[PLUG] Remote host lost ssh key verification

[King Beowulf]

On 02/24/2017 12:06 PM, Rich Shepard wrote:
> On Fri, 24 Feb 2017, King Beowulf wrote:
> 
>> In that case, the only entries that you care about are in "known_hosts"
>> unless sshd is stopped. As root:
>> /etc/rc.d/rc.sshd restart
> 
> Ed,
> 
>    Did this.
> 
>> $ ssh susan at glaurung
> 
>    It generates the new known_hosts file then denies the connection.
> 
>> Since you have an authorized keys file did you try
>> $ ssh -i private-key-file username at host
> 
>    ssh on the laptop tells me that id_ed25519.pub on the desktop is not
> accessible so the connection's denied. The perms on
> salmo/.ssh/id_ed25519.pub are 644 so it _should_ be readable by others.
> 

The username, password, public key and/or passphrase is wrong.  To login
in you MUST have a user set up to log into the DESTINATION computer.

On DESTINATION computer: delete ~/.ssh/authorized_keys
On DESTINATION computer:
  1. to use username/password (no keys or passphrase),
     check /etc/ssh/sshd_config lines:

  PermitRootLogin no
  PubkeyAuthentication no

  These are the defaults.  I also have "AllowUsers" as
  a further restriction.

  2. /etc/rc.d/rc.sshd restart

  now pick ANY existing user on the DESTINATION and

  some_user at SOURCE$ ssh a_user at DESTINATION
  a_user at DESTINATION's password:
  ...
  a_user at DESTINATION$ _

  3. Once this works, on SOURCE computer:

     ssh-copy-id -i ~/.ssh/id_rsa.pub a_user at DESTINATION

     (to use the default key). If you created id_rsa (etc)
     with passphrase, you will need that AND a_user's password.
     This will create a new ~/.ssh/authorized_keys on DESTINATION.

  4. you should now be able to login in:
     $ ssh a_user at DESTINATION
     or
     $ ssh -i id_rsa.pub a_user at DESTINATION

     (id_rsa is the default, use -i for if you create different key)

  5. "PubkeyAuthentication yes" to disable user/password and
      use ONLY keys.

Clear as mud?  I hope!

-Ed