Ingress Access Control

11 minute read page test

This task shows you how to enforce IP-based access control on an Istio ingress gateway using an authorization policy.

Istio supports the Kubernetes Gateway API and intends to make it the default API for traffic management in the future. The following instructions allow you to choose to use either the Gateway API or the Istio configuration API when configuring traffic management in the mesh. Follow instructions under either the Gateway API or Istio APIs tab, according to your preference.

Note that the Kubernetes Gateway API CRDs do not come installed by default on most Kubernetes clusters, so make sure they are installed before using the Gateway API:

$ kubectl get crd gateways.gateway.networking.k8s.io &> /dev/null || \
  { kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.2.0/standard-install.yaml; }

Before you begin

Before you begin this task, do the following:

Read the Istio authorization concepts.
Install Istio using the Istio installation guide.

Deploy a workload, httpbin, in namespace foo with sidecar injection enabled:

$ kubectl create ns foo
$ kubectl label namespace foo istio-injection=enabled
$ kubectl apply -f @samples/httpbin/httpbin.yaml@ -n foo

Expose httpbin through an ingress gateway:

Configure the gateway:

$ kubectl apply -f @samples/httpbin/httpbin-gateway.yaml@ -n foo

Turn on RBAC debugging in Envoy for the ingress gateway:

$ kubectl get pods -n istio-system -o name -l istio=ingressgateway | sed 's|pod/||' | while read -r pod; do istioctl proxy-config log "$pod" -n istio-system --level rbac:debug; done

Follow the instructions in Determining the ingress IP and ports to define the INGRESS_PORT and INGRESS_HOST environment variables.

Create the gateway:

$ kubectl apply -f @samples/httpbin/gateway-api/httpbin-gateway.yaml@ -n foo

Wait for the gateway to be ready:

$ kubectl wait --for=condition=programmed gtw -n foo httpbin-gateway

Turn on RBAC debugging in Envoy for the ingress gateway:

$ kubectl get pods -n foo -o name -l gateway.networking.k8s.io/gateway-name=httpbin-gateway | sed 's|pod/||' | while read -r pod; do istioctl proxy-config log "$pod" -n foo --level rbac:debug; done

Set the INGRESS_PORT and INGRESS_HOST environment variables:

$ export INGRESS_HOST=$(kubectl get gtw httpbin-gateway -n foo -o jsonpath='{.status.addresses[0].value}')
$ export INGRESS_PORT=$(kubectl get gtw httpbin-gateway -n foo -o jsonpath='{.spec.listeners[?(@.name=="http")].port}')

Verify that the httpbin workload and ingress gateway are working as expected using this command:
```
$ curl "$INGRESS_HOST:$INGRESS_PORT"/headers -s -o /dev/null -w "%{http_code}\n"
200
```
If you don’t see the expected output, retry after a few seconds. Caching and propagation overhead can cause a delay.

Getting traffic into Kubernetes and Istio

All methods of getting traffic into Kubernetes involve opening a port on all worker nodes. The main features that accomplish this are the NodePort service and the LoadBalancer service. Even the Kubernetes Ingress resource must be backed by an Ingress controller that will create either a NodePort or a LoadBalancer service.

A NodePort just opens up a port in the range 30000-32767 on each worker node and uses a label selector to identify which Pods to send the traffic to. You have to manually create some kind of load balancer in front of your worker nodes or use Round-Robin DNS.
A LoadBalancer is just like a NodePort, except it also creates an environment specific external load balancer to handle distributing traffic to the worker nodes. For example, in AWS EKS, the LoadBalancer service will create a Classic ELB with your worker nodes as targets. If your Kubernetes environment does not have a LoadBalancer implementation, then it will just behave like a NodePort. An Istio ingress gateway creates a LoadBalancer service.

What if the Pod that is handling traffic from the NodePort or LoadBalancer isn’t running on the worker node that received the traffic? Kubernetes has its own internal proxy called kube-proxy that receives the packets and forwards them to the correct node.

Source IP address of the original client

If a packet goes through an external proxy load balancer and/or kube-proxy, then the original source IP address of the client is lost. The following subsections describe some strategies for preserving the original client IP for logging or security purpose for different load balancer types:

For reference, here are the types of load balancers created by Istio with a LoadBalancer service on popular managed Kubernetes environments:

Cloud Provider	Load Balancer Name	Load Balancer Type
AWS EKS	Classic Elastic Load Balancer	TCP Proxy
GCP GKE	TCP/UDP Network Load Balancer	Network
Azure AKS	Azure Load Balancer	Network
IBM IKS/ROKS	Network Load Balancer	Network
DO DOKS	Load Balancer	Network

You can instruct AWS EKS to create a Network Load Balancer with an annotation on the gateway service:

apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  meshConfig:
    accessLogEncoding: JSON
    accessLogFile: /dev/stdout
  components:
    ingressGateways:
    - enabled: true
      k8s:
        hpaSpec:
          maxReplicas: 10
          minReplicas: 5
        serviceAnnotations:
          service.beta.kubernetes.io/aws-load-balancer-type: "nlb"

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: httpbin-gateway
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-type: "nlb"
spec:
  gatewayClassName: istio
  ...

