mongodb - show dbs gives "Not Authorized to execute command" error

Question

I've spent some time trying to figure out what is wrong but as I could not find out, I decided to ask here.

I am running MongoDB(Windows 64-bit 2008 R2+) version 3.2.3 on Windows 8, the paths are :

C:MongoDBin for the installation

C:datadb for the data folder

I've installed following this video and this tutorial from the official documentation.

The first issue might be, as I don't really know if it is an issue at all, the connection between the client(mongo.exe) and the server(mongod.exe).

I lauched mongod.exe via the command line (with administrator rights), everything went fine, I got the message :

waiting for connections on port 27017

but when I launch mongo.exe via a new instance of the command line, the server(mongod.exe) doesn't print a message saying there is a new connection (it was the case in the tutorials I watched)

On the other side, mongo.exe prints

connecting to : test

I don't know if everything is correct at this point but I still tried some basics commands like :

show dbs returns not authorized on admin to execute command

Basically, all the commands I tried had the same error message, even with "fresh" db I just created with use 'dbName'

Some answers online said I have to create a user with proper roles, I tried this one. Still the same error message not authorized to execute command

My question is the following :

Is is normal that mongod.exe doesn't show a new connection when I launch mongo.exe ? If it is correct then what can I do to make even the basic commands work ?

Additional Informations :

I tried to uninstall/re-install few times, with the "Custom mode" and the "Complete mode" in the Windows installer but it always lead to the same problem.

I also tried to create a MongoDB Service following the official documentation but I'm not really sure if it was a good idea. (I can't add more links but it is in a section in the second link I shared.

Edit section :

I decided to try it on another computer which I have not touched for years, running on Windows 7 64-bit.

I copied the MongoDB installation folder at the root of this computer, created datadb folder and launched mongod.exe.

Then I launched mongo.exe and this time, mongod.exe printed a message saying there is a new open connection which it doesn't on my actual computer. I think the problem is here because I was able to start the basic tutorial from the official documentation and perform simple commands like create a new db, insert, find, show dbs, etc. Everything that I am not able to do on my actual computer.

So I think the problem is coming from the connection between mongod.exe and mongo.exe

Do you have any idea how I could solve this problem as I have tried uninstalling few times.

Answer 1

You should have started the mongod instance with access control, i.e., the --auth command line option, such as:

$ mongod --auth

Let's start the mongo shell, and create an administrator in the admin database:

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

Now if you run command "db.stats()", or "show users", you will get error "not authorized on admin to execute command..."

> db.stats()
{
        "ok" : 0,
        "errmsg" : "not authorized on admin to execute command { dbstats: 1.0, scale: undefined }",
        "code" : 13,
        "codeName" : "Unauthorized"
}

The reason is that you still have not granted role "read" or "readWrite" to user myUserAdmin. You can do it as below:

> db.auth("myUserAdmin", "abc123")
> db.grantRolesToUser("myUserAdmin", [ { role: "read", db: "admin" } ])

Now You can verify it (Command "show users" now works):

> show users
{
        "_id" : "admin.myUserAdmin",
        "user" : "myUserAdmin",
        "db" : "admin",
        "roles" : [
                {
                        "role" : "read",
                        "db" : "admin"
                },
                {
                        "role" : "userAdminAnyDatabase",
                        "db" : "admin"
                }
        ]
}

Now if you run "db.stats()", you'll also be OK:

> db.stats()
{
        "db" : "admin",
        "collections" : 2,
        "views" : 0,
        "objects" : 3,
        "avgObjSize" : 151,
        "dataSize" : 453,
        "storageSize" : 65536,
        "numExtents" : 0,
        "indexes" : 3,
        "indexSize" : 81920,
        "ok" : 1
}

This user and role mechanism can be applied to any other databases in MongoDB as well, in addition to the admin database.

(MongoDB version 3.4.3)