# JWT Verification

This example demonstrates how to verify the Pomerium JWT assertion header (opens new window) using Envoy (opens new window). This is useful for legacy or 3rd party applications which can't be modified to perform verification themselves.

This guide is a practical demonstration of some of the topics discussed in Mutual Authentication: A Component of Zero Trust.

# Requirements

This guide assumes you already have a working IdP connection to provide user data. See our Identity Provider docs for more information.

# Overview

Three services are configured in a docker-compose.yaml file:

  • pomerium running an all-in-one deployment of Pomerium on *.localhost.pomerium.io
  • envoy-jwt-checker running envoy with a JWT Authn filter
  • httpbin as our example legacy application without JWT verifivation.

In our Docker Compose configuration we'll define two networks. pomerium and envoy-jwt-checker will be on the frontend network, simulating your local area network (LAN). envoy-jwt-checker will also be on the backend network, along with httpbin. This means that envoy-jwt-checker is the only other service that can communicate with httpbin.

For a detailed explanation of this security model, see Mutual Authentication With a Sidecar

Once running, the user visits verify.localhost.pomerium.io (opens new window), is authenticated through authenticate.localhost.pomerium.io (opens new window), and then the HTTP request is sent to envoy which proxies it to the httpbin app.

Before allowing the request Envoy will verify the signed JWT assertion header using the public key defined by authenticate.localhost.pomerium.io/.well-known/pomerium/jwks.json.

# Setup

The configuration presented here assumes a working route to the domain space *.localhost.pomerium.io. You can make entries in your hosts file for the domains used, or change this value to match your local environment.

TIP

Mac and Linux users can use DNSMasq to map the *.localhost.pomerium.io domain (including all subdomains) to a specified test address:

  1. Create a docker-compose.yaml file containing:

    version: "3.9"
    networks:
      frontend:
        driver: "bridge"
      backend:
        driver: "bridge"
    services:
      pomerium:
        image: pomerium/pomerium:latest
        ports:
          - "443:443"
        volumes:
          - type: bind
            source: ./cfg/pomerium.yaml
            target: /pomerium/config.yaml
          - type: bind
            source: ./certs/_wildcard.localhost.pomerium.io.pem
            target: /pomerium/_wildcard.localhost.pomerium.io.pem
          - type: bind
            source: ./certs/_wildcard.localhost.pomerium.io-key.pem
            target: /pomerium/_wildcard.localhost.pomerium.io-key.pem
        networks:
          - frontend
    
      envoy-jwt-checker:
        image: envoyproxy/envoy:v1.17.1
        ports:
          - "10000:10000"
        volumes:
          - type: bind
            source: ./cfg/envoy.yaml
            target: /etc/envoy/envoy.yaml
        networks:
          frontend:
            aliases:
              - "httpbin-sidecar"
          backend:
    
      httpbin:
        image: kennethreitz/httpbin
        ports:
          - "80:80"
        networks:
          - backend
    
  2. Using mkcert (opens new window), generate a certificate for *.localhost.pomerium.io in a certs directory:

    mkdir certs
    cd certs
    mkcert '*.localhost.pomerium.io'
    
  3. Create a cfg directory containing the following envoy.yaml file. Envoy configuration can be quite verbose, but the crucial bit is the HTTP filter (highlighted below):






























     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     


































    admin:
      access_log_path: /dev/null
      address:
        socket_address: { address: 127.0.0.1, port_value: 9901 }
    
    static_resources:
      listeners:
        - name: ingress-http
          address:
            socket_address: { address: 0.0.0.0, port_value: 10000 }
          filter_chains:
            - filters:
                - name: envoy.filters.network.http_connection_manager
                  typed_config:
                    "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
                    stat_prefix: ingress_http
                    codec_type: AUTO
                    route_config:
                      name: verify
                      virtual_hosts:
                        - name: httpbin
                          domains: ["httpbin-sidecar"]
                          routes:
                            - match:
                                prefix: "/"
                              route:
                                cluster: egress-httpbin
                                auto_host_rewrite: true
                    http_filters:
                      - name: envoy.filters.http.jwt_authn
                        typed_config:
                          "@type": type.googleapis.com/envoy.extensions.filters.http.jwt_authn.v3.JwtAuthentication
                          providers:
                            pomerium:
                              issuer: authenticate.localhost.pomerium.io
                              audiences:
                                - httpbin.localhost.pomerium.io
                              from_headers:
                                - name: X-Pomerium-Jwt-Assertion
                              remote_jwks:
                                http_uri:
                                  uri: https://authenticate.localhost.pomerium.io/.well-known/pomerium/jwks.json
                                  cluster: egress-authenticate
                                  timeout: 1s
                          rules:
                            - match:
                                prefix: /
                              requires:
                                provider_name: pomerium
                      - name: envoy.filters.http.router
      clusters:
        - name: egress-httpbin
          connect_timeout: 0.25s
          type: STRICT_DNS
          lb_policy: ROUND_ROBIN
          load_assignment:
            cluster_name: httpbin
            endpoints:
              - lb_endpoints:
                  - endpoint:
                      address:
                        socket_address:
                          address: httpbin
                          port_value: 80
        - name: egress-authenticate
          connect_timeout: '0.25s'
          type: STRICT_DNS
          lb_policy: ROUND_ROBIN
          load_assignment:
            cluster_name: authenticate
            endpoints:
              - lb_endpoints:
                  - endpoint:
                      address:
                        socket_address:
                          address: pomerium
                          port_value: 443
          transport_socket:
            name: tls
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.transport_sockets.tls.v3.UpstreamTlsContext
              sni: authenticate.localhost.pomerium.io
    

    This configuration pulls the JWT out of the X-Pomerium-Jwt-Assertion header, verifies the iss and aud claims and checks the signature via the public key defined at the jwks.json endpoint. Documentation for additional configuration options is available here: Envoy JWT Authentication (opens new window).

  4. Create a pomerium.yaml file in the cfg directory containing:

    authenticate_service_url: https://authenticate.localhost.pomerium.io
    
    certificate_file: "/pomerium/_wildcard.localhost.pomerium.io.pem"
    certificate_key_file: "/pomerium/_wildcard.localhost.pomerium.io-key.pem"
    
    idp_provider: google
    idp_client_id: REPLACE_ME
    idp_client_secret: REPLACE_ME
    
    cookie_secret: REPLACE_ME
    shared_secret: REPLACE_ME
    signing_key: REPLACE_ME
    
    routes:
      - from: https://httpbin.localhost.pomerium.io
        to: http://httpbin-sidecar:10000
        pass_identity_headers: true
        policy:
          - allow:
              or:
                - domain:
                    is: example.com
    

Replace the identity provider credentials, secrets, and signing key. Adjust the policy to match your configuration.

# Run

You should now be able to run the example with:

  1. Turn on the example configuration in Docker:

    docker-compose up
    
  2. Visit httpbin.localhost.pomerium.io (opens new window). Login and you will be redirected to the httpbin page.

  3. In this network configuration you cannot access httpbin directly. However, visiting Envoy directly via localhost.pomerium.io:10000/ (opens new window) will return a Jwt is missing error, confirming that you must authenticate with Pomerium to access Envoy, and any services accessible through it.

Last Updated: 1/11/2022, 6:36:47 PM



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