3.2.5 Ensure that the --streaming-connection-idle-timeout argument is not set to 0

Information

Do not disable timeouts on streaming connections.

Setting idle timeouts ensures that you are protected against Denial-of-Service attacks, inactive connections and running out of ephemeral ports.

Note: By default, --streaming-connection-idle-timeout is set to 4 hours which might be too high for your environment. Setting this as appropriate would additionally ensure that such streaming connections are timed out after serving legitimate use cases.

Solution

Remediation Method 1:

If modifying the Kubelet config file, edit the kubelet-config.json file /etc/kubernetes/kubelet-config.yaml and set the below parameter to a non-zero value in the format of #h#m#s

"streamingConnectionIdleTimeout": "4h0m0s"

You should ensure that the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubelet-args.conf does not specify a --streaming-connection-idle-timeout argument because it would override the Kubelet config file.

Remediation Method 2:

If using executable arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubelet-args.conf on each worker node and add the below parameter at the end of the KUBELET_ARGS variable string.

--streaming-connection-idle-timeout=4h0m0s

Remediation Method 3:

If using the api configz endpoint consider searching for the status of "streamingConnectionIdleTimeout": by extracting the live configuration from the nodes running kubelet.

**See detailed step-by-step configmap procedures in

Reconfigure a Node's Kubelet in a Live Cluster

, and then rerun the curl statement from audit process to check for kubelet configuration changes

kubectl proxy --port=8001 &

export HOSTNAME_PORT=localhost:8001 (example host and port number)
export NODE_NAME=gke-cluster-1-pool1-5e572947-r2hg (example node name from "kubectl get nodes")

curl -sSL "http://${HOSTNAME_PORT}/api/v1/nodes/${NODE_NAME}/proxy/configz"

For all three remediations: Based on your system, restart the kubelet service and check status

systemctl daemon-reload
systemctl restart kubelet.service
systemctl status kubelet -l

Impact:

Long-lived connections could be interrupted.

See Also

https://workbench.cisecurity.org/benchmarks/16093

Item Details

Category: ACCESS CONTROL, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|AC-18, 800-53|SC-23, CSCv7|9.2

Plugin: Unix

Control ID: 2833cf35f7ddae79ffdf54c7fcbd1f309fad6c13e68e3006ed597f86f041c5eb