istio.io/content/en/docs/concepts/security/index.md

---
title: Security
description: Describes Istio's authorization and authentication functionality.
weight: 30
keywords: [security,policy,policies,authentication,authorization,rbac,access-control]
aliases:
    - /docs/concepts/network-and-auth/auth.html
    - /docs/concepts/security/authn-policy/
    - /docs/concepts/security/mutual-tls/
    - /docs/concepts/security/rbac/
    - /docs/concepts/security/mutual-tls.html
    - /docs/concepts/policies/
owner: istio/wg-security-maintainers
test: n/a
---

Breaking down a monolithic application into atomic services offers various
benefits, including better agility, better scalability and better ability to
reuse services. However, microservices also have particular security needs:

- To defend against man-in-the-middle attacks, they need traffic encryption.
- To provide flexible service access control, they need mutual TLS and
   fine-grained access policies.
- To determine who did what at what time, they need auditing tools.

Istio Security provides a comprehensive security solution to solve these issues.
This page gives an overview on how you can use Istio security features to secure
your services, wherever you run them. In particular, Istio security mitigates
both insider and external threats against your data, endpoints, communication,
and platform.

{{< image width="75%"
    link="./overview.svg"
    caption="Security overview"
    >}}

The Istio security features provide strong identity, powerful policy,
transparent TLS encryption, and authentication, authorization and audit (AAA)
tools to protect your services and data. The goals of Istio security are:

- Security by default: no changes needed to application code and
    infrastructure
- Defense in depth: integrate with existing security systems to provide
    multiple layers of defense
- Zero-trust network: build security solutions on distrusted networks

Visit our
[mutual TLS Migration docs](/docs/tasks/security/authentication/mtls-migration/)
to start using Istio security features with your deployed services. Visit our
[Security Tasks](/docs/tasks/security/) for detailed
instructions to use the security features.

## High-level architecture

Security in Istio involves multiple components:

- A Certificate Authority (CA) for key and certificate management
- The configuration API server distributes to the proxies:

    - [authentication policies](/docs/concepts/security/#authentication-policies)
    - [authorization policies](/docs/concepts/security/#authorization-policies)
    - [secure naming information](/docs/concepts/security/#secure-naming)

- Sidecar and perimeter proxies work as [Policy Enforcement Points](https://www.jerichosystems.com/technology/glossaryterms/policy_enforcement_point.html)
    (PEPs) to  secure communication between clients and servers.
- A set of Envoy proxy extensions to manage telemetry and auditing

The control plane handles configuration from the API server and
configures the PEPs in the data plane. The PEPs are implemented using Envoy. The
following diagram shows the architecture.

{{< image width="75%"
    link="./arch-sec.svg"
    caption="Security Architecture"
    >}}

In the following sections, we introduce the Istio security features in detail.

## Istio identity

Identity is a fundamental concept of any security infrastructure. At the
beginning of a workload-to-workload communication, the two parties must exchange
credentials with their identity information for mutual authentication purposes.
On the client side, the server's identity is checked against the
[secure naming](/docs/concepts/security/#secure-naming)
information to see if it is an authorized runner of the workload. On the server
side, the server can determine what information the client can access based on
the
[authorization policies](/docs/concepts/security/#authorization-policies),
audit who accessed what at what time, charge clients based on the workloads they
used, and reject any clients who failed to pay their bill from accessing the
workloads.

The Istio identity model uses the first-class `service identity` to
determine the identity of a request's origin. This model allows for great
flexibility and granularity for service identities to represent a human user, an
individual workload, or a group of workloads. On platforms without a service
identity, Istio can use other identities that can group workload
instances, such as service names.

The following list shows examples of service identities that you can use on different
platforms:

- Kubernetes: Kubernetes service account
- GCE: GCP service account
- On-premises (non-Kubernetes): user account, custom service account,
   service name, Istio service account, or GCP service account. The custom
   service account refers to the existing service account just like the
   identities that the customer's Identity Directory manages.

