[pve-devel] [PATCH pve-network] dnsmasq: configure static range for each subnet

DERUMIER, Alexandre alexandre.derumier at groupe-cyllene.com
Thu Nov 16 14:43:31 CET 2023

>>I experimented with several approaches with dnsmasq leases.
>>I cannot reproduce your example because it works in my examples.
>>My procedure:

>>dnsmasq config:

>>VM 108 net1: MAC: bc:24:11:ad:0e:2e
>>qm set 108 --delete net1
>>dnsmasq lease file still contains the lease for MAC bc:24:11:ad:0e:2e
>>qm set 108 --net1 model=virtio,bridge=dhcpnat
>>- ethers file gets updated to new mac: BC:24:11:51:10:AD
>>- soon after dnsmasq lease gets updated to the new lease as well!
>>- correct IP assigned in the VM

>>I also tried:
>>- ip link set down > ip link set upi
>>- reboot
>>- force Stop the VM
>>So far, *this all works!*

mmm, and you reassign the same ip address to the new mac ?

>>I also tried with a short dhcp lease in dnsmasq. With this
>>configuration, the new IP will even propagate to the VM and set
>>correctly after IPAM update.
>>In my tests I used 30s but something like 5 or 10min should be fine
>>as well.
>>The VM is polling every ~60s as seen on the wire with tcpdump:
>>tcpdump -i dhcpnat -n port 67 or port 68
>>After I manually update the ethers file and `systemctl *reload*
>>dnsmasq`, it will respond with the new IP.
>>dnsmasq is running *locally only* so any DHCP queries are limited to
>>local bridge.
>>The biggest problem and for me the reason I think it's not a feasible
>>solution, is that dnsmasq becomes a single point of failure.
>>If dnsmasq is offline, all of the VMs will have *NO IP*.

Yes, personnality, I'm more for infinite leases to not have spof

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