Tetrate Enterprise Gateway for Envoy—the cloud-native service gateway—has reached 1.0!

Learn more › close
Tetrate Enterprise ready service mesh
Get Demo
Pricing
Home

|

Blog

|

ISTIO: How to enforce egress traffic using Istio’s authorization policies

ISTIO: How to enforce egress traffic using Istio’s authorization policies

| Author: Michael Acostamadiedo

Service Mesh Architecture

Article content

Istio - Enforce egress traffic

An Istio Egress gateway is just another envoy instance similar to the Ingress but with the purpose to control outbound traffic. Istio uses ingress and egress gateways to configure load balancers executing at the edge of a service mesh. An ingress gateway allows you to define entry points into the mesh that all incoming traffic flows through. Egress gateway is a symmetrical concept; it defines exit points from the mesh. Egress gateways allow you to apply Istio features, for example, monitoring and route rules, to traffic exiting the mesh.

This article describes how to enforce outbound authorization policies using Istio’s Egress gateway in a similar matter when enforcing inbound policies. For this we use the sleep service in two separate namespaces within the mesh to access external services at Google and Yahoo.

NOTE: One important consideration to be aware of is that Istio cannot securely enforce that all egress traffic actually flows through the egress gateways. Istio only enables such flow through its sidecar proxies. If attackers bypass the sidecar proxy, they could directly access external services without traversing the egress gateway. Kubernetes network policies (see k8s-network-policy.yaml file) can be used to prevent outbound traffic at the cluster level, see Egress Gateways.

Before starting

Before starting you need:

  • a kubernetes cluster
  • istioctl
  • sleep service

Prep-work
Install istio:

istioctl install -y --set profile=demo --set meshConfig.outboundTrafficPolicy.mode=ALLOW_ANY

Notice the demo profile installs an instance of an Egress gateway and we are configuring the handling of external services by using the outboundTrafficPolicy option. ALLOW_ANY is the default option enabling access to outbound services and REGISTRY_ONLY gets the proxies to block access if the host is not defined in the service registry using the ServiceEntry resource.

This article’s resources can be found here.

Install the sleep service in the default namespace

Label the namespace for sidecar injection:

kubectl label ns default istio-injection=enabled
kubectl apply -f https://raw.githubusercontent.com/istio/istio/master/samples/sleep/sleep.yaml

Install the sleep service in the otherns namespace

kubectl create ns otherns

Label the namespace for sidecar injection:

kubectl label ns otherns istio-injection=enabled

Apply the service resources:

raw.githubusercontent.com/istio/istio/master/samples/sleep/sleep.yaml

Export sleep pods name into variables

export SLEEP_POD1=$(kubectl get pod -l app=sleep -ojsonpath='{.items[0].metadata.name}')
export SLEEP_POD2=$(kubectl get pod -n otherns -l app=sleep -ojsonpath='{.items[0].metadata.name}')

Test sleep accessing Google and Yahoo

kubectl exec $SLEEP_POD1 -it -- curl -I https://developers.google.com

You should expect a similar response like:

HTTP/2 200 
last-modified: Mon, 18 Apr 2022 19:50:38 GMT
content-type: text/html; charset=utf-8
set-cookie: _ga_devsite=GA1.3.17352200.1651777078; Expires=Sat, 04-May-2024 18:57:58 GMT; Max-Age=63072000; Path=/
content-security-policy: base-uri 'self'; object-src 'none'; script-src 'strict-dynamic' 'unsafe-inline' https: http: 'nonce-6YT4DgbNb9SFKpYNAAh6BVQ1HrIWUp' 'unsafe-eval'; report-uri <https://csp.withgoogle.com/csp/devsite/v2>
strict-transport-security: max-age=63072000; includeSubdomains; preload
x-frame-options: SAMEORIGIN
x-xss-protection: 0
x-content-type-options: nosniff
cache-control: no-cache, must-revalidate
expires: 0
pragma: no-cache
x-cloud-trace-context: 3943a8b1bdf28d721eae4f82696ba2c4
content-length: 142275
date: Thu, 05 May 2022 18:57:58 GMT
server: Google Frontend

Now the other service:

kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

You should expect a similar response like:

