Using Firewall Rules

This page describes the commands for working with firewall rules and offers some examples in using them. To learn more about firewall rules, read the Firewall Rules Overview.

Creating firewall rules

Firewall rules apply to one network only, but the firewall rule name must be unique within the project.

Console

  1. Go to the Firewall rules page in the Google Cloud Platform Console.
    Go to the Firewall rules page
  2. Click Create firewall rule.
  3. Enter a Name for the firewall rule.
    This name must be unique for the project.
  4. Specify the Network where the firewall rule is implemented.
  5. Specify the Priority of the rule.
    If this rule will not conflict with any other rules, you can leave the priority on the default of 1000. If you want to give it a higher or lower priority than other rules, give it a lower number to have it evaluated earlier or a higher number to have it evaluated later.
  6. Indicate the Direction of traffic to which you want the rule to apply.
  7. Indicate the Action on match, whether to Allow or Deny the matching traffic.
  8. Specify the Targets of the rule.
    • If you want the rule to apply to all instances in the network, select All instances in the network.
    • If you want it to apply to certain instances only based on target tags, select Specified target tags, then list those tags in the Target tags field.
    • If you want it to apply to certain instances based on the the service account that owns those instances, select Specified service account, then indicate whether the service account is in the current project or another project in the Service account scope field, then specify the service account in the Target service account field.
  9. For an Ingress rule, specify the Source filter.
    • Select IP ranges if you want the rule to apply to packets from certain source IP ranges only, then specify those ranges in the Source IP ranges field.
    • If you want it to apply to all ranges, specify 0.0.0.0/0. Select Subnetworks if you want the rule to apply to traffic coming from one or more subnets in the network, then specify which subnets in the Subnetworks field.
    • If you want the rule to apply to instances with certain source tags only, select Specified source tags, then list those tags in the Source tags field.
    • If you want the to apply to certain instances based on the the service account that owns those instances, select Service account, then indicate whether the service account is in the current project or another project in the Service account scope field, then specify the service account in the Source service account field.
  10. Specify a Second source filter if desired.
  11. For an Egress rule, specify the Destination filter.
    Select IP ranges if you want the rule to apply to packets destined to certain IP ranges only, then specify those ranges in the Destination IP ranges field. If you want it to apply to all ranges, specify 0.0.0.0/0. Select Subnetworks if you want the rule to apply to traffic traveling to one or more subnets in the network, then specify which subnets in the Subnetworks field.
  12. Specify which Protocols and ports the rule should apply to.
    Either select Allow all, if it's an allow rule; Deny all, if it's a deny rule, or specify the protocols and ports that should be allowed or denied.
  13. Click Create.

gcloud

gcloud compute firewall-rules create [NAME] \
    [--network [NETWORK]; default=”default”] \
    [--allow ([PROTOCOL][:PORT[-PORT]],[PROTOCOL[:PORT[-PORT]],...]] | all ) \
    [--action (deny | allow )] \
    [--rules ([PROTOCOL][:PORT[-PORT]],[PROTOCOL[:PORT[-PORT]],...]] | all ) \
    [--direction (ingress|egress|in|out); default=”ingress”] \
    [--priority [PRIORITY];default=1000] \
    [--destination-ranges [CIDR-RANGE][,CIDR-RANGE...]] \
    [--source-ranges [CIDR-RANGE][,CIDR-RANGE…]] \
    [--source-tags [TAG][,TAG,...]] \
    [--target-tags [TAG][,TAG,...]] \
    [--source-service-accounts=[EMAIL] \
    [--target-service-accounts=[EMAIL]

