Configuring firewall rules

This page provides guidance for configuring Google Cloud firewall rules and your peer network firewall rules.

When you configure Cloud VPN tunnels to connect to your peer network, review and modify firewall rules in your Google Cloud and peer networks to make sure that they meet your needs. If your peer network is another Virtual Private Cloud (VPC) network, then configure Google Cloud firewall rules for both sides of the network connection.

For more information about Cloud VPN, see the following resources:

Google Cloud firewall rules

Google Cloud firewall rules apply to packets sent to and from virtual machine (VM) instances within your VPC network and through Cloud VPN tunnels.

The implied allow egress rule allows VM instances and other resources in your Google Cloud network to make outgoing requests and receive established responses. However, the implied deny ingress rule blocks all incoming traffic to your Google Cloud resources.

At a minimum, create firewall rules to allow ingress traffic from your peer network to Google Cloud. If you created egress rules to deny certain types of traffic, you might also need to create other egress rules.

Traffic containing the protocols UDP 500, UDP 4500, and ESP (IPsec, IP protocol 50) is always allowed to and from one or more external IP addresses on a Cloud VPN gateway. However, Google Cloud firewall rules do not apply to the post-encapsulated IPsec packets that are sent from a Cloud VPN gateway to a peer VPN gateway.

For more information about Google Cloud firewall rules, see the VPC firewall rules overview.

Example configurations

For multiple examples of restricting ingress or egress traffic, see the configuration examples in the VPC documentation.

The following example creates an ingress allow firewall rule. This rule permits all TCP, UDP, and ICMP traffic from your peer network's CIDR to your VMs in your VPC network.

Console

  1. In the Google Cloud Console, go to the VPN tunnels page.

    Go to VPN tunnels

  2. Click the VPN tunnel that you want to use.

  3. In the VPN gateway section, click the name of the VPC network. This action directs you to the VPC network details page that contains the tunnel.

  4. Click the Firewall rules tab.

  5. Click Add firewall rule. Add a rule for TCP, UDP, and ICMP:

    • Name: Enter allow-tcp-udp-icmp.
    • Source filter: Select IP ranges.
    • Source IP ranges: Enter a Remote network IP range value from when you created the tunnel. If you have more than one peer network range, enter each one. Press the Tab key between entries.
    • Allowed protocols or ports: Enter tcp; udp; icmp.
    • Target tags: Add any valid tag or tags.
  6. Click Create.

  7. Create other firewall rules if necessary.

Alternatively, you can create rules from the Cloud Console Firewall page.

  1. Go to the Firewall page.

    Go to Firewall

  2. Click Create firewall rule.

  3. Populate the following fields by entering these values:

    • Name: vpnrule1
    • VPC network: my-network
    • Source filter: IP ranges
    • Source IP ranges: the peer network's IP address ranges to accept from the peer VPN gateway
    • Allowed protocols and ports: tcp;udp;icmp
  4. Click Create.

gcloud

Run the following command:

gcloud  compute --project PROJECT_ID firewall-rules create vpnrule1 \
    --network NETWORK \
    --allow tcp,udp,icmp \
    --source-ranges PEER_SOURCE_RANGE

If you have more than one peer network range, provide a comma-separated list in the source-ranges field (--source-ranges 192.168.1.0/24,192.168.2.0/24).

For more information about the firewall-rules command, see the gcloud firewall rules documentation.

Peer firewall rules

When configuring your peer firewall rules, consider the following:

  • Configure rules to allow egress and ingress traffic to and from the IP ranges used by the subnets in your VPC network.
  • You can choose to permit all protocols and ports, or you can restrict traffic to only the necessary set of protocols and ports to meet your needs.
  • Allow ICMP traffic if you need to use ping to be able to communicate among peer systems and instances or resources in Google Cloud.
  • Both your network devices (security appliances, firewall devices, switches, routers, and gateways) and software running on your systems (such as firewall software included with an operating system) can implement on-premises firewall rules. To allow traffic, configure all firewall rules in the path to your VPC network appropriately.
  • If your VPN tunnel uses dynamic (BGP) routing, make sure that you allow BGP traffic for the link-local IP addresses. For more details, see the next section.

BGP considerations for peer gateways

Dynamic (BGP) routing exchanges route information by using TCP port 179. Some VPN gateways, including Cloud VPN gateways, allow this traffic automatically when you choose dynamic routing. If your peer VPN gateway does not, configure it to allow incoming and outgoing traffic on TCP port 179. All BGP IP addresses use the link-local 169.254.0.0/16 CIDR block.

If your peer VPN gateway is not directly connected to the internet, make sure that it and peer routers, firewall rules, and security appliances are configured to at least pass BGP traffic (TCP port 179) and ICMP traffic to your VPN gateway. ICMP is not required, but it is useful to test connectivity between a Cloud Router and your VPN gateway. The range of IP addresses to which your peer firewall rule should apply must include the BGP IP addresses of the Cloud Router and your gateway.

What's next