TCP/UDP Proxy Load Balancer

If you are using a TCP/UDP Proxy external load balancer (AWS Classic ELB), it can use the PROXY Protocol to embed the original client IP address in the packet data. Both the external load balancer and the Istio ingress gateway must support the PROXY protocol for it to work.

Here is a sample configuration that shows how to make an ingress gateway on AWS EKS support the PROXY Protocol:

apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  meshConfig:
    accessLogEncoding: JSON
    accessLogFile: /dev/stdout
    defaultConfig:
      gatewayTopology:
        proxyProtocol: {}
  components:
    ingressGateways:
    - enabled: true
      name: istio-ingressgateway
      k8s:
        hpaSpec:
          maxReplicas: 10
          minReplicas: 5
        serviceAnnotations:
          service.beta.kubernetes.io/aws-load-balancer-proxy-protocol: "*"
        ...

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: httpbin-gateway
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-proxy-protocol: "*"
    proxy.istio.io/config: '{"gatewayTopology" : { "proxyProtocol": {} }}'
spec:
  gatewayClassName: istio
  ...
---
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: httpbin-gateway
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: httpbin-gateway-istio
  minReplicas: 5
  maxReplicas: 10

Network Load Balancer

If you are using a TCP/UDP network load balancer that preserves the client IP address (AWS Network Load Balancer, GCP External Network Load Balancer, Azure Load Balancer) or you are using Round-Robin DNS, then you can use the externalTrafficPolicy: Local setting to also preserve the client IP inside Kubernetes by bypassing kube-proxy and preventing it from sending traffic to other nodes.

Update the ingress gateway to set externalTrafficPolicy: Local to preserve the original client source IP on the ingress gateway using the following command:

$ kubectl patch svc istio-ingressgateway -n istio-system -p '{"spec":{"externalTrafficPolicy":"Local"}}'

$ kubectl patch svc httpbin-gateway-istio -n foo -p '{"spec":{"externalTrafficPolicy":"Local"}}'

HTTP/HTTPS Load Balancer

If you are using an HTTP/HTTPS external load balancer (AWS ALB, GCP ), it can put the original client IP address in the X-Forwarded-For header. Istio can extract the client IP address from this header with some configuration. See Configuring Gateway Network Topology. Quick example if using a single load balancer in front of Kubernetes:

apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  meshConfig:
    accessLogEncoding: JSON
    accessLogFile: /dev/stdout
    defaultConfig:
      gatewayTopology:
        numTrustedProxies: 1

IP-based allow list and deny list

When to use ipBlocks vs. remoteIpBlocks: If you are using the X-Forwarded-For HTTP header or the PROXY Protocol to determine the original client IP address, then you should use remoteIpBlocks in your AuthorizationPolicy. If you are using externalTrafficPolicy: Local, then you should use ipBlocks in your AuthorizationPolicy.

Load Balancer Type	Source of Client IP	`ipBlocks` vs. `remoteIpBlocks`
TCP Proxy	PROXY Protocol	`remoteIpBlocks`
Network	packet source address	`ipBlocks`
HTTP/HTTPS	X-Forwarded-For	`remoteIpBlocks`

The following command creates the authorization policy, ingress-policy, for the Istio ingress gateway. The following policy sets the action field to ALLOW to allow the IP addresses specified in the ipBlocks to access the ingress gateway. IP addresses not in the list will be denied. The ipBlocks supports both single IP address and CIDR notation.

ipBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: istio-system
spec:
  selector:
    matchLabels:
      app: istio-ingressgateway
  action: ALLOW
  rules:
  - from:
    - source:
        ipBlocks: ["1.2.3.4", "5.6.7.0/24"]
EOF

remoteIpBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: istio-system
spec:
  selector:
    matchLabels:
      app: istio-ingressgateway
  action: ALLOW
  rules:
  - from:
    - source:
        remoteIpBlocks: ["1.2.3.4", "5.6.7.0/24"]
EOF

ipBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: foo
spec:
  targetRef:
    kind: Gateway
    group: gateway.networking.k8s.io
    name: httpbin-gateway
  action: ALLOW
  rules:
  - from:
    - source:
        ipBlocks: ["1.2.3.4", "5.6.7.0/24"]
EOF

remoteIpBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: foo
spec:
  targetRef:
    kind: Gateway
    group: gateway.networking.k8s.io
    name: httpbin-gateway
  action: ALLOW
  rules:
  - from:
    - source:
        remoteIpBlocks: ["1.2.3.4", "5.6.7.0/24"]
EOF

Verify that a request to the ingress gateway is denied:

$ curl "$INGRESS_HOST:$INGRESS_PORT"/headers -s -o /dev/null -w "%{http_code}\n"
403

Assign your original client IP address to an env variable. If you don’t know it, you can an find it in the Envoy logs using the following command:

ipBlocks:

$ CLIENT_IP=$(kubectl get pods -n istio-system -o name -l istio=ingressgateway | sed 's|pod/||' | while read -r pod; do kubectl logs "$pod" -n istio-system | grep remoteIP; done | tail -1 | awk -F, '{print $3}' | awk -F: '{print $2}' | sed 's/ //') && echo "$CLIENT_IP"
192.168.10.15

remoteIpBlocks:

