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5.6.3 Ensure Master Authorized Networks is Enabled
Information
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.
Master Authorized Networks blocks untrusted IP addresses. Google Cloud Platform IPs (such as traffic from Compute Engine VMs) can reach your master through HTTPS provided that they have the necessary Kubernetes credentials.
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-GCP 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 GCP and outside the authorized IP ranges (for example, from addresses outside your company) are still denied access.
Solution
Using Google Cloud ConsoleGo to Kubernetes Engine by visiting https://console.cloud.google.com/kubernetes/list
Select Kubernetes clusters for which Master Authorized Networks is disabled
Click on EDIT
Set 'Master authorized networks' to 'Enabled' and add authorize networks
Click SAVE.
Using Command Line
To enable Master Authorized Networks for an existing cluster, run the following command:
gcloud container clusters update [CLUSTER_NAME] \
--zone [COMPUTE_ZONE] \
--enable-master-authorized-networks
Along with this, you can list authorized networks using the --master-authorized-networks flag which contains a list of up to 20 external networks that are allowed to connect to your cluster's control plane through HTTPS. You provide these networks as a comma-separated list of addresses in CIDR notation (such as 90.90.100.0/24).
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.
Default Value:
By default, Master Authorized Networks is disabled.
See Also
Item Details
References: CSCv7|14.6
Plugin: GCP
Control ID: a0f60d9b1c8f2ea157b3be240954f05487ef28e2ee1dcc3e8014611753f4c634