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IPsec encryption configuration

With IPsec enabled, all network traffic between nodes on the OVN-Kubernetes Container Network Interface (CNI) cluster network travels through an encrypted tunnel.

IPsec is disabled by default.

IPsec encryption can be enabled only during cluster installation and cannot be disabled after it is enabled. For installation documentation, refer to Selecting a cluster installation method and preparing it for users.

Types of network traffic flows encrypted by IPsec

With IPsec enabled, only the following network traffic flows between pods are encrypted:

  • Traffic between pods on different nodes on the cluster network

  • Traffic from a pod on the host network to a pod on the cluster network

The following traffic flows are not encrypted:

  • Traffic between pods on the same node on the cluster network

  • Traffic between pods on the host network

  • Traffic from a pod on the cluster network to a pod on the host network

The encrypted and unencrypted flows are illustrated in the following diagram:

IPsec encrypted and unencrypted traffic flows

Network connectivity requirements when IPsec is enabled

You must configure the network connectivity between machines to allow OpenShift Container Platform cluster components to communicate. Each machine must be able to resolve the hostnames of all other machines in the cluster.

Table 1. Ports used for all-machine to all-machine communications
Protocol Port Description

UDP

500

IPsec IKE packets

4500

IPsec NAT-T packets

ESP

N/A

IPsec Encapsulating Security Payload (ESP)

Encryption protocol and IPsec mode

The encrypt cipher used is AES-GCM-16-256. The integrity check value (ICV) is 16 bytes. The key length is 256 bits.

The IPsec mode used is Transport mode, a mode that encrypts end-to-end communication by adding an Encapsulated Security Payload (ESP) header to the IP header of the original packet and encrypts the packet data. OpenShift Container Platform does not currently use or support IPsec Tunnel mode for pod-to-pod communication.

Security certificate generation and rotation

The Cluster Network Operator (CNO) generates a self-signed X.509 certificate authority (CA) that is used by IPsec for encryption. Certificate signing requests (CSRs) from each node are automatically fulfilled by the CNO.

The CA is valid for 10 years. The individual node certificates are valid for 5 years and are automatically rotated after 4 1/2 years elapse.