## Identity and certificate management {#pki}

Istio securely provisions strong identities
to every workload with X.509 certificates. Istio agents, running alongside each Envoy proxy,
work together with `istiod` to automate key and certificate
rotation at scale. The following diagram shows the identity
provisioning flow.

{{< image width="40%"
    link="./id-prov.svg"
    caption="Identity Provisioning Workflow"
    >}}

Istio provisions keys and certificates through the following flow:

1. `istiod` offers a gRPC service to take [certificate signing requests](https://en.wikipedia.org/wiki/Certificate_signing_request) (CSRs).
1. When started, the Istio agent creates the private key
   and CSR, and then sends the CSR with its credentials to `istiod` for signing.
1. The CA in `istiod` validates the credentials carried in the CSR.
   Upon successful validation, it signs the CSR to generate the certificate.
1. When a workload is started, Envoy requests the certificate and key from the Istio agent in the
   same container via the
   [Envoy secret discovery service (SDS)](https://www.envoyproxy.io/docs/envoy/latest/configuration/security/secret#secret-discovery-service-sds)
   API.
1. The Istio agent sends the certificates received from `istiod` and the
   private key to Envoy via the Envoy SDS API.
1. Istio agent monitors the expiration of the workload certificate.
   The above process repeats periodically for certificate and key rotation.

## Authentication

Istio provides two types of authentication:

- Peer authentication: used for service-to-service authentication to verify
   the client making the connection. Istio offers [mutual
   TLS](https://en.wikipedia.org/wiki/Mutual_authentication) as a full stack
   solution for transport authentication, which can be enabled without
   requiring service code changes. This solution:
    - Provides each service with a strong identity representing its role
      to enable interoperability across clusters and clouds.
    - Secures service-to-service communication.
    - Provides a key management system to automate key and certificate
      generation, distribution, and rotation.

- Request authentication: Used for end-user authentication to verify the
   credential attached to the request. Istio enables request-level
   authentication with JSON Web Token (JWT) validation and a streamlined
   developer experience using a custom authentication provider or any OpenID
   Connect providers, for example:
    - [ORY Hydra](https://www.ory.sh/)
    - [Keycloak](https://www.keycloak.org/)
    - [Auth0](https://auth0.com/)
    - [Firebase Auth](https://firebase.google.com/docs/auth/)
    - [Google Auth](https://developers.google.com/identity/protocols/OpenIDConnect)

In all cases, Istio stores the authentication policies in the `Istio config
store` via a custom Kubernetes API. {{< gloss >}}Istiod{{< /gloss >}} keeps them up-to-date for each proxy,
along with the keys where appropriate. Additionally, Istio supports
authentication in permissive mode to help you understand how a policy change can
affect your security posture before it is enforced.

### Mutual TLS authentication

Istio tunnels service-to-service communication through the client- and
server-side PEPs, which are implemented as [Envoy
proxies](https://www.envoyproxy.io/). When a workload sends a request
to another workload using mutual TLS authentication, the request is handled as
follows:

1. Istio re-routes the outbound traffic from a client to the client's local
   sidecar Envoy.
1. The client side Envoy starts a mutual TLS handshake with the server side
   Envoy. During the handshake, the client side Envoy also does a
   [secure naming](/docs/concepts/security/#secure-naming)
   check to verify that the service account presented in the server certificate
   is authorized to run the target service.
1. The client side Envoy and the server side Envoy establish a mutual TLS
   connection, and Istio forwards the traffic from the client side Envoy to the
   server side Envoy.
1. The server side Envoy authorizes the request. If authorized, it forwards the traffic to the
   backend service through local TCP connections.

