istio.io/content/en/docs/tasks/security/authentication/mutual-tls/index.md

title	description	weight	keywords	aliases
Mutual TLS Deep-Dive	Shows you how to verify and test Istio's automatic mutual TLS authentication.	20	security mutual-tls	/docs/tasks/security/mutual-tls/

Through this task, you can have closer look at mutual TLS and learn its settings. This task assumes:

• You have completed the authentication policy task.

• You are familiar with using authentication policy to enable mutual TLS.

• Istio runs on Kubernetes with global mutual TLS enabled. You can follow our instructions to install Istio. If you already have Istio installed, you can add or modify authentication policies and destination rules to enable mutual TLS as described in this task.

• You have deployed the [httpbin]({{< github_tree >}}/samples/httpbin) and [sleep]({{< github_tree >}}/samples/sleep) with Envoy sidecar in the default namespace. For example, below is the command to deploy those services with manual sidecar injection:

  {{< text bash >}} $ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/httpbin.yaml@) $ kubectl apply -f <(istioctl kube-inject -f @samples/sleep/sleep.yaml@) {{< /text >}}

Verify Citadel runs properly

Citadel is Istio's key management service. Citadel must run properly for mutual TLS to work correctly. Verify the cluster-level Citadel runs properly with the following command:

{{< text bash >}} $ kubectl get deploy -l istio=citadel -n istio-system NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE istio-citadel 1 1 1 1 1m {{< /text >}}

Citadel is up if the "AVAILABLE" column is 1.

Verify keys and certificates installation

Istio automatically installs necessary keys and certificates for mutual TLS authentication in all sidecar containers. Run command below to confirm key and certificate files exist under /etc/certs:

{{< text bash >}} kubectl exec(kubectl get pod -l app=httpbin -o jsonpath={.items..metadata.name}) -c istio-proxy -- ls /etc/certs cert-chain.pem key.pem root-cert.pem {{< /text >}}

{{< tip >}} cert-chain.pem is Envoy's cert that needs to be presented 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. {{< /tip >}}

Use the openssl tool to check if certificate is valid (current time should be in between Not Before and Not After)

{{< text bash >}} kubectl exec(kubectl get pod -l app=httpbin -o jsonpath={.items..metadata.name}) -c istio-proxy -- cat /etc/certs/cert-chain.pem | openssl x509 -text -noout | grep Validity -A 2 Validity Not Before: May 17 23:02:11 2018 GMT Not After : Aug 15 23:02:11 2018 GMT {{< /text >}}

You can also check the identity of the client certificate:

{{< text bash >}} kubectl exec(kubectl get pod -l app=httpbin -o jsonpath={.items..metadata.name}) -c istio-proxy -- cat /etc/certs/cert-chain.pem | openssl x509 -text -noout | grep 'Subject Alternative Name' -A 1 X509v3 Subject Alternative Name: URI:spiffe://cluster.local/ns/default/sa/default {{< /text >}}

Please check Istio identity for more information about service identity in Istio.

Verify mutual TLS configuration

Use istioctl authn tls-check to check if the mutual TLS settings are in effect. The istioctl command needs the client's pod because the destination rule depends on the client's namespace. You can also provide the destination service to filter the status to that service only.

{{< tip >}} This tool only checks the consistency of the static TLS settings between destination rules and authentication policies. It doesn't take into account whether or not the corresponding workloads have sidecars or not. When they don't, the policy and destination rules are not enforced, so note that status CONFLICT doesn't always mean that traffic is broken. {{< /tip >}}

The following commands identify the authentication policy for the httpbin.default.svc.cluster.local service and identify the destination rules for the service as seen from the same pod of the sleep app:

{{< text bash >}} SLEEP_POD=(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name}) istioctl authn tls-check{SLEEP_POD} httpbin.default.svc.cluster.local {{< /text >}}

In the following example output you can see that:

• Mutual TLS is consistently setup for httpbin.default.svc.cluster.local on port 8000.
• Istio uses the mesh-wide default authentication policy.
• Istio has the default destination rule in the istio-system namespace.

