A Complete Guide - MongoDB Authentication and Authorization

Last Updated: 03 Jul, 2025

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MongoDB Authentication and Authorization: Explained in Detail and Important Info

1. Authentication

Authentication is the process of verifying the identity of users or processes attempting to access your MongoDB instance. In simple terms, it's about making sure the user is who they claim to be before granting them any further permissions.

Types of Authentication:
- Local Authentication: Users log in with credentials stored in the local admin database. This is the most common type.
- SCRAM (Salted Challenge Response Authentication Mechanism): A popular and default method for authentication. It involves a hashed password for secure communication without sending plaintext passwords.
- LDAP (Lightweight Directory Access Protocol): Allows MongoDB to use an organization’s existing LDAP directory for user authentication.
- X.509 Certificates: Provides a secure way to authenticate users using certificates signed by a trusted certificate authority.
- Kerberos: Utilizes the Kerberos protocol for authentication between MongoDB and clients over a network.
Steps to Enable Authentication:
- Start MongoDB with the --auth parameter or set up the configuration file (mongod.conf) with security.authorization: enabled.
- Create administrative users during the first connection to the database. You need at least one admin user to manage other users effectively.
- For applications, ensure you configure your application to connect using authentication. Typically, this is done by specifying a username and password in your connection string.
Example of enabling authentication:
```
mongod --dbpath /var/lib/mongodb --auth
```
Or via mongod.conf:
```
security: authorization: enabled
```

User Management in MongoDB:

Creating Users:

use admin
db.createUser( { user: "adminUser", pwd: "securepassword", roles: [ { role: "userAdminAnyDatabase", db: "admin" } ] }
)

Updating Users:

db.changeUserPassword("adminUser", "newSecurePassword");

Deleting Users:
```
db.dropUser("adminUser");
```

2. Authorization

Once a user is authenticated, authorization determines what actions they are permitted to perform within the MongoDB databases and collections. Authorization is based on roles that can be assigned to users.

Types of Roles:
- Built-in Roles: MongoDB comes with many built-in roles that cover various levels of access, such as read-only, read-write, cluster administration, etc.
- User-defined Roles: Administrators can create custom roles that combine privileges tailored to specific application needs.
Privileges: Privileges include actions (like find, update, dropCollection) and resources (databases, collections, cluster) on which the action can be performed.

Assigning Roles to Users: When creating a new user, roles can be assigned directly:

db.createUser( { user: "appUser", pwd: "appPass", roles: [ { role: "readWrite", db: "myDatabase" }, { role: "read", db: "otherDatabase" } ] }
)

Managing Roles:

Creating Roles:

use myDatabase;
db.createRole( { role: "customRole", privileges: [ { resource: { db: "myDatabase", collection: "myCollection" }, actions: ["insert"] }, { resource: { db: "myDatabase", collection: "anotherCollection" }, actions: ["find"] } ], roles: [] }
)

Updating Roles:

use myDatabase;
db.updateRole( "customRole", { $push: { privileges: { resource: { db: "myDatabase", collection: "myCollection" }, actions: ["delete"] } } }
)

Deleting Roles:

use myDatabase;
db.dropRole("customRole");

3. Network Encryption

To secure data in transit, MongoDB supports SSL/TLS encryption. This ensures that all communications between clients and the server are encrypted, preventing eavesdropping and tampering.

Configuring SSL/TLS:
- Generate SSL certificates.
- Update mongod.conf to enable SSL and specify paths to certificate files.
- Restart MongoDB service.
Example of enabling SSL in mongod.conf:

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Step-by-Step Guide: How to Implement MongoDB Authentication and Authorization

Step 1: Install MongoDB

First, ensure that MongoDB is installed on your system. If you haven't installed it yet, you can follow the installation instructions on the sudo mongod --dbpath /path/to/your/db

Step 3: Connect to MongoDB

In a separate terminal, connect to the MongoDB server using the mongo shell:

mongo

Step 4: Create the First User Admin

Before enabling authentication, you need to create the first user admin. This user will be able to create other users and roles.

Switch to the admin database:

use admin

Create the first user admin:

db.createUser( { user: "admin", pwd: "password", roles: [ { role: "userAdminAnyDatabase", db: "admin" } ] }
)

Replace "admin" and "password" with your desired username and password.

Step 5: Enable Authentication

To enable authentication, you need to restart the MongoDB server with the --auth parameter. You can also add --auth to your MongoDB configuration file (mongod.conf).

Add the following lines to your mongod.conf file:

security: authorization: enabled

Restart the MongoDB server to apply the changes:

sudo systemctl restart mongod

Step 6: Connect to MongoDB with Authentication

Now, connect to the MongoDB server using the mongo shell and authenticate with the admin user:

mongo -u admin -p password --authenticationDatabase admin

Replace "admin" and "password" with your username and password.

