I can't SSH without a password
 

I followed this procedure:

Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): ~/.ssh/sshkey

(blah blah blah done)

(it requests the target machine's ssh password. I type it. Done)
(I checks the /root/.ssh/authorized_keys file in the target mmachine. The new key is there. I know because this file was empty until one minute ago.)

I restart sshd on the target machine. I try to login from the client machine. It still wants the password.

I google. I find some suggestions. I add 'PubkeyAcceptedKeyTypes=+ssh-dss' to several files:

client machine:
/etc/ssh/ssh_config
/etc/ssh/sshd_config
~/.ssh/config

target machine:
/etc/ssh/ssh_config
/etc/ssh/sshd_config

I restart sshd on the target machine. I try to login from the client machine. It still wants the password.

What am I doing wrong, or what have the OpenSSH people disabled or made secret this time?

I can't SSH without a password
 

Have you tried doing it as a user other than root?

I just tried, it works as a lesser user. It takes a long time, it hangs for almost one minute, but it works.

How do I enable it for root too?

Indeed root login is disabled by default. On my Raspi I have it set to the second method in the link below so I can back it up with rsync over the network as I use the passwordless key like the OP attempts.

https://www.liquidweb.com/kb/enable-root-login-via-ssh/

Dunno, and I can't be bothered fighting it. I just use SSH to log in as a user and then "su" to root whenever it's needed.

I'd say there are probably very good reasons for this.

What is in your config file?

Keys are on a per user basis. The user on the client must have the private keys owned by them with 600 permissions.

While the ssh client will automatically check for keys with default names i.e. id_rsa otherwise you need to specify the key name on the command line or in the ssh config file.

if ssh-copy-id worked as root@@192.168.1.6 then PermitRootLogin is set to yes. Most distributions do disable root login by default or use prohibit-password but some do not. The default is yes.

Use ssh -v or multiple -vvv option to see why the key is not being accepted.

What version of ssh is running on the client as compared to the server?

That option enables login as root on the server, with the server's root account. I can do that. What I can't do is login using the root account on the client machine. This is something new because I know I used to be able to do it until a few years ago.

First, the error was "not in PubkeyAcceptedKeyTypes."

Now, the error seems to be "no such identity." But I'm not sure.

What keys are currently in your /root/.ssh directory. Did you really create the key with the name sshkey? Try:

ssh -i ~/.ssh/sshkey root@192.168.1.6

You haven't specified to use this key.

Eh. It's working now.

Instead of

I did

Now it works. It's very slow. It hangs for a long time then I'm in. That is annoying. Is there a log file to troubleshoot that?

That sounds like you have not copied the secret key that matches the public key to your root/.ssh directory on the client. This is how mine is setup both keys match in the normal user directory and in the root directory. In fact I only use the single key for all my machines this solves the problem of different keys on different users and machines. It is the only way my backup works as I need to be root on my backup machine to keep the proper permissions in place when doing it.

Edit: I turned on the spare machine to show you, try adding -vvvv to the command to see where it fails.

Edit2: Almost forgot the machine logged into. All have the same keys.

Check your sshd_config file in the past having GSAPPIAutentication yes will slow down logins. Try commenting or setting

GSSAPIAuthentication no

or maybe check

UseDNS no

And suddenly it's not slow anymore. Login is instant as expected. Shrug.

Anyway, it seems to me that the actual problem was that I generated a key and saved it to a file named sshkey, and it seems that OpenSSH absolutely expects it to be id_rsa. That's what broke everything. I thought that the ssh-copy-id command would be enough to send the key to the remote authorized_keys file and everything would fall into place. That was my mistake.

I'm closing this issue. Many thanks to all. I certainly appreciate the attention.

SOLVED.

As a FYI If I use different key names I add them to my ~/.ssh/config file per host.

Then all you need to do is

ssh name