---
title: Splunk Heavy or Universal Forwarders (TCP) Source
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Observability Pipelines > Sources > Splunk Heavy or Universal
  Forwarders (TCP) Source
---

> For the complete documentation index, see [llms.txt](https://docs.datadoghq.com/llms.txt).

# Splunk Heavy or Universal Forwarders (TCP) Source

{% callout %}
# Important note for users on the following Datadog sites: app.ddog-gov.com, us2.ddog-gov.com

{% alert level="danger" %}
This product is not supported for your selected [Datadog site](https://docs.datadoghq.com/getting_started/site.md). ({% placeholder "user-datadog-site-name" /%}).
{% /alert %}

{% /callout %}
Available for:
{% icon name="icon-logs" /%}
 Logs 
## Overview{% #overview %}

Use Observability Pipelines' Splunk Heavy and Universal Forwards (TCP) source to receive logs sent to your Splunk forwarders.

## Prerequisites{% #prerequisites %}

To use Observability Pipelines' Splunk TCP source, you have a Splunk Enterprise or Cloud Instance alongside either a Splunk Universal Forwarder or a Splunk Heavy Forwarder routing data to your Splunk instance. You also have the following information available:

- The bind address that your Observability Pipelines Worker will listen on to receive logs from your applications. For example, `0.0.0.0:8088`. Later on, you configure your applications to send logs to this address.
- The appropriate [TLS certificates](https://docs.splunk.com/Documentation/Splunk/9.2.0/Security/StepstosecuringSplunkwithTLS#2._Obtain_the_certificates_that_you_need_to_secure_your_Splunk_platform_deployment) and the password you used to create your private key if your forwarders are globally configured to enable SSL.

See [Deploy a Universal Forwarder](https://docs.splunk.com/Documentation/Forwarder/9.2.0/Forwarder/Installtheuniversalforwardersoftware) or [Deploy a Heavy Forwarder](https://docs.splunk.com/Documentation/Splunk/9.2.1/Forwarding/Deployaheavyforwarder) for more information on Splunk forwarders.

## Setup{% #setup %}

{% alert level="danger" %}
For Secrets Management: Only enter the identifiers for the Splunk TCP address and, if applicable, the TLS key pass. Do not enter the actual values.
{% /alert %}

Set up this source when you [set up a pipeline](https://docs.datadoghq.com/observability_pipelines/configuration/set_up_pipelines.md). You can set up a pipeline in the [UI](https://app.datadoghq.com/observability-pipelines), using the [API](https://docs.datadoghq.com/api/latest/observability-pipelines.md), or with [Terraform](https://registry.terraform.io/providers/datadog/datadog/latest/docs/resources/observability_pipeline). The instructions in this section are for setting up the source in the UI.

After you select the Splunk TCP source in the pipeline UI, enter the identifier for your Splunk TCP address. If you leave it blank, the default is used.

**Notes**:

- By default, the Splunk TCP source doesn't limit the size of an event. To prevent unbounded memory consumption, such as from malformed connections or connections that remain open indefinitely, use the environment variable `DD_OP_SPLUNK_TCP_MAX_FRAME_LENGTH` to set a maximum frame length in bytes.
- If you enter secret identifiers and then choose to use environment variables, the environment variable is the identifier entered and prepended with `DD_OP_`. For example, if you entered `PASSWORD_1` for a password identifier, the environment variable for that password is `DD_OP_PASSWORD_1`.

### Optional TLS settings{% #optional-tls-settings %}

Toggle the switch to **Enable TLS**.

- If you are using Secrets Management, enter the identifier for the key pass. See Secret defaults for the default used if the field is left blank.
- Enter the following certificate and key files:
  - `Server Certificate Path`: The path to the certificate file that has been signed by your Certificate Authority (CA) root file in DER, PEM, or CRT (X.509).
  - (Optional) `CA Certificate Path`: The path to the certificate file that is your Certificate Authority (CA) root file in DER, PEM, or CRT (X.509).
  - (Optional) `Private Key Path`: The path to the `.key` private key file that belongs to your Server Certificate Path in DER, PEM, or CRT (PKCS #8) format.
  - **Notes**:
    - The configuration data directory `/var/lib/observability-pipelines-worker/config/` is automatically appended to the file paths. See [Advanced Worker Configurations](https://docs.datadoghq.com/observability_pipelines/configuration/install_the_worker/advanced_worker_configurations.md) for more information.
    - The file must be readable by the `observability-pipelines-worker` group and user.

- (Optional) Toggle **Verify certificate** to require connecting clients to present a valid client certificate. This enforces mutual TLS (mTLS), where the Worker verifies the identity of each connecting client.

## Secret defaults{% #secret-defaults %}

These are the defaults used for secret identifiers and environment variables.

{% tab title="Secrets Management" %}

- Splunk TCP address identifier:
  - References the socket address, such as `0.0.0.0:9997` on which the Observability Pipelines Worker listens to receive logs from the Splunk Forwarder.
  - The default identifier is `SOURCE_SPLUNK_TCP_ADDRESS`.
- Splunk TCP TLS passphrase identifier (when TLS is enabled):
  - The default identifier is `SOURCE_SPLUNK_TCP_KEY_PASS`.

{% /tab %}

{% tab title="Environment Variables" %}

- Splunk TCP address:
  - The Observability Pipelines Worker listens to this socket address to receive logs from the Splunk Forwarder. For example, `0.0.0.0:9997`.
  - The default environment variable is `DD_OP_SOURCE_SPLUNK_TCP_ADDRESS`.
- Splunk TCP TLS passphrase (when enabled):
  - The default environment variable is `DD_OP_SOURCE_SPLUNK_TCP_KEY_PASS`.

{% /tab %}

## Connect Splunk Forwarder to the Observability Pipelines Worker{% #connect-splunk-forwarder-to-the-observability-pipelines-worker %}

To forward your logs to the Worker, add the following configuration to your Splunk Heavy/Universal Forwarder's `etc/system/local/outputs.conf` and replace `<OPW_HOST>` with the IP/URL of the host (or load balancer) associated with the Observability Pipelines Worker:

```
[tcpout]
compressed=false
sendCookedData=false
defaultGroup=opw

[tcpout:opw]
server=<OPW_HOST>:8099
```

`<OPW_HOST>` is the IP/URL of the host (or load balancer) associated with the Observability Pipelines Worker. For CloudFormation installs, the `LoadBalancerDNS` CloudFormation output has the correct URL to use. For Kubernetes installs, the internal DNS record of the Observability Pipelines Worker service can be used. For example: `opw-observability-pipelines-worker.default.svc.cluster.local`.

At this point, your logs should be going to the Worker, processed by the pipeline, and delivered to the configured destination.