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As organizations continue their digital transformation journey, one of the main factors that helps them is the ability to build and deploy solutions quickly.

Solutions built on a microservices-based architecture help solve the problem of breaking down complex tasks into manageable portions that can be built and deployed independently. However, managing a growing set of microservices across different business units within organizations can quickly become a huge headache, if not done well.

A service mesh framework like Istio provides the following advanced features to help improve availability and resiliency:. One of the main challenges of managing microservices-based solutions is how to properly secure not just the microservices themselves but also the communication between them and the access to these services by different kinds of users and external services. In a microservices-based architecture, you can implement security at the application layer, which includes architecting identity management and various authentication mechanisms to verify the identity of users and services into the application code itself.

This approach can quickly become painful to manage if you take into account scaling out these services. Here is where a service mesh technology like Istio can help. This tutorial focuses on how Istio manages security within a service mesh, specifically on how to use mutual transport layer security TLS to secure communication between services.


Istio supports two types of authentication:. TLS, a protocol designed to provide secure communication between apps, supports many algorithms to exchange keys and verify message integrity, and various ciphers to encrypt messages. As the number of services scales across multiple deployments, securing them properly can be a daunting task. Istio completely shifts the burden of configuring security for each individual service away from developers. Istio supports mutual TLS, which validates the identify of both the client and the server services.

The Citadel component in Istio manages the lifecycle of keys and certificates issued for services. When Istio establishes mutual TLS authentication, it uses these keys and certificates to exchange the identities of services. To establish a mutual TLS connection between two services, the envoy proxy on the client side establishes a mutual TLS handshake with the envoy proxy on the server side during which the client side envoy proxy verifies the identity of the server side and whether it is authorized to run the target service.

When the identities of the services are verified, the mutual TLS connection is established and the client service sends communication through the client side proxy to the server side proxy and finally to the target service. Services use authentication policies to define the kind of requests that a service receives, whether it is encrypted using mutual TLS or plain text.

Istio uses these authentication policies, along with service identities and service name checks, to establish mutual TLS connection between services. The authentication policies and secure naming information is distributed to the Envoy proxies by the Pilot component. The Mixer component handles the authorization and auditing part of Istio security. The following sections walk through the process of enabling mutual TLS connections between services in Istio.

You need to define a Policy object and DestinationRule object. You use a Policy object also called an authentication policy to define what kind of requests a service receives. A DestinationRule object applies to the traffic that is destined for a target service. It tells the client services whether to send encrypted traffic to the target service or to send plain-text requests. However in the Istio 1.

If you turn on this setting, services are automatically enabled with mutual TLS, and you only need to specify a Policy object a DestinationRule object is not needed. However, this tutorial details how to define the Policy object and a DestinationRule object to enable mutual TLS between services. You can apply a Policy object to specific services as defined in the targets section. Or, you can apply it to a wider scope, for example, to all services in a namespace or a mesh wide scope.

This example shows a MeshPolicy definition that applies to all services in the service mesh scope. There can be only one MeshPolicy defined for a service mesh, and its name should be defaultwith no targets key specified.

This example shows a namespace-scoped policy definition that applies to all services in the namespace, as specified in the namespace key.

Istio (v1.5) Demo of Features \u0026 Authorization on Kubernetes

There can be only one namespace-scoped definition for a namespace, with no targets key specified. Because no targets key is specified, the name must be default.

istio policy mtls

This example shows a policy definition for a specific service, as specified in the targets key.Imagine you have an Istio installation where mTLS is enabled for the whole cluster. You should have something like this:. In terms of configuration, you should have the following pieces:. Workloads are all the entities on the service mesh that are able to start communications with other services or ServiceEntries endpoints outside the service mesh.

For more information about the integrity of both rules, Kiali have the Istio Config Section. There you can list all the Istio Objects that are living in your cluster.

Thanks to the filtering, you can easily find both pieces of config described just above. Two different things need to be done. We will have to change the behavior for both clients and services again. It is important to apply the Policy first in order to allow all services to receive both plain and mTLS connections. If you apply the DestinationRule first, you would have all the workloads starting connections in plain but any service would be available to respond.

Regarding clients, we need to define a new DestinationRule overriding the trafficPolicy declared in the mesh-wide one. The overriding mechanism of Istio has nothing to do with the names of the config names.

Once both configs are published in the Service Mesh, this is what you should see:. Open lock in the edges of your service mesh shows that either part or all of the traffic is unencrypted not using mTLS. Right after applying the previous configs most of the traffic still uses mTLS. Nevertheless, locks on the edges warn that there is unencrypted traffic going through. The exact amount of mTLS traffic is displayed in the right hand side panel. After some time with mTLS disabled for the namespace, the graph snould be fully green with full traffic unencrypted.

