Using Firewall Rules

This page describes the commands for working with firewall rules and offers some examples in using them.

Before you begin

To learn more about firewall rules, read the Firewall Rules Overview.

Before configuring firewall rules, review the firewall rule components to become familiar with firewall components as used in GCP.

Creating firewall rules

Firewall rules are defined at the network level, and only apply to the network where they are created; however, the name you choose for each of them must be unique to the project.

Note: If you want to specify multiple service accounts for the target or source service account field, use the gcloud command or API.

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. (Optional) You can enable firewall rules logging:
   • Click Logs > On.
   • Click Turn on.
5. Specify the Network where the firewall rule will be implemented.
6. Specify the Priority of the rule.
   The lower the number, the higher the priority.
7. For the Direction of traffic, choose ingress or egress.
8. For the Action on match, choose allow or deny.
9. Specify the Targets of the rule.
   • If you want the rule to apply to all instances in the network, choose All instances in the network.
   • If you want the rule to apply to select instances by network (target) tags, choose Specified target tags, then type the tags to which the rule should apply into the Target tags field.
   • If you want the rule to apply to select instances by associated service account, choose Specified service account, indicate whether the service account is in the current project or another one under Service account scope, and choose or type the service account name in the Target service account field.
10. For an ingress rule, specify the Source filter:
    
    • Choose IP ranges and type the CIDR blocks into the Source IP ranges field to define the source for incoming traffic by IP address ranges. Use 0.0.0.0/0 for a source from any network.
    • Choose Subnets then mark the ones you need from the Subnets pop-up button to define the source for incoming traffic by subnet name.
    • To limit source by network tag, choose Source tags, then type the network tags in to the Source tags field. For the limit on the number of source tags, see VPC Quotas and Limits. Filtering by source tag is only available if the target is not specified by service account. For more information, see filtering by service account vs.network tag.
    • To limit source by service account, choose Service account, indicate whether the service account is in the current project or another one under Service account scope, and choose or type the service account name in the Source service account field. Filtering by source service account is only available if the target is not specified by network tag. For more information, see filtering by service account vs. network tag.
    • Specify a Second source filter if desired. Secondary source filters cannot use the same filter criteria as the primary one.
11. For an egress rule, specify the Destination filter:
    
    • Choose IP ranges and type the CIDR blocks into the Destination IP ranges field to define the destination for outgoing traffic by IP address ranges. Use 0.0.0.0/0 to mean everywhere.
    • Choose Subnets then mark the ones you need from the Subnets pop-up button to define the destination for outgoing traffic by subnet name.

12. Define the Protocols and ports to which the rule will apply:
    

    • Select Allow all or Deny all, depending on the action, to have the rule apply to all protocols and ports.

    • Define specific protocols and ports:

      • Select tcp to include the TCP protocol and ports. Enter all or a comma delimited list of ports, such as 20-22, 80, 8080.
      • Select udp to include the UDP protocol and ports. Enter all or a comma delimited list of ports, such as 67-69, 123.
      • Select Other protocols to include protocols such as icmp or sctp.

13. (Optional) You can create the firewall rule but not enforce it by setting its enforcement state to disabled. Click Disable rule, then select Disabled.

14. Click Create.

gcloud

The gcloud command for creating firewall rules is:

gcloud compute firewall-rules create NAME \
    [--network NETWORK; default="default"] \
    [--priority PRIORITY;default=1000] \
    [--direction (ingress|egress|in|out); default="ingress"] \
    [--action (deny | allow )] \
    [--target-tags TAG,TAG,...] \
    [--target-service-accounts=IAM Service Account,IAM Service Account,...] \
    [--source-ranges CIDR-RANGE,CIDR-RANGE...] \
    [--source-tags TAG,TAG,...] \
    [--source-service-accounts=IAM Service Account,IAM Service Account,...] \
    [--destination-ranges CIDR-RANGE,CIDR-RANGE...] \
    [--rules (PROTOCOL[:PORT[-PORT]],[PROTOCOL[:PORT[-PORT]],...]] | all ) \
    [--disabled | --no-disabled]
    [--enable-logging | --no-enable-logging]

Use the parameters as follows. More details about each are available in the SDK reference documentation.

