These docs are for Cribl Edge 4.0 and are no longer actively maintained.
See the latest version (4.13).
Cribl TCP
The Cribl TCP Destination is available only in distributed deployments. It enables Edge Nodes to send data to peer Nodes, as long as all Nodes are connected to the same Leader.
You’ll find the Cribl TCP Destination/Source pair especially valuable in a hybrid Cloud deployment, where it ensures that you’re billed for ingress only once – when Cribl first receives the data. All data subsequently transferred to other Workers via the Cribl TCP Destination/Source pair is not charged. However, the Cribl TCP Destination/Source pair can similarly reduce your metered data ingress in other scenarios, such as on-prem Edge to on-prem Stream.
Type: Streaming | TLS Support: Configurable | PQ Support: Yes
You might choose this Destination over the Cribl HTTP Destination in certain circumstances, such as when a firewall or proxy allows raw TCP egress. In single‑instance mode or for testing, you can substitute the TCP JSON Destination. (However, this substitution will not facilitate sending all internal fields, as described below.)
Configuration Requirements
Configuring Cribl TCP flow between peer Edge Nodes imposes some particular requirements:
The Cribl TCP Destination must be on a Edge Node that is connected to the same Leader as the Cribl TCP Source(s).
You must specify the same Leader Address on the Edge Nodes that host both the Destination and Source. Otherwise, token verification will fail – breaking the connection and preventing data flow.
To get the Leader Address specifically for Cribl.Cloud hybrid Workers, see Hybrid Cribl HTTP/Cribl TCP Configuration.
To configure the Leader Address via the UI, log directly into each Edge Node’s UI. Then select Settings > Global Settings > Distributed Settings > Leader Settings > Address.
To configure the Leader Address via the instance.yml file, the
hostvalues on the connecting Edge Nodes must be identical. In this example, both Edge Nodes must point tocribl-leader:distributed: mode: master master: host: cribl-leader port: 4200This Destination’s Address and Port values must match the Address and Port you’ve configured on its peer Cribl TCP Source(s).
Cribl 3.5.4 was a breakpoint in Cribl TCP Leader/Worker communications. Edge Nodes running the Cribl TCP Destination on Cribl Edge 3.5.4 and later can receive data only from Edge Nodes running v.3.5.4 and later. Edge Nodes running the Cribl TCP Destination on Cribl Edge 3.5.3 and earlier can receive data only from Edge Nodes running v.3.5.3 and earlier.
Configuring a Cribl TCP Destination
From the top nav, click Manage, then select a Fleet to configure. Next, you have two options:
To configure via the graphical QuickConnect UI, click Routing > QuickConnect (Stream) or Collect (Edge). Next, click + Add Destination at right. From the resulting drawer’s tiles, select Cribl TCP. Next, click either + Add Destination or (if displayed) Select Existing. The resulting drawer will provide the options below.
Or, to configure via the Routing UI, click Data > Destinations (Stream) or More > Destinations (Edge). From the resulting page’s tiles or the Destinations left nav, select Cribl TCP. Next, click New Destination to open a New Destination modal that provides the options below.
General Settings
Output ID: Enter a unique name to identify this Destination definition.
Load balancing: When toggled to Yes, see Load Balancing Settings below.
The following two fields appear only with Load balancing’s default
Nosetting, and must match the Address and Port you’ve configured on the peer Cribl TCP Source to which you’re sending.
Address: Hostname of the receiver.
Port: Port number to connect to on the host, e.g., 10300.
Optional Settings
Compression: Codec to use to compress the data before sending. Defaults to None.
Throttling: Throttle rate, in bytes per second. Defaults to 0, meaning no throttling. Multiple-byte units such as KB, MB, GB etc. are also allowed, e.g., 42 MB. When throttling is engaged, your Backpressure behavior selection determines whether Cribl Edge will handle excess data by blocking it, dropping it, or queueing it to disk.
Backpressure behavior: Specifies whether to block, drop, or queue events when all receivers are exerting backpressure. Defaults to Block. See Persistent Queue Settings below.
Tags: Optionally, add tags that you can use for filtering and grouping at the final destination. Use a tab or hard return between (arbitrary) tag names.
Load Balancing Settings
Enabling the Load balancing slider displays the following controls:
Exclude Current Host IPs
This slider determines whether to exclude all IPs of the current host from the list of any resolved hostnames. Defaults to No.
Destinations
The Destinations table is where you specify a set of receivers on which to load-balance data. Click + Add Destination to specify more receivers on new rows. Each row provides the following fields:
Address: Hostname of a receiver. Optionally, you can paste in a comma-separated list, in <host>:<port> format.
Port: Port number to send data to on the host.
Each Address/Port combination must match the Address and Port configured on a peer Cribl HTTP Source to which you’re sending.
TLS: Whether to inherit TLS configs from group setting, or disable TLS. Defaults to inherit.