Istio configures `TLSv1_2` as the minimum TLS version for both client and server with
the following cipher suites:

- `ECDHE-ECDSA-AES256-GCM-SHA384`

- `ECDHE-RSA-AES256-GCM-SHA384`

- `ECDHE-ECDSA-AES128-GCM-SHA256`

- `ECDHE-RSA-AES128-GCM-SHA256`

- `AES256-GCM-SHA384`

- `AES128-GCM-SHA256`

#### Permissive mode

Istio mutual TLS has a permissive mode, which allows a service to accept both
plaintext traffic and mutual TLS traffic at the same time. This feature greatly
improves the mutual TLS onboarding experience.

Many non-Istio clients communicating with a non-Istio server presents a problem
for an operator who wants to migrate that server to Istio with mutual TLS
enabled. Commonly, the operator cannot install an Istio sidecar for all clients
at the same time or does not even have the permissions to do so on some clients.
Even after installing the Istio sidecar on the server, the operator cannot
enable mutual TLS without breaking existing communications.

With the permissive mode enabled, the server accepts both plaintext and mutual
TLS traffic. The mode provides greater flexibility for the on-boarding process.
The server's installed Istio sidecar takes mutual TLS traffic immediately
without breaking existing plaintext traffic. As a result, the operator can
gradually install and configure the client's Istio sidecars to send mutual TLS
traffic. Once the configuration of the clients is complete, the operator can
configure the server to mutual TLS only mode. For more information, visit the
[Mutual TLS Migration tutorial](/docs/tasks/security/authentication/mtls-migration).

#### Secure naming

Server identities are encoded in certificates, but service names are retrieved
through the discovery service or DNS. The secure naming information maps the
server identities to the service names. A mapping of identity `A` to service
name `B` means "`A` is authorized to run service `B`". The control plane watches
the `apiserver`, generates the secure naming mappings, and distributes them
securely to the PEPs. The following example explains why secure naming is
critical in authentication.

Suppose the legitimate servers that run the service `datastore` only use the
`infra-team` identity. A malicious user has the certificate and key for the
`test-team` identity. The malicious user intends to impersonate the service to
inspect the data sent from the clients. The malicious user deploys a forged
server with the certificate and key for the `test-team` identity. Suppose the
malicious user successfully hijacked (through DNS spoofing, BGP/route hijacking,
ARP spoofing, etc.) the traffic sent to the `datastore` and redirected it to the
forged server.

When a client calls the `datastore` service, it extracts the `test-team`
identity from the server's certificate, and checks whether `test-team` is
allowed to run `datastore` with the secure naming information. The client
detects that `test-team` is not allowed to run the `datastore` service and the
authentication fails.

Note that, for non HTTP/HTTPS traffic, secure naming doesn't protect from DNS spoofing,
in which case the attacker modifies the destination IPs for the service.
Since TCP traffic does not contain `Host` information and Envoy can only
rely on the destination IP for routing, Envoy may route traffic to
services on the hijacked IPs. This DNS spoofing can happen even
before the client-side Envoy receives the traffic.

### Authentication architecture

You can specify authentication requirements for workloads receiving requests in
an Istio mesh using peer and request authentication policies. The mesh operator
uses `.yaml` files to specify the policies. The policies are saved in the Istio
configuration storage once deployed. The Istio controller watches the
configuration storage.

Upon any policy changes, the new policy is translated to the appropriate
configuration telling the PEP how to perform the required authentication
mechanisms. The control plane may fetch the public key and attach it to the
configuration for JWT validation. Alternatively, Istiod provides the path to the
keys and certificates the Istio system manages and installs them to the
application pod for mutual TLS. You can find more info in the [Identity and certificate management section](#pki).

Istio sends configurations to the targeted endpoints asynchronously. Once the
proxy receives the configuration, the new authentication requirement takes
effect immediately on that pod.

