What is IAM? An explanation of the user and permission management system for beginners.

When you start using Amazon Web Services (AWS), the first thing you'll encounter is a system called "IAM (Identity and Access Management)." Many people have probably experienced confusion when encountering terms like users, roles, and policies while trying to configure EC2 or S3.

IAM is the foundation for managing "who" can perform "what operations" on AWS. Building an environment without a proper understanding of IAM can lead to problems such as operational errors, permission leaks, and increased costs due to misuse. On the other hand, understanding the basics of the mechanism makes AWS operations much easier to manage.

This article will organize the basic roles and structure of IAM, and then clearly explain the concepts and operational points that beginners should understand first. Let's understand the overall picture of IAM as a foundation for using AWS safely and efficiently.

What is IAM?

IAM is a mechanism for managing "who" is allowed to do "what" on AWS.

Rather than being a service that directly manipulates and manages resources like EC2 and S3, it's positioned as a platform for assigning and controlling operational permissions to people and systems.

In AWS, having the necessary permissions means you can perform actions such as changing settings, deleting files, and even exfiltrating data. Therefore, understanding IAM is a prerequisite that you should grasp before mastering other services. If you misunderstand the concept of IAM, no matter how carefully you configure other settings, it will not lead to secure operation.

Why is IAM mandatory on AWS?

AWS is a world where "you can do it = you can change everything."

Having access to the administration panel and API means that, in principle, you can perform all operations, including starting and stopping the server, changing and deleting settings, and retrieving data.

Given this premise, if access control is lax, realistic risks will directly surface.

For example, it is not uncommon for resources to be stopped or deleted due to unintended operations, for information to be leaked through excessive privileges, or for unexpected costs to be incurred due to unauthorized use by third parties.

IAM is not "insurance" that will protect you after these kinds of problems occur.

IAM is a fundamental prerequisite for securely using AWS and should be incorporated from the start. If you proceed with other settings while postponing IAM, the risks will only accumulate as operations progress.

Basic IAM Configuration

IAM manages permissions by combining several elements. Here, we will first organize the three basic elements that you should understand: IAM users, IAM roles, and IAM policies.

What is an IAM user?

IAM users areA unit representing "people" or "users"..

Logging into the AWS Management Console and performing operations using APIs are always done through this IAM user.

In practical terms, it's easiest to understand this as representing the entities that actually operate AWS, such as administrators, operations personnel, and developers. It's the most basic unit for clearly defining who performed which operation.

What is an IAM role?

IAM roles are,Set of permissions used temporarily".

Unlike IAM users, these are not tied to a specific person.

Its primary uses include integrating AWS services with each other and with external systems. For example, it's used when you want to allow EC2 to access S3, or when you want to temporarily operate AWS in conjunction with an external identity infrastructure.

Roles don't define "who uses it," but rather "what role and what permissions they should have."

Related article:What is the difference between IAM roles and IAM users? An explanation of how to use them correctly in AWS permission management.

What is an IAM policy?

The IAM policy is:What is allowed to do / What is not allowed to doThis is a rule that defines "

This section specifically describes the services or resources to be operated on, and the actions to be allowed or denied.

By linking this policy to IAM users and IAM roles, actual permission management is achieved. It's important to note that permissions are granted through the policy, not directly to the user or role itself.

The first thing you should understand about IAM is

When working with IAM, the important thing is "how you think" rather than the detailed configuration procedures. You don't need to aim for a perfect permission design from the start, but you should avoid simply carrying over the "allow all" setting you implemented during the testing and setup phase into production.

The so-called principle of least authority is not an idealistic theory or an overly strict rule. It is a practical approach to prevent accidents such as user errors and breaches of authority. By assuming that only necessary operations will be permitted, the scope of impact can be minimized.

Furthermore, the later you try to organize IAM, the more costly it becomes. Reviewing permissions as the number of users and systems increases is time-consuming and difficult to decide. That's why it's important to have an "operation-oriented mindset" from the very beginning.

Related article:What is the principle of least privilege? The risks of excessive privileges and specific steps for designing IAM.

Minimum initial setup

Even if you don't have time to dedicate to designing your IAM environment, there are some essential initial settings you should implement. These aren't advanced configurations, but rather prerequisites to avoid operational problems.

First, it's crucial not to use administrator accounts for everyday operations. Administrator privileges have a wide range of impact, and the risk of errors or leaks of authentication information is extremely high. The basic principle is to perform daily tasks using IAM users with only the necessary permissions.

Next, IAM users should be separated by purpose. Using the same user for different roles such as administration, operations, and development can lead to them having unnecessary permissions. Separating who performs which operations makes future reviews easier.

It's also important not to leave unnecessary permissions in place. Leaving permissions granted for testing purposes or temporary operational permissions unattended can lead to unintended operations or accidents. Keep permissions to a minimum, with the understanding that they will be reviewed regularly.

Initially, it's practical to utilize the managed policies provided by AWS. Creating policies from scratch is prone to design errors, so it's safer to start with pre-built policies and adjust them as needed.

Common misconceptions and stumbling blocks with IAM

IAM is not a security measure that enhances security on its own. It is merely a mechanism for managing operational permissions, and it is often misunderstood that simply setting up IAM does not make things safe. It only becomes effective when combined with other measures such as log monitoring and network control.

Furthermore, the idea that "increasing the number of IAM users makes things safer" is incorrect. Even if the number of users increases, the risk will not decrease if the permission design is poor. What is important is not the number of users, but who is allowed to perform which operations.

Furthermore, confusing IAM roles and IAM users can easily lead to design flaws. Mistaking roles that should be assigned to individuals for those used for systems or integrations makes it difficult to understand the location of permissions and makes revisions later on challenging. It is important to be mindful of using each role appropriately.

The difference with IAM lies more in the design than the configuration.

IAM is not a task that ends simply by correctly filling in the configuration fields. The design decisions themselves—how to divide permissions, what to allow, and what to restrict—affect both ease of operation and security. Even if the settings look the same, different approaches can lead to vastly different results.

This difference is often overlooked in smaller environments. When there are few users, problems are less likely to surface, and it's easy to assume that "this is sufficient for now." However, if the environment expands while the initial thinking remains flawed, it becomes difficult to correct later.

Furthermore, the design of IAM is directly linked to future operations, audits, and scalability. A configuration that doesn't clearly explain who has what permissions will make troubleshooting and external audits cumbersome. What you should be mindful of is not just how it's used now, but whether the structure is understandable even when reviewed later.

Summary

IAM is often an area of ​​AWS that gets put off until later, but in reality, it's a prerequisite that you should address first. If you start using other services without properly understanding IAM, the effort and risk of making corrections will accumulate as you progress with configuration and operation.

The important thing isn't memorizing detailed setup procedures. It's the thinking and design decisions regarding who is allowed to perform which operations and what assumptions are made that determine the overall usability and security of AWS.

Instead of viewing IAM as a "difficult configuration item," understand it as the foundation for using AWS. Simply adopting this perspective will significantly change your design and operational decisions from then on.