Keyless SSH using ssh-keygen and ssh-copy-id

11 Oct

It is tedious to require to enter password for multiple Linux systems especially for maintainence purpose. To resolve this problem, make you access to remote systems without requiring password using SSH.

1. Create public and private keys using ssh-key-gen

pigeon@ubuntu:~$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/pigeon/.ssh/id_rsa):
Created directory ‘/home/pigeon/.ssh’.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/pigeon/.ssh/id_rsa.
Your public key has been saved in /home/pigeon/.ssh/
The key fingerprint is:
44:db:db:fd:ad:70:4e:a6:88:79:6d:14:d8:01:40:52 pigeon@ubuntu
The key’s randomart image is:
+–[ RSA 2048]—-+
| .oE… |
| o o . |
| o .o . |
| . .oo. |
| S . … |
| . ..|
| o. + o|
| o..oB . |
| o…. o |

2. Copy the public key to remote systems using ssh-copy-id

pigeon@ubuntu:~$ ssh-copy-id -i /home/pigeon/.ssh/’s password:
Now try logging into the machine, with “ssh ‘'”, and check in:


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

3. Login to remote system without password

Last login: Tue Oct 11 14:33:23 2011 from
$ uname

If you encountered problem to access remote system after ssh-trusted completed.
Sometimes, it might due to permission file and directory. For troubleshooting purpose, always check the log files for errors.

Always make sure $HOME/.ssh/authorized_keys is set to 600
$ chmod 600 $HOME/.ssh/authorized_keys

“StrictModes yes” under sshd_config

Require that users set the correct permissions on their key files and the directories that they are stored in. In order for keys to pass strict mode, they must not be writable by anyone but the owner. Suggest a chmod of 600 for the keyfile.


Posted by on October 11, 2011 in linux


Tags: , , , ,

4 responses to “Keyless SSH using ssh-keygen and ssh-copy-id

  1. mrqrcode

    October 11, 2011 at 12:01 pm

    Definitely this blog is very informative and neatly designed. Really you\’ve motivated me strongly in my new project by this article. As a constant reader of your blog I want to tell you that your writing skills are superb.

  2. linuxreference

    October 16, 2011 at 12:14 pm

    Thank you for your feedback, I will continually post quality articles. 🙂

  3. raj

    November 25, 2011 at 12:15 am

    Thanks linuxreference for the share

  4. rasna

    November 28, 2011 at 7:43 am

    Excellent post,
    I like the way of your writing,
    Thanks a lot for the information.


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