I have a problem with public and private key authentication. I do this steps and then, public-key based doesn't work. 1- generate a pair of private and public key (RSA) using the following command:

Generating public/private rsa key pair.
Enter file in which to save the key (/home/rc_ss/.ssh/id_rsa): 
Created directory '/home/rc_ss/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/rc_ss/.ssh/id_rsa.
Your public key has been saved in /home/rc_ss/.ssh/id_rsa.pub.
The key fingerprint is:
ac:fd:d1:2e:e5:1e:db:87:98:77:9e:14:62:db:97:f0 rc_ss@rc_ss-network
The key's randomart image is:
+--[ RSA 2048]----+
|                 |
|                 |
|                 |
|       .         |
|        S    + . |
|       o   .o * o|
|      . . .oo+ E.|
|         ..o+++ =|
|          .o+..=.|

2- copy it through network with ssh-copy-id as follows

rc_ss@rc_ss-network:~$ ssh-copy-id -i .ssh/id_rsa.pub root@
The authenticity of host ' (' can't be established.
ECDSA key fingerprint is 33:67:e0:02:b1:10:46:76:78:6b:1f:e2:55:9b:6a:a8.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '' (ECDSA) to the list of known hosts.
root@'s password: 
Now try logging into the machine, with "ssh 'root@'", and check in:


to make sure we haven't added extra keys that you weren't expecting.

3- then, I want to get connected to server ssh without password, and deal with following:

rc_ss@rc_ss-network:~$ ssh root@
root@'s password: 

Which means the password required yet. Can anybody help me? Appreciate it.

  • If you run a cat /root/.ssh/authorized_keys on the target machine, do you see the public key from the original machine?
    – Ross
    Jun 6, 2014 at 19:47
  • Yes, I can see that.
    – Rc Ss
    Jun 6, 2014 at 19:48
  • Can you confirm that the permissions on /root/.ssh/authorized_keys are rwx------, and that the ssh server's sshd_config specifies PubkeyAuthentication yes? Jun 6, 2014 at 19:51
  • the permission of /root/.ssh/authorized_keys is : -rw------- and that sshd_config is :PubkeyAuthentication yes
    – Rc Ss
    Jun 6, 2014 at 19:54
  • Oh sorry, my permission statement was wrong. What you specified is correct. Jun 6, 2014 at 20:00

1 Answer 1


Assuming that the public key was correctly copied to the target server, you'll need to make sure that the SSH daemon supports passwordless login. This configuration is set in the /etc/ssh/sshd_config file, and you need to make sure the following values are set:

PermitRootLogin yes
RSAAuthentication yes
PubkeyAuthentication yes

If those values are not set, you will need to set them and then restart SSH with sudo service ssh restart in a terminal.

  • These settings are correct in both of the server and client. But Public Key Authentication doesn't work yet. Thanks for your answer.
    – Rc Ss
    Jun 6, 2014 at 19:59
  • Do you have any other idea? Appreciate it.
    – Rc Ss
    Jun 6, 2014 at 20:31

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