Firewall

Firewall setup for various components

To set up the Kubernetes cluster, you need to open a few ports on all nodes as mentioned below.

Firewall rules for Kubernetes node

Set up firewall rules on each node according to the following table.

Protocol	Port	Access	Purpose
TCP	22	Public/Internet	SSH
TCP	80	Public/Internet	HTTP
TCP	443	Public/Internet	HTTPS
TCP	5432	Intranet	Postgres
TCP	9345	Intranet	RKE
TCP	6443	Intranet	K8s API
UDP	8472	Intranet	K8s Flannel VXLAN
TCP	10250	Intranet	kubelet
TCP	2379	Intranet	etcd client
TCP	2380	Intranet	etcd peer
TCP	9796	Intranet	Prometheus
TCP	30000:32767	Intranet	K8s NodePort

Firewall rules for Load Balancer

Protocol	Port	Access	Purpose
TCP	22	Public/Internet	SSH
TCP	80	Public/Internet	HTTP
TCP	443	Public/Internet	HTTPS
TCP	5432	Intranet	Postgres

Firewall rules for Wireguard

Protocol	Port	Access	Purpose
TCP	22	Public/Internet	SSH
UDP	51820-5182n	Public/Internet	Multiple Wireguard servers

Firewall rules for NFS

Protocol	Port	Access	Purpose
TCP	22	Public/Internet	SSH
TCP	2049	Intranet	NFS server

Firewall setup

The exact method to set up the firewall rules will vary from cloud to cloud and on-prem. (For example on AWS, EC2 security groups can be used. For on-prem cluster, ufw can be used and so on)

Using Ansible

• On your machine install ansible

• Make sure you have SSH access to all nodes of the cluster

• Create hosts.ini file. Sample given here.

• Copy ports.yaml file and inspect for any changes w.r.t to above table.

• Run

ansible-playbook -i hosts.ini ports.yaml

Manual

• You can use ufw to set up the firewall on each cluster node.

  • SSH into each node, and change to superuser

  • Run the following command for each rule in the above table

    ufw allow from <from-ip-range-allowed> to any port <port/range> proto <tcp/udp>

  • Example:

    ufw allow from any to any port 22 proto tcp
    ufw allow from 10.3.4.0/24 to any port 9345 proto tcp

  • Enable ufw:

    ufw enable
    ufw default deny incoming

• Additional Reference: RKE2 Networking Requirements