Kubelet not managing IP tables

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Metadata

Id: 5f89001f-6dd9-49ff-9b15-d8cd71b617f4

Cloud Provider: k8s

Platform: Kubernetes

Severity: Medium

Category: Networking and Firewall

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Description

The kubelet argument --make-iptables-util-chains should be set to true. This policy identifies kubelet invocations that explicitly include --make-iptables-util-chains=false (for example in initContainers or containers command arrays) or KubeletConfiguration resources where makeIPTablesUtilChains is set to false. Disabling this option prevents the kubelet from creating required iptables utility chains, which can disrupt network routing and kube-proxy behavior.

Compliant Code Examples

apiVersion: v1
kind: Pod
metadata:
  name: command-demo
  labels:
    purpose: demonstrate-command
spec:
  containers:
    - name: command-demo-container
      image: foo/bar
      command: ["kubelet"]
      args: ["--make-iptables-util-chains=true"]
  restartPolicy: OnFailure

{
    "port": 20250,
    "evictionHard": {
        "memory.available": "200Mi"
    },
    "kind": "KubeletConfiguration",
    "makeIPTablesUtilChains": true,
    "serializeImagePulls": false,
    "address": "192.168.0.8",
    "apiVersion": "kubelet.config.k8s.io/v1beta1"
}

apiVersion: v1
kind: Pod
metadata:
  name: command-demo
  labels:
    purpose: demonstrate-command
spec:
  containers:
    - name: command-demo-container
      image: foo/bar
      command: ["kubelet"]
      args: [""]
  restartPolicy: OnFailure

Non-Compliant Code Examples

apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
address: "192.168.0.8"
port: 20250
serializeImagePulls: false
evictionHard:
    memory.available:  "200Mi"
makeIPTablesUtilChains: false

{
    "apiVersion": "kubelet.config.k8s.io/v1beta1",
    "evictionHard": {
        "memory.available": "200Mi"
    },
    "kind": "KubeletConfiguration",
    "makeIPTablesUtilChains": false,
    "port": 20250,
    "serializeImagePulls": false,
    "address": "192.168.0.8"
}

apiVersion: v1
kind: Pod
metadata:
  name: command-demo
  labels:
    purpose: demonstrate-command
spec:
  containers:
    - name: command-demo-container
      image: foo/bar
      command: ["kubelet"]
      args: ["--make-iptables-util-chains=false"]
  restartPolicy: OnFailure