Mongodb basic administration command- Create DB, Create User, Assign Permission, restrict access

MongoDB:

MongoDB is an open-source document database that provides high performance, high availability, and automatic scaling. MongoDB obviates the need for an Object Relational Mapping (ORM) to facilitate development.

• Basic MongoDB admin related commands:

1- Check MongoDB server version:
Run below command mongo to check mongodb version

root@US16:~# mongo
MongoDB shell version v3.6.0
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.6.0

2-List all the database: To list all the DBs hit command show dbs;

> show dbs;
admin   0.000GB
config  0.000GB
local   0.000GB
>

3-Enable MongoDB authentication:
By default, mongodb installation have open access to the shell. that mean anyone can run the command and modify the dbs.

Let's enable authentication : Follow the steps below

3A-Create a user with full privileges: Run the following command 

use admin
db.createUser({user:"admin", pwd:"redhat", roles:[{role:"root", db:"admin"}]})

Command output would be like this:

Now exit from the mongo shell- type command exit

3B- Stop mongod service

root@US16:~# systemctl stop mongod.service

3C-Modify /lib/systemd/system/mongod.service :

root@US16:~# vi /lib/systemd/system/mongod.service

Append --quiet --auth syntax in line start with 

ExecStart=/usr/bin/mongod --quiet --auth --config /etc/mongod.conf

[Service]
User=mongodb
Group=mongodb
ExecStart=/usr/bin/mongod --quiet --auth --config /etc/mongod.conf
# file size
LimitFSIZE=infinity

Your ExecStart line should be like 

Save and Exit from the file

4- Reload service daemon: Run the command below

root@US16:~# systemctl daemon-reload

5- Start mongo service:Run the command below

root@US16:~# systemctl start mongod.service

6- Check mongo service status: We need to validate mongo service after applied the changes let's check mongo service status using below command.

root@US16:~# systemctl status mongod.service

7- Everything look good and mongo service is back authentication has enabled, let validate access.

7A- Access mongo shell with authentication 

root@US16:~# mongo -u root -p

We are successfully able to login with username and password!

8- List all users: Login to mongo shell with admin user
select database admin

> use admin

Execute the following command show users; to list users

> show users;
{
        "_id" : "test.admin",
        "user" : "admin",
        "db" : "test",
        "roles" : [
                {
                        "role" : "root",
                        "db" : "admin"
                }
        ]
}
{
        "_id" : "test.amar",
        "user" : "amar",
        "db" : "test",
        "roles" : [
                {
                        "role" : "root",
                        "db" : "admin"
                }
        ]
}
>

In the above out there are two user available highlighted in red color 

9- Check current selected database:

To check current select database use command db

> db
admin
>

10- Check current selected database's collection:

 To check current select database's collection use command show collections

> show collections
system.users
system.version
>

11- Update password for existing user:

Use the following command to update existing user's password

> use admin
switched to db admin
> db.changeUserPassword("amar", "newpassword")
>

Where "use admin" command to select database and db.changeUserPassword("username","Newpassword")