Testing mutual TLS

Through this task, you will learn how to:

  • Verify the Istio mutual TLS Authentication setup

  • Manually test the authentication

Before you begin

This task assumes you have a Kubernetes cluster:

Starting with Istio 0.7, you can use authentication policy to config mTLS for all/selected services in a namespace (repeated for all namespaces to get global setting). See authentication policy task

Verifying Istio’s mutual TLS authentication setup

The following commands assume the services are deployed in the default namespace. Use the parameter -n yournamespace to specify a namespace other than the default one.

Verifying Citadel

Verify the cluster-level Citadel is running:

$ kubectl get deploy -l istio=citadel -n istio-system
NAME            DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
istio-citadel   1         1         1            1           1m

Citadel is up if the “AVAILABLE” column is 1.

Verifying service configuration

  1. Verify AuthPolicy setting in ConfigMap.

    $ kubectl get configmap istio -o yaml -n istio-system | grep authPolicy | head -1
    

    Istio mutual TLS authentication is enabled if the line authPolicy: MUTUAL_TLS is uncommented (doesn’t have a #).

Testing the authentication setup

When running Istio with mutual TLS authentication turned on, you can use curl in one service’s Envoy to send request to other services. For example, after starting the Bookinfo sample application you can ssh into the Envoy container of productpage service, and send request to other services by curl.

There are several steps:

  1. get the productpage pod name command $ kubectl get pods -l app=productpage NAME READY STATUS RESTARTS AGE productpage-v1-4184313719-5mxjc 2/2 Running 0 23h

Make sure the pod is “Running”.

  1. ssh into the Envoy container

    $ kubectl exec -it productpage-v1-4184313719-5mxjc -c istio-proxy /bin/bash
    
  2. make sure the key/cert is in /etc/certs/ directory

    $ ls /etc/certs/
    cert-chain.pem   key.pem   root-cert.pem
    

cert-chain.pem is Envoy’s cert that needs to present to the other side. key.pem is Envoy’s private key paired with Envoy’s cert in cert-chain.pem. root-cert.pem is the root cert to verify the peer’s cert. In this example, we only have one Citadel in a cluster, so all Envoys have the same root-cert.pem.

  1. make sure ‘curl’ is installed by command $ curl If curl is installed, you should see something like plain curl: try 'curl --help' or 'curl --manual' for more information

Otherwise run the command below to start over

   $ kubectl apply -f <(istioctl kube-inject --debug -f samples/bookinfo/kube/bookinfo.yaml)

Istio proxy image does not have curl installed while the debug image does. The “–debug” flag in above command redeploys the service with debug image.

  1. send requests to another service, for example, details. command $ curl https://details:9080/details/0 -v --key /etc/certs/key.pem --cert /etc/certs/cert-chain.pem --cacert /etc/certs/root-cert.pem -k ... error fetching CN from cert:The requested data were not available. ... < HTTP/1.1 200 OK < content-type: text/html; charset=utf-8 < content-length: 1867 < server: envoy < date: Thu, 11 May 2017 18:59:42 GMT < x-envoy-upstream-service-time: 2 ...

The service name and port are defined here.

Note that Istio uses Kubernetes service accounts as service identity, which offers stronger security than service name (refer here for more information). Thus the certificates used in Istio do not have service names, which is the information that curl needs to verify server identity. As a result, we use curl option -k to prevent the curl client from aborting when failing to find and verify the server name (i.e., productpage.ns.svc.cluster.local) in the certificate provided by the server.

Please check secure naming for more information about how the client verifies the server’s identity in Istio.

What we are demonstrating and verifying above is that the server accepts the connection from the client. Try not giving the client --key and --cert and observe you are not allowed to connect and you do not get an HTTP 200.

What’s next

  • Learn more about the design principles behind Istio’s automatic mTLS authentication between all services in this blog.