> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/appsec-rules/iac-security/logging/appsec-gcp-26.md).

# GCP VPC Flow logs for the subnet is set to Off misconfiguration detected in code

## Rule Details

|                        |                                      |
| ---------------------- | ------------------------------------ |
| Cortex AppSec Rule ID  | APPSEC\_GCP\_26                      |
| Category - Subcategory | Logging - Disabled or missing        |
| Provider               | GCP                                  |
| Severity               | LOW                                  |
| Framework              | Terraform, Terraform Plan            |
| Mapped CSPM/KSPM Rule  | 4e0039a6-ead7-4a28-8041-ef4889c312df |

## Impact

Flow Logs capture information about IP traffic going to and from network interfaces. This information can be used to detect anomalous traffic and insight about security workflows. You can view and retrieve flow log data in Stackdriver Logging. VPC networks and subnetworks provide logically isolated and secure network partitions to launch Google Cloud Platform (GCP) resources. When Flow Logs are enabled for a subnet, VMs within that subnet report on all Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) flows. Each VM samples the inbound and outbound TCP and UDP flows it sees, whether the flow is to or from another VM, a host in the on-premises datacenter, a Google service, or a host on the Internet. If two GCP VMs are communicating and both are in subnets that have VPC Flow Logs enabled, both VMs report the flows. We recommended you set *Flow Logs* to *On* to capture this data. Because the volume of logs may be high, you may wish to enable flow logs only for business-critical VPC Network Subnets. Flow Logs supports the following use cases:

* Network monitoring
* Understanding network usage and optimizing network traffic expenses
* Network forensics
* Real-time security analysis

## How to Fix

*Resource:* google\_compute\_subnetwork

* *Arguments:* log\_config \[source,go]

***

resource "google\_compute\_subnetwork" "example" { name = "log-test-subnetwork" ip\_cidr\_range = "10.2.0.0/16" region = "us-central1" network = google\_compute\_network.custom-test.id

* log\_config { aggregation\_interval = "INTERVAL\_10\_MIN" flow\_sampling = 0.5 metadata = "INCLUDE\_ALL\_METADATA" } }

***


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://cortex-docs.paloaltonetworks.com/appsec-rules/iac-security/logging/appsec-gcp-26.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.