However, your mesh-wide mTLS is still enabled. Therefore, when you want to disable traffic for either a namespace or a service you do not want to have traffic using mTLS. So this goes against the MeshPolicy definition. As we can see, our service mesh has:. The important point here is that the DestinationRule has a problem.

Also important: Kiali warns you. See below:. Also, Kiali suggests that you add a permissive policy. In order to fix that, you have two options: either set MeshPolicy to permissive mode which is not good practice or add a Policy in permissive mode to bookinfo namespace as we saw in the first part of this article.

Sign in. Istio adventures — disabling mTLS for one namespace. Xavier Canal Follow. Thanks to Alissa Bonas.

Software engineer at Red Hat. Written by Xavier Canal Follow. More From Medium. Angular Refactoring Examples. Go Modules Done Better.Many techniques evolved to help ease this requirement and enable businesses to focus on business value. Unless you are a security expert, it is challenging to implement these techniques correctly. Even seasoned security professionals can find it difficult to implement and audit such systems. A service mesh helps to alleviate these concerns with the goal of drastically lessening the burden of securing and auditing such systems, enabling users to focus on their core products.

However, very few deployments of Istio are in green-field environments where services are slowly adopted, created and can be monitored independently before new services are rolled out. In these cases, users will most likely adopt mTLS gradually service-by-service and will carefully monitor traffic behavior before proceeding to the next service. A common problem that many users experience when enabling mTLS for service communication in their service mesh is inadvertently breaking traffic.

Until such capability exists there are techniques and tools which we will discuss to aid you in debugging traffic management issues. At Aspen Mesh we are trying to enable our users to feel confident in their ability to manage their infrastructure. We will now walk-through debugging policy issues when using Aspen Mesh. The graph suggests that there is a problem with traffic generator communicating with productpage.

We will first inspect policy settings and logs of our services. The output will be similar to the following:. For this example it was a fairly simple fix. Here are a couple of checks to aid you in diagnosing the issue to see if it is related to an mTLS issue.

In most cases this will be all of the debugging you will have to do. However, we can also dig deeper to understand the issue and it never hurts to know more about the underlying infrastructure of your system. Remember that in a distributed system changes may take a while to propagate through a system and both Pilot and Mixer are responsible for passing configuration and enforcing policy, respectively. This helps us understand that it is likely to be an mTLS issue. This is a very strong indication that the TLS handshake failed.

If you look closely at that returned object you can also inspect and verify rules being applied.

istio policy mtls

Istio is a incredibly sophisticated and powerful tool. Similar to other such tools, it requires expertise to get the most out of it, but the rewards are greater than the challenge.

Aspen Mesh is committed to enabling Istio and our customers to succeed. As our platform matures, we will continue to help users by surfacing use cases and examples like in the above service graph, along with further in-depth ways to diagnose and troubleshoot issues. Keep an eye on our blog for future announcements. Save my name, email, and website in this browser for the next time I comment.This task shows how to ensure your workloads only communicate using mutual TLS as they are migrated to Istio.

Istio automatically configures workload sidecars to use mutual TLS when calling other workloads. Understand Istio authentication policy and related mutual TLS authentication concepts. Read the authentication policy task to learn how to configure authentication policy. Have a Kubernetes cluster with Istio installed, without global mutual TLS enabled for example, use the default configuration profile as described in installation steps.

Create two namespaces, foo and barand deploy httpbin and sleep with sidecars on both of them:. Create another namespace, legacyand deploy sleep without a sidecar:. Verify the setup by sending http requests using curl from the sleep pods, in namespaces foobar and legacyto httpbin. All requests should succeed with return code After migrating all clients to Istio and injecting the Envoy sidecar, you can lock down workloads in the foo namespace to only accept mutual TLS traffic.

Now, you should see the request from sleep. If you installed Istio with values. You will see plain text and encrypted text in the output when requests are sent from sleep. We recommend you use Istio Authorization to configure different paths with different authorization policies.

Now, both the foo and bar namespaces enforce mutual TLS only traffic, so you should see requests from sleep. Authentication Policy. Shows you how to use Istio authentication policy to setup mutual TLS and basic end-user authentication. Authorization Policy Trust Domain Migration. Shows how to migrate from one trust domain to another without changing authorization policy. Introducing Workload Entries. Istio in - Following the Trade Winds.

Remove cross-pod unix domain sockets.

Application security with mutual TLS (mTLS) via Istio

Concepts What is Istio? Traffic Management Security Observability Extensibility. Authentication Policy Shows you how to use Istio authentication policy to setup mutual TLS and basic end-user authentication.

Authorization Policy Trust Domain Migration Shows how to migrate from one trust domain to another without changing authorization policy. Security Describes Istio's authorization and authentication functionality. Remove cross-pod unix domain sockets A more secure way to manage secrets. Was this information useful? Yes No.This task covers the primary activities you might need to perform when enabling, configuring, and using Istio authentication policies.

