C:mongodbbin>use admin
db.createUser(
  {
    user: "myUserAdmin",
    pwd: "abc123",
    roles: [ { role: "userAdminAnyDatabase", db: "admin" } ]
  }
)

C:Windowssystem32>mongo
MongoDB shell version v3.4.9
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.4.9
Server has startup warnings:
2018-03-28T16:53:43.515+0800 I CONTROL  [initandlisten]
2018-03-28T16:53:43.516+0800 I CONTROL  [initandlisten] ** WARNING: Access contr
ol is not enabled for the database.
2018-03-28T16:53:43.516+0800 I CONTROL  [initandlisten] **          Read and wri
te access to data and configuration is unrestricted.
2018-03-28T16:53:43.516+0800 I CONTROL  [initandlisten]
2018-03-28T16:53:43.516+0800 I CONTROL  [initandlisten] Hotfix KB2731284 or late
r update is not installed, will zero-out data files.
2018-03-28T16:53:43.516+0800 I CONTROL  [initandlisten]
> show dbs
admin  0.000GB
local  0.000GB
> use admin
switched to db admin
>

C:mongodbbin>sc delete MongoDB
C:mongodbbin>mongod --dbpath C:mongodbdata --logpath C:mongodblogMongoDB.log --auth --install

C:Windowssystem32>mongo
MongoDB shell version v3.4.9
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.4.9
> show dns
2018-03-28T17:59:06.344+0800 E QUERY    [thread1] Error: don't know how to show
[dns] :
shellHelper.show@src/mongo/shell/utils.js:906:11
shellHelper@src/mongo/shell/utils.js:659:15
@(shellhelp2):1:1
> show dbs
2018-03-28T17:59:10.073+0800 E QUERY    [thread1] Error: listDatabases failed:{
        "ok" : 0,
        "errmsg" : "not authorized on admin to execute command { listDatabases:
1.0 }",
        "code" : 13,
        "codeName" : "Unauthorized"
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:62:1
shellHelper.show@src/mongo/shell/utils.js:769:19
shellHelper@src/mongo/shell/utils.js:659:15
@(shellhelp2):1:1
>

C:Windowssystem32>mongod --auth --port 27017 --dbpath C:mongodbdata
2018-03-28T16:49:43.874+0800 I CONTROL  [initandlisten] MongoDB starting : pid=7
988 port=27017 dbpath=C:mongodbdata 64-bit host=wolf-PC
.....
2018-03-28T16:49:43.877+0800 I STORAGE  [initandlisten] exception in initAndList
en: 98 Unable to create/open lock file: C:mongodbdatamongod.lock Another program is using this file.... Is a mongod instance already running?, terminating

security:
  authorization: enabled

db.createUser(
  {
    user: <app db user>,
    pwd: <password>,
    roles: [ { role: "readWrite", db: <app db> } ]
  }
);