Client services, those that send requests, are responsible for following the
necessary authentication mechanism. For request authentication, the application is
responsible for acquiring and attaching the JWT credential to the request. For
peer authentication, Istio automatically upgrades all traffic between two PEPs to mutual
TLS. If authentication policies disable mutual TLS mode, Istio continues to use
plain text between PEPs. To override this behavior explicitly disable mutual
TLS mode with
[destination rules](/docs/concepts/traffic-management/#destination-rules).
You can find out more about how mutual TLS works in the
[Mutual TLS authentication section](/docs/concepts/security/#mutual-tls-authentication).

{{< image width="50%"
    link="./authn.svg"
    caption="Authentication Architecture"
    >}}

Istio outputs identities with both types of authentication, as well as other
claims in the credential if applicable, to the next layer:
[authorization](/docs/concepts/security/#authorization).

### Authentication policies

This section provides more details about how Istio authentication policies work.
As you'll remember from the
[Architecture section](/docs/concepts/security/#authentication-architecture),
authentication policies apply to requests that a service receives. To specify
client-side authentication rules in mutual TLS, you need to specify the
`TLSSettings` in the `DestinationRule`. You can find more information in our
[TLS settings reference docs](/docs/reference/config/networking/destination-rule#ClientTLSSettings).

Like other Istio configurations, you can specify authentication policies in
`.yaml` files. You deploy policies using `kubectl`.
The following example authentication policy specifies that transport
authentication for the workloads with the `app:reviews` label must use mutual
TLS:

{{< text yaml >}}
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: "example-peer-policy"
  namespace: "foo"
spec:
  selector:
    matchLabels:
      app: reviews
  mtls:
    mode: STRICT
{{< /text >}}

#### Policy storage

Istio stores mesh-scope policies in the root namespace. These policies have an
empty selector apply to all workloads in the mesh. Policies that have a
namespace scope are stored in the corresponding namespace. They only apply to
workloads within their namespace. If you configure a `selector` field, the
authentication policy only applies to workloads matching the conditions you
configured.

Peer and request authentication policies are stored separately by kind,
`PeerAuthentication` and `RequestAuthentication` respectively.

#### Selector field

Peer and request authentication policies use `selector` fields to specify the
label of the workloads to which the policy applies. The following example shows
the selector field of a policy that applies to workloads with the
`app:product-page` label:

{{< text yaml >}}
selector:
  matchLabels:
    app: product-page
{{< /text >}}

If you don't provide a value for the `selector` field, Istio matches the policy
to all workloads in the storage scope of the policy. Thus, the `selector` fields
help you specify the scope of the policies:

- Mesh-wide policy: A policy specified for the root namespace without or
   with an empty `selector` field.
- Namespace-wide policy: A policy specified for a non-root namespace without
   or with an empty `selector` field.
- Workload-specific policy: a policy defined in the regular namespace, with
   non-empty selector field.

Peer and request authentication policies follow the same hierarchy principles
for the `selector` fields, but Istio combines and applies them in slightly
different ways.

There can be only one mesh-wide peer authentication policy, and only one
namespace-wide peer authentication policy per namespace. When you configure
multiple mesh- or namespace-wide peer authentication policies for the same mesh
or namespace, Istio ignores the newer policies. When more than one
workload-specific peer authentication policy matches, Istio picks the oldest
one.

Istio applies the narrowest matching policy for each workload using the
following order:

1. workload-specific
1. namespace-wide
1. mesh-wide

Istio can combine all matching request authentication policies to work as if
they come from a single request authentication policy. Thus, you can have
multiple mesh-wide or namespace-wide policies in a mesh or namespace. However,
it is still a good practice to avoid having multiple mesh-wide or namespace-wide
request authentication policies.

#### Peer authentication

Peer authentication policies specify the mutual TLS mode Istio enforces on
target workloads. The following modes are supported:

- PERMISSIVE: Workloads accept both mutual TLS and plain text traffic. This
    mode is most useful during migrations when workloads without sidecar cannot
    use mutual TLS. Once workloads are migrated with sidecar injection, you should
    switch the mode to STRICT.
- STRICT: Workloads only accept mutual TLS traffic.
- DISABLE: Mutual TLS is disabled. From a security perspective, you
    shouldn't use this mode unless you provide your own security solution.

