Managing access controls
You can control a user's access to AWS Transfer Family resources by using an AWS Identity and Access Management (IAM) policy. An IAM policy is a statement, typically in JSON format, that allows a certain level of access to a resource. You use an IAM policy to define what file operations that you want to allow your users to perform and not perform. You can also use an IAM policy to define what Amazon S3 bucket or buckets that you want to give your users access to. To specify these policies for users, you create an IAM role for AWS Transfer Family that has the IAM policy and trust relationship associated with it.
Each user is assigned an IAM role. The type of IAM role that AWS Transfer Family uses is called a service role. When a user logs in to your server, AWS Transfer Family assumes the IAM role mapped to the user. To learn about creating an IAM role that provides a user access to an Amazon S3 bucket, see Creating a role to delegate permissions to an AWS service in the IAM User Guide.
You can grant write-only access to Amazon S3 objects by using certain permissions within an IAM policy. For details, see Grant ability to only write and list files.
The AWS Storage Blog contains a post detailing how to set up least privilege access. For details, see
Implementing least privilege access in an AWS Transfer Family workflow
Note
If your Amazon S3 bucket is encrypted using AWS Key Management Service (AWS KMS), you must specify additional permissions in your policy. For details, see Data encryption in Amazon S3. Additionally, you can see more information about session policies in the IAM User Guide.
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