@julianswebb

Adding a new user can be done with useradd, though getting everything to work with an SSH Key requires a little more work.

1). Create Users’ Home and .ssh Directories

mkdir -p /home/newuser/.ssh

2). Touch authorized_keys (creates the file)

touch /home/newuser/.ssh/authorized_keys

3). Add Public Key to authorized_keys. You’ll replace .... with the public key.

echo "...." >> /home/newuser/.ssh/authorized_keys

4). Add new user and set home directory.

useradd -d /home/newuser newuser

5). Setup proper permissions.

chown -R newuser:newuser /home/newuser/*

chmod 700 /home/newuser/.ssh

chmod 600 /home/newuser/.ssh/authorized_keys

6). Reduce permissions on /home/newuser.

chmod 750 /home/newuser

…

Keep in mind, this isn’t a sudo user - it’s a basic user with no real privileges other than the ability to login using SSH (not SFTP), thus can’t escalate to root. If you need to make this user a sudo user, you can use:

usermod -aG sudo newuser

The above appends the sudo group to the user, which will allow them to run commands using:

sudo [command-name]

For example:

sudo apt-get update

adduser foo, public keys go into ~/.ssh/authorized_keys