How to Enable Authentication in MongoDB: Step-by-Step Guide

To enable authentication in MongoDB, first create an admin user with proper roles, then start the MongoDB server with the --auth option or set security.authorization to enabled in the configuration file. This makes MongoDB require users to authenticate before accessing the database.

Syntax

Enabling authentication in MongoDB involves two main steps:

• Create an admin user with the userAdminAnyDatabase role.
• Start MongoDB with authentication enabled by using the --auth flag or setting security.authorization: enabled in the config file.

This setup ensures MongoDB requires valid credentials for database access.

bash

mongod --auth --port 27017 --dbpath /data/db

# Or in the config file (mongod.conf):
security:
  authorization: enabled

Example

This example shows how to create an admin user and enable authentication:

bash

# Start MongoDB without auth to create admin user
mongod --port 27017 --dbpath /data/db

# Connect to Mongo shell
mongo --port 27017

# Create admin user
use admin
 db.createUser({
   user: "admin",
   pwd: "password123",
   roles: [ { role: "userAdminAnyDatabase", db: "admin" } ]
 })

# Stop MongoDB and restart with auth enabled
mongod --auth --port 27017 --dbpath /data/db

# Connect with authentication
mongo --port 27017 -u admin -p password123 --authenticationDatabase admin

Output

Successfully added user: { "user" : "admin", "roles" : [ { "role" : "userAdminAnyDatabase", "db" : "admin" } ] }

MongoDB server started with authentication enabled

MongoDB shell connected with authentication

Common Pitfalls

Common mistakes when enabling authentication include:

• Not creating an admin user before enabling --auth, which locks you out.
• Forgetting to restart MongoDB after changing the config to enable authentication.
• Using incorrect roles or missing the userAdminAnyDatabase role for the admin user.
• Trying to connect without specifying the authentication database.

Always create users first, then enable authentication.

bash

## Wrong way: Enabling auth before creating user
mongod --auth --port 27017 --dbpath /data/db
# No users exist, so you cannot log in

## Right way:
# 1. Start without auth
mongod --port 27017 --dbpath /data/db
# 2. Create admin user
# 3. Restart with auth
mongod --auth --port 27017 --dbpath /data/db

Quick Reference

Step	Command or Setting	Description
Create admin user	db.createUser({user: "admin", pwd: "password", roles: [{role: "userAdminAnyDatabase", db: "admin"}]})	Creates admin user with user management rights
Enable auth (command line)	mongod --auth --port 27017 --dbpath /data/db	Starts MongoDB requiring authentication
Enable auth (config file)	security: authorization: enabled	Sets authentication in mongod.conf
Connect with auth	mongo -u admin -p password --authenticationDatabase admin	Connects to MongoDB with credentials

Key Takeaways

Always create an admin user before enabling authentication to avoid lockout.

Enable authentication by starting mongod with --auth or setting security.authorization to enabled.

Use the admin database for user creation and authentication.

Restart MongoDB after changing authentication settings.

Specify the authentication database when connecting with credentials.