Which mechanism is primarily used in OCI for managing user access across various services?

In Oracle Cloud Infrastructure (OCI), Identity and Access Management (IAM) serves as the primary mechanism for managing user access across various services. IAM enables organizations to define who can access specific resources and to what extent, providing a robust framework for security and compliance.

IAM allows you to create and manage users, groups, policies, and roles. Policies are particularly crucial because they define permissions that dictate what actions users or groups can perform on cloud resources, making it easier to implement the principle of least privilege. By configuring these elements, administrators can ensure that only authorized users have the necessary access to the services and data they need to perform their jobs.

In contrast, while IP whitelisting is used to restrict access based on network origin, it does not provide the granular control over user permissions that IAM offers. Virtual Private Cloud (VPC) deals with network configurations and is focused on creating isolated network environments rather than user access. Database User Management relates specifically to managing access and permissions for database users, which is a narrower scope compared to the overall user and resource access management that IAM provides.

Thus, IAM is essential for comprehensive user access management across the diverse services available within OCI.