HTTP/2 200 
referrer-policy: no-referrer-when-downgrade
strict-transport-security: max-age=15552000
x-frame-options: SAMEORIGIN
x-powered-by: Express
cache-control: private, max-age=0, no-cache
content-security-policy-report-only: default-src 'none'; connect-src 'self' *.yimg.com <https://www.google-analytics.com> *.yahoo.com *.doubleclick.net; font-src 'self' *.bootstrapcdn.com; frame-src 'self' *.soundcloud.com *.twitter.com; img-src 'self' data: *.yimg.com <https://www.google-analytics.com> *.yahoo.com <https://www.google.com/ads/ga-audiences> *.pendo.io *.twitter.com *.twimg.com; script-src 'self' 'nonce-25FqRrNIte3nmHy7Es/O4Q==' *.yimg.com <https://www.google-analytics.com> <https://ssl.google-analytics.com> *.github.com/flurrydev/ *.pendo.io *.twitter.com *.twimg.com; style-src 'self' 'unsafe-inline' *.yimg.com *.twitter.com *.twimg.com <https://github.githubassets.com/assets/> *.bootstrapcdn.com; report-uri /csp-report
content-type: text/html; charset=utf-8
content-length: 61158
etag: W/"eee6-355CS9JqgK79WnB2sdI2zK9AvBw"
vary: Accept-Encoding
date: Thu, 05 May 2022 19:00:06 GMT
x-envoy-upstream-service-time: 2315
server: ATS
age: 3
expect-ct: max-age=31536000, report-uri="<https://csp.yahoo.com/beacon/csp?src=yahoocom-expect-ct-report-only">
x-xss-protection: 1; mode=block
x-content-type-options: nosniff

If you want you can test the other other address on the other sleep pod. We can confirm the pods have outbound access to Google and Yahoo.

Block outbound access

Using istioctl we modify the istio installation to change the outbound traffic policy from ALLOW_ANY to REGISTRY_ONLY which enforces that only hosts defined with ServiceEntry resources are part of the mesh service registry; could be accessed to by sidecars of the mesh:

istioctl install -y --set profile=demo --set meshConfig.outboundTrafficPolicy.mode=REGISTRY_ONLY

Test sleep access again

kubectl exec $SLEEP_POD1 -it -- curl -I https://developers.google.com

You should expect a similar response like:

curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to developers.google.com:443 
command terminated with exit code 35

Now the other service:

kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

You should expect a similar response like:

curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to developer.yahoo.com:443 
command terminated with exit code 35

The error is due to the new policy enforcing only services part of the registry are allowed for outbound traffic.

NOTE: There could be a slight delay on the configuration being propagated to the sidecars where the still allow access to the external services.

Add the Google and Yahoo services to the mesh service registry

Our Google ServiceEntry looks like this:

apiVersion: networking.istio.io/v1beta1
kind: ServiceEntry
metadata:
  name: external-developers-google-com
spec:
  hosts:
  - developers.google.com
  exportTo:
  - "."
  location: MESH_EXTERNAL
  resolution: DNS
  ports:
  - number: 443
    name: https
    protocol: HTTPS
  - number: 80
    name: http
    protocol: HTTP

Apply the Google ServiceEntry resource:

kubectl apply -f google-serviceentry.yaml

Notice the exportTo: – “.” section of the service entry resource specifying that is only applicable to the current namespace where applied. You can also change this to “*” for all namespaces in the mesh.

Test access to the service:

P_POD1 -it -- curl -I https://developers.google.com

You should expect a 200 response code now. But what if we test this sleep service to Yahoo?

kubectl exec $SLEEP_POD1 -it -- curl -I https://developer.yahoo.com

You should expect an error along the lines:

curl: (35) OpenSSL SSL_connect: Connection reset by peer in connection to developer.yahoo.com:443 
command terminated with exit code 35

This is because we only allowed outbound traffic to Google from the default namespace where the SLEEP_POD1 lives. Any outbound traffic from SLEEP_POD2 should still be blocked, lets enabled traffic to Google:

kubectl apply -n otherns -f google-serviceentry.yaml

You should expect a 200 response code from both pods:

kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD1 -it -- curl -I https://developers.google.com

