Creating a Classic VPN using dynamic routing

This page describes how to create a Classic VPN gateway and one tunnel using dynamic routing, which uses the Border Gateway routing Protocol (BGP).

With dynamic routing, you do not specify local or remote traffic selectors; instead, you use a Cloud Router. Route information is exchanged dynamically.

For best practices to consider before setting up Cloud VPN, see Best practices for Cloud VPN.

Requirements

General requirements and guidelines

Creating Cloud Routers

When configuring a new HA VPN gateway, you can create a new Cloud Router or you can use a Cloud Router that you are already using with existing Cloud VPN tunnels or interconnect attachments (VLANs). However, the Cloud Router that you use must not already manage a BGP session for an interconnect attachment (VLAN) associated with a Partner Interconnect connection, because of the attachment's specific ASN requirements.

Before you begin

Setting up the following items in Google Cloud makes it easier to configure Cloud VPN:

  1. Sign in to your Google Account.

    If you don't already have one, sign up for a new account.

  2. In the Cloud Console, on the project selector page, select or create a Cloud project.

    Go to the project selector page

  3. Make sure that billing is enabled for your Google Cloud project. Learn how to confirm billing is enabled for your project.

  4. Install and initialize the Cloud SDK.
  1. If you are using gcloud commands, set your project ID with the following command. The gcloud instructions on this page assume that you have set your project ID before issuing commands.
  gcloud config set project PROJECT_ID

You can also view a project ID that has already been set:

  gcloud config list --format='text(core.project)'

Creating a custom Virtual Private Cloud network and subnet

Before creating an Classic VPN gateway and tunnel, you must create a Virtual Private Cloud network and at least one subnet in the region where the Classic VPN gateway will reside.

Creating a gateway and tunnel

The VPN setup wizard is the only console option for creating a Classic VPN gateway. The wizard includes all required configuration steps for creating a Classic VPN gateway, tunnels, BGP sessions, and an external VPN gateway resource. However, you can complete certain steps later. For example, configuring BGP sessions.

The Create VPN gateway button only supports creating HA VPN gateways.

Console

Configure the Gateway

  1. Go to the VPN page in the Google Cloud Console.
    Go to the VPN page
    1. If you are creating a gateway for the first time, select the Create VPN connection button.
    2. Select the VPN setup wizard.
  2. Select the radio button for Classic VPN.
  3. Click Continue.
  4. On the Create a VPN connection page, specify the following gateway settings:
    • Name — The name of the VPN gateway. The name cannot be changed later.
    • Description — Optionally, add a description.
    • Network — Specify an existing VPC network in which to create the VPN gateway and tunnel.
    • Region — Cloud VPN gateways and tunnels are regional objects. Choose a Google Cloud region where the gateway will be located. Instances and other resources in different regions can use the tunnel for egress traffic subject to the order of routes. For best performance, locate the gateway and tunnel in the same region as relevant Google Cloud resources.
    • IP address — Create or choose an existing regional external IP address.

Configure Tunnels

  1. Specify the following in the Tunnels section for the new tunnel item:
    • Name — The name of the VPN tunnel. The name cannot be changed later.
    • Description — Optionally, type a description.
    • Remote peer IP address — Specify the external IP address of the peer VPN gateway.
    • IKE version — Choose the appropriate IKE version supported by the peer VPN gateway. IKEv2 is preferred if it's supported by the peer device.
    • Shared secret — Provide a pre-shared key used for authentication. The shared secret for the Cloud VPN tunnel must match the one used when you configure the counterpart tunnel on the peer VPN gateway. You can follow these directions to generate a cryptographically strong shared secret.
    • Routing options — Select Dynamic (BGP).
    • Cloud router — If you haven't already, create a new Cloud Router specifying the options as noted below. Alternatively, you can use an existing Cloud Router, if the Cloud Router does not already manage a BGP session for an interconnect attachment associated with a Partner Interconnect. If you choose an existing Cloud Router, you'll still create a new BGP session, but the Google ASN is the same. To create a new Cloud Router, specify the following details:
      • Name — The name of the Cloud Router. The name cannot be changed later.
      • Description — Optionally, type a description.
      • Google ASN — Choose a private ASN (64512 - 65534, 4200000000 - 4294967294). This Google ASN is used for all BGP sessions managed by the Cloud Router. The ASN cannot be changed later.
      • Click Save and continue.
    • BGP session — Click the pencil icon, then specify the following details. When you are done, click Save and continue:
      • Name — The name of the BGP session. It cannot be changed later.
      • Peer ASN — A public or private (64512 - 65534, 4200000000 - 4294967294) ASN used by your peer VPN gateway.
      • Advertised route priority — (Optional) The base priority Cloud Router uses when advertising the "to Google Cloud" routes. For more information, see Route metrics. Your peer VPN gateway imports these as MED values.
      • Cloud Router BGP IP and BGP peer IP — The two BGP interface IP addresses must be link-local IP addresses belonging to a common /30 CIDR from the 169.254.0.0/16 block. Each BGP IP defines the respective link-local IP used to exchange route information. For example, 169.254.1.1 and 169.254.1.2 belong to a common /30 block.
  2. If you need to create more tunnels on the same gateway, click Add tunnel and repeat the previous step. You can add more tunnels later.
  3. Click Create.