$ CLIENT_IP=$(kubectl get pods -n istio-system -o name -l istio=ingressgateway | sed 's|pod/||' | while read -r pod; do kubectl logs "$pod" -n istio-system | grep remoteIP; done | tail -1 | awk -F, '{print $4}' | awk -F: '{print $2}' | sed 's/ //') && echo "$CLIENT_IP"
192.168.10.15

ipBlocks:

$ CLIENT_IP=$(kubectl get pods -n foo -o name -l gateway.networking.k8s.io/gateway-name=httpbin-gateway | sed 's|pod/||' | while read -r pod; do kubectl logs "$pod" -n foo | grep remoteIP; done | tail -1 | awk -F, '{print $3}' | awk -F: '{print $2}' | sed 's/ //') && echo "$CLIENT_IP"
192.168.10.15

remoteIpBlocks:

$ CLIENT_IP=$(kubectl get pods -n foo -o name -l gateway.networking.k8s.io/gateway-name=httpbin-gateway | sed 's|pod/||' | while read -r pod; do kubectl logs "$pod" -n foo | grep remoteIP; done | tail -1 | awk -F, '{print $4}' | awk -F: '{print $2}' | sed 's/ //') && echo "$CLIENT_IP"
192.168.10.15

Update the ingress-policy to include your client IP address:

ipBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: istio-system
spec:
  selector:
    matchLabels:
      app: istio-ingressgateway
  action: ALLOW
  rules:
  - from:
    - source:
        ipBlocks: ["1.2.3.4", "5.6.7.0/24", "$CLIENT_IP"]
EOF

remoteIpBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: istio-system
spec:
  selector:
    matchLabels:
      app: istio-ingressgateway
  action: ALLOW
  rules:
  - from:
    - source:
        remoteIpBlocks: ["1.2.3.4", "5.6.7.0/24", "$CLIENT_IP"]
EOF

ipBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: foo
spec:
  targetRef:
    kind: Gateway
    group: gateway.networking.k8s.io
    name: httpbin-gateway
  action: ALLOW
  rules:
  - from:
    - source:
        ipBlocks: ["1.2.3.4", "5.6.7.0/24", "$CLIENT_IP"]
EOF

remoteIpBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: foo
spec:
  targetRef:
    kind: Gateway
    group: gateway.networking.k8s.io
    name: httpbin-gateway
  action: ALLOW
  rules:
  - from:
    - source:
        remoteIpBlocks: ["1.2.3.4", "5.6.7.0/24", "$CLIENT_IP"]
EOF

Verify that a request to the ingress gateway is allowed:

$ curl "$INGRESS_HOST:$INGRESS_PORT"/headers -s -o /dev/null -w "%{http_code}\n"
200

Update the ingress-policy authorization policy to set the action key to DENY so that the IP addresses specified in the ipBlocks are not allowed to access the ingress gateway:

ipBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: istio-system
spec:
  selector:
    matchLabels:
      app: istio-ingressgateway
  action: DENY
  rules:
  - from:
    - source:
        ipBlocks: ["$CLIENT_IP"]
EOF

remoteIpBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: istio-system
spec:
  selector:
    matchLabels:
      app: istio-ingressgateway
  action: DENY
  rules:
  - from:
    - source:
        remoteIpBlocks: ["$CLIENT_IP"]
EOF

ipBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: foo
spec:
  targetRef:
    kind: Gateway
    group: gateway.networking.k8s.io
    name: httpbin-gateway
  action: DENY
  rules:
  - from:
    - source:
        ipBlocks: ["$CLIENT_IP"]
EOF

remoteIpBlocks:

$ kubectl apply -f - <<EOF
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: ingress-policy
  namespace: foo
spec:
  targetRef:
    kind: Gateway
    group: gateway.networking.k8s.io
    name: httpbin-gateway
  action: DENY
  rules:
  - from:
    - source:
        remoteIpBlocks: ["$CLIENT_IP"]
EOF

Verify that a request to the ingress gateway is denied:

$ curl "$INGRESS_HOST:$INGRESS_PORT"/headers -s -o /dev/null -w "%{http_code}\n"
403

You could use an online proxy service to access the ingress gateway using a different client IP to verify the request is allowed.
If you are not getting the responses you expect, view the ingress gateway logs which should show RBAC debugging information:

$ kubectl get pods -n istio-system -o name -l istio=ingressgateway | sed 's|pod/||' | while read -r pod; do kubectl logs "$pod" -n istio-system; done

$ kubectl get pods -n foo -o name -l gateway.networking.k8s.io/gateway-name=httpbin-gateway | sed 's|pod/||' | while read -r pod; do kubectl logs "$pod" -n foo; done

Clean up

Remove the authorization policy:

$ kubectl delete authorizationpolicy ingress-policy -n istio-system

$ kubectl delete authorizationpolicy ingress-policy -n foo

Remove the namespace foo:
```
$ kubectl delete namespace foo
```