• --network The network where the rule will be created. If omitted, the rule will be created in the default network. If you don't have a default network or want to create the rule in a specific network, you must use this field.
• --priority A numerical value that indicates the priority for the rule. The lower the number, the higher the priority.
• --direction The direction of traffic, either ingress or egress.
• --action The action on match, either allow or deny. Must be used with the --rules flag.
• Specify a target in one of three ways:
  • Omit --target-tags and --target-service-accounts if the rule should apply to all targets in the network.
  • --target-tags Use this flag to define targets by network tags.
  • --target-service-accounts Use this flag to define targets by associated service accounts.
• For an ingress rule, specify a source:
  • Omit --source-ranges, source-tags, and --source-service-accounts if the ingress source should be everywhere, 0.0.0.0/0.
  • --source-ranges Use this flag to specify ranges of source IP addresses in CIDR format.
  • --source-tags Use this flag to specify source instances by network tags. Filtering by source tag is only available if the target is not specified by service account. For more information, see filtering by service account vs. network tag.
  • --source-ranges and --source-tags can be used together. If both are specified, the effective source set is the union of the source range IP addresses and the instances identified by network tags, even if the tagged instances do not have IPs in the source ranges.
  • --source-service-accounts Use this flag to specify instances by the service accounts they use. Filtering by source service account is only available if the target is not specified by network tag. For more information, see filtering by service account vs. network tag.
• For an egress rule, specify a destination:
  • Omit --destination-ranges if the egress destination should be anywhere, 0.0.0.0/0.
  • --destination-ranges Use this flag to specify ranges of destination IP addresses in CIDR format.
• --rules A list of protocols and ports to which the rule will apply. Use all to make the rule applicable to all protocols and all ports. Requires the --action flag.
• By default, firewall rules are created and enforced automatically; however, you can change this behavior.
  • If both --disabled and --no-disabled are omitted, the firewall rule is created and enforced.
  • --disabled Add this flag to create the firewall rule but not enforce it. The firewall rule will remain in a disabled state until you update the firewall rule to enable it.
  • --no-disabled Add this flag to ensure the firewall rule is enforced.
• You can enable Firewall Rules Logging for a rule when you create or update it. Firewall Rules Logging allows you audit, verify, and analyze the effects of your firewall rules. See Firewall Rules Logging for details.

Note: If you are creating firewall rules whose action is allow, you can use the deprecated --allow flag to specify a range of allowed protocols and ports instead of using --action=allow and --rules. Refer to the SDK documentation for more details.

API

Create a firewall rule.

POST https://www.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls
{
  "name": "FIREWALL_NAME",
  "network": "projects/PROJECT_ID/global/networks/NETWORK_NAME",
  ... other fields
}

Replace the placeholders with valid values:

• PROJECT_ID is the ID of the project where the VPC network is located.
• NETWORK_NAME is the name the VPC network where the firewall rule is created.

• FIREWALL_NAME a name for the firewall rule.

• For an ingress firewall rule, use the following fields to specify the ingress source: sourceRanges, sourceTags, or sourceServiceAccounts. Specify no field to use the range 0.0.0.0/0. You cannot use the sourceTags and sourceServiceAccounts fields together. However, you can use sourceRanges with sourceTags or sourceServiceAccounts. If you do, the connection just needs to match one or the other for the firewall rule to apply.

  For the target fields, if you use the sourceTags field, you cannot use the targetServiceAccounts field. You must use the targetTags field or no target field. Similarly, if you use the sourceServiceAccounts field, you cannot use the targetTags field. If you don't specify a target field, the rule applies to all targets in the network.

• For an egress firewall rule, use the destinationRanges field to specify the destination. If you don't specify a destination, GCP uses 0.0.0.0/0. Use the targetTags or targetServiceAccounts field to specify which targets the rule applies to. If you don't specify a target field, the rule applies to all targets in the network.

For more information and descriptions for each field, refer to the firewalls.insert method.

Updating firewall rules

You can modify some components of a firewall rule, such as the specified protocols and ports for the match condition. You cannot modify a firewall rule's name, network, the action on match, and the direction of traffic.

If you need to change the name, network, or the action or direction component, you must delete the rule and create a new one instead.

Note: If you want to add or remove multiple service accounts, use the gcloud command or API. You cannot use the console to specify multiple target service accounts or source service accounts.

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 of the editable components to meet your needs.

   In the Specified protocols and ports field, use a semicolon-delimited list to specify multiple protocols.

5. Click Save.

gcloud

The gcloud command for updating firewall rules is:

gcloud compute firewall-rules update NAME \
    [--priority=PRIORITY] \
    [--description=DESCRIPTION] \
    [--target-tags=TAG,...] \
    [--target-service-accounts=IAM Service Account, ...] \
    [ --source-ranges=CIDR_RANGE, ...] \
    [--source-tags=TAG,...] \
    [--source-service-accounts=IAM Service Account, ...] \
    [--destination-ranges=CIDR_RANGE, ...] \
    [--rules=[PROTOCOL[:PORT[-PORT]],…]] \
    [--disabled | --no-disabled]
    [--enable-logging | --no-enable-logging]

The descriptions for each flag are the same as for creating firewall rules, and more details about each are available in the SDK reference documentation.

Note: If you are editing a firewall rule whose action is allow, you can use the deprecated --allow flag instead of the --rules flag if you prefer.

API

Use PATCH to update the following fields: allowed, description, sourceRanges, sourceTags, or targetTags. Use PUT or POST for all other fields.

(PATCH|(POST|PUT)) https://www.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls/FIREWALL_NAME
{
  "name": "FIREWALL_NAME",
  "network": "projects/PROJECT_ID/global/networks/NETWORK_NAME",
  ... other fields
}

Replace the placeholders with valid values:

• PROJECT_ID is the ID of the project where the VPC network is located.
• NETWORK_NAME is the name the VPC network where the firewall rule is located.
• FIREWALL_NAME is the name of the firewall rule to update.

For more information and descriptions for each field, refer to the firewalls.patch or firewalls.update method.

Listing firewall rules for a VPC network

Console

To show all firewall rules for all networks in your project:

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

To show firewall rules in a particular network:

1. Go to the VPC networks page in the Google Cloud Platform Console.
   Go to the VPC networks page
2. Click the Name of a VPC network to go to its details page.
3. On the details page for the network, click the Firewall rules tab.

gcloud

The following command produces a sorted list of firewall rules for a given network ([NETWORK_NAME]).

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
        )"

API

List all firewall rules for a given network.

GET https://www.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls/?filter=network="NETWORK_NAME

Replace the placeholders with valid values:

• PROJECT_ID is the ID of the project where the VPC network is located.
• NETWORK_NAME is the name of the VPC network that contains the firewall rules to list.

For more information, refer to the firewalls.list method.

Listing firewall rules for a network interface of a VM instance

For each network interface, the GCP Console lists all of the firewall rules that apply to the interface and the rules that are actually being used by the interface. Firewall rules can mask other rules, so all of the rules that apply to an interface might not actually be used by the interface.

Firewall rules are associated and applied to a VM instances through a rule's target parameter. By viewing all of the applied rules, you can check whether a particular rule is being applied to an interface.

To view all of the firewall rules that apply to a specific network interface of a VM instance:

1. Go to the VM instances page in the Google Cloud Platform Console and find the instance to view.
   Go to the VM instances page
2. In the instance's more actions menu (), select View network details.
3. If an instance has multiple network interfaces, select the network interface to view in the Network interface details section.
4. Click the Firewall rules tab to see all the rules that apply to the network interface, sorted by rule name.

Of the rules that apply to a network interface, the interface might not use all of them. Some rules might be overridden by a rule with a more specific range or a higher priority. By viewing the rules that are in use, you can quickly verify which IP ranges, protocols, and ports are open or closed to the instance.

To view the rules that are being used by a specific network interface of a VM instance:

1. Go to the VM instances page in the Google Cloud Platform Console and find the instance to view.
   Go to the VM instances page
2. In the instance's more actions menu (), select View network details.
3. If an instance has multiple network interfaces, select the network interface to view in the Network interface details section.
4. In the Network Analysis section, select the Ingress analysis or Egress analysis tab.
5. View the table, which is sorted from the most specific to least specific IP address range, to determine if traffic to or from a specific IP address is permitted.

Viewing firewall rules details

You can inspect a firewall rule to see its name, applicable network, and components, including whether the rule is enabled or disabled.

Console

1. List your firewall rules. You can view a list of all rules or just those in a particular network.
2. Click the rule to view.

gcloud

The following command describes an individual firewall rule. Replace [FIREWALL_RULE_NAME] with the name of the firewall rule. Because firewall rule names are unique to the project, you don't have to specify a network when describing an existing one.

gcloud compute firewall-rules describe [FIREWALL_RULE_NAME]

API

Describe a given firewall rule.

GET https://www.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls/FIREWALL_NAME

Replace the placeholders with valid values:

• PROJECT_ID is the ID of the project where the firewall rule is located.
• FIREWALL_NAME is the name of the firewall rule to describe.

For more information, refer to the firewalls.get method.

Deleting firewall rules

Console

1. List your firewall rules. You can view a list of all rules or just those in a particular network.
2. Click the rule to delete.
3. Click Delete.
4. Click Delete again to confirm.

gcloud

The following command deletes a firewall rule. Replace [FIREWALL_RULE_NAME] with the name of the rule to be deleted.

gcloud compute firewall-rules delete [FIREWALL_RULE_NAME]

API

Delete a firewall rule.

DELETE https://www.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls/FIREWALL_NAME

Replace the placeholders with valid values:

• PROJECT_ID is the ID of the project where the firewall rule is located.
• FIREWALL_NAME is the name of the firewall rule to delete.

For more information, refer to the firewalls.delete method.

Monitoring firewall rules

You can enable logging for firewall rules to see which rule allowed or blocked which traffic. See Using Firewall Rules Logging for instructions.

Configuration examples

The diagram below demonstrates 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)

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 instances tagged with webserver to send egress TCP traffic to port 443 of a sample external IP address, 192.0.2.5.

gcloud 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 \
    --source-tags 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)

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 [e-mail] a serviceAccountUser role for service account my-sa-web by setting an IAM policy.

   gcloud iam service-accounts add-iam-policy-binding \
      [e-mail] \
      --member='user:[e-mail]' \
      --role='roles/iam.serviceAccountUser'
   

3. A project OWNER assigns the database developer "[e-mail]" a serviceAccountUser role for service account my-sa-db by setting an IAM policy.

   gcloud iam service-accounts add-iam-policy-binding \
      [e-mail] \
      --member='user:[e-mail]' \
      --role='roles/iam.serviceAccountUser'
   

4. Developer [e-mail], 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 [e-mail]
   

5. Developer [e-mail], which has the Instance Admin role, creates the database instance template and authorize instances to run as service account my-sa-db.

   gcloud compute instance-templates create [INSTANCE_TEMPLATE_NAME] \
       --service-account [e-mail]
   

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 compute firewall-rules create [NAME] \
       --network network_a \
       --allow TCP:1443 \
       --source-service-accounts [e-mail] \
       --target-service-accounts [e-mail]
   

Troubleshooting

Error messages when creating or updating 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.

• 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.

• Service accounts must be valid RFC 822 email addresses. The service account specified in firewall rule must be an email address formatted per RFC 822.

  gcloud compute firewall-rules create bad --allow tcp --source-service-accounts invalid-email
  

  Creating firewall...failed.
  ERROR: (gcloud.compute.firewall-rules.create) Could not fetch resource:
  
  
  
  Invalid value for field 'resource.sourceServiceAccounts[0]': 'invalid-email'. Service accounts must be valid RFC 822 email addresses.
  

ServiceAccounts and Tags are mutually exclusive and can't be combined in the same firewall rule. You cannot specify both both service accounts and tags in the same rule.

gcloud compute firewall-rules create bad --allow tcp --source-service-accounts [e-mail] --target-tags target

Creating firewall...failed.
 ERROR: (gcloud.compute.firewall-rules.create) Could not fetch resource:



ServiceAccounts and Tags are mutually exclusive and can't be combined in the same firewall rule.

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 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,
           sourceServiceAccounts.list():label=SRC_SVC_ACCT,
           targetTags.list():label=TARGET_TAGS,
           targetServiceAccounts.list():label=TARGET_SVC_ACCT
           )"
   

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 that contains the destination VM instance.

   gcloud compute firewall-rules list --filter network=[NETWORK_NAME] \
       --filter 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,
           sourceServiceAccounts.list():label=SRC_SVC_ACCT,
           targetTags.list():label=TARGET_TAGS,
           targetServiceAccounts.list():label=TARGET_SVC_ACCT
           )"
   

   Sample output. Your output will depend on your list of firewall rules

   NAME                    NETWORK  DIRECTION  PRIORITY  SRC_RANGES    DEST_RANGES  ALLOW                         DENY  SRC_TAGS  SRC_SVC_ACCT      TARGET_TAGS  TARGET_SVC_ACCT
   default-allow-icmp      default  INGRESS    65534     0.0.0.0/0                  icmp
   default-allow-internal  default  INGRESS    65534     10.128.0.0/9               tcp:0-65535,udp:0-65535,icmp
   default-allow-rdp       default  INGRESS    65534     0.0.0.0/0                  tcp:3389
   default-allow-ssh       default  INGRESS    65534     0.0.0.0/0                  tcp:22
   firewall-with-sa        default  INGRESS    1000                                 tcp:10000                                     [e-mail]               [e-mail]
   

Is my firewall rule enabled or disabled?

To see if a firewall rule is enabled or disabled, view the firewall rules details.

In the Google Cloud Platform Console, look for Enabled or Disabled under Enforcement.

In the gcloud command line tool output, look for the disabled field. If it says disabled:false, the rule is enabled and being enforced. If it says disabled: true, the rule is disabled.

Which rule is being applied on a VM instance?

Imagine that you add a new firewall rule to a VPC network, which allows traffic to a database server at 10.1.2.3 over tcp:1433. After you create the rule, you can check to see if it's being applied correctly on a particular instance. For more information, see Listing firewall rules for a network interface of a VM instance.

In the following example, the console lists the database-access rule in the Egress analysis tab for this VM instance, meaning 10.1.2.3 egress traffic on port 1433 is permitted. Other egress traffic in the 10.1.0.0/16 range is blocked due to the deny-database-subnet firewall rule.

Permitted egress traffic for a VM instance (click to enlarge)

What's next

• See the Firewall Rules Overview for an introduction to firewall rules