Cribl LogStream – Docs

Cribl LogStream Documentation

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Cribl LogStream supports receiving of data over TCP in JSON format (see protocol below).


Type: Push | TLS Support: YES | Event Breaker Support: No

Configuring Cribl LogStream to Receive TCP JSON Data

Select Data > Sources, then select TCP JSON from the Data Sources page's tiles or left menu. Click Add New to open the TCP JSON > New Source modal, which provides the fields outlined below.


LogStream ships with a TCP JSON Source preconfigured to listen on Port 10070. You can clone or directly modify this Source to further configure it, and then enable it.

General Settings

Input ID: Enter a unique name to identify this TCP JSON Source definition.

Address: Enter hostname/IP to listen for TCP JSON data. E.g., localhost or

Port: Enter the port number to listen on.

IP whitelist regex: Regex matching IP addresses that are allowed to establish a connection. Defaults to .* (i.e., all IPs).

Shared secret (authToken): Shared secret to be provided by any client (in authToken header field). Click Generate to create a new secret. If empty, unauthenticated access will be permitted.

TLS Settings (Server Side)

Enabled defaults to No. When toggled to Yes:

Certificate name: Name of the predefined certificate.

Private key path: Path on server where to find the private key to use in PEM format. Path can reference $ENV_VARS.

Passphrase: Passphrase to use to decrypt private key.

Certificate path: Server path at which to find certificates (in PEM format) to use. Path can reference $ENV_VARS.

CA certificate path: Server path at which to find CA certificates (in PEM format) to use. Path can reference $ENV_VARS.

Authenticate client (mutual auth): Require clients to present their certificates. Used to perform mutual authentication using SSL certs. Defaults to No. When toggled to Yes:

  • Validate client certs: Reject certificates that are not authorized by a CA in the CA certificate path, or by another trusted CA (e.g., the system's CA). Defaults to No.

  • Common name: Regex matching subject common names in peer certificates allowed to connect. Defaults to .*. Matches on the substring after CN=. As needed, escape regex tokens to match literal characters. E.g., to match the subject CN=worker.cribl.local, you would enter: worker\.cribl\.local.

Minimum TLS version: Optionally, select the minimum TLS version to accept from connections.

Maximum TLS version: Optionally, select the maximum TLS version to accept from connections.

Processing Settings

Fields (Metadata)

In this section, you can add fields/metadata to each event, using Eval-like functionality.

Name: Field name.

Value: JavaScript expression to compute field's value (can be a constant).


In this section's Pipeline drop-down list, you can select a single existing Pipeline to process data from this input before the data is sent through the Routes.

Advanced Settings

  • Enable proxy protocol: Toggle to Yes if the connection is proxied by a device that supports Proxy Protocol v1 or v2.

Internal Fields

Cribl LogStream uses a set of internal fields to assist in handling of data. These "meta" fields are not part of an event, but they are accessible, and Functions can use them to make processing decisions.

Field for this Source:

  • __inputId


LogStream expects TCP JSON events in newline-delimited JSON format:

  1. A header line. Can be empty – e.g., {}. If authToken is enabled (see above) it should be included here as a field called authToken. When authToken is not set, the header line is optional. In this case, the first line will be treated as an event if does not look like a header record.
In addition, if events need to contain common fields, they can be included here under fields. In the example below, region and AZ will be automatically added to all events.
  1. A JSON event/record per line.
{"authToken":"myToken42", "fields": {"region": "us-east-1", "AZ":"az1"}}

{"_raw":"this is a sample event ", "host":"myHost", "source":"mySource", "fieldA":"valueA", "fieldB":"valueB"}
{"host":"myOtherHost", "source":"myOtherSource", "_raw": "{\"message\":\"Something informative happened\", \"severity\":\"INFO\"}"}

TCP JSON Field Mapping to Splunk

If a TCP JSON Source is routed to a Splunk destination, fields within the JSON payload are mapped to Splunk fields. Fields that do not have corresponding (native) Splunk fields become index-time fields. For example, let's assume we have a TCP JSON event as below:

{"_time":1541280341, "host":"myHost", "source":"mySource", "_raw":"this is a sample event ", "fieldA":"valueA"}

Here, _time, host, and source become their corresponding fields in Splunk. The value of _raw becomes the actual body of the event, and fieldA becomes an index-time field (fieldA::`valueA``).


  1. Configure Cribl LogStream to listen on port 10001 for TCP JSON. Set authToken to myToken42.
  2. Create a file called test.json with the payload above.
  3. Send it over to your Cribl LogStream host: cat test.json | nc <myCriblHost> 10001

Updated about a month ago


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