kubernetes: kube-proxy fails to delete nat entries with IPv6

What happened:

kube-proxy fails to clear IPv6 conntrack entries

What you expected to happen:

conntrack entries should be cleared

How to reproduce it (as minimally and precisely as possible):

Deploying a cluster with kind and IPv6 and restarting the coredns pods

Error in kube-proxy

conntrack command returned: "conntrack v1.4.4 (conntrack-tools): mismatched address family\nTry `conntrack -h' or 'conntrack --help' for more information.\n", error message: exit status 2
E0821 15:22:29.549792       1 proxier.go:635] Failed to delete kube-system/kube-dns:dns endpoint connections, error: error deleting conntrack entries for UDP peer {fd00:10:96::a, fd00:10:244::3}, error: conntrack command returned: "conntrack v1.4.4 (conntrack-tools): mismatched address family\nTry `conntrack -h' or 'conntrack --help' for more information.\n", error message: exit status 2

Running conntrack from the host

root@kind-control-plane:/# conntrack -f ipv6 -D --orig-dst fd00:10:96::a --dst-nat fd00:10:244::3 -p udp
conntrack v1.4.5 (conntrack-tools): 0 flow entries have been deleted.
root@kind-control-plane:/# conntrack -f ipv6 -D --orig-dst fd00:10:96::a --dst-nat fd00:10:244::3 -p tcp
conntrack v1.4.5 (conntrack-tools): 0 flow entries have been deleted.
root@kind-control-plane:/# conntrack -f ipv6 -D --orig-dst fd00:10:96::a --dst-nat fd00:10:244::3
conntrack v1.4.5 (conntrack-tools): 0 flow entries have been deleted.

Running conntrack from the kube-proxy container

root@kind-control-plane:/# crictl ps
CONTAINER ID        IMAGE               CREATED             STATE               NAME                      ATTEMPT             POD ID
da8c90d79a13c       7987f0908caf3       2 hours ago         Running             coredns                   0                   b76ad55de5756
fd2be218f5227       7987f0908caf3       2 hours ago         Running             coredns                   0                   024d498118bf2
c270083cac0a1       ef97cccdfdb50       2 hours ago         Running             kindnet-cni               0                   afa0a0e5310ef
09539af960455       d6f7fd86934c2       2 hours ago         Running             kube-proxy                0                   c8fd75dced320
9a468e0cac7b4       2c4adeb21b4ff       2 hours ago         Running             etcd                      0                   1c44a4fe1d33a
978f3d9319e49       b599d33ed5a7b       2 hours ago         Running             kube-controller-manager   0                   3ec62550d5915
e22fe1f8bbf4c       2b7262d4b0fbb       2 hours ago         Running             kube-scheduler            0                   09f0ac50a30e5
f6944e9451fd5       bb8dba7182b8a       2 hours ago         Running             kube-apiserver            0                   356f94ddca189
root@kind-control-plane:/# crictl exec -it 09539af960455 sh
# conntrack -f ipv6 -D --orig-dst fd00:10:96::a --dst-nat fd00:10:244::3 -p udp
conntrack v1.4.4 (conntrack-tools): mismatched address family
Try `conntrack -h' or 'conntrack --help' for more information.

Anything else we need to know?:

Seems to be a bug in the conntrack tools 1.4.4 per snippet pasted previously

Environment:

• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration:
• OS (e.g: cat /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Network plugin and version (if this is a network-related bug):
• Others: