How to open a specific port such as 9090 in Google Compute Engine

Question

You need to:

1. Go to cloud.google.com

2. Go to my Console

3. Choose your Project

4. Choose Networking > VPC network

5. Choose "Firewall"

6. Choose "Create Firewall Rule"

7. To apply the rule to select VM instances, select Targets > "Specified target tags", and enter into "Target tags" the name of the tag. This tag will be used to apply the new firewall rule onto whichever instance you'd like. Then, make sure the instances have the network tag applied.

8. Set Source IP ranges to allow traffic from all IPs: 0.0.0.0/0

9. To allow incoming TCP connections to port 9090, in "Protocols and Ports", check “tcp” and enter 9090

10. Click Create (or click “Equivalent Command Line” to show the gcloud command to create the same rule)

I hope this helps you.

Update Please refer to docs to customize your rules.

Here is the command-line approach to answer this question:

gcloud compute firewall-rules create <rule-name> --allow tcp:9090 --source-tags=<list-of-your-instances-names> --source-ranges=0.0.0.0/0 --description="<your-description-here>"

This will open the port 9090 for the instances that you name. Omitting --source-tags and --source-ranges will apply the rule to all instances. More details are in the Gcloud documentation and the firewall-rule create command manual

The previous answers are great, but Google recommends using the newer gcloud commands instead of the gcutil commands.

PS: To get an idea of Google's firewall rules, run gcloud compute firewall-rules list and view all your firewall rules

Creating firewall rules

Please review the firewall rule components [1] if you are unfamiliar with firewall rules in GCP. 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.

For Cloud Console:

1. Go to the Firewall rules page in the Google Cloud Platform Console.
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 will be implemented.
5. Specify the Priority of the rule. The lower the number, the higher the priority.
6. For the Direction of traffic, choose ingress or egress.
7. For the Action on match, choose allow or deny.

8. 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.

9. 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.

10. 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.

11. 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.

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

13. (Optional) You can enable firewall rules logging:

    • Click Logs > On.
    • Click Turn on.

14. Click Create.

Link: [1] https://cloud.google.com/vpc/docs/firewalls#firewall_rule_components

You'll need to add a firewall rule to open inbound access to tcp:9090 to your instances. If you have more than the two instances, and you only want to open 9090 to those two, you'll want to make sure that there is a tag that those two instances share. You can add or update tags via the console or the command-line; I'd recommend using the GUI for that if needed because it handles the read-modify-write cycle with setinstancetags.

If you want to open port 9090 to all instances, you can create a firewall rule like:

gcutil addfirewall allow-9090 --allowed=tcp:9090

which will apply to all of your instances.

If you only want to open port 9090 to the two instances that are serving your application, make sure that they have a tag like my-app, and then add a firewall like so:

gcutil addfirewall my-app-9090 --allowed=tcp:9090 --target_tags=my-app

You can read more about creating and managing firewalls in GCE here.