gcloud


In the following commands, replace:

  • PROJECT_ID with the ID of your project.
  • NETWORK with the name of your Google Cloud network.
  • REGION with the Google Cloud region where you need to create the gateway and tunnel.
  • (Optional) The --target-vpn-gateway-region is the region of the Classic VPN gateway to operate on. Its value should be the same as --region. If not specified, this option is automatically set. This option overrides the default compute/region property value for this command invocation.
  • GW_NAME with the name of the gateway.
  • GW_IP_NAME with a name for the external IP used by the gateway.

Complete the following command sequence to create a Google Cloud gateway:

  1. Create the resources for the Cloud VPN gateway:

    1. Create the target VPN gateway object.

      gcloud compute target-vpn-gateways create GW_NAME \
          --network NETWORK \
          --region REGION \
          --project PROJECT_ID
      
    2. Reserve a regional external (static) IP address:

      gcloud compute addresses create GW_IP_NAME \
          --region REGION \
          --project PROJECT_ID
      
    3. Note the IP address (so you can use it when you configure your peer VPN gateway):

      gcloud compute addresses describe GW_IP_NAME \
          --region REGION \
          --project PROJECT_ID \
          --format='flattened(address)'
      
    4. Create three forwarding rules. These rules instruct Google Cloud to send ESP (IPsec), UDP 500, and UDP 4500 traffic to the gateway.

       gcloud compute forwarding-rules create fr-GW_NAME-esp \
           --ip-protocol ESP \
           --address GW_IP_NAME \
           --target-vpn-gateway GW_NAME \
           --region REGION \
           --project PROJECT_ID
      
      gcloud compute forwarding-rules create fr-GW_NAME-udp500 \
          --ip-protocol UDP \
          --ports 500 \
          --address GW_IP_NAME \
          --target-vpn-gateway GW_NAME \
          --region REGION \
          --project PROJECT_ID
      
      gcloud compute forwarding-rules create fr-GW_NAME-udp4500 \
          --ip-protocol UDP \
          --ports 4500 \
          --address GW_IP_NAME \
          --target-vpn-gateway GW_NAME \
          --region REGION \
          --project PROJECT_ID
      
  2. If you haven't already, complete the following command to create a Cloud Router. Replace the options as noted below. Alternatively, you can use an existing Cloud Router, as long as the Cloud Router does not already manage a BGP session for an interconnect attachment associated with a Partner Interconnect.

    • Replace ROUTER_NAME with a name for the Cloud Router.
    • Replace GOOGLE_ASN with a private ASN (64512 - 65534, 4200000000 - 4294967294). The Google ASN is used for all BGP sessions on the same Cloud Router, and it cannot be changed later.
      gcloud compute routers create ROUTER_NAME \
      --asn GOOGLE_ASN \
      --network NETWORK \
      --region REGION \
      --project PROJECT_ID
    
  3. Create the Cloud VPN tunnel with the following details:

    • Replace TUNNEL_NAME with a name for the tunnel.
    • Replace ON_PREM_IP with the external IP address of the peer VPN gateway.
    • Replace IKE_VERS with 1 for IKEv1 or 2 for IKEv2.
    • Replace SHARED_SECRET with your shared secret. The shared secret for the Cloud VPN tunnel must match the one used when you configure the counterpart tunnel on the peer VPN gateway. You can follow these directions to generate a cryptographically strong shared secret.
    • Replace ROUTER_NAME with the name of the Cloud Router you want to use to manage routes for the Cloud VPN tunnel. The Cloud Router must exist before you create the tunnel.

      gcloud compute vpn-tunnels create TUNNEL_NAME \
          --peer-address ON_PREM_IP \
          --ike-version IKE_VERS \
          --shared-secret SHARED_SECRET \
          --router ROUTER_NAME \
          --target-vpn-gateway GW_NAME \
          --region REGION \
          --project PROJECT_ID
      
  4. Configure a BGP session for the Cloud Router by creating an interface and BGP peer. Choose one of the following methods:

    • To let Google Cloud automatically choose the link-local BGP IP addresses:

      1. Add a new interface to the Cloud Router. Supply a name for the interface by replacing INTERFACE_NAME.

        gcloud compute routers add-interface ROUTER_NAME \
            --interface-name INTERFACE_NAME \
            --vpn-tunnel TUNNEL_NAME \
            --region REGION \
            --project PROJECT_ID
        
      2. Add a BGP peer to the interface. Replace PEER_NAME with a name for the peer, and PEER_ASN with the ASN configured for the peer VPN gateway.

