Official Installation Guide

https://docs.mongodb.com/manual/tutorial/install-mongodb-on-ubuntu/

Security Configuration

The default MongoDB configuration bind the server to localhost but does not have any security. To enable security:

1. Start MongoDB without security

sudo systemctl start mongod

2. Create an admin user (see Enable Access Control) in mongo shell

use admin
db.createUser({
    user: "cysun",
    pwd: "abcd",
    roles: [ { role: "userAdminAnyDatabase", db: "admin" }, "readWriteAnyDatabase" ]
})

3. Edit /etc/mongod.conf to add the following:

security:
  authorization: enabled

and to allow remote access, change bindIp to 0.0.0.0.

4. Create additional database and user in mongo shell

use admin
db.auth("cysun", "abcd")
use student
db.createUser({
    user: "student",
    pwd: "abcd",
    roles: ["dbOwner"]
})

Also see mongo.js in cs3-scripts for how to create additional databases/users using MongoDB Node.js client.