Configure Cribl Stream to Receive TCP Data

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Cribl Stream ships with a TCP Source preconfigured to listen on Port 10060. You can clone or directly modify this Source to further configure it, and then enable it.

1. On the top bar, select Products, and then select Cribl Stream. Under Worker Groups, select a Worker Group. Next, you have two options:
   • To configure via QuickConnect, navigate to Routing > QuickConnect (Stream) or Collect (Edge). Select Add Source and select the Source you want from the list, choosing either Select Existing or Add New.
   • To configure via the Routes, select Data > Sources (Stream) or More > Sources (Edge). Select the Source you want. Next, select Add Source.
2. Configure the following under General Settings:
   • Input ID: Enter a unique name to identify this TCP Source definition. If you clone this Source, Cribl Stream will add -CLONE to the original Input ID.
   • Description: Optionally, enter a description.
   • Address: Enter hostname/IP to listen for raw TCP data. For example, localhost or 0.0.0.0.
   • Port: Enter port number.
   • Enable header: Toggle on to indicate that client will pass a header record with every new connection. The header can contain an authToken, and an object with a list of fields and values to add to every event. These fields can be used to simplify Event Breaker selection, routing, and so forth. Header format: { "authToken" : "myToken", "fields": { "field1": "value1", "field2": "value2" }}.
   • Authentication method: Select Manual to enter an auth token directly, or Secret to use a text secret to authenticate.
     • Auth token: If you selected Manual, enter an auth token, or select Generate to automatically generate a token. If empty, unauthorized access is permitted.
     • Shared secret (authToken): If you selected Secret, enter a shared secret to be provided by any client (in authToken header field). Select Create to create a new secret. If empty, unauthorized access will be permitted.
3. Next, you can configure the following Optional Settings:
   • Tags: Optionally, add tags that you can use to filter and group Sources in Cribl Stream’s UI. These tags aren’t added to processed events. Use a tab or hard return between (arbitrary) tag names.
4. Optionally, you can adjust the TLS Settings, Persistent Queue Settings, Processing, and Advanced settings, or Connected Destinations outlined in the sections below.
5. Select Save, then Commit & Deploy.

TLS Settings (Server Side)

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Enabled: Defaults to toggled off. When toggled on:

Certificate name: Name of the predefined certificate.

Private key path: Server path containing the private key (in PEM format) to use. Path can reference $ENV_VARS.

Passphrase: Passphrase to use to decrypt private key.

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

CA certificate path: Server path containing 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. Default is toggled off. When toggled on:

• Validate client certificates: Reject certificates that are not authorized by a CA in the CA certificate path, or by another trusted CA (for example, the system’s CA). Default is toggled on.

• Common name: Regex that a peer certificate’s subject attribute must match in order to connect. Defaults to .*. Matches on the substring after CN=. As needed, escape regex tokens to match literal characters. (For example, to match the subject CN=worker.cribl.local, you would enter: worker\.cribl\.local.) If the subject attribute contains Subject Alternative Name (SAN) entries, the Source will check the regex against all of those but ignore the Common Name (CN) entry (if any). If the certificate has no SAN extension, the Source will check the regex against the single name in the CN.

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.

Persistent Queue Settings

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In the Persistent Queue Settings tab, you can optionally specify persistent queue storage, using the following controls. Persistent queue buffers and preserves incoming events when a downstream Destination has an outage or experiences backpressure.

Before enabling persistent queue, learn more about persistent queue behavior and how to optimize it with your system:

• About Persistent Queues
• Optimize Source Persistent Queues (sPQ)

On Cribl-managed Cloud Workers (with an Enterprise plan), this tab exposes only the Enable Persistent Queue toggle. If enabled, PQ is automatically configured in Always On mode, with a maximum queue size of 1 GB disk space allocated per PQ‑enabled Source, per Worker Process.

The 1 GB limit is on uncompressed inbound data, and the queue does not perform any compression. This limit is not configurable. For configurable queue size, compression, mode, and other options below, use a hybrid Group.

Enable persistent queue: Default is toggled off. When toggled on:

Mode: Select a condition for engaging persistent queues.

• Always On: This default option will always write events to the persistent queue, before forwarding them to the Cribl Stream data processing engine.
• Smart: This option will engage PQ only when the Source detects backpressure from the Cribl Stream data processing engine.

Smart mode only engages when necessary, such as when a downstream Destination becomes blocked and the Buffer size limit reaches its limit. When persistent queue is set to Smart mode, Cribl attempts to flush the queue when every new event arrives. The only time events stay in the buffer is when a downstream Destination becomes blocked.

Buffer size limit: The maximum number of events to hold in memory before reporting backpressure to the sender and writing the queue to disk. Defaults to 1000. This buffer is for all connections, not just per Worker Process. For that reason, this can dramatically expand memory usage. Connections share this limit, which may result in slightly lower throughput for higher numbers of connections. For higher numbers of connections, consider increasing the limit.

Commit frequency: The number of events to send downstream before committing that Stream has read them. Defaults to 42.

File size limit: The maximum data volume to store in each queue file before closing it and (optionally) applying the configured Compression. Enter a numeral with units of KB, MB, and so forth. If not specified, Cribl Stream applies the default 1 MB.

Queue size limit: The maximum amount of disk space that the queue is allowed to consume on each Worker Process. Once this limit is reached, this Source will stop queueing data and block incoming data. Required, and defaults to 5 GB. Accepts positive numbers with units of KB, MB, GB, and so forth. Can be set as high as 1 TB, unless you’ve configured a different Worker Process PQ size limit in Group or Fleet settings.