        gcloud compute routers add-bgp-peer ROUTER_NAME \
            --peer-name PEER_NAME \
            --peer-asn PEER_ASN \
            --interface INTERFACE_NAME \
            --region REGION \
            --project PROJECT_ID
        
      3. List the BGP IP addresses chosen by the Cloud Router. If you added a new interface to an existing Cloud Router, the BGP IP addresses for the new interface should be listed with the highest index number. The Peer IP Address is the BGP IP you should use to configure your peer VPN gateway.

        gcloud compute routers get-status ROUTER_NAME \
             --region REGION \
             --project PROJECT_ID \
             --format='flattened(result.bgpPeerStatus[].ipAddress, \
             result.bgpPeerStatus[].peerIpAddress)'
        

        Expected output for a Cloud Router managing a single Cloud VPN tunnel (index 0) looks like the following, where GOOGLE_BGP_IP represents the BGP IP of the Cloud Router's interface and ON_PREM_BGP_IP represents the BGP IP of its peer.

        result.bgpPeerStatus[0].ipAddress:     GOOGLE_BGP_IP
        result.bgpPeerStatus[0].peerIpAddress: ON_PREM_BGP_IP
        
    • To manually assign the BGP IP addresses associated with the Google Cloud BGP interface and peer:

      1. Decide on a pair of link-local BGP IP addresses in a /30 block from the 169.254.0.0/16 range. Assign one of these BGP IP addresses to the Cloud Router in the next command by replacing GOOGLE_BGP_IP. The other BGP IP address is used for your peer VPN gateway. You must configure your device to use that address, and replace ON_PREM_BGP_IP in the last command, below.

      2. Add a new interface to the Cloud Router. Specify a name for the interface by replacing INTERFACE_NAME.

        gcloud compute routers add-interface ROUTER_NAME \
            --interface-name INTERFACE_NAME \
            --vpn-tunnel TUNNEL_NAME \
            --ip-address GOOGLE_BGP_IP \
            --mask-length 30 \
            --region REGION \
            --project PROJECT_ID
        
      3. Add a BGP peer to the interface. Replace PEER_NAME with a name for the peer, and PEER_ASN with the ASN configured for the peer VPN gateway.

        gcloud compute routers add-bgp-peer ROUTER_NAME \
            --peer-name PEER_NAME \
            --peer-asn PEER_ASN \
            --interface INTERFACE_NAME \
            --peer-ip-address ON_PREM_BGP_IP \
            --region REGION \
            --project PROJECT_ID
        

Follow-up steps

You must complete the following steps before you can use a new Cloud VPN gateway and tunnel:

  1. Set up the peer VPN gateway and configure the corresponding tunnel there. Refer to these pages:
  2. Configure firewall rules in Google Cloud and your peer network as required. Refer to the firewall rules page for suggestions.
  3. Check the status of your tunnel, including forwarding rules.
Applying a VPN organization policy

Applying an organization policy constraint that restricts the IP addresses of peer VPN gateways

You can create a Google Cloud organization policy constraint that defines a set of IP addresses that are allowed or denied to peer VPN gateways through Classic VPN or HA VPN tunnels. This constraint contains an allow list or a deny list of these peer IP addresses, which goes into effect for Cloud VPN tunnels created after you apply the constraint. For details, see the Cloud VPN overview.

Required permissions

To set a peer IP constraint at the organization or project level, you must first be granted the Organization Policy Administrator (orgpolicy.policyAdmin) role for your organization.

How to set constraints

To create an organization policy and associate it with an organization, a folder, or a project, use the examples listed in the next sections and follow the steps in Using constraints.

Constraining connectivity from specific peer IP addresses through a Cloud VPN tunnel

To only allow specific peer IP addresses, perform the following steps:

  1. Find your organization ID by entering the following command:
    gcloud organizations list

    The command output should look like the following example.

          DISPLAY NAME             ID
          example-organization     29252605212
        
  2. Create a JSON file that defines your policy. You must provide a policy as a JSON file, as in the following example:

         {
           "constraint": "constraints/compute.restrictVpnPeersIPs",
           "listPolicy": {
             "allowedValues": [
               "100.1.1.1",
             ],
           }
         }
       
  3. Use the gcloud Resource Manager set-policy command to set the organization policy, passing in the JSON file and using the `ORGANIZATION_ID` that you found in the previous step.

Constraining connectivity from any peer IPs through a Cloud VPN tunnel

To prohibit the creation of any new Cloud VPN tunnel, follow the steps in this example constraint.

  1. Find your organization ID or the ID for the node in your resource hierarchy where you want to set a policy.
  2. Create a JSON file like the following example.

        {
          "constraint": "constraints/compute.restrictVpnPeersIPs",
          "listPolicy": {
            "allValues": "DENY"
          }
        }
    
  3. Pass in the JSON file by entering the same command that you would use for restricting specific peer IP addresses.