When the mode is unset, the mode of the parent scope is inherited. Mesh-wide
peer authentication policies with an unset mode use the `PERMISSIVE` mode by
default.

The following peer authentication policy requires all workloads in namespace
`foo` to use mutual TLS:

{{< text yaml >}}
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: "example-policy"
  namespace: "foo"
spec:
  mtls:
    mode: STRICT
{{< /text >}}

With workload-specific peer authentication policies, you can specify different
mutual TLS modes for different ports. You can only use ports that workloads have
claimed for port-wide mutual TLS configuration. The following example disables
mutual TLS on port `80` for the `app:example-app` workload, and uses the mutual TLS
settings of the namespace-wide peer authentication policy for all other ports:

{{< text yaml >}}
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: "example-workload-policy"
  namespace: "foo"
spec:
  selector:
     matchLabels:
       app: example-app
  portLevelMtls:
    80:
      mode: DISABLE
{{< /text >}}

The peer authentication policy above works only because the service
configuration below bound the requests from the `example-app` workload to port
`80` of the `example-service`:

{{< text yaml >}}
apiVersion: v1
kind: Service
metadata:
  name: example-service
  namespace: foo
spec:
  ports:
  - name: http
    port: 8000
    protocol: TCP
    targetPort: 80
  selector:
    app: example-app
{{< /text >}}

#### Request authentication

Request authentication policies specify the values needed to validate a JSON Web
Token (JWT). These values include, among others, the following:

- The location of the token in the request
- The issuer or the request
- The public JSON Web Key Set (JWKS)

Istio checks the presented token, if presented against the rules in the request
authentication policy, and rejects requests with invalid tokens. When requests
carry no token, they are accepted by default. To reject requests without tokens,
provide authorization rules that specify the restrictions for specific
operations, for example paths or actions.

Request authentication policies can specify more than one JWT if each uses a
unique location. When more than one policy matches a workload, Istio combines
all rules as if they were specified as a single policy. This behavior is useful
to program workloads to accept JWT from different providers. However, requests
with more than one valid JWT are not supported because the output principal of
such requests is undefined.

#### Principals

When you use peer authentication policies and mutual TLS, Istio extracts the
identity from the peer authentication into the `source.principal`. Similarly,
when you use request authentication policies, Istio assigns the identity from
the JWT to the `request.auth.principal`. Use these principals to set
authorization policies and as telemetry output.

### Updating authentication policies

You can change an authentication policy at any time and Istio pushes the new
policies to the workloads almost in real time. However, Istio can't guarantee
that all workloads receive the new policy at the same time. The following
recommendations help avoid disruption when updating your authentication
policies:

- Use intermediate peer authentication policies using the `PERMISSIVE` mode
  when changing the mode from `DISABLE` to `STRICT` and vice-versa. When all
  workloads  switch successfully to the desired mode, you can apply the policy
  with the final mode. You can use Istio telemetry to verify that workloads
  have switched successfully.
- When migrating request authentication policies from one JWT to another, add
  the rule for the new JWT to the policy without removing the old rule.
  Workloads then accept both types of JWT, and you can remove the old rule
  when all traffic switches to the new JWT. However, each JWT has to use a
  different location.

## Authorization

Istio's authorization features provide mesh-, namespace-, and workload-wide
access control for your workloads in the mesh. This level of control provides
the following benefits:

- Workload-to-workload and end-user-to-workload authorization.
- A simple API: it includes a single [`AuthorizationPolicy` CRD](/docs/reference/config/security/authorization-policy/),
  which is easy to use and maintain.
- Flexible semantics: operators can define custom conditions on Istio attributes, and use CUSTOM, DENY and ALLOW actions.
- High performance: Istio authorization (`ALLOW` and `DENY`) is enforced natively on Envoy.
- High compatibility: supports gRPC, HTTP, HTTPS and HTTP/2 natively, as well as any plain TCP protocols.

