How to set up passwordless SSH access for root user [duplicate]
Solution 1:
Part 1 : SSH key without a password
To set up a passwordless SSH connection for the root user you need to have root access on the server. Easiest method is to temporarily allow root to log in over ssh via password. One way or another you need root access on the server to do this. If you do not have root access on the server, contact the server administrator for help.
On the client (where you ssh FROM)
First make a ssh key with no password. I highly suggest you give it a name rather then using the default
ssh-keygen -f foo
The -f option specifies a file name, foo is an example, use whatever name you wish.
When you are prompted for a password, just hit the enter key and you will generate a key with no password.
Next you need to transfer the key to the server. Easiest method is to use ssh-copy-id . To do this you must temporarily allow root to ssh into the server.
On the server (where you ssh TO)
edit /etc/ssh/sshd_config
sudo nano /etc/ssh/sshd_config
Make sure you allow root to log in with the following syntax
PasswordAuthentication yes
PermitRootLogin yes
Restart the server
sudo service ssh restart
Set a root password, use a strong one
sudo passwd
On the client :
From the client, Transfer the key to the server
ssh-copy-id -i ~/.ssh/foo root@server
change "foo" the the name of your key and enter your server root password when asked.
Test the key
ssh -i ~/.ssh/foo root@server
Assuming it works, unset a root password and disable password login.
On the server :
sudo passwd -l root
Edit /etc/ssh/sshd_config
sudo nano `/etc/ssh/sshd_config`
Change the following :
PasswordAuthentication no
PermitRootLogin without-password
Restart the server
sudo service ssh restart
On the client (Test):
You should now be able to ssh in with your key without a password and you should not be able to ssh in as any user without a key.
ssh -i ~/.ssh/foo root@server
Part 2 : Running commands via sudo without entering a password
You configure sudo to allow you to run commands without a password.
This is answered here in two places:
- How do I run specific sudo commands without a password?
- How to run sudo command with no password?
Of the two, I suggest allowing as few commands as possible (first answer) rather then all commands (second answer).
Solution 2:
You are confusing two different things:
passwordless log is used to make sure that people can't log into your system remotely by guessing your password. If you can ssh username@machine and connect without a password, this is set up correctly, and has nothing else to do with this.
sudo is used to permit a normal user account to do something with super user permissions. This does require the user to type their password. This happens whether you are connected remotely (via passwordless or password-protected SSH) or are local on the machine. You are trying to set sudo to not ask for your password, which is not recommended, but you can learn how to do that via an answer like https://askubuntu.com/a/74083/6161
Note to future readers of this answer:
My above answer does not answer the original poster's actual question, it describes what you should do instead. If you really want to allow remote connections directly to the root account, you need to enable the root account (see my comment below). Again, let me say DO NOT allow remote remote log-ins to your root account.