  • --network The network to which this rule is attached. If omitted, the rule is attached to the default network.
  • --allow A list of protocols and ports whose traffic will be allowed. Use keyword “all” means any IP protocols with any port ranges. Must NOT specify together with --action deny flag. (Will be deprecated in the future.)
  • --action The action for the firewall rule: whether to allow or deny matching traffic. If given, the flag --rules must also be given.
  • --rules A list of protocols and ports whose traffic will be affected according to --action parameter; Use keyword “all” to mean any IP protocols with any port ranges; Must specify together with --action.
  • --direction Direction of connection to which this firewall rule applies, either ingress (default) or egress. For ingress traffic, destination ranges are not supported. For egress traffic, source-ranges or source-tags are not supported..
  • --priority Priority for this firewall rule. This is an integer from 0 to 65535, both inclusive. When NOT specified, the value assumed is 1000. Relative priority determine precedence of conflicting rules. Lower value of priority implies higher precedence. In other words, 1 is higher priority than 2. deny rules take precedence over allow rules having equal priority.
  • --destination-ranges If destination ranges are specified, the firewall will apply only to traffic that has destination IP address in this range. This range must be expressed in CIDR format.
  • --source-ranges If source ranges are specified, the firewall will apply only to traffic that has source IP address in this ranges. These ranges must be expressed in CIDR format. One or both of source-ranges and source-tags may be set. If both properties are set, the firewall will apply to traffic that has source IP address within source-ranges or the source IP that belongs to a tag listed in the source-tags property. The connection does not need to match both properties for the firewall to apply.
  • --source-tags If source tags are specified, the firewall rule matches ingress connections with a source IP address that matches the primary IP address of an instance with that tag. Source tags cannot be used to control traffic to an instance’s external IP address or secondary internal IP addresses. You cannot specify both tags and service accounts in a rule.
  • --target-tags A list of instance tags. The rule in question is assigned to any instances in the network with any of the tags and does not apply to instances without one. You cannot specify both tags and service accounts in a rule.
  • --source-service-accounts If source service account is specified, the rule matches connections that have a source IP address that matches the primary internal IP address of instances created with that service account. Source service accounts cannot be used to control traffic to an instance’s external IP address or secondary internal IP addresses. You cannot specify both tags and service accounts in a rule.
  • --target-service-accounts The rule in question is assigned to instances in the network that were created by that service account and not to any that weren't. You cannot specify both tags and service accounts in a rule.

Updating firewall rules

To update a firewall rule, use one of the following options.

Not all fields can be modified. If you want to change a field that can't be change, you will have to delete the existing rule and create a new rule with the same name.

Console

  1. Go to the Firewall rules page in the Google Cloud Platform Console.
    Go to the Firewall rules page
  2. Click the firewall rule you want to modify.
  3. Click Edit.
  4. Modify any fields you wish to change.
  5. Click Save.

gcloud

gcloud compute firewall-rules update [NAME] \
    [--allow=[[PROTOCOL][:PORT[-PORT]],…]] \
    [--description=[DESCRIPTION]] \
    [--destination-ranges=[CIDR_RANGE,…]] \
    [--priority=[PRIORITY]] \
    [--rules=[[PROTOCOL][:PORT[-PORT]],…]] \
    [--source-ranges=[[CIDR_RANGE],…]] \
    [--source-tags=[[TAG],…]] \
    [--target-tags=[[TAG],…]] \
    [--source-service-accounts=[EMAIL] \
    [--target-service-accounts=[EMAIL]

You only need to specify the flags you want to change. All other flags remain as they were.

Other firewall rules commands

Console

Listing firewall rules

  1. Go to the Firewall rules page in the Google Cloud Platform Console.
    Go to the Firewall rules page

Viewing details

  1. Go to the Firewall rules page in the Google Cloud Platform Console.
    Go to the Firewall rules page
  2. On the firewall rules page, click the rule you want to view.

Deleting rules

  1. Go to the Firewall rules page in the Google Cloud Platform Console.
    Go to the Firewall rules page
  2. On the firewall rules page, click the rule you want to delete.
  3. Click Delete.
  4. Click Delete again to confirm.

gcloud

Sorted list of firewall rules

gcloud compute firewall-rules list --filter network=[NETWORK_NAME] \
    --sort-by priority \
    --format="table(
        name,
        network,
        direction,
        priority,
        sourceRanges.list():label=[SRC_RANGES],
        destinationRanges.list():label=[DEST_RANGES],
        allowed[].map().firewall_rule().list():label=ALLOW,
        denied[].map().firewall_rule().list():label=DENY,
        sourceTags.list():label=[SRC_TAGS],
        targetTags.list():label=[TARGET_TAGS]
        )"

Other firewall rules commmands

For other firewall rules gcloud commands, see the SDK documentation

Configuration examples

Shown below is an example firewall configuration. The scenario involves a my-network that contains the following:.