### Authorization architecture

The authorization policy enforces access control to the inbound traffic in the
server side Envoy proxy. Each Envoy proxy runs an authorization engine that authorizes requests at
runtime. When a request comes to the proxy, the authorization engine evaluates
the request context against the current authorization policies, and returns the
authorization result, either `ALLOW` or `DENY`. Operators specify Istio
authorization policies using `.yaml` files.

{{< image width="50%"
    link="./authz.svg"
    caption="Authorization Architecture"
    >}}

### Implicit enablement

You don't need to explicitly enable Istio's authorization features; they are available after installation.
To enforce access control to your workloads, you apply an authorization policy.

For workloads without authorization policies applied, Istio allows all requests.

Authorization policies support `ALLOW`, `DENY` and `CUSTOM` actions. You can apply multiple policies, each with a
different action, as needed to secure access to your workloads.

Istio checks for matching policies in layers, in this order: `CUSTOM`, `DENY`, and then `ALLOW`. For each type of action,
Istio first checks if there is a policy with the action applied, and then checks if the request matches the policy's
specification. If a request doesn't match a policy in one of the layers, the check continues to the next layer.

The following graph shows the policy precedence in detail:

{{< image width="50%" link="./authz-eval.png" caption="Authorization Policy Precedence">}}

When you apply multiple authorization policies to the same workload, Istio applies them additively.

### Authorization policies

To configure an authorization policy, you create an
[`AuthorizationPolicy` custom resource](/docs/reference/config/security/authorization-policy/).
An authorization policy includes a selector, an action, and a list of rules:

- The `selector` field specifies the target of the policy
- The `action` field specifies whether to allow or deny the request
- The `rules` specify when to trigger the action
    - The `from` field in the `rules` specifies the sources of the request
    - The `to` field in the `rules` specifies the operations of the request
    - The `when` field specifies the conditions needed to apply the rule

The following example shows an authorization policy that allows two sources, the
`cluster.local/ns/default/sa/sleep` service account and the `dev` namespace, to
access the workloads with the `app: httpbin` and `version: v1` labels in the
`foo` namespace when requests sent have a valid JWT token.

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
 name: httpbin
 namespace: foo
spec:
 selector:
   matchLabels:
     app: httpbin
     version: v1
 action: ALLOW
 rules:
 - from:
   - source:
       principals: ["cluster.local/ns/default/sa/sleep"]
   - source:
       namespaces: ["dev"]
   to:
   - operation:
       methods: ["GET"]
   when:
   - key: request.auth.claims[iss]
     values: ["https://accounts.google.com"]
{{< /text >}}

The following example shows an authorization policy that denies requests if the
source is not the `foo` namespace:

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
 name: httpbin-deny
 namespace: foo
spec:
 selector:
   matchLabels:
     app: httpbin
     version: v1
 action: DENY
 rules:
 - from:
   - source:
       notNamespaces: ["foo"]
{{< /text >}}

The deny policy takes precedence over the allow policy. Requests matching allow
policies can be denied if they match a deny policy. Istio evaluates deny
policies first to ensure that an allow policy can't bypass a deny policy.

#### Policy Target

You can specify a policy's scope or target with the
`metadata/namespace` field and an optional `selector` field.
A policy applies to the namespace in the `metadata/namespace` field. If
set its value to the root namespace, the policy applies to all namespaces in a
mesh. The value of the root namespace is configurable, and the default is
`istio-system`. If set to any other namespace, the policy only applies to the
specified namespace.

You can use a `selector` field to further restrict policies to apply to specific
workloads. The `selector` uses labels to select the target workload. The
selector contains a list of `{key: value}` pairs, where the `key` is the name of
the label. If not set, the authorization policy applies to all workloads in the
same namespace as the authorization policy.

