First, you have to begin MongoDB without any access control, for that refer to the following code:

mongod --port 27017 --dbpath /data/db1

Then you have to connect to the instance, refer the following code:

mongo --port 27017

After that, you can create a user administrator.

use admin

db.createUser(

  {

    user: "myUserAdmin",

    pwd: "abc123",

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

  }

)

Then just restart the MongoDB instance this time with the access control:

mongod --auth --port 27017 --dbpath /data/db1

Then, at last, validate as the user administrator.

mongo --port 27017 -u "myUserAdmin" -p "abc123" --authenticationDatabase "admin"