Notice how Yahoo is still blocked on both services. Take a look at the Yahoo’s ServiceEntry:

apiVersion: networking.istio.io/v1beta1
kind: ServiceEntry
metadata:
  name: external-developer-yahoo-com
spec:
  hosts:
  - developer.yahoo.com
  exportTo:
  - "."
  location: MESH_EXTERNAL
  resolution: DNS
  ports:
  - number: 443
    name: https
    protocol: HTTPS
  - number: 80
    name: http
    protocol: HTTP

Enable traffic on the default namespace and test it:

kubectl apply -f yahoo-serviceentry.yaml
kubectl exec $SLEEP_POD1 -it -- curl -I https://developer.yahoo.com

Now Yahoo on the otherns namespace:

kubectl apply -n otherns -f yahoo-serviceentry.yaml
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

You should expect a 200 response code from both pods. Any other request to other hosts that are not Yahoo or Google should be blocked and only allowed from the default and otherns namespaces.

Cleanup

kubectl delete -f google-serviceentry.yaml
kubectl delete -n otherns -f google-serviceentry.yaml
kubectl delete -f yahoo-serviceentry.yaml
kubectl delete -n otherns -f yahoo-serviceentry.yaml

Enforcing egress traffic using authorization policies

So far by changing the outbound traffic policy to REGISTRY_ONLY we can enforce how our proxy sidecars allow outbound traffic from the mesh to the external hosts only defined with our Service Entry resources, but we don’t have a fine-grained control with them.

Using the service entries is more like a opening/closing a “faucet” in the namespace and having to create resources per namespace will create a maintenance burden. You can change the resource to be scoped for all namespaces (“*”) and not just the target namespace but just with the ServiceEntry resource you can’t control which workload within the namespace can or cannot access an external host.

We can accomplish this fine-grained control with an AuthorizationPolicy after we flow internally originated outbound traffic to the Egress gateway making act as a proxy with the help of VirtualService, Gateway, DestinationRule resources along with ServiceEntrys on how outbound traffic should flow.

In a similar manner when dealing with inbound traffic routing, we can create DestinationRules that flow internal traffic from the sidecars to the egress and then a second DestinationRule that flows the traffic to actual external host.

These DestinationRules are bound to a VirtualService that matches traffic to the whole mesh Gateway and the Gateway defined for the external host. By doing this setup, we can rely on the previously explained ServiceEntry and AuthorizationPolicy resources to ensure that only allowed/denied outbound traffic defined for namespaces or principals (k8s ServiceAccount) can reach the external hosts.

NOTE: Is important to note that for this example relies on Istio’s automatic mutual TLS, this means services within the mesh send TLS traffic and we are only sending SIMPLE TLS traffic at the egress when requests leave the mesh to the actual external host. For mTLS origination for egress traffic the DestinationRule needs to define the secret name that holds the client credentials certificate and be on MUTUAL mode. See more details here.

Route internal outbound traffic to the egress gateway

After deleting the ServiceEntrys used on the previous section, make sure your mesh is still blocking outbound access, and that there are no other resources that can conflict with the configuration like other DestinationRules, VirtualServices, Gateways and AuthorizationPolicy:

kubectl exec $SLEEP_POD1 -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD1 -it -- curl -I https://developer.yahoo.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

For all requests expect an error along the lines:

curl: (35) OpenSSL SSL_connect: Connection reset by peer in connection to developer.yahoo.com:443 
command terminated with exit code 35

Analyze the following files: external-google.yaml and external-yahoo.yaml, where you can find:

  • a ServiceEntry to enable external access to these hosts
  • a Gateway resource for each host configuring the egress gateway instance for originating traffic to the external host
  • a VirtualService for each host bound for the entire mesh and the created Gateway resource configuration in order to match traffic from within the mesh (sidecars) to the egress and from the egress outbound to the external host
  • and a couple DestinationRules applied to the traffic after being routed by the VirtualService where the first defines internal traffic using the sni and relying on Istio’s automatic mTLS ISTIO_MUTUAL. The second rule defines how to initiate https connections to the actual external host.

Apply these resources and test accessing the services:

kubectl apply -f external-google.yaml -n istio-system
kubectl apply -f external-yahoo.yaml -n istio-system

NOTE: Notice this time we are applying all these resources on the istio-system namespace where the egress gateway instance resides. This is with the intention to easily manage egress traffic where the egress gateway instance resides, facilitating the management of the AuthorizationPolicys.

