# Cis Oke V150 5.4.1

> Restrict Access to the Control Plane Endpoint (Automated)

- Skill: `cyberstrikeus/cis-oke-v150-5-4-1` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-oke-v150-5-4-1`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-oke-v150-5-4-1/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/cis-oke-v150-5-4-1

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# 5.4.1 Restrict Access to the Control Plane Endpoint (Automated)

## Profile Applicability

- Level 1

## Description

Enable Master Authorized Networks to restrict access to the cluster's control plane (master endpoint) to only an allowlist (whitelist) of authorized IPs.

## Rationale

Authorized networks are a way of specifying a restricted range of IP addresses that are permitted to access your cluster's control plane. Kubernetes Engine uses both Transport Layer Security (TLS) and authentication to provide secure access to your cluster's control plane from the public internet. This provides you the flexibility to administer your cluster from anywhere; however, you might want to further restrict access to a set of IP addresses that you control. You can set this restriction by specifying an authorized network.

Restricting access to an authorized network can provide additional security benefits for your container cluster, including:

- Better protection from outsider attacks: Authorized networks provide an additional layer of security by limiting external, non-OCP access to a specific set of addresses you designate, such as those that originate from your premises. This helps protect access to your cluster in the case of a vulnerability in the cluster's authentication or authorization mechanism.
- Better protection from insider attacks: Authorized networks help protect your cluster from accidental leaks of master certificates from your company's premises. Leaked certificates used from outside OCP and outside the authorized IP ranges (for example, from addresses outside your company) are still denied access.

## Impact

When implementing Master Authorized Networks, be careful to ensure all desired networks are on the allowlist (whitelist) to prevent inadvertently blocking external access to your cluster's control plane.

## Audit

Check for the following:

```bash
export OKE_CLUSTERID=<oke cluster id>
oci ce cluster get --cluster-id $OKE_CLUSTERID
```

Check for endpoint URL of the Kubernetes API Server in output.

## Remediation

Configure Master Authorized Networks for the cluster to restrict access to approved IP ranges.

## Default Value

By default, Master Authorized Networks is disabled.

## References

1. [https://docs.cloud.oracle.com/en-us/iaas/Content/ContEng/Concepts/contengclustersnodes.htm](https://docs.cloud.oracle.com/en-us/iaas/Content/ContEng/Concepts/contengclustersnodes.htm)

## CIS Controls

| Controls Version | Control                                                                                                                                                                                                                                                                                                                                                             | IG 1 | IG 2 | IG 3 |
| ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---- | ---- | ---- |
| v8               | 9.3 Maintain and Enforce Network-Based URL Filters - Enforce and update network-based URL filters to limit an enterprise asset from connecting to potentially malicious or unapproved websites. Example implementations include category-based filtering, reputation-based filtering, or through the use of block lists. Enforce filters for all enterprise assets. |      | x    | x    |
| v7               | 7.5 Subscribe to URL-Categorization service - Subscribe to URL categorization services to ensure that they are up-to-date with the most recent website category definitions available. Uncategorized sites shall be blocked by default.                                                                                                                             |      | x    | x    |

## Profile

Level 1 - OKE