{{< text plain >}} HOST:PORT STATUS SERVER CLIENT AUTHN POLICY DESTINATION RULE httpbin.default.svc.cluster.local:8000 OK STRICT ISTIO_MUTUAL /default istio-system/default {{< /text >}}

The output shows:

• STATUS: whether the TLS settings are consistent between the server, the httpbin service in this case, and the client or clients making calls to httpbin.

• SERVER: the mode used on the server.

• CLIENT: the mode used on the client or clients.

• AUTHN POLICY: the namespace and name of the authentication policy. If the policy is the mesh-wide policy, namespace is blank, as in this case: /default

• DESTINATION RULE: the namespace and name of the destination rule used.

To illustrate the case when there are conflicts, add a service-specific destination rule for httpbin with incorrect TLS mode:

{{< text bash >}} $ cat <<EOF | kubectl apply -f - apiVersion: "networking.istio.io/v1alpha3" kind: "DestinationRule" metadata: name: "bad-rule" namespace: "default" spec: host: "httpbin.default.svc.cluster.local" trafficPolicy: tls: mode: DISABLE EOF {{< /text >}}

Run the same istioctl command as above, you now see the status is CONFLICT, as client is in HTTP mode while server is in mTLS.

{{< text bash >}} istioctl authn tls-check{SLEEP_POD} httpbin.default.svc.cluster.local HOST:PORT STATUS SERVER CLIENT AUTHN POLICY DESTINATION RULE httpbin.default.svc.cluster.local:8000 CONFLICT mTLS HTTP /default default/bad-rule {{< /text >}}

You can also confirm that requests from sleep to httpbin are now failing:

{{< text bash >}} kubectl exec(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name}) -c sleep -- curl httpbin:8000/headers -o /dev/null -s -w '%{http_code}\n' 503 {{< /text >}}

Before you continue, remove the bad destination rule to make mutual TLS work again with the following command:

{{< text bash >}} $ kubectl delete destinationrule --ignore-not-found=true bad-rule {{< /text >}}

Verify requests

This task shows how a server with mutual TLS enabled responses to requests that are:

• In plain-text
• With TLS but without client certificate
• With TLS with a client certificate

To perform this task, you want to by-pass client proxy. A simplest way to do so is to issue request from istio-proxy container.

1. Confirm that plain-text requests fail as TLS is required to talk to httpbin with the following command:

   {{< text bash >}} kubectl exec(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name}) -c istio-proxy -- curl http://httpbin:8000/headers -o /dev/null -s -w '%{http_code}\n' 000 command terminated with exit code 56 {{< /text >}}

   {{< tip >}} Note that the exit code is 56. The code translates to a failure to receive network data. {{< /tip >}}

2. Confirm TLS requests without client certificate also fail:

   {{< text bash >}} kubectl exec(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name}) -c istio-proxy -- curl https://httpbin:8000/headers -o /dev/null -s -w '%{http_code}\n' -k 000 command terminated with exit code 35 {{< /text >}}

   {{< tip >}} This time the exit code is 35, which corresponds to a problem occurring somewhere in the SSL/TLS handshake. {{< /tip >}}

3. Confirm TLS request with client certificate succeed:

   {{< text bash >}} kubectl exec(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name}) -c istio-proxy -- curl https://httpbin:8000/headers -o /dev/null -s -w '%{http_code}\n' --key /etc/certs/key.pem --cert /etc/certs/cert-chain.pem --cacert /etc/certs/root-cert.pem -k 200 {{< /text >}}

{{< tip >}} Istio uses Kubernetes service accounts as service identity, which offers stronger security than service name (for more details, see Istio identity). Thus, the certificates Istio uses do not have service names, which is the information that curl needs to verify server identity. To prevent the curl client from aborting, we use curl with the -k option. The option prevents the client from verifying and looking for the server name, for example, httpbin.default.svc.cluster.local in the certificate provided by the server. {{< /tip >}}

Cleanup

{{< text bash >}} $ kubectl delete --ignore-not-found=true -f @samples/httpbin/httpbin.yaml@ $ kubectl delete --ignore-not-found=true -f @samples/sleep/sleep.yaml@ {{< /text >}}