c12s-kubespray/docs/centos8.md

CentOS 8 and derivatives

CentOS 8 / Oracle Linux 8 / AlmaLinux 8 ship only with iptables-nft (ie without iptables-legacy similar to RHEL8) The only tested configuration for now is using Calico CNI You need to add calico_iptables_backend: "NFT" or calico_iptables_backend: "Auto" to your configuration.

If you have containers that are using iptables in the host network namespace (hostNetwork=true), you need to ensure they are using iptables-nft. An example how k8s do the autodetection can be found in this PR