Queue file path: The location for the persistent queue files. Defaults to $CRIBL_HOME/state/queues. To this field’s specified path, Cribl Stream will append /<worker-id>/inputs/<input-id>.

Compression: Optional codec to compress the persisted data after a file closes. Defaults to None; Gzip is also available.

In Cribl Stream 4.1 and later, the Source persistent queue default Mode is Always on, to best ensure events’ delivery. For details on optimizing this selection, see Optimize Source Persistent Queues (sPQ).

You can optimize Workers’ startup connections and CPU load at Group/Fleet settings > Worker Processes.

Processing Settings

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Custom Command

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In this section, you can pass the data from this input to an external command for processing before the data continues downstream.

Enabled: Default is toggled off. When toggled on:

Command: Enter the command that will consume the data (via stdin) and will process its output (via stdout).

Arguments: Click Add Argument to add each argument for the command. You can drag arguments vertically to resequence them.

Event Breakers

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Event Breaker rulesets: A list of event breaking rulesets that will be applied to the input data stream before the data is sent through the Routes. Defaults to System Default Rule.

Event Breaker buffer timeout: How long (in milliseconds) the Event Breaker will wait for new data to be sent to a specific channel, before flushing out the data stream, as-is, to the Routes. Minimum 10 ms, default 10000 (10 sec), maxiumum 43200000 (12 hours).

Fields

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In this section, you can define new fields or modify existing ones using JavaScript expressions, similar to the Eval function.

• The Name specifies the field name, which can either be a new field (unique within the event) or an existing field name to modify its value.
• The Value is a JavaScript expression (enclosed in quotes or backticks) to compute the field’s value (can be a constant). Select this field’s advanced mode icon (far right) if you’d like to open a modal where you can work with sample data and iterate on results.

This flexibility means you can:

• Add new fields to enrich the event.
• Modify existing fields by overwriting their values.
• Compute logic or transformations using JavaScript expressions.

Pre-Processing

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

Advanced Settings

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Enable Proxy Protocol: Toggle on if the connection is proxied by a device that supports Proxy Protocol v1 or v2. When this setting is enabled, the __srcIpPort internal field will show the original source IP address and port. When it is disabled, the __srcIpPort field will show the IP address and port of the proxy that forwarded the connection.

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

Active connection limit: Maximum number of active connections allowed per Worker Process. Defaults to 1000. Set a lower value if connection storms are causing the Source to hang. Set 0 for unlimited connections.

Socket idle timeout (seconds): The duration that Cribl Stream will wait for activity on an idle TCP socket before closing the connection. Disabled when set to 0, the default.

Forced socket termination timeout (seconds): The extra time the server waits before forcibly closing a socket that has been idle (TCP socket idle timeout) or exceeded its maximum lifespan (TCP socket max lifespan) but has not yet properly closed. This prevents resource leaks caused by unresponsive clients or network issues. Configure based on network latency and client behavior. Default: 30 seconds. Set to 0 to disable.

Socket max lifespan (seconds): The duration that a socket is allowed to remain open, regardless of activity. This setting prevents resource exhaustion (such as TCP pinning) by limiting the lifespan of connections. Configure based on expected connection durations and resource availability. Disabled when set to 0, the default.

Environment: If you’re using GitOps, optionally use this field to specify a single Git branch on which to enable this configuration. If empty, the config will be enabled everywhere.

Connected Destinations

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Select Send to Routes to enable conditional routing, filtering, and cloning of this Source’s data via the Routing table.

Select QuickConnect to send this Source’s data to one or more Destinations via independent, direct connections.

Internal Fields

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Cribl Stream 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.

Fields accessible for this Source:

• __inputId
• __srcIpPort
• __channel

TCP Source Examples

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Every new TCP connection may contain an optional header line, with an authToken and a list of fields and values to add to every event. To use the Cribl Stream Cloud sample, copy the <token_value> out of your Cribl Stream Cloud TCP Source.

{"authToken":"myToken42", "fields": {"region": "us-east-1", "AZ":"az1"}}

this is event number 1
this is event number 2

{"authToken":"<token_value>", "fields": {"region": "us-east-1", "AZ":"az1"}}
this is event number 1
this is event number 2

Enabling the Example – Cribl Stream

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1. Configure Cribl Stream to listen on port 7777 for raw TCP. Set authToken to myToken42.
2. Create a file called test.raw, with the payload above.
3. Send it over to your Cribl Stream host, using this command: cat test.raw | nc <myCriblHost> 7777

Enabling the Example – Cribl.Cloud

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Use netcat with --ssl and --ssl-verify:

cat test.raw | nc --ssl --ssl-verify default.main.<Your-Org-ID>.cribl.cloud 10060

With a Cribl.Cloud Enterprise plan, generalize the above URL’s default.main substring to <group-name>.main when sending to other Worker Groups.

Troubleshooting

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The Source’s configuration modal has helpful tabs for troubleshooting:

Live Data: Try capturing live data to see real-time events as they are ingested. On the Live Data tab, click Start Capture to begin viewing real-time data.

Logs: Review and search the logs that provide detailed information about the ingestion process, including any errors or warnings that may have occurred.

You can also view the Monitoring page that provides a comprehensive overview of data volume and rate, helping you identify ingestion issues. Analyze the graphs showing events and bytes in/out over time.