For example, the `allow-read` policy allows `"GET"` and `"HEAD"` access to the
workload with the `app: products` label in the `default` namespace.

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: allow-read
  namespace: default
spec:
  selector:
    matchLabels:
      app: products
  action: ALLOW
  rules:
  - to:
    - operation:
         methods: ["GET", "HEAD"]
{{< /text >}}

#### Value matching

Most fields in authorization policies support all the following matching
schemas:

- Exact match: exact string match.
- Prefix match: a string with an ending `"*"`. For example, `"test.abc.*"`
   matches `"test.abc.com"`, `"test.abc.com.cn"`, `"test.abc.org"`, etc.
- Suffix match: a string with a starting `"*"`. For example, `"*.abc.com"`
   matches `"eng.abc.com"`, `"test.eng.abc.com"`, etc.
- Presence match: `*` is used to specify anything but not empty. To specify
   that a field must be present, use the `fieldname: ["*"]`format. This is
   different from leaving a field unspecified, which means match anything,
   including empty.

There are a few exceptions. For example, the following fields only support exact
match:

- The `key` field under the `when` section
- The `ipBlocks` under the `source` section
- The `ports` field under the `to` section

The following example policy allows access at paths with the `/test/*` prefix
or the `*/info` suffix.

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: tester
  namespace: default
spec:
  selector:
    matchLabels:
      app: products
  action: ALLOW
  rules:
  - to:
    - operation:
        paths: ["/test/*", "*/info"]
{{< /text >}}

#### Exclusion matching

To match negative conditions like `notValues` in the `when` field, `notIpBlocks`
in the `source` field, `notPorts` in the `to` field, Istio supports exclusion
matching.
The following example requires a valid request principals, which is derived from
JWT authentication, if the request path is not `/healthz`. Thus, the policy
excludes requests to the `/healthz` path from the JWT authentication:

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: disable-jwt-for-healthz
  namespace: default
spec:
  selector:
    matchLabels:
      app: products
  action: ALLOW
  rules:
  - to:
    - operation:
        notPaths: ["/healthz"]
    from:
    - source:
        requestPrincipals: ["*"]
{{< /text >}}

The following example denies the request to the `/admin` path for requests
without request principals:

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: enable-jwt-for-admin
  namespace: default
spec:
  selector:
    matchLabels:
      app: products
  action: DENY
  rules:
  - to:
    - operation:
        paths: ["/admin"]
    from:
    - source:
        notRequestPrincipals: ["*"]
{{< /text >}}

#### `allow-nothing`, `deny-all` and `allow-all` policy

The following example shows an `ALLOW` policy that matches nothing. If there are no other `ALLOW` policies, requests
will always be denied because of the "deny by default" behavior.

Note the "deny by default" behavior applies only if the workload has at least one authorization policy with the `ALLOW` action.

{{< tip >}}
It is a good security practice to start with the `allow-nothing` policy and incrementally add more `ALLOW` policies to open more
access to the workload.
{{< /tip >}}

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: allow-nothing
spec:
  action: ALLOW
  # the rules field is not specified, and the policy will never match.
{{< /text >}}

The following example shows a `DENY` policy that explicitly denies all access. It will always deny the request even if
there is another `ALLOW` policy allowing the request because the `DENY` policy takes precedence over the `ALLOW` policy.
This is useful if you want to temporarily disable all access to the workload.

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: deny-all
spec:
  action: DENY
  # the rules field has an empty rule, and the policy will always match.
  rules:
  - {}
{{< /text >}}

The following example shows an `ALLOW` policy that allows full access to the workload. It will make other `ALLOW` policies
useless as it will always allow the request. It might be useful if you want to temporarily expose full access to the
workload. Note the request could still be denied due to `CUSTOM` and `DENY` policies.