Find out more about the underlying concepts in the authentication overview. Understand Istio authentication policy and related mutual TLS authentication concepts.

Install Istio on a Kubernetes cluster with the default configuration profile, as described in installation steps. Our examples use two namespaces foo and barwith two services, httpbin and sleepboth running with an Envoy proxy.

We also use second instances of httpbin and sleep running without the sidecar in the legacy namespace. You can verify setup by sending an HTTP request with curl from any sleep pod in the namespace foobar or legacy to either httpbin. All requests should succeed with HTTP code For example, here is a command to check sleep.

Last but not least, verify that there are no destination rules that apply on the example services. You can do this by checking the host: value of existing destination rules and make sure they do not match. For example:. By default, Istio tracks the server workloads migrated to Istio proxies, and configures client proxies to send mutual TLS traffic to those workloads automatically, and to send plain text traffic to workloads without sidecars.

Thus, all traffic between workloads with proxies uses mutual TLS, without you doing anything. While Istio automatically upgrades all traffic between the proxies and the workloads to mutual TLS, workloads can still receive plain text traffic.

The mesh-wide peer authentication policy should not have a selector and must be applied in the root namespacefor example:. This peer authentication policy configures workloads to only accept requests encrypted with TLS. This is expected because mutual TLS is now strictly required, but the workload without sidecar cannot comply.

To change mutual TLS for all workloads within a particular namespace, use a namespace-wide policy. The specification of the policy is the same as for a mesh-wide policy, but you specify the namespace it applies to under metadata. For example, the following peer authentication policy enables strict mutual TLS for the foo namespace:. As this policy is applied on workloads in namespace foo only, you should see only request from client-without-sidecar sleep.Authorization policy supports both allow and deny policies.

When allow and deny policies are used for a workload at the same time, the deny policies are evaluated first. The evaluation is determined by the following rules:. AUDIT policies do not affect whether requests are allowed or denied to the workload. A request will be internally marked that it should be audited if there is an AUDIT policy on the workload that matches the request.

A separate plugin must be configured and enabled to actually fulfill the audit decision and complete the audit behavior. The request will not be audited if there are no such supporting plugins enabled. Currently, the only supported plugin is the Telemetry v2 Stackdriver plugin. For example, the following authorization policy denies all requests to workloads in namespace foo. Workload selector decides where to apply the authorization policy.

Secure communication between services in Istio with mutual TLS

If not set, the authorization policy will be applied to all workloads in the same namespace as the authorization policy. A list of rules to match the request. A match occurs when at least one rule matches the request. If not set, the match will never occur.

This is equivalent to setting a default of deny for the target workloads.

istio policy mtls

Rule matches requests from a list of sources that perform a list of operations subject to a list of conditions. A match occurs when at least one source, operation and condition matches the request. An empty rule is always matched. A list of source peer identities i. This field requires mTLS enabled. A list of request identities i. Single IP e. The name of an Istio attribute. See the full list of supported attributes. A list of allowed values for the attribute.

A list of negative match of values for the attribute. Concepts What is Istio? Traffic Management Security Observability Extensibility. From Rule.

To AuthorizationPolicy. Authorization Policy Conditions. Was this information useful? Yes No. Do you have any suggestions for improvement? If not set, any source is allowed. If not set, any operation is allowed.

If not set, any condition is allowed. If not set, any principal is allowed.For external, public-facing websites, this is an acceptable and well-established implementation of TLS.

But what about communication between different microservices? But this does raise some challenges. For example:. Installing and configuring Istio can be found on a previous blog post. By default, the policy specifies no mTLS between the respective services. As such, the topology of the solution is depicted below:.

Therefore mTLS has not been configured yet. This is accomplished with Policy and Destination rules. This example enforces the use of mutual TLS when communicating with any service in the wordpress-app namespace.

Applying these and re-running the previous istioctl command yields the following result:. This differs from a standard HTTPs site described earlier on where only the client was validating the server. Your email address will not be published.

Save my name, email, and website in this browser for the next time I comment. Virtual Thoughts. Search for:. The web server responds with its public key. The client validates the key with its list of known Certificate Authorities. The web server decrypts the session key with its private key.

End to end encryption is established. For example: How do we ensure service-to-service communication is always encrypted? How can we automatically secure communication when we introduce a new service to an application?

WordPress Envoy sidecar pod intercepts this and establishes a connection to the destination sidecar pod and presents its certificate for authenticity. A more flexible alternative to this is to employ an Istio gateway that provides TLS termination at the cluster boundary. This negates the need to provision x certs to each and every client, whilst maintaining mTLS within the cluster.

Envoy sidecar pods can affect liveness probes and might require you to implement sidecarInjectorWebhook.

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