# Infrastructure security in Amazon CloudWatch
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As a managed service, Amazon CloudWatch is protected by Amazon global network security. For information about Amazon security services and how Amazon protects infrastructure, see [Amazon Cloud Security](https://www.amazonaws.cn/security/). To design your Amazon environment using the best practices for infrastructure security, see [Infrastructure Protection](https://docs.amazonaws.cn/wellarchitected/latest/security-pillar/infrastructure-protection.html) in *Security Pillar Amazon Well‐Architected Framework*.

You use Amazon published API calls to access CloudWatch through the network. Clients must support the following:
+ Transport Layer Security (TLS). We require TLS 1.2 and recommend TLS 1.3.
+ Cipher suites with perfect forward secrecy (PFS) such as DHE (Ephemeral Diffie-Hellman) or ECDHE (Elliptic Curve Ephemeral Diffie-Hellman). Most modern systems such as Java 7 and later support these modes.

## Network isolation
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A virtual private cloud (VPC) is a virtual network in your own logically isolated area in the Amazon Web Services Cloud. A subnet is a range of IP addresses in a VPC. You can deploy a variety of Amazon resources in the subnets of your VPCs. For example, you can deploy Amazon EC2 instances, EMR clusters, and DynamoDB tables in subnets. For more information, see the [Amazon VPC User Guide](https://docs.amazonaws.cn/vpc/latest/userguide/).

To enable CloudWatch to communicate with resources in a VPC without going through the public internet, use Amazon PrivateLink. For more information, see [Using CloudWatch, CloudWatch Synthetics, and CloudWatch Network Monitoring with interface VPC endpoints](cloudwatch-and-interface-VPC.md).

A private subnet is a subnet with no default route to the public internet. Deploying an Amazon resource in a private subnet does not prevent Amazon CloudWatch from collecting built-in metrics from the resource.

If you need to publish custom metrics from an Amazon resource in a private subnet, you can do so using a proxy server. The proxy server forwards those HTTPS requests to the public API endpoints for CloudWatch.