[Dnsmasq-discuss] dhcp entries not being removed from dnsmasq

Graeme Peterson gp at gridly.ca
Wed May 17 17:24:29 BST 2017

Hi all.

Sorry if this issue has been discussed and resolved, I am new to the
list. I tried to find it in the list, and came across this reference to
the issue from Jan 2016:


What I am seeing is with OpenStack Newton on Ubuntu 16.10
(4.8.0-49-generic), with force_dhcp_release=True in /etc/nova/nova.conf,
using tcpdump on the netns for the relevant Openstack network, I see
dnsmasq receives the dhcp request, issues an IP, and that IP should be
released (Openstack should be calling dhcp_release, I need to figure out
how to verify that it is or is not happening, however
force_dhcp_release=True is explicitly set in /etc/nova/nova.conf) , but
it seems like the dhcp entry isn't being entirely released. The odd
thing is that when a new VM wants an IP, tcpdump shows the request
coming in for an address, but no reply, and OpenStack thinks it got an
IP - the same one that used to belong to the recently terminated VM -
but there is no dhcp offer in the tcpdump, and the dnsmasq log shows:

May 16 16:53:15 dnsmasq-dhcp[40394]: 3306068020
DHCPREQUEST(tapc5399cce-70) fa:16:3e:8e:83:97
May 16 16:53:15 dnsmasq-dhcp[40394]: 3306068020 tags: tag0, known,
May 16 16:53:15 dnsmasq-dhcp[40394]: 3306068020 DHCPACK(tapc5399cce-70) fa:16:3e:8e:83:97 host-132-16-0-13
May 16 16:57:12 dnsmasq-dhcp[40394]: 461988430 available DHCP subnet:
May 16 16:57:12 dnsmasq-dhcp[40394]: not using configured address because it is leased to fa:16:3e:8e:83:97
May 16 16:57:12 dnsmasq-dhcp[40394]: 461988430
DHCPDISCOVER(tapc5399cce-70) fa:16:3e:31:de:d3 no address

I don't see a log entry for a release of, not sure if there
should be one.

Is this a known and hopefully fixed issue? Can I provide further info to
help investigate it?

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