. The cause seems to be this: an access point's IP addresses are
all used on the same interface on the access point so when it renews these
addresses, the requests all come from the same mac address. Dnsmasq
services these requests but only the last address allocated is stored in
the lease file (I'm assuming the other addresses allocated are briefly
stored but then overwritten by subsequent allocations). So the access
points are happy enough - they have the addresses they need correctly
allocated by dnsmasq - but dnsmasq's lease file only records the last
address allocated. When the access points renew the leases, dnsmasq
generates the 'lease not found' error because there's no record of the
allocation in the lease file.

The error messages themselves are no big deal and the access points do get
the correct addresses. The problem I can foresee is that dnsmasq might
allocate addresses to other clients that it has already allocated to the
access points because it has no record of those allocations in its lease
file.

Is there any way dnsmasq can record more than 1 IP address against a mac
address? Or is there any other way round this problem? The access points
don't give any options for IP configuration apart from the address on the
management vlan; there aren't any configuration options for these DHCP
requested addresses.

Any help would be greatly appreciated.

David
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