User Groups Best Practices in Ubuntu Server

Question

I reciently decided to manage my own web server (Ubuntu/Nginx) and as best practices I went and disabled the root user and created a new one with root privileges. When I created the new user I didn't specify what group to add it to, this is how I created it.

adduser newUserName

Then I added to the sudo group

gpasswd -a newUserName sudo

What confuses me is that when I type cat /etc/group to see all groups there is a group with the name of the user I created.

root
...
newUserName

So I started wondering if the way I created the new user is the right way to do it or it's better to create a group first and then add any user with the same privileges to the same group.

• Can someone suggest a best practice to manage users/groups in Ubuntu Server or direct me to where I can find more information?

• What would happen if I create a new group with the same privileges as the existing user and move the existing user newUserName to this folder?

I guess I'm looking to have a better understanding of how users are typically managed in Ubuntu Server.

Thanks a lot.

Answer 1

useradd / usermod command have an option to specify the primary group( -g). If you create a user without -g option a primarygroup will be created with the same name as the new username and the new user will be added to this group. When user creates a file/directory it gets the group of user's primary group. You can have only one primary group assigned to a user. But you can have multiple secondary groups per user. Use option -G with useradd / usermod command to add secondary groups.

So if you want to create a user and with primary group as sudo , use command:

useradd -g sudo <newusername>

useradd syntax:

useradd -g <primary group> -G <secondarygroup1>,<secondarygroup2> <NewUsername> 

In linux the primary group will stored to /etc/passwd file. /etc/groups file will have only list of secondary groups of a user, so getent group sudo ( which looks in /etc/group for group info) won't show the primary group of that user ie. sudo . Use id <username> or groups <Username> to list all the groups, the user is member of. You can also check the 4th field of the /etc/passwd for the primary group gid of a user.

Google and Man pages are your best friend when in doubt.