How to create a ssh user with sudo privileges’ in Ubuntu

sudo stands for either “superuser do” or “switch user do“, and sudo users can execute commands with root/administrative permissions, even malicious ones. Be careful who you grant sudo permissions to – you are quite literally handing them all access to your instance.

1. Creating a sudo user

a) ssh in to your server as the user with superuser privilege or as a root user

ssh -i key.pem root@server_ip_address

b) Create a new user

For this, we use adduser command. Don’t be confused with the useradd command here. useradd is a low level binary command compiled with the system, whereas adduser is a high level Perl script built on top of useradd.

You should always use adduser to create new user as it provides more user friendly and interactive procedure.

sudo adduser newuser

Then follow the instruction to finish the procedure

Adding user `newuser' ...
Adding new group `newuser' (1005) ...
Adding new user `newuser' (1004) with group `newuser' ...
Creating home directory `/home/newuser' ...
Copying files from `/etc/skel' ...
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
Changing the user information for newuser
Enter the new value, or press ENTER for the default
 Full Name []: Rajesh Kumar               
 Room Number []: 12345
 Work Phone []: 0123456789929
 Home Phone []: 0000002222002
 Other []: 
Is the information correct? [Y/n] Ysudo

c) Add the user to the sudo group

usermod -aG sudo newuser

d) Test new user

su - newuser

Verify the superuser privileges by the sudo command

sudo ls -la /root

2. Add public key to allow remote SSH login for the new user

Generate ssh key pair in your local system for the newuser using “ssh-keygen -t rsa” in linux or using putty-gen in windows.

a. Switch to the new user account

su - newuser

b. Create .ssh folder in home directory

mkdir ~/.ssh

c. Create authorized_keys file inside the .ssh folder and add the public key

vi ~/.ssh/authorized_keys

And paste your SSH public key here, save and close file.

d. Verify SSH remote login

Open another terminal on your machine and try to remote SSH login using new user.

ssh -i /path/to/your/ssh_private.key newuser@server_ip_address