PeerAuthentication

3 minute read

PeerAuthentication defines mutual TLS (mTLS) requirements for incoming connections.

In sidecar mode, PeerAuthentication determines whether or not mTLS is allowed or required for connections to an Envoy proxy sidecar.

In ambient mode, security is transparently enabled for a pod by the ztunnel node agent. (Traffic between proxies uses the HBONE protocol, which includes encryption with mTLS.) Because of this, DISABLE mode is not supported. STRICT mode is useful to ensure that connections that bypass the mesh are not possible.

Examples:

Policy to require mTLS traffic for all workloads under namespace foo:

apiVersion: security.istio.io/v1 kind: PeerAuthentication metadata: name: default namespace: foo spec: mtls: mode: STRICT

For mesh level, put the policy in root-namespace according to your Istio installation.

Policies to allow both mTLS and plaintext traffic for all workloads under namespace foo, but require mTLS for workload finance.

apiVersion: security.istio.io/v1 kind: PeerAuthentication metadata: name: default namespace: foo spec: mtls: mode: PERMISSIVE --- apiVersion: security.istio.io/v1 kind: PeerAuthentication metadata: name: finance namespace: foo spec: selector: matchLabels: app: finance mtls: mode: STRICT

Policy that enables strict mTLS for all finance workloads, but leaves the port 8080 to plaintext. Note the port value in the portLevelMtls field refers to the port of the workload, not the port of the Kubernetes service.

apiVersion: security.istio.io/v1 kind: PeerAuthentication metadata: name: default namespace: foo spec: selector: matchLabels: app: finance mtls: mode: STRICT portLevelMtls: 8080: mode: DISABLE

Policy that inherits mTLS mode from namespace (or mesh) settings, and disables mTLS for workload port 8080.

apiVersion: security.istio.io/v1 kind: PeerAuthentication metadata: name: default namespace: foo spec: selector: matchLabels: app: finance mtls: mode: UNSET portLevelMtls: 8080: mode: DISABLE

PeerAuthentication

Field Description

Field	Description
`selector` WorkloadSelector	The selector determines the workloads to apply the PeerAuthentication on. The selector will match with workloads in the same namespace as the policy. If the policy is in the root namespace, the selector will additionally match with workloads in all namespace. If not set, the policy will be applied to all workloads in the same namespace as the policy. If it is in the root namespace, it would be applied to all workloads in the mesh.
`mtls` MutualTLS	Mutual TLS settings for workload. If not defined, inherit from parent.
`portLevelMtls` map<uint32, MutualTLS>	Port specific mutual TLS settings. These only apply when a workload selector is specified. The port refers to the port of the workload, not the port of the Kubernetes service.

selector

WorkloadSelector

The selector determines the workloads to apply the PeerAuthentication on. The selector will match with workloads in the same namespace as the policy. If the policy is in the root namespace, the selector will additionally match with workloads in all namespace.

If not set, the policy will be applied to all workloads in the same namespace as the policy. If it is in the root namespace, it would be applied to all workloads in the mesh.

mtls

MutualTLS

Mutual TLS settings for workload. If not defined, inherit from parent.

portLevelMtls

map<uint32, MutualTLS>

Port specific mutual TLS settings. These only apply when a workload selector is specified. The port refers to the port of the workload, not the port of the Kubernetes service.

MutualTLS

Mutual TLS settings.

Field	Description
`mode` Mode	Defines the mTLS mode used for peer authentication.

Mode

Name	Description
`UNSET`	Inherit from parent, if has one. Otherwise treated as `PERMISSIVE`.
`DISABLE`	Connection is not tunneled.
`PERMISSIVE`	Connection can be either plaintext or mTLS tunnel.
`STRICT`	Connection is an mTLS tunnel (TLS with client cert must be presented).