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How are S3 buckets blocked from public access? I mean I know there is literally a “Block public access” feature that keeps S3 buckets from being read or written by unauthenticated users. But as far as I know without some really weird bucket ACLs you can still access S3 buckets if you have the IAM credentials.

Before anyone well actually’s me. Yes I know you can also route S3 via AWS internal network with VPC Endpoints between AWS services.



In general, condition keys

https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_p...

And https://docs.aws.amazon.com/service-authorization/latest/ref...

Specifically the vpce one as the other poster mentioned but there's other like IP limits

Another way is an IdP that supports network or device rules. For instance, Cloudflare Access and Okta you can add policies where they'll only let you auth if you meet device or network requirements which achieved the same thing


> Specifically the vpce one as the other poster mentioned but there's other like IP limits

IPs don't cut it to prevent public access. I can create my own personal AWS account, with the private IP I want, and use the credentials from there. There's really just VPC endpoints AFAIK.


You essentially add a policy that limits the access to only come from your VPC endpoint.




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