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: allow-all
spec:
  action: ALLOW
  # This matches everything.
  rules:
  - {}
{{< /text >}}

#### Custom conditions

You can also use the `when` section to specify additional conditions. For
example, the following `AuthorizationPolicy` definition includes a condition
that `request.headers[version]` is either `"v1"` or `"v2"`. In this case, the
key is `request.headers[version]`, which is an entry in the Istio attribute
`request.headers`, which is a map.

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
 name: httpbin
 namespace: foo
spec:
 selector:
   matchLabels:
     app: httpbin
     version: v1
 action: ALLOW
 rules:
 - from:
   - source:
       principals: ["cluster.local/ns/default/sa/sleep"]
   to:
   - operation:
       methods: ["GET"]
   when:
   - key: request.headers[version]
     values: ["v1", "v2"]
{{< /text >}}

The supported `key` values of a condition are listed on the [conditions page](/docs/reference/config/security/conditions/).

#### Authenticated and unauthenticated identity

If you want to make a workload publicly accessible, you need to leave the
`source` section empty. This allows sources from all (both authenticated and
unauthenticated) users and workloads, for example:

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
 name: httpbin
 namespace: foo
spec:
 selector:
   matchLabels:
     app: httpbin
     version: v1
 action: ALLOW
 rules:
 - to:
   - operation:
       methods: ["GET", "POST"]
{{< /text >}}

To allow only authenticated users, set `principals` to `"*"` instead, for
example:

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
 name: httpbin
 namespace: foo
spec:
 selector:
   matchLabels:
     app: httpbin
     version: v1
 action: ALLOW
 rules:
 - from:
   - source:
       principals: ["*"]
   to:
   - operation:
       methods: ["GET", "POST"]
{{< /text >}}

### Using Istio authorization on plain TCP protocols

Istio authorization supports workloads using any plain TCP protocols, such as
MongoDB. In this case, you configure the authorization policy in the same way
you did for the HTTP workloads. The difference is that certain fields and
conditions are only applicable to HTTP workloads. These fields include:

- The `request_principals` field in the source section of the authorization policy object
- The `hosts`, `methods` and `paths` fields in the operation section of the authorization policy object

The supported conditions are listed in the
[conditions page](/docs/reference/config/security/conditions/).
If you use any HTTP only fields for a TCP workload, Istio will ignore HTTP-only
fields in the authorization policy.

Assuming you have a MongoDB service on port `27017`, the following example
configures an authorization policy to only allows the `bookinfo-ratings-v2`
service in the Istio mesh to access the MongoDB workload.

{{< text yaml >}}
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: mongodb-policy
  namespace: default
spec:
 selector:
   matchLabels:
     app: mongodb
 action: ALLOW
 rules:
 - from:
   - source:
       principals: ["cluster.local/ns/default/sa/bookinfo-ratings-v2"]
   to:
   - operation:
       ports: ["27017"]
{{< /text >}}

### Dependency on mutual TLS

Istio uses mutual TLS to securely pass some information from the client to the server. Mutual TLS must be enabled before
using any of the following fields in the authorization policy:

- the `principals` and `notPrincipals` field under the `source` section
- the `namespaces` and `notNamespaces` field under the `source` section
- the `source.principal` custom condition
- the `source.namespace` custom condition

Note it is strongly recommended to always use these fields with **strict** mutual TLS mode in the `PeerAuthentication` to avoid
potential unexpected requests rejection or policy bypass when plain text traffic is used with the permissive mutual TLS mode.

Check the [security advisory](/news/security/istio-security-2021-004) for more details and alternatives if you cannot enable
strict mutual TLS mode.

## Learn more

After learning the basic concepts, there are more resources to review:

- Try out the security policy by following the [authentication](/docs/tasks/security/authentication/authn-policy)
  and [authorization](/docs/tasks/security/authorization) tasks.

- Learn some security [policy examples](/docs/ops/configuration/security/security-policy-examples) that could be
  used to improve security in your mesh.

- Read [common problems](/docs/ops/common-problems/security-issues/) to better troubleshoot security policy issues
  when something goes wrong.