Access developers.google.com:

kubectl exec $SLEEP_POD1 -it -- curl -I <https://developers.google.com>

Expect a 200 response along the lines:

HTTP/1.1 200 OK
last-modified: Mon, 18 Apr 2022 19:50:38 GMT
content-type: text/html; charset=utf-8
set-cookie: _ga_devsite=GA1.3.878699971.1652214977; Expires=Thu, 09-May-2024 20:36:17 GMT; Max-Age=63072000; Path=/
content-security-policy: base-uri 'self'; object-src 'none'; script-src 'strict-dynamic' 'unsafe-inline' https: http: 'nonce-yp4hjMbNOIwavPWy28V4k9lOdtSb6X' 'unsafe-eval'; report-uri <https://csp.withgoogle.com/csp/devsite/v2>
strict-transport-security: max-age=63072000; includeSubdomains; preload
x-frame-options: SAMEORIGIN
x-xss-protection: 0
x-content-type-options: nosniff
cache-control: no-cache, must-revalidate
expires: 0
pragma: no-cache
x-cloud-trace-context: 61c3fe6ffc0bc6bc209d455b04d9d86e
content-length: 142287
date: Tue, 10 May 2022 20:36:17 GMT
server: envoy
x-envoy-upstream-service-time: 420

Tail the logs of the istio-proxy sidecar:

kubectl logs $SLEEP_POD1 -f -c istio-proxy

Expect and entry from the sidecar to the egress:

[2022-05-10T20:36:16.973Z] "HEAD / HTTP/1.1" 200 - via_upstream - "-" 0 0 421 420 "-" "curl/7.83.0-DEV" "5ab0ed38-2e77-92a8-bb44-0a07573cd530" "developers.google.com" "10.100.2.6:8080" outbound|80|google|istio-egressgateway.istio-system.svc.cluster.local 10.100.0.5:48236 173.194.217.101:80 10.100.0.5:48764 - -

Tail the logs of the egressgateway:

kubectl logs istio-egressgateway-66fdd867f4-kbrh4 -f -n istio-system

Expect and entry from the egress to the external host:

[2022-05-10T20:36:16.981Z] "HEAD / HTTP/2" 200 - via_upstream - "-" 0 0 395 394 "10.100.0.5" "curl/7.83.0-DEV" "5ab0ed38-2e77-92a8-bb44-0a07573cd530" "developers.google.com" "173.194.217.101:443" outbound|443||developers.google.com 10.100.2.6:51492 10.100.2.6:8080 10.100.0.5:48236 developers.google.com -

NOTE: Notice how the internal outbound traffic is intentionally originated using http in order to rely on Istio’s automatic mTLS within the mesh and then using the DestinationRule tls mode SIMPLE the egress instance does a secure request to the external host.

Repeat the same steps using the sleep service on the otherns for the Yahoo host:

kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

Expect an entry like the following on the sidecar logs:

[2022-05-10T20:51:37.091Z] "HEAD / HTTP/1.1" 200 - via_upstream - "-" 0 0 2389 2389 "-" "curl/7.83.0-DEV" "b2e32c17-2db4-925f-bbd7-c201b549f7ef" "developer.yahoo.com" "10.100.2.6:8080" outbound|80|yahoo|istio-egressgateway.istio-system.svc.cluster.local 10.100.1.6:38682 69.147.92.11:80 10.100.1.6:47940 - -

And on the egress:

[2022-05-10T20:51:37.099Z] "HEAD / HTTP/2" 200 - via_upstream - "-" 0 0 2364 2363 "10.100.1.6" "curl/7.83.0-DEV" "b2e32c17-2db4-925f-bbd7-c201b549f7ef" "developer.yahoo.com" "69.147.92.11:443" outbound|443||developer.yahoo.com 10.100.2.6:40486 10.100.2.6:8080 10.100.1.6:38682 developer.yahoo.com -

At this time you can test the other external host on the opposite sleep service and notice is still accessible:

kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD1 -it -- curl -I https://developer.yahoo.com

Expect 200 responses from either sleep service.

Enforce authorization polices

Although we can enforce denying access by removing ServiceEntry resources we can also do it with a more fine-grained control using AuthorizationPolicys after the correct configuration is in place.

