IP Allowlist/Denylist

This task provides instructions for configuring IP allowlist/denylist on Envoy Gateway. IP allowlist/denylist checks if an incoming request is from an allowed IP address before routing the request to a backend service.

Envoy Gateway introduces a new CRD called SecurityPolicy that allows the user to configure IP allowlist/denylist. This instantiated resource can be linked to a Gateway, HTTPRoute or GRPCRoute resource.

Prerequisites

Follow the steps from the Quickstart task to install Envoy Gateway and the example manifest. Before proceeding, you should be able to query the example backend using HTTP.

Verify the Gateway status:

• kubectl
• egctl (experimental)

kubectl get gateway/eg -o yaml

egctl x status gateway -v

Configuration

Create a SecurityPolicy

The below SecurityPolicy restricts access to the backend service by allowing requests only from the IP addresses 10.0.1.0/24.

In this example, the default action is set to Deny, which means that only requests from the specified IP addresses with Allow action are allowed, and all other requests are denied. You can also change the default action to Allow to allow all requests except those from the specified IP addresses with Deny action.

• Apply from stdin
• Apply from file

cat <<EOF | kubectl apply -f -
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: authorization-client-ip
spec:
  targetRefs:
  - group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: backend
  authorization:
    defaultAction: Deny
    rules:
    - action: Allow
      principal:
        clientCIDRs:
        - 10.0.1.0/24
EOF

---
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: authorization-client-ip
spec:
  targetRefs:
  - group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: backend
  authorization:
    defaultAction: Deny
    rules:
    - action: Allow
      principal:
        clientCIDRs:
        - 10.0.1.0/24

Verify the SecurityPolicy configuration:

kubectl get securitypolicy/authorization-client-ip -o yaml

Original Source IP

It’s important to note that the IP address used for allowlist/denylist is the original source IP address of the request. You can use a ClientTrafficPolicy to configure how Envoy Gateway should determine the original source IP address.

For example, the below ClientTrafficPolicy configures Envoy Gateway to use the X-Forwarded-For header to determine the original source IP address. The numTrustedHops field specifies the number of trusted hops in the X-Forwarded-For header. In this example, the numTrustedHops is set to 1, which means that the first rightmost IP address in the X-Forwarded-For header is used as the original source IP address.

• Apply from stdin
• Apply from file

cat <<EOF | kubectl apply -f -
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: ClientTrafficPolicy
metadata:
  name: enable-client-ip-detection
spec:
  clientIPDetection:
    xForwardedFor:
      numTrustedHops: 1
  targetRefs:
    - group: gateway.networking.k8s.io
      kind: Gateway
      name: eg
EOF

---
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: ClientTrafficPolicy
metadata:
  name: enable-client-ip-detection
spec:
  clientIPDetection:
    xForwardedFor:
      numTrustedHops: 1
  targetRefs:
    - group: gateway.networking.k8s.io
      kind: Gateway
      name: eg

Testing

Ensure the GATEWAY_HOST environment variable from the Quickstart is set. If not, follow the Quickstart instructions to set the variable.

echo $GATEWAY_HOST

Send a request to the backend service without the X-Forwarded-For header:

curl -v -H "Host: www.example.com" "http://${GATEWAY_HOST}/"

You should see 403 Forbidden in the response, indicating that the request is not allowed.

* Connected to 172.18.255.200 (172.18.255.200) port 80
> GET /get HTTP/1.1
> Host: www.example.com
> User-Agent: curl/8.8.0-DEV
> Accept: */*
> 
* Request completely sent off
< HTTP/1.1 403 Forbidden
< content-length: 19
< content-type: text/plain
< date: Mon, 08 Jul 2024 04:23:31 GMT
< 
* Connection #0 to host 172.18.255.200 left intact
RBAC: access denied

Send a request to the backend service with the X-Forwarded-For header:

curl -v -H "Host: www.example.com" -H "X-Forwarded-For: 10.0.1.1" "http://${GATEWAY_HOST}/"

The request should be allowed and you should see the response from the backend service.

Clean-Up

Follow the steps from the Quickstart to uninstall Envoy Gateway and the example manifest.

Delete the SecurityPolicy and the ClientTrafficPolicy

kubectl delete securitypolicy/authorization-client-ip
kubectl delete clientTrafficPolicy/enable-client-ip-detection

Next Steps

Checkout the Developer Guide to get involved in the project.