Step 7: Create a New Database and User

Let's create a new database and a user with specific roles.

Switch to a new database (e.g., myDB):

use myDB

Create a new user with specific roles:

db.createUser( { user: "user1", pwd: "password1", roles: [ { role: "readWrite", db: "myDB" } ] }
)

Replace "user1", "password1", and "myDB" with your desired username, password, and database name.

Step 8: Connect to MongoDB with New User

Connect to the MongoDB server and authenticate with the new user:

mongo -u user1 -p password1 --authenticationDatabase myDB

Replace "user1", "password1", and "myDB" with your username, password, and database name.

Step 9: Authorize Actions

Now that you are authenticated as user1, you should be able to perform actions within myDB that match the readWrite role.

For example, insert a document into a collection:

db.myCollection.insert({name: "John Doe", age: 30})

Step 10: Verify Role Permissions

Try performing an action that does not match the user's role. For example, try to drop the database:

db.dropDatabase()

You should receive an error indicating that you do not have the required permissions.

Conclusion

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Top 10 Interview Questions & Answers on MongoDB Authentication and Authorization

Top 10 Questions and Answers: MongoDB Authentication and Authorization

1. What is Authentication in MongoDB?

2. How do I enable Authentication in MongoDB?

Answer: To enable authentication in MongoDB, you need to start the mongod server with the --auth option or by setting "security.authorization": "enabled" in the MongoDB configuration file (mongod.conf). After enabling authentication, you need to create administrative users who can create other users and manage roles.

3. What is Authorization in MongoDB?

Answer: Authorization in MongoDB is the process of granting specific users and roles permission to access certain database resources and perform specific operations. MongoDB uses the Role-Based Access Control (RBAC) model where roles are assigned to users, and permissions (privileges) are assigned to roles.

4. How do I create a user with specific privileges in MongoDB?

Answer: To create a user with specific privileges in MongoDB, you can use the db.createUser() method. For example, to create a user with read access to a database, you can run the following command:

use myDatabase
db.createUser({ user: "myUser", pwd: "myPass", roles: [ { role: "read", db: "myDatabase" } ]
})

This command creates a user named "myUser" in the "myDatabase" database with read-only privileges.

5. How do I assign roles to a user in MongoDB?

Answer: You can assign roles to a user using the db.grantRolesToUser() method. For example:

use myDatabase
db.grantRolesToUser( "myUser", [ { role: "readWrite", db: "myDatabase" }, { role: "dbAdmin", db: "myDatabase" } ]
)

This command assigns the roles readWrite and dbAdmin to the user "myUser" in the "myDatabase" database.

6. What are built-in roles in MongoDB?

Answer: MongoDB comes with a set of built-in roles that provide various levels of access. Some of the key built-in roles are:

User roles: read, readWrite, userAdmin, etc.
Database roles: dbAdmin, dbOwner, etc.
Cluster roles: clusterAdmin, backup, restore, etc.
All-Database roles: readAnyDatabase, readWriteAnyDatabase, dbAdminAnyDatabase, etc.
Superuser roles: root

7. What is Role-Based Access Control (RBAC) in MongoDB?

Answer: Role-Based Access Control (RBAC) in MongoDB is a method of regulating access to database system by both granting and restricting specific permissions to users through the use of roles. Each role specifies a set of privileges that can be granted to users, and users can be assigned one or more roles.

8. How do I revoke roles from a user in MongoDB?

Answer: To revoke roles from a user in MongoDB, you can use the db.revokeRolesFromUser() method. For example:

use myDatabase
db.revokeRolesFromUser( "myUser", [ { role: "readWrite", db: "myDatabase" }, { role: "dbAdmin", db: "myDatabase" } ]
)

This command revokes the roles readWrite and dbAdmin from the user "myUser" in the "myDatabase" database.

9. How do I create a custom role in MongoDB?

Answer: To create a custom role in MongoDB, you can use the db.createRole() method. For example, to create a custom role that allows reading from a collection and finding documents with a specific criteria, you can run the following command:

use myDatabase
db.createRole( { role: "readProductReviews", privileges: [ { resource: { db: "myDatabase", collection: "productReviews" }, actions: [ "find" ] } ], roles: [] }
)

This command creates a role named readProductReviews that allows reading from the productReviews collection in the myDatabase database.

10. What are the best practices for MongoDB security, particularly regarding authentication and authorization?

Answer: Here are some best practices for MongoDB security, especially in authentication and authorization:

Always enable authentication and use strong, unique passwords.
Use encrypted connections (TLS/SSL) to protect data in transit.
Regularly review and audit user roles and privileges.
Implement the principle of least privilege by granting users only the permissions they need to do their jobs.
Use the MongoDB Atlas for managed cloud services which provides many security best practices by default.
Keep MongoDB server and drivers up to date to protect against vulnerabilities.