Take a look at this authz-policy-allow-nothing.yaml policy that allows no traffic out:

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
 name: allow-nothing
 namespace: istio-system
spec:
  {}

Apply the authz-policy-allow-nothing.yaml file that enforces this purpose:

kubectl apply -f authz-policy-allow-nothing.yaml

Try to access the services again:

kubectl exec $SLEEP_POD1 -it -- curl -I https://developer.yahoo.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD1 -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

NOTE: Keep in mind some requests could be allowed while the configuration takes place

Expect a response along the lines:

HTTP/1.1 403 Forbidden
content-length: 19
content-type: text/plain
date: Tue, 10 May 2022 21:08:13 GMT
server: envoy
x-envoy-upstream-service-time: 13

Notice that even when applying the authz-policy-allow-google.yaml allowing the default ns to do requests to developers.google.com it still gets forbidden. This is because AuthorizationPolicys the DENY action is evaluated before the ALLOW one.

Delete the resources:

kubectl delete authorizationpolicies.security.istio.io -n istio-system allow-nothing external-allow-developers-google-com

Enforce policies per namespace

This use case allows the sleep service on the default namespace to access google but not yahoo and the for the sleep service on the otherns namespace it allows yahoo but not google.

Analyze the following policies:

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: external-deny-developers-google-com
  # No ns means that applies to all ns in a mesh
spec:
  # allow-list for the identities that can call the host
  action: DENY
  rules:
  - from:
    - source:
        namespaces: ["otherns"]
    when:
    - key: connection.sni
      values: 
      - developers.google.com
apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: external-deny-developer-yahoo-com
  # No ns means that applies to all ns in a mesh
spec:
  # allow-list for the identities that can call the host
  action: DENY
  rules:
  - from:
    - source:
        namespaces: ["default"]
    when:
    - key: connection.sni
      values: 
      - developer.yahoo.com

Apply the following policies:

kubectl apply -f authz-policy-deny-google.yaml -n istio-system
kubectl apply -f authz-policy-deny-yahoo.yaml -n istio-system

Try to access the services again:

kubectl exec $SLEEP_POD1 -it -- curl -I https://developer.yahoo.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD1 -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

For the first couple requests expect a 403 Forbidden response and for the last couple expect a 200 response.

Tail the logs for the egress gateway and expect an entry describing the policy matched:

[2022-05-10T21:51:49.396Z] "HEAD / HTTP/2" 403 - rbac_access_denied_matched_policy[ns[istio-system]-policy[external-deny-developer-yahoo-com]-rule[0]] - "-" 0 0 0 - "10.100.0.6" "curl/7.83.0-DEV" "a503ba03-f09a-914d-85a4-995a0c1d5b16" "developer.yahoo.com" "-" outbound|443||developer.yahoo.com - 10.100.2.6:8080 10.100.0.6:58370 developer.yahoo.com -

Delete the resources:

kubectl delete authorizationpolicies.security.istio.io -n istio-system external-deny-developer-yahoo-com external-deny-developers-google-com

Enforce policies per workload using service account principals

For this use case deploy another set of sleep services on the otherns namespace:

kubectl delete authorizationpolicies.security.istio.io -n istio-system external-deny-developer-yahoo-com external-deny-developers-google-com

The yaml file above is the traditional sleep service with custom names, see here.

This would create two new sleep-google and sleep-yahoo services besides the existing one. Save the pods names:

export SLEEP_POD_G=$(kubectl get pod -n otherns -l app=sleep-google -ojsonpath='{.items[0].metadata.name}')
export SLEEP_POD_Y=$(kubectl get pod -n otherns -l app=sleep-yahoo -ojsonpath='{.items[0].metadata.name}')

Apply the following policies that block the sleep-google service to access Yahoo and sleep-yahoo service to access Google within the otherns namespace still leaving access to both from the sleep service:

