Add a New User Account on Linux

Login as root into the system. You can do this remotely with ssh sometimes or others you might have to do sudo su - instead and type your password.

ssh root@<serverip>

Then run the adduser command.

adduser <username>

For example, to create an account named mc you would do adduser mc.

Adding user `mc' ...
  Adding new group `mc' (1002) ...
  Adding new user `mc' (1002) with group `mc' ...
  Creating home directory `/home/mc' ...
  Copying files from `/etc/skel' ...
  Enter new UNIX password:

Type in the new UNIX password. Note that you will not see anything on the screen for security reasons — not even stars — but it is taking in what you are typing. Remember this is just the password for the specific (mc) user account not root.

Enter new UNIX password:
  Retype new UNIX password:
  passwd: password updated successfully
  Changing the user information for mc
  Enter the new value, or press ENTER for the default
          Full Name []:

You don’t really need any of the prompted information but you can provide it if you want it. Otherwise, just tap enter for everything to accept blanks.

Enter the new value, or press ENTER for the default
          Full Name []:
          Room Number []:
          Work Phone []:
          Home Phone []:
          Other []:
  Is the information correct? [Y/n] y

Okay. Now you are ready to test it out.

First we will just change to the account without even logging in. Replace <username> with the user name you created above.

su - <username>

So in this example, su - mc and should see the prompt change. (This is not something you type in. It is what you should see after you type in what’s above.)

mc@live:~$

That means everything worked.

Now while we are here let’s setup our SSH public keys which we probably already have setup in the root account.

First check to see if the .ssh directory exists.

ls .ssh
  ls -ad

If it says no such file or directory then we need to create it. There are a couple of ways to create it, but let’s just use mkdir and chmod.

mkdir .ssh
  chmod 700 .ssh
  ls -ld .ssh

You should see the permissions are locked down.

drwx------ 2 mc mc 4096 Jul 23 18:43 .ssh

We’re not done yet. Now we need to add the public key from our workstation system into a file called .ssh/authorized_keys. First let’s use touch to create the file.

touch .ssh/authorized_keys
  ls -l .ssh/authorized_keys

Don’t forget to lock down the permissions on this file as well.

chmod 600 .ssh/authorized_keys

Now we can paste your public SSH key into the file. To be safe, just cut it from your terminal that is not logged into the remote server. Open a new terminal if needed.

On your local system (not the server) cat your public key. Any of them will do, but you should have an id_ed25519.pub if you are current and using the best.

cd
  cat .ssh/id_*.pub

ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOxsQnKQcnJ3zymnCdfdGvYZX898LVkDhz9gvMY5FRFj rwxrob@live

Copy that however you want. Most will just select it and later middle or right-click to paste using UNIX cut and paste style.

YOU NEED THE WHOLE THING! Yes, the ssh- part. Yes, the ...@... part. [I really am so tired of answering that question.]

Now it’s time to write the public key into the .ssh/authorized_keys file on the server.

Open the file for editing.

cd
  ls -a
  vi .ssh/authorized_keys

Paste it in. If you have stuff already just add it to the end. Save and exit your editor.

Now we need to test the remote connection.

Open a local terminal. (You might still have one open from cutting the SSH public key.)

Test the connection with the ssh command and the server IP.

ssh mc@<serverip>

Accept the man in the middle warning and boom, you should be on the server ready to work.