  • a subnet subnet1 with IP range 10.240.10.0/24
  • a subnet subnet2 with IP range 192.168.1.0/24
  • instance vm1 in subnet2 having tag webserver and internal IP 192.168.1.2
  • instance vm2 in subnet2 having tag database and internal IP 192.168.1.3
Sample network configuration (click to enlarge)
Sample network configuration (click to enlarge)

Example 1: Deny all ingress TCP connections except those to port 80 from subnet1

This example creates a set of firewall rules that deny all ingress TCP connections except connections destined to port 80 from subnet1.

  1. Create a firewall rule to deny all ingress TCP traffic to instances tagged with webserver

    gcloud compute firewall-rules create deny-subnet1-webserver-access \
        --network my-network \
        --action deny \
        --direction ingress \
        --rules tcp \
        --source-ranges 0.0.0.0/0 \
        --priority 1000 \
        --target-tags webserver
    

  2. Create a firewall rule to allow all IPs in subnet1 (10.240.10.0/24) to access TCP port 80 on instances tagged with webserver.

    gcloud compute firewall-rules create vm1-allow-ingress-tcp-port80-from-subnet1 \
        --network my-network \
        --action allow \
        --direction ingress \
        --rules tcp:80 \
        --source-ranges 10.240.10.0/24 \
        --priority 50 \
        --target-tags webserver
    

Example 2: Deny all egress TCP connections except those to port 80 of vm1

  1. Create a firewall rule to deny all egress TCP traffic

    gcloud compute firewall-rules create deny-all-access \
        --network my-network \
        --action deny \
        --direction egress \
        --rules tcp \
        --destination-ranges 0.0.0.0/0 \
        --priority 1000
    

  2. Create firewall rule to allow TCP traffic destined to vm1 port 80

    gcloud compute firewall-rules create vm1-allow-egress-tcp-port80-to-vm1 \
        --network my-network \
        --action allow \
        --direction egress \
        --rules tcp:80 \
        --destination-ranges 192.168.10.2/32 \
        --priority 60
    

Example 3: Allow egress TCP connections to port 443 of an external host

Create a firewall rule that allows for instances with tag webserver to egress TCP traffic to port 443 of an sample external IP address, 192.0.2.5.

gcloud beta compute firewall-rules create vm1-allow-egress-tcp-port443-to-192-0-2-5 \
    --network my-network \
    --action allow \
    --direction egress \
    --rules tcp:443 \
    --destination-ranges 192.0.2.5/32 \
    --priority 70 \
    --target-tags webserver

Example 4: Allow SSH connections from vm2 to vm1

Create firewall rule that allows SSH traffic from instances with tag database (vm2) to reach instances with tag webserver (vm1).

gcloud compute firewall-rules create vm1-allow-ingress-tcp-ssh-from-vm2 \
    --network my-network \
    --action allow \
    --direction ingress \
    --rules tcp:22 \
    --sourceTags database \
    --priority 80 \
    --target-tags webserver

Example 5: Allow TCP:1443 from webserver to database using service accounts

For additional information on service accounts and roles, see "Granting roles to service accounts".

Consider the scenario in the diagram below, in which there are two applications that are autoscaled through templates, a webserver application my-sa-web, and a database application 'my-sa-db". A Security admin wants to allow TCP flows on port 1443 from my-sa-web to my-sa-db.