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: external-deny-developers-google-com
  # No ns means that applies to all ns in a mesh
spec:
  # allow-list for the identities that can call the host
  action: DENY
  rules:
  - from:
    - source:
        principals: ["cluster.local/ns/otherns/sa/sleep-yahoo"]
    when:
    - key: connection.sni
      values: 
      - developers.google.com
apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: external-deny-developer-yahoo-com
  # No ns means that applies to all ns in a mesh
spec:
  # allow-list for the identities that can call the host
  action: DENY
  rules:
  - from:
    - source:
        principals: ["cluster.local/ns/otherns/sa/sleep-google"]
    when:
    - key: connection.sni
      values: 
      - developer.yahoo.com
kubectl apply -f authz-policy-deny-google-custom.yaml -n istio-system 
kubectl apply -f authz-policy-deny-yahoo-custom.yaml -n istio-system

Test the policies:

kubectl exec $SLEEP_POD_G -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD_G -n otherns -it -- curl -I https://developer.yahoo.com
kubectl exec $SLEEP_POD_Y -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD_Y -n otherns -it -- curl -I https://developer.yahoo.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

The second and third responses should be 403 forbidden as they are from sleep-google to Yahoo and the third from sleep-yahoo to Google while the rest should be 200.

Enforce policies per workload using service account principals and TLS originated traffic

This is really similar to the use case described above, the difference is on the way the policies are matched using the sni and the configuration of the resources to be able to rely on istio’s mTLS between the sidecar and egress. Review the configuration for google and yahoo.

Review the policies:

For the sleep-yahoo svc SA principal on the otherns ns to block outbound traffic to google matching the sni host:

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: external-deny-developers-google-com
  # No ns means that applies to all ns in a mesh
spec:
  # allow-list for the identities that can call the host
  action: DENY
  rules:
  - from:
    - source:
        principals: ["cluster.local/ns/otherns/sa/sleep-yahoo"]
    when:
    - key: connection.sni
      values: 
      - developers.google.com

For the sleep-google svc SA principal on the otherns ns to block outbound traffic to yahoo matching the sni host:

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: external-deny-developer-yahoo-com
  # No ns means that applies to all ns in a mesh
spec:
  # allow-list for the identities that can call the host
  action: DENY
  rules:
  - from:
    - source:
        principals: ["cluster.local/ns/otherns/sa/sleep-google"]
    when:
    - key: connection.sni
      values: 
      - developer.yahoo.com

The connection.sni key is the main takeaway when doing TLS origination as the sni key prevents SSL errors mismatching the SAN.

Now testing you should get the following results (make sure only the two previous policies are in place):

kubectl exec $SLEEP_POD1 -it -- curl -I https://developer.yahoo.com
kubectl exec $SLEEP_POD1 -it -- curl -I https://developers.google.com

Both should be 200.

kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD2 -n otherns -it -- curl -I https://developer.yahoo.com

Both should be 200.

kubectl exec $SLEEP_POD_G -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD_G -n otherns -it -- curl -I https://developer.yahoo.com

The first one being the google pod should be able to access and get a 200, the second one should be blocked.

kubectl exec $SLEEP_POD_Y -n otherns -it -- curl -I https://developers.google.com
kubectl exec $SLEEP_POD_Y -n otherns -it -- curl -I https://developer.yahoo.com

The first one being the yahoo pod should be blocked because is trying to access google, the second one should be 200.

You successfully used AuthorizationPolicys to enforce internal outbound traffic through the egress gateway at the namespace level and the workload level. Feel free to contact us if you have any questions or request a meeting directly.

For future reference the code can be found here.

###

If you’re new to service mesh, Tetrate has a bunch of free online courses available at Tetrate Academy that will quickly get you up to speed with Istio and Envoy.

Are you using Kubernetes? Tetrate Enterprise Gateway for Envoy (TEG) is the easiest way to get started with Envoy Gateway for production use cases. Get the power of Envoy Proxy in an easy-to-consume package managed by the Kubernetes Gateway API. Learn more ›

Getting started with Istio? If you’re looking for the surest way to get to production with Istio, check out Tetrate Istio Subscription. Tetrate Istio Subscription has everything you need to run Istio and Envoy in highly regulated and mission-critical production environments. It includes Tetrate Istio Distro, a 100% upstream distribution of Istio and Envoy that is FIPS-verified and FedRAMP ready. For teams requiring open source Istio and Envoy without proprietary vendor dependencies, Tetrate offers the ONLY 100% upstream Istio enterprise support offering.

Get a Demo

Let's Get In Touch

For more information or a demo request, just drop us a message.

Contact Us