I just created my first Ubuntu droplet and supplied my public SSH key which is contained in ~/.ssh/id_rsa.pub on my local machine at the time I was creating my droplet. I can SSH into my machine as root just fine via the command ssh root@remote_host where remote_host is my droplet’s IP address as given in the console. However, I would like to prohibit root logon to my droplet.
I created a new user by executing the commands adduser newusername followed by gpasswd -a newusername sudo to give the new user elevated privileges. I then manually copied over the contents of my public SSH key (from my local machine) following these instructions over to newusername.
$ mkdir .ssh
$ chmod 700 .ssh
$ cd .ssh
$ vim authorized_keys
I then pasted in the public key and saved the file
$ chmod 600 authorized_keys
$ exit
# service ssh restart
When I tried to SSH in from my local machine using the command ssh newusername@remote_host, I get the message Permission denied (publickey). I even went back into the droplet and added the line AllowUsers newusername to the /etc/ssh/sshd_config file but keep getting the same error.
UPDATE: I also tried running the following commands on my local machine, which is also running Ubuntu, but this did not work either:
$ eval `ssh-agent -s`
$ ssh-add ~/.ssh/id_rsa
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Accepted Answer
I finally ended up solving this issue by following these directions from another thread.
I fixed the problem by putting my root public key to user’s .ssh/authorized_keys file. now I can login from my machine with root username to remote machine with myuser account.
issue this command by root
ssh -p ‘ssh port’ myuser@remoteip
The users home directory needs to be owned by the user in question, as does the .ssh directory and the authorized_keys file.
For example, a slightly different way of doing it that I use.
Create Directories and Files
mkdir -p /home/myuser/.ssh
touch /home/myuser/.ssh/authorized_keys
Add The New User
useradd -d /home/myuser myuser
Add User to sudo Group
usermod -aG sudo myuser
Set Proper Permissions
chown myuser:myuser /home/myuser/.ssh
chown myuser:myuser /home/myuser/.ssh/authorized_keys
chmod 700 /home/myuser/.ssh
chmod 600 /home/myuser/.ssh/authorized_keys
Setup SSH Keys for myuser
echo "ssh-rsa ...." >> /home/myuser/.ssh/authorized_keys
Setup a Password for myuser
passwd myuser
That way you can escalate using sudo .....
Login
ssh myuser@droplet_ip -i myuser
Where myuser is the user we just created and setup, and -i myuser tells SSH to use the key that I have locally on my MacBook.
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