Chapter 5. Configure Public Key based SSH Authentication without a password

1. Log in to the first hyperconverged host as the root user.

2. Perform the following steps for each host in the cluster, including the first host.

   1. Use SSH to log in to a host as the root user.

      [root@server1]# ssh root@server1.example.com

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   2. Enter yes to continue connecting.

      [root@server1]# ssh root@server2.example.com
      The authenticity of host 'server2.example.com (192.51.100.28)' can't be established.
      ECDSA key fingerprint is SHA256:Td8KqgVIPXdTIasdfa2xRwn3/asdBasdpnaGM.
      Are you sure you want to continue connecting (yes/no)?

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      This automatically adds the host key of the first host to the known_hosts file on the target host.

      Are you sure you want to continue connecting (yes/no)? yes
      Warning: Permanently added '192.51.100.28' (ECDSA) to the list of known hosts.

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   3. Enter the password for the root user on the target host to complete the login process.

      root@server2.example.com's password: ***************
      Last login: Mon May 27 10:04:49 2019
      [root@server2]#

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   4. Log out of the host.

      [root@server2]# exit
      [root@server1]#

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      Note

      When you log out of the SSH session from the first host to itself, the user and server in the command line prompt stay the same; it is only the session that changes.

      [root@server1]# exit
      [root@server1]#

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Procedure

1. Log in to the first hyperconverged host as the root user.

2. Generate an SSH key that does not use a password.

   1. Start the key generation process.

      # ssh-keygen -t rsa
      Generating public/private rsa key pair.

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   2. Enter a location for the key.

      The default location, shown in parentheses, is used if no other input is provided.

      Enter file in which to save the key (/home/username/.ssh/id_rsa): <location>/<keyname>

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   3. Specify and confirm an empty passphrase by pressing Enter twice.

      Enter passphrase (empty for no passphrase):
      Enter same passphrase again:

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      The private key is saved in <location>/<keyname>. The public key is saved in <location>/<keyname>.pub.

      Your identification has been saved in <location>/<keyname>.
      Your public key has been saved in <location>/<keyname>.pub.
      The key fingerprint is SHA256:8BhZageKrLXM99z5f/AM9aPo/KAUd8ZZFPcPFWqK6+M root@server1.example.com
      The key's randomart image is:
      +---[ECDSA 256]---+
      |      . .      +=|
      | . . . =      o.o|
      |  + . * .    o...|
      | = . . *  . + +..|
      |. + . . So o * ..|
      |   . o . .+ =  ..|
      |      o oo ..=. .|
      |        ooo...+  |
      |        .E++oo   |
      +----[SHA256]-----+

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      Warning

      Your identification in this output is your private key. Never share your private key. Possession of your private key allows someone else to impersonate you on any system that has your public key.

Procedure

1. Log in to the first host as the root user.

2. Copy your public key to the host that you want to access.

   # ssh-copy-id -i <location>/<keyname>.pub <user>@<hostname>

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   Enter the password for <user>@<hostname> if prompted.

   Warning

   Make sure that you use the file that ends in .pub. Never share your private key. Possession of your private key allows someone else to impersonate you on any system that has your public key.