TLS servername: Servername to use if establishing a TLS connection. If not specified, defaults to connection host (if not an IP); otherwise, uses the global TLS settings.
Load Weight: Specify a weight to apply to the receiver for load-balancing purposes.
The final column provides an X button to delete any row from the table.
Persistent Queue Settings
This section displays when the Backpressure behavior is set to Persistent Queue.
Max file size: The maximum data volume to store in each queue file before closing it. Enter a numeral with units of KB, MB, etc. Defaults to 1 MB.
Max queue size: The maximum amount of disk space the queue is allowed to consume. Once this limit is reached, Cribl Stream stops queueing and applies the fallback Queue‑full behavior. Enter a numeral with units of KB, MB, etc.
Queue file path: The location for the persistent queue files. Defaults to $CRIBL_HOME/state/queues. To this value, Cribl Stream will append /<worker‑id>/<output‑id>.
Compression: Codec to use to compress the persisted data, once a file is closed. Defaults to None; Gzip is also available.
Queue-full behavior: Whether to block or drop events when the queue is exerting backpressure (because disk is low or at full capacity). Block is the same behavior as non-PQ blocking, corresponding to the Block option on the Backpressure behavior drop-down. Drop new data throws away incoming data, while leaving the contents of the PQ unchanged.
Clear persistent queue: Click this button if you want to flush out files that are currently queued for delivery to this Destination. A confirmation modal will appear. (Appears only after Output ID has been defined.)
TLS Settings (Client Side)
Use TLS defaults to No. When toggled to Yes:
Autofill?: This setting is experimental.
Validate server 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.
Server name (SNI): Server name for the SNI (Server Name Indication) TLS extension. This must be a host name, not an IP address.
Minimum TLS version: Optionally, select the minimum TLS version to use when connecting.
Maximum TLS version: Optionally, select the maximum TLS version to use when connecting.
Certificate name: The name of the predefined certificate.
CA certificate path: Path on client containing CA certificates (in PEM format) to use to verify the server’s cert. Path can reference $ENV_VARS.
Private key path (mutual auth): Path on client containing the private key (in PEM format) to use. Path can reference $ENV_VARS. Use only if mutual auth is required.
Certificate path (mutual auth): Path on client containing certificates in (PEM format) to use. Path can reference $ENV_VARS. Use only if mutual auth is required.
Passphrase: Passphrase to use to decrypt private key.
Timeout Settings
Connection timeout: Amount of time (in milliseconds) to wait for the connection to establish before retrying. Defaults to 10000.
Write timeout: Amount of time (in milliseconds) to wait for a write to complete before assuming connection is dead. Defaults to 60000.
Processing Settings
Post‑Processing
Pipeline: Pipeline to process data before sending the data out using this output.
System fields: A list of fields to automatically add to events that use this output. By default, includes cribl_pipe (identifying the Cribl Stream Pipeline that processed the event). Supports wildcards. Other options include:
cribl_host– Cribl Stream Node that processed the event.cribl_wp– Cribl Stream Worker Process that processed the event.cribl_input– Cribl Stream Source that processed the event.cribl_output– Cribl Stream Destination that processed the event.
Advanced Settings
Auth Token TTL minutes: The number of minutes before the internally generated authentication token expires, valid values between 1 and 60.
Exclude fields: Fields to exclude from the event. By default, this Destination forwards all useful internal fields.
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.
The following options are added if you enable the General Settings tab’s Load balancing option:
DNS resolution period (seconds): Re-resolve any hostnames after each interval of this many seconds, and pick up destinations from A records. Defaults to 600 seconds.
Load balance stats period (seconds): Lookback traffic history period. Defaults to 300 seconds. (Note that If multiple receivers are behind a hostname – i.e., multiple A records – all resolved IPs will inherit the weight of the host, unless each IP is specified separately. In Cribl Stream load balancing, IP settings take priority over those from hostnames.)
Max connections: Constrains the number of concurrent receiver connections, per Worker Process, to limit memory utilization. If set to a number > 0, then on every DNS resolution period, Cribl Edge will randomly select this subset of discovered IPs to connect to. Cribl Edge will rotate IPs in future resolution periods – monitoring weight and historical data, to ensure fair load balancing of events among IPs.
Internal Fields Loopback to Sources
The Cribl TCP and Cribl HTTP Destinations differ from all other Destinations in the way they handle internal fields: They normally send data back to their respective Cribl Sources – where Cribl internal fields, metrics, and sender-generated fields can all be useful.
These Destinations forward all internal fields by default, except for any that you exclude in Advanced Settings > Exclude fields.
As examples, if the following fields are present on an event forwarded by a Cribl HTTP or Cribl TCP Destination, they’ll be accessible in the ingesting Cribl HTTP/TCP Source:__criblMetrics, __srcIpPort, __inputId, and __outputId.