Using firewall rules with service accounts (click to enlarge)
Using firewall rules with service accounts (click to enlarge)

The configuration steps, including the creation of the service accounts, is as follows:

  1. A project EDITOR or project OWNER creates the service accounts my-sa-web and my-sa-db.

    gcloud iam service-accounts create my-sa-web \
        --display-name "webserver service account"
    

    gcloud iam service-accounts create my-sa-db \
        --display-name "database service account"
    

  2. A project OWNER assigns the webserver developer web-dev@example.com a serviceAccountActor role for service account my-sa-web by setting an IAM policy.

    gcloud iam service-accounts add-iam-policy-binding \
       my-sa-web@my-project.iam.gserviceaccount.com \
       --member='user:web-dev@example.com' \
       --role='roles/iam.serviceAccountActor'
       

  3. A project OWNER assigns the database developer "db-dev@example.com" a serviceAccountActor role for service account my-sa-db by setting an IAM policy.

    gcloud iam service-accounts add-iam-policy-binding \
       my-sa-db@my-project.iam.gserviceaccount.com \
       --member='user:db-dev@example.com' \
       --role='roles/iam.serviceAccountActor'
       

  4. Developer web-dev@example.com, which has the Instance admin role, creates webserver instance template and authorize instances to run as service account my-sa-web.

    gcloud compute instance-templates create [INSTANCE_TEMPLATE_NAME]  \
        --service-account my-sa-web@my-project-123.iam.gserviceaccount.com
    

  5. Developer db-dev@example.com, which has the Instance Admin role, creates the database instance template and authorize instances to run as service account my-sa-web.

    gcloud compute instance-templates create [INSTANCE_TEMPLATE_NAME] \
        --service-account my-sa-db@my-project-123.iam.gserviceaccount.com
    

  6. Security admin creates the firewall rules using service accounts to allow traffic TCP:1443 from service account my-sa-web to service account my-sa-db.

    gcloud beta compute firewall-rules create [NAME] \
        --network network_a \
        --allow TCP:1443 \
        --source-service-accounts my-sa-web@my-project.iam.gserviceaccount.com \
        --target-service-accounts my-sa-db@my-project.iam.gserviceaccount.com
       

Troubleshooting

Error messages when creating a firewall rule

You may see one of the following error messages:

  • Should not specify destination range for ingress direction.

    Destination ranges are not valid parameters for ingress firewall rules. Firewall rules are assumed to be ingress rules unless a direction of egress is specifically specified. If you create a rule that does not specify a direction, it will be created as an ingress rule, which does not allow a destination range. Also, source ranges are not valid parameters for egress rules.

Error messages when updating a firewall rule

You may see one of the following error messages:

  • Firewall direction cannot be changed once created.

    You cannot change the direction of an existing firewall rule. You have to create a new rule with the correct parameters, then delete the old one.

  • Firewall traffic control action cannot be changed once created.

    You cannot change the action of an existing firewall rule. You have to create a new rule with the correct parameters, then delete the old one.

Cannot connect to VM instance

If you cannot connect to a VM instance, check your firewall rules.

  1. If you are initiating the connection from another VM instance, list the egress firewall rules for that instance.

    gcloud compute firewall-rules list --filter network=[NETWORK_NAME] \
        --filter direction=EGRESS \
        --sort-by priority \
        --format="table(
            name,
            network,
            direction,
            priority,
            sourceRanges.list():label=[SRC_RANGES],
            destinationRanges.list():label=[DEST_RANGES],
            allowed[].map().firewall_rule().list():label=ALLOW,
            denied[].map().firewall_rule().list():label=DENY,
            sourceTags.list():label=[SRC_TAGS],
            targetTags.list():label=[TARGET_TAGS]
            )"
    

  2. Check if the destination IP is denied by any egress rules. The rule with the highest priority (lowest priority number) overrides lower priority rules. For two rules with same priority, the deny rule take precedence.

  3. Check ingress firewall rule for the network contains the destination VM instance.

    gcloud compute firewall-rules list --filter network=[NETWORK_NAME] \
        --filter direction=INGRESS \
        --sort-by priority \
        --format="table(
            name,
            network,
            direction,
            priority,
            sourceRanges.list():label=[SRC_RANGES],
            destinationRanges.list():label=[DEST_RANGES],
            allowed[].map().firewall_rule().list():label=ALLOW,
            denied[].map().firewall_rule().list():label=DENY,
            sourceTags.list():label=[SRC_TAGS],
            targetTags.list():label